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Concurrent Endurance and Explosive Type Strength Training Increases Activation and Fast Force Production of Leg Extensor Muscles in Endurance Athletes

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Abstract

The purpose of this experiment was to examine the effects of concurrent endurance and explosive strength training on electromyography (EMG) and force production of leg extensors, sport-specific rapid force production, aerobic capacity, and work economy in cross-country skiers. Nineteen male cross-country skiers were assigned to an experimental group (E, n = 8) or a control group (C, n = 11). The E group trained for 8 weeks with the same total training volume as C, but 27% of endurance training in E was replaced by explosive strength training. The skiers were measured at pre- and post training for concentric and isometric force-time parameters of leg extensors and EMG activity from the vastus lateralis (VL) and medialis (VM) muscles. Sport-specific rapid force production was measured by performing a 30-m double poling test with the maximal velocity (V(30DP)) and sport-specific endurance economy by constant velocity 2-km double poling test (CVDP) and performance (V(2K)) by 2-km maximal double poling test with roller skis on an indoor track. Maximal oxygen uptake (Vo(2)max) was determined during the maximal treadmill walking test with the poles. The early absolute forces (0-100 ms) in the force-time curve in isometric action increased in E by 18 +/- 22% (p < 0.05), with concomitant increases in the average integrated EMG (IEMG) (0-100 ms) of VL by 21 +/- 21% (p < 0.05). These individual changes in the average IEMG of VL correlated with the changes in early force (r = 0.86, p < 0.01) in E. V(30DP) increased in E (1.4 +/- 1.6%) (p < 0.05) but not in C. The V(2K) increased in C by 2.9 +/- 2.8% (p < 0.01) but not significantly in E (5.5 +/- 5.8%, p < 0.1). However, the steady-state oxygen consumption in CVDP decreased in E by 7 +/- 6% (p < 0.05). No significant changes occurred in Vo(2)max either in E or in C. The present concurrent explosive strength and endurance training in endurance athletes produced improvements in explosive force associated with increased rapid activation of trained leg muscles. The training also led to more economical sport-specific performance. The improvements in neuromuscular characteristics and economy were obtained without a decrease in maximal aerobic capacity, although endurance training was reduced by about 20%.

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... Interventions for improving strength and/or power (Table 2) The interventions designed to improve strength and/or power involved activities described as 1) maximal Hoff et al., 1999;Østerås et al., 2002) or heavy strength training (Losnegard et al., 2011;Ofsteng et al., 2018;Ronnestad et al., 2012;Skattebo et al., 2016), 2) explosive strength training (Mikkola et al., 2007), 3) sprint interval (Nilsson et al., 2004;Vandbakk et al., 2017), 4), explosive strength, heavy resistance strength and sprint training combined (Paavolainen et al., 1991) and 5) circuit, roller-board, ski-specific or weight training (Nesser et al., 2004). ...
... Five of the interventions employed only exercise on machines Hoff et al., 1999;Ofsteng et al., 2018;Østerås et al., 2016;Skattebo et al., 2016). One study utilized a DP ergometer (Nilsson et al., 2004), two a combination of free weights and bodyweight resistance (Mikkola et al., 2007;Paavolainen et al., 1991), two a machine and free weights combined (Losnegard et al., 2011;Ronnestad et al., 2012), and one either circuit, roller-board, ski-specific training or weights (Nesser et al., 2004). Most of the interventions involved a single exercise (seated poling) Hoff et al., 1999;Østerås et al., 2002), two exercises (seated and standing poling together with triceps extension) (Ofsteng et al., 2018;Skattebo et al., 2016) or squats (Losnegard et al., 2011;Ronnestad et al., 2012)), whereas two involved more than 10 different exercises (Carlsson et al., 2017;Mikkola et al., 2007). ...
... One study utilized a DP ergometer (Nilsson et al., 2004), two a combination of free weights and bodyweight resistance (Mikkola et al., 2007;Paavolainen et al., 1991), two a machine and free weights combined (Losnegard et al., 2011;Ronnestad et al., 2012), and one either circuit, roller-board, ski-specific training or weights (Nesser et al., 2004). Most of the interventions involved a single exercise (seated poling) Hoff et al., 1999;Østerås et al., 2002), two exercises (seated and standing poling together with triceps extension) (Ofsteng et al., 2018;Skattebo et al., 2016) or squats (Losnegard et al., 2011;Ronnestad et al., 2012)), whereas two involved more than 10 different exercises (Carlsson et al., 2017;Mikkola et al., 2007). Of the exercises, seated pulldown was used in seven (58%) cases Hoff et al., 1999;Losnegard et al., 2011;Ofsteng et al., 2018;Østerås et al., 2002;Ronnestad et al., 2012;Skattebo et al., 2016) and standing pulldown in four (33%) (Losnegard et al., 2011;Ofsteng et al., 2018;Ronnestad et al., 2012;Skattebo et al., 2016). ...
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To identify and evaluate current scientific literature concerning the effect of strength, power and speed training on relevant physiological and biomechanical characteristics and performance of competitive cross-country skiers (XCS), the databases Scopus and PubMed were searched systematically for original articles in peer-reviewed journals. Of the 599 studies retrieved, 12 met the inclusion criteria (i.e., assessment of outcome measures with relevance for XCS performance; involvement of traditional resistance training; application of external resistance to the body; intervention longer than 4 weeks; randomized controlled trial). The methodological rigor of each study was assessed using the PEDro scale, which were mostly poor-to-fair, with good methodological quality in only two articles. All of the strength/power/speed interventions improved 1RM (0.8-6.8 ES), but findings with respect to jump performance, ability to generate force rapidly and body composition were mixed. Interventions demonstrated moderate-to-high ES on XCS specific performance compared with control (mean ES = 0.56), but the pattern observed was not consistent. None of the interventions changed anaerobic capacity, while in most studies VO2max was either unchanged or increased. Work economy or efficiency was enhanced by most of the interventions. In conclusion, present research indicates that strength training improves general strength, with moderate effects on XCS performance, and inconclusive effects on work economy and VO2max/VO2peak. Strength training with high loads, explosive strength training, or sprint interval training seem to be promising tools for modern XCS training. Future investigations should include long-term (e.g., >6 months) strength training to allow sufficient time for increased strength and speed to influence actual XCS performance. Moreover, they should include both sexes, as well as upper- and lower-body muscles (trained separately and together) and employ free weights and core training. Methodological differences and limitations highlighted here may explain discrepancies in findings and should be taken into consideration in future research in this area.
... Moreover, Losnegard et al. [16] reported significant improvements in aerobic parameters such as VO 2 max. On the other hand, various studies did not observe significant improvements in VO 2 max after a period of strength training [17,18]. Furthermore, Carlsson et al. [19] compared strength training versus ski ergometer training and found no significant between-group differences for gross efficiency, upper-body strength or time to exhaustion (TTE). ...
... In terms of age, most of the participants were young, with a mean age of 20.22 years. In addition, five studies included male skiers [13,14,17,18,24], two studies female skiers [15,23] and three studies mixed samples [16,19,25]. ...
... All studies conducted maximal strength training [13][14][15][16][17]19,23,24], except Mikkola et al. [18], which implemented explosive type strength training. However, this was not the only study that included explosive strength exercises in the training routine, as two other studies combined maximal and explosive strength exercises in the designed workouts [17,25]. ...
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Traditionally, cross-country skiing has been known for having a strong endurance component; however, strength demands have significantly increased in recent years. Given this importance, several studies have assessed the effects of strength training in cross-country skiing. Therefore, the aim of this systematic review was to analyze the results of those studies. A detailed search of four databases (Pubmed, Scopus, Web of Science and Cochrane Library) was conducted until February 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Ten eligible studies were selected from the 212 records identified, all of them including young well-trained skiers and interventions of 6-12 weeks. Results showed that maximal strength training may improve some important variables: for instance, performance, double-poling economy and maximal strength. However, this type of training failed to change other indicators such as peak oxygen consumption. Concurrent training, which combines endurance and maximal strength training, seems to be effective to improve performance. The mechanisms responsible for the improved economy of double poling might be due to a lower percentage of maximal strength during double poling at a given workload, which could increase performance. Future studies should include longer interventions which analyze a more varied sample.
... Häkkinen (1989) found that elite athletes' muscle cross-sectional area and body mass were highly correlated with force production [8]. Furthermore, it has been indicated that body composition as lean mass (LM), upper-body lean Sports 2022, 10, 15 2 of 10 mass [9], body weight, and the resulting upper body strength and power were significantly related to better skiing performance [10][11][12][13]. However, it should be taken into account that increased lean mass might have negative effects on the skier's performance, as higher mass is transported [3,14,15]. ...
... For example, a significant (3.0 ± 1.1%) increase in upper-body lean mass resulted in a significant increase in oxygen consumption during XC skating techniques, while remaining unchanged for running in high-level junior and senior skiers [7]. Heavy strength training may also increase muscle mass [7,18] and body mass that potentially may have negative effects on some aspects of endurance performance [13], especially in disciplines where body mass is not supported. However, the combined large volumes of endurance and heavy strength training seem to reduce the hypertrophic adaptation to strength training [7,[19][20][21]. ...
... Every repetition was executed with high intended movement velocity during the Sports 2022, 10, 15 4 of 10 concentric phase [6,8]. Additionally, every strength training consisted of 3-4 explosive exercises with low loads, for example, including medicine ball, bodyweight, different jumping exercises, and short sprints [13]. Cross-country skiing-specific strength exercises were selected and included bar-tips, chin-ups, bench pulls, standing double poling, etc. ...
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The aim of the study was to compare the effects of different types and periodization of strength training on body composition and maximal aerobic performance in 10-week training period in adolescent XC skiers. Twenty-eight adolescent competitive cross-country skiers, including 10 females (age 17.9 ± 1.8 years; body mass 69.6 ± 9.7 kg; height 1.77 ± 0.1 m; training experience 8.6 ± 3.2 years) took part in this study. Pre- and post-intervention performance was measured with the incremental exercise test (Pmax) on a double poling ski ergometer. Changes in body composition were measured with DXA. In addition to regular endurance training, experimental group one (EXP1) performed maximal and explosive strength training two times per week, experimental group two (EXP2) performed maximal and explosive strength training 1–3 times per week, and the traditional (TRAD) group performed low intensity–high volume strength training 2 times per week. Increases in arm, trunk, and overall lean mass were found in TRAD (p < 0.05). Increases in arm lean-mass was found in EXP1 (p < 0.05), while no changes in body composition occurred in EXP2 (p ≥ 0.05). Pmax improved significantly in all groups (p < 0.05). Changes in body mass, overall and arm lean mass was related to changes in absolute performance (W; p < 0.05), while no relationships were found between changes in body composition parameters and relative performance (W/kg; p ≥ 0.05). In conclusion, different periodization of strength training led to similar improvements in double poling ergometer performance, but resulted in different changes in body composition (lean mass) in adolescent cross-country skiers.
... As a result of endurance exercises, muscle mass does not increase and the actual size of muscle fibers decreases (Maiorana, 2002 andIzquierdo, 2004). Strength exercises lead to muscle hypertrophy due to the increase in the number of fibril proteins (McCarthy, 1995 andMikkola, et al, 2007). Muscle hypertrophy usually occurs in slow-twitch and fast-twitch fibers and this type of training results in a special neuromuscular adjustment (Peterson, MD. and Rhea and, Alvar, BA, 2005). ...
... Muscle hypertrophy usually occurs in slow-twitch and fast-twitch fibers and this type of training results in a special neuromuscular adjustment (Peterson, MD. and Rhea and, Alvar, BA, 2005). Unlike endurance exercises, mass density of mitochondria decreases in contrast to the increase in muscle mass (Mikkola, J et al, 2007 ). These contradictory results of endurance and strength exercises has led to uncertainties among some endurance and strength athletes in applying different training methods, fearing it might risk the desired training adjustments (Edwards, AM. and,Wells, C. and,Butterly, 2008). ...
... Thus, these concurrent and strength exercises significantly increase relative maximum strength of muscles which is consistent with Moritani and DeVries model regarding neural adjustment and muscle hypertrophy. The increase of strength in this research is consistent with the studies of Mikkola et al. (2007), Kraemer et al. (1995), Jeffery Mador (2004) and Leveritt et al. (2003) who reported the increase of strength in strength and concurrent training groups. In their research, Glowacki et al. (2004) reported a significant increase of strength in strength, concurrent and endurance training groups. ...
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The objective of the present research was to compare the effect of the sequence of concurrent strength and endurance exercises on aerobic capacity, anaerobic capacity and maximum strength of male adolescents. 50 high school students with the average age of 17.22±0.94 years, 175.62±7.11 centimeters of height, and 62.82±7.78 kilograms of body mass were randomly chosen and divided into five groups of ten subjects-i.e. strength training (ST), endurance training (ET), strength-endurance training (SE), endurance-strength training (ES) and control (CO). Maximal aerobic capacity (VO 2 max) was assessed by a 1600-meter run, lactic anaerobic capacity and fatigue index by RAST test, alactic anaerobic capacity by vertical jump test, strength by one-repetition maximum test (1RM), agility by Illinois Agility Run test and muscle endurance by sit-ups test. Based on the findings of the research, a significant increase was observed in VO 2 max of the endurance and concurrent training groups. Alactic anaerobic capacity of the five groups did not have a significant increase. A significant increase was observed in the lactic anaerobic capacity and fatigue index in the strength training group. According to the findings of the research, relative maximum strength increased significantly in the strength and endurance-strength training groups. Moreover, the increase in agility and muscle endurance was significant in the four experimental groups. Combining strength and endurance exercises improves strength and endurance and adding strength training to the endurance training program does not risk the improvement of VO 2 max. Also the endurance-strength sequence of training has the greatest effect on maximum strength and agility.
... The inclusion of ST into longdistance (LD) triathletes' programs can improve both cycling economy (CE) and running economy (RE) which is considered critical for success in LD triathlon (58,62). Furthermore, research has demonstrated that ST can significantly improve performance variables (economy, time-trial performance, reduced heart rate [HR] at submaximal intensities, velocity at VȮ 2 max [vVȮ 2max], and power at VȮ 2 max [wVȮ 2max]) in single mode endurance sports such as cycling and running (10,11,25,61,71,72,79,80,83,90,91,98,100). Long-distance triathlon is classified as any triathlon distance greater than an Olympic distance race (.1,500-m swim, 40-km cycle, and 10-km run) (59) with the 2 most common forms known as a half-iron distance (1.9-km swim, 90-km cycle, and 21.1-km run) and full irondistance (3.8-km swim, 180-km cycle, and 42.2-km run) distance races. ...
... Although there are numerous studies supporting the implementation of ST to improve performance and physiological variables in endurance athletes (10,11,25,61,71,72,79,80,83,90,91,98,, practical application papers primarily focus on running (8), singlemode sports (9), or are outdated (20). Therefore, the purpose of this paper is to educate coaches and athletes on the benefits of completing concurrent strength and endurance training to improve physiological factors contributing to LD triathlon performance. ...
... In addition, significant improvements in RE have been seen from a plyometric/explosive-based ST program (83) or a "combination" program (including both plyometric and heavy strength exercises) (10). Significant improvements in 3000-m-5000-m timetrials and vVȮ2max have also been seen as the result of plyometric/explosive STbased programs in runners (14,61,71,88). ...
... Researchers placed primary focus on treatment group procedures, whereas explanations on endurance training were brief and vague (i.e. 'Normal Endurance training') (18,25,26). Despite the studies having success in eliciting performance enhancements, a more defined endurance protocol would allow readers to interpret the results better. ...
... Despite the studies having success in eliciting performance enhancements, a more defined endurance protocol would allow readers to interpret the results better. Mikkola (18) and Paavolainen (21) provided the percentage of total training volume that was replaced with resistance/plyometric training (19% & 32%, respectively), meanwhile others simply listed the types of aerobic exercises performed (7,24,25). Furthermore, only one of the reviewed studies measured morphological changes within the MTU post intervention (26), giving rise to 'educated guesses' from the other studies as to the impact the MTU had on performance enhancement. ...
... A handful of studies utilised open-chain resistance exercises (i.e. leg extension/flexion, hamstring curl) with a maximum movement velocity focus (18,21,24,25). Traditional multi-jointed compound exercises, such as the back squat and walking lunges, are heavily utilised within the athletic population as they require coordinated and controlled movement, resulting in interand intra-muscular strength adaptations (5,9). ...
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BLUF Appropriate periodisation of explosive-based resistance training methods such as Plyometrics has the ability to improve both physiological and neurological adaptations of musculotendinous units within the major joints of the lower body in endurance runners. ABSTRACT Strength and Power training modalities continue to emerge amongst elite-level endurance athletes. Despite common misconceptions surrounding such training, enhancements in overall running performance, most notably Running Economy, has the ability for individuals to overcome their competitors. A total of seven original experimental articles were used for this review. The primary finding from this review was that endurance performance characteristics, specifically Running Economy, were enhanced after participating in strength and power-based training (2-8%). Improvements in Rate of Force Development with a concomitant decreased demand for oxygen at a given speed showed improvements in time trials and time to exhaustion. Differing magnitudes of results may be due to subjects previous history, exercise selection, volume load and testing protocols. There was shown to be a lack of direct measurement for the stiffness and/or compliance qualities of the Musculotendinous Unit from the studies chosen. Strength and Power based training has the potential to elicit positive enhancements in performance characteristics amongst elite-level endurance athletes. The use of multi-joint explosive exercises such as unloaded and loaded jump squats, scissor jumps, bounding, and wall sprints are recommended as they closely resemble running mechanics. Programming factors such as progressive overload, work:rest ratio, training frequency and intensity must be individualised appropriately in order to maximise training adaptations and limit accumulative fatigue. Based on the reviewed studies, elite distance runners are recommended to engage in specific explosive strength training 2-3 days per week for 8-12 weeks in order to improve overall running performance (decreased energy expenditure and oxygen demand at particular velocities).
... An overview of the effect of heavy strength training on XC skiing performance is shown in Figure 1. The early studies conducted by Hoff et al. (1999; and Østerås et al. (2002) found large effects of heavy strength training on XC performance, while more recent investigations (Mikkola et al. 2007, Losnegard et al. 2011, Rønnestad et al. 2012, Skattebo et al. 2016 found mostly trivial effects. The reason for the discrepancy is unknown, but different outcome measures (i.e. ...
... However, results from more sport-specific movements (such as rollerskiing outdoors) indicate that the effect of strength training is less pronounced (Mikkola et al. 2007, Losnegard et al. 2011, Rønnestad et al. 2012. This is probably attributed to the finding that rollerskiing outdoors demands a higher technical ability than a double poling ergometer, which in turn demands a higher technical ability than a strength test (e.g., more complex timing of force application). ...
... Further, it has been shown that strength training influences work economy in endurance sports such as cycling (Rønnestad & Mujika 2013, Montero & Lundby 2015 and running (Saunders et al. 2004). In XC skiing, Mikkola et al. (2007), Østerås et al. (2002) and Rønnestad et al. (2012) treadmill. In addition, Hoff et al (1999; used unconventional methods to measure work economy and it has recently been argued that they actually did not measure the O2-cost (see Skattebo et al. 2016 for details). ...
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This chapter provides an updated synopsis of the importance of strength abilities for performance in high-level cross-country skiers, with a focus on the upper body. It also provides an overview of the effect of training models in enhancing upper-body power, with a special emphasis on heavy strength training. In addition, the effect of alternative models on performance such as sport-specific speed training and muscular endurance training is discussed. Finally, a practical application of efficient strength training is provided, based on the distinctiveness of movement patterns in skiing techniques, and thus, the specificity of training for cross-country skiers.
... While STR improved performance and work economy in a DP ergometer, [12][13][14] other studies report similar improvements in roller ski time trial performance between STR and endurance training only. 7,15, 16 The importance of DP performance is further exaggerated in long-distance XC races, which are often performed as mass starts with submaximal DP for 2-4 hours followed by an all-out performance at the end of the race. This is the first study to examine the effects of STR on DP performance after prolonged submaximal DP in XC-skiers. ...
... In the latter case, our data support previous studies measuring the effect of strength training on performance on roller skis, where no significant ergogenic effect of strength training in male XC-skiers was reported. 7,15,16 In comparison, some studies observed superior effect of concurrent strength and endurance training on time trails or TTE in DP ergometers. 7,[12][13][14] In all of these previous studies, performance tests were performed without an initial prolonged exercise, and their findings are therefore difficult to compare with our TTE test performed after prolonged exercise. ...
... There was no difference in VO 2peak from pre-to post-test in either of the groups. This is in line with most previous strength training studies on XC-skiers, [12][13][14]16,38 although Losnegard et al 7 found an increase and Skattebo et al 35 a reduction in VO 2max after 10-12 weeks of concurrent strength and endurance training. Furthermore, there was no difference between our groups in the change in power output at 4 mmol·L −1 [la − ], a finding that agrees with other studies on XC-skiers. ...
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The purpose of this study was to investigate the effects of adding strength training with or without vibration to cross-country (XC) skiers' endurance training on double poling (DP) performance, physiological and kinematic adaptations. Twenty-one well-trained male XC skiers combined endurance- and upper-body strength-training three times per week, either with (n=11) or without (n=10) superimposed vibrations for 8 weeks, whereas eight skiers performed endurance training only (CON). Testing included 1RM in upper-body exercises, work economy, neural activation, oxygen saturation in muscle and DP kinematics during a prolonged submaximal DP roller ski test which was directly followed by a time to exhaustion (TTE) test. TTE was also performed in rested state and the difference between the two TTE-tests (TTEdiff ) determined the ability to maintain DP performance after prolonged exercise. Vibration induced no additional effect on strength or endurance gains. Therefore, the two strength-training groups were pooled (STR, n=21). 1RM in STR increased more than in CON (P < 0.05), and there were no differences in changes between STR and CON in any measurements during prolonged submaximal DP. STR improved TTE following prolonged DP (20±16%, P < 0.001) and revealed a moderate effect size compared to CON (ES = 0.80; P = 0.07). Furthermore, STR improved TTEdiff more than CON (P = 0.049). In conclusion, STR superiorly improved 1RM strength, DP performance following prolonged submaximal DP and TTEdiff , indicating a specific effect of improved strength on the ability to maintain performance after long-lasting exercise. This article is protected by copyright. All rights reserved.
... Eight hundred-meter running is a middle-distance event where usually both strength and endurance training are performed concurrently. Positive adaptations to concurrent strength and endurance training have been reported in high-level endurance athletes (Paavolainen et al., 1999;Hoff et al., 2002;Mikkola et al., 2007). ...
... Recently, there has been a growing interest in assessing muscle strength in middle and long-distance athletes, due to the demonstrated benefits of resistance training in such athletes (Saunders et al., 2004;Aagaard and Andersen, 2010;Taipale et al., 2010Taipale et al., , 2014Beattie et al., 2014;Ronnestad and Mujika, 2014). For instance, Mikkola et al. (2007) reported that both heavy and explosive resistance training induced improvements in maximal endurance capacity in long-distance runners. Taipale et al. (2010Taipale et al. ( , 2014 showed a positive effect of maximal and explosive strength training performed concurrently with endurance training on the specific performance in recreational endurance runners. ...
... Recently, Bachero-Mena et al. (2017) have found significant correlations between running performance in 800 m event and sprint times (20 and 200 m), squat strength and loaded and unloaded jumps height in 800 m high-level athletes. Despite the extensive published data confirming the strong correlation between strength manifestations and endurance performance (Mikkola et al., 2007;Taipale et al., 2010Taipale et al., , 2014, there are limited data on the long-term changes in strength variables associated with long-term middle-distance training. ...
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The purpose of this study was to analyze changes in sprint, strength, hematological, and hormonal parameters in high-level 800 m athletes during a complete athletics season. Thirteen male athletes of national and international level in 800 m (personal best ranging from 1:43 to 1:58 min:ss) participated in this study. A total of 5 tests were conducted during a complete athletics season. Athletes performed sprint tests (20 and 200 m), countermovement jump (CMJ), jump squat (JS), and full squat (SQ) tests. Blood samples (red and white blood profile) and hormones were collected in test 1 (T1), test 3 (T3), and test 5 (T5). A general increase in the performance of the strength and sprint parameters analyzed (CMJ, JS, SQ, 20 m, and 200 m) during the season was observed, with a significant time effect in CMJ (P < 0.01), SQ (P < 0.01), and 200 m (P < 0.05). This improvement was accompanied by a significant enhancement of the 800 m performance from T3 to T5 (P < 0.01). Significant changes in some hematological variables: hematocrit (Hct) (P < 0.01), mean corpuscular volume (MCV) (P < 0.001), mean corpuscular hemoglobin content (MCHC) (P < 0.001), white blood cells count (WBC) (P < 0.05), neutrophils (P < 0.05), monocytes (P < 0.05), and mean platelet volume (MPV) (P < 0.05) were observed throughout the season. The hormonal response and creatin kinase (CK) did not show significant variations during the season, except for insulin-like growth factor I (IGF-1) (P < 0.05). In conclusion, our results suggest the importance of strength levels in middle-distance athletes. On the other hand, variations in some hematological parameters and a depression of the immune system occurred during the season. Therefore, monitoring of the mechanical, hematological and hormonal response in athletes may help coaches and athletes to optimize the regulation of training contents and may be useful to diagnose states of overreaching or overtraining in athletes throughout the season.
... Several studies have investigated the effect of different training regimes, such as strength training (Hoff et al. 1999Losnegard et al. 2011;Mikkola et al. 2007;Nesser et al. 2004;Paavolainen et al. 1991;Skattebo et al. 2016;Østerås et al. 2002) and ski-specific training (i.e. doublepoling training on ski-ergometer or roller skis) (Downing and Wilcox 2003;Mikkola et al. 2007;Nilsson et al. 2004;Terzis et al. 2006) on the development of skiers' doublepoling capacity. ...
... Several studies have investigated the effect of different training regimes, such as strength training (Hoff et al. 1999Losnegard et al. 2011;Mikkola et al. 2007;Nesser et al. 2004;Paavolainen et al. 1991;Skattebo et al. 2016;Østerås et al. 2002) and ski-specific training (i.e. doublepoling training on ski-ergometer or roller skis) (Downing and Wilcox 2003;Mikkola et al. 2007;Nilsson et al. 2004;Terzis et al. 2006) on the development of skiers' doublepoling capacity. Improvement of V O 2peak in elite skiers has been found after a 6-week training period with 3-min intervals on a ski-ergometer (Nilsson et al. 2004), whereas no change in V O 2peak compared to controls was shown as a result of strength training (Hoff et al. 1999;Mikkola et al. 2007;Skattebo et al. 2016) or short (10-20 s) double-poling intervals (Mikkola et al. 2007;Nilsson et al. 2004). ...
... doublepoling training on ski-ergometer or roller skis) (Downing and Wilcox 2003;Mikkola et al. 2007;Nilsson et al. 2004;Terzis et al. 2006) on the development of skiers' doublepoling capacity. Improvement of V O 2peak in elite skiers has been found after a 6-week training period with 3-min intervals on a ski-ergometer (Nilsson et al. 2004), whereas no change in V O 2peak compared to controls was shown as a result of strength training (Hoff et al. 1999;Mikkola et al. 2007;Skattebo et al. 2016) or short (10-20 s) double-poling intervals (Mikkola et al. 2007;Nilsson et al. 2004). The ability to generate a high V max was improved subsequent to an intervention with combined strength training and skispecific training (Mikkola et al. 2007). ...
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Purpose: To compare the effects of strength training versus ski-ergometer training on double-poling gross efficiency (GE), maximal speed (V max), peak oxygen uptake ([Formula: see text]) for elite male and female junior cross-country skiers. Methods: Thirty-three elite junior cross-country skiers completed a 6-week training-intervention period with two additional 40-min training sessions per week. The participants were matched in pairs and within each pair randomly assigned to either a strength-training group (STR) or a ski-ergometer-training group (ERG). Before and after the intervention, the participants completed three treadmill roller-skiing tests to determine GE, V max, and [Formula: see text]. Mixed between-within subjects analysis of variance (ANOVA) was conducted to evaluate differences between and within groups. Paired samples t tests were used as post hoc tests to investigate within-group differences. Results: Both groups improved their V max and [Formula: see text] expressed absolutely (all P < 0.01). For the gender-specific sub-groups, it was found that the female skiers in both groups improved both V max and [Formula: see text] expressed absolutely (all P < 0.05), whereas the only within-group differences found for the men were improvements of V max in the STR group. No between-group differences were found for any of the investigated variables. Conclusions: Physiological and performance-related variables of importance for skiers were improved for both training regimes. The results demonstrate that the female skiers' physiological adaptations to training, in general, were greater than those of the men. The magnitude of the physiological adaptations was similar for both training regimes.
... As the force requirements increase, as they would during heavy resistance exercise, higher threshold motor units are recruited. As such, it seems that resistance exercise using heavy to near maximal loads activates the full spectrum of motor units (Mikkola et al., 2007). Neural firing frequency refers to the rate at which the neuromuscular system is able to recruit muscle fibres in response to a resistance. ...
... Based on these data it has been suggested that training frequency may be a key determinant for the presence of interference. It may also be hypothesised that if training frequency is too high, the overall training stress becomes too great and strength development plateaus regardless of the interference phenomenon itself (Häkkinen et al., 2003;Mikkola et al., 2007;Davis et al., 2008). ...
... basketball, rugby union and football), sprint kayaking, and rowing, require the expression of high levels of muscular strength, yet at the same time they also demand endurance-type capabilities in order to optimize performance. As such it is inevitable that concurrent training will be performed at particular stages during an athlete's training cycle ( recently, research has also investigated the effects of implementing strength training within specific populations; most notably groups of endurance trained athletes (Mikkola et al., 2007;Rønnestad et al., 2010;Rønnestad, Hansen & Raastad, 2011). ...
... Given that the original conjecture of VO 2max as the ultimate performance predictor in endurance sports has been questioned [3], the importance of strength training for endurance athletes cannot be neglected. Maximal and explosive strength training has been shown to improve running economy [23,35,37], velocity at the lactate threshold [15,22], maximal running speed [23] and running time over a given distance [24,33], while also no or little changes in strength training-induced improvements in running economy [22] and the velocity at the lactate threshold [19,23,24] have been observed. When performing endurance and strength training concurrently, special attention regarding exercise sequencing is required in order to optimize training adaptations [6]. ...
... Given that the original conjecture of VO 2max as the ultimate performance predictor in endurance sports has been questioned [3], the importance of strength training for endurance athletes cannot be neglected. Maximal and explosive strength training has been shown to improve running economy [23,35,37], velocity at the lactate threshold [15,22], maximal running speed [23] and running time over a given distance [24,33], while also no or little changes in strength training-induced improvements in running economy [22] and the velocity at the lactate threshold [19,23,24] have been observed. When performing endurance and strength training concurrently, special attention regarding exercise sequencing is required in order to optimize training adaptations [6]. ...
... Furthermore, while not possible for organizational constraints, the inclusion of a group training with the S + E order or performing endurance and strength training on alternating days would have strengthened the present findings. Even though the strength training program utilized in the present study was similar to that utilized in previous studies [22,37] and has recently been recommended for endurance athletes [27], it cannot be conclusively stated that the present program would have beneficially affected endurance performance when performed on alternating days. ...
Article
This study examined neuromuscular adaptations in recreational endurance runners during 24 weeks of same-session combined endurance and strength training (E+S, n=13) vs. endurance training only (E, n=14). Endurance training was similar in the 2 groups (4-6x/week). Additional maximal and explosive strength training was performed in E+S always after incremental endurance running sessions (35-45 min, 65-85% HRmax). Maximal dynamic leg press strength remained statistically unaltered in E+S but decreased in E at week 24 (-5±5%, p=0.014, btw-groups at week 12 and 24, p=0.014 and 0.011). Isometric leg press and unilateral knee extension force, EMG of knee extensors and voluntary activation remained statistically unaltered in E+S and E. The changes in muscle cross-sectional (CSA) differed between the 2 groups after 12 (E+S+6±8%, E -5±6%, p<0.001) and 24 (E+S+7±7%, E -6±5%, p<0.001) weeks. 1 000 m running time determined during an incremental field test decreased in E+S and E after 12 (-7±3%, p<0.001 and -8±5%, p=0.001) and 24 (-9±5%, p=0.001 and -13±5%, p<0.001) weeks. Strength training performed always after an endurance running session did not lead to increased maximal strength, CSA, EMG or voluntary activation. This possibly contributed to the finding of no endurance performance benefits in E+S compared to E. © Georg Thieme Verlag KG Stuttgart · New York.
... Studies have demonstrated that systematic heavy strength training (and subsequent strength gains) can reduce O 2 cost during double poling on roller skis and double poling ergometers in highly trained skiers (Østerås et al., 2002;Mikkola et al., 2007), albeit that not all studies have confirmed this during roller ski skating (Losnegard et al., 2011;Rønnestad et al., 2012). Increased maximal strength has resulted in increased time to exhaustion (Hoff et al., 1999(Hoff et al., , 2002Østerås et al., 2002) and 5 min power output on double poling ergometers (Losnegard et al., 2011). ...
... Increased maximal strength has resulted in increased time to exhaustion (Hoff et al., 1999(Hoff et al., , 2002Østerås et al., 2002) and 5 min power output on double poling ergometers (Losnegard et al., 2011). However, improvements in skating or double poling time trials (1.1-7.5 km) have not been found after concurrent strength and endurance training in XC skiers (Mikkola et al., 2007;Losnegard et al., 2011;Rønnestad et al., 2012). ...
... Surprisingly, INT showed small negative changes in VO 2max and VO 2peak compared with CON during the intervention period. This is in contrast with previous studies, where concurrent heavy strength and endurance training compared with only endurance training has led to similar or more favorable changes in VO 2max and VO 2peak (Hoff et al., 1999(Hoff et al., , 2002Østerås et al., 2002;Mikkola et al., 2007;Losnegard et al., 2011;Rønnestad et al., 2012). Heavy strength training has a long recovery period, where muscle function can be lowered for more than 48 h after exercise (Raastad et al., 2003). ...
Article
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We investigated the effects of adding heavy strength training to a high volume of endurance training on performance and related physiological determinants in junior female cross-country skiers. Sixteen well-trained athletes (17 ± 1 years, 60 ± 6 kg, 169 ± 6 cm, VO2max running: 60 ± 5 mL/kg/min) were assigned either to an intervention group (INT; n = 9) or a control group (CON; n = 7). INT completed two weekly sessions of upper body heavy strength training in a linear periodized fashion for 10 weeks. Both groups continued their normal aerobic endurance and muscular endurance training. One repetition maximum in seated pull-down increased significantly more in INT than in CON, with a group difference of 15 ± 8% (P < 0.01). Performance, expressed as average power output on a double poling ergometer over 20 s and as 3 min with maximal effort in both rested (sprint-test) and fatigued states (finishing-test), showed similar changes in both groups. Submaximal O2 -cost and VO2peak in double poling showed similar changes or were unchanged in both groups. In conclusion, 10 weeks of heavy strength training increased upper body strength but had trivial effects on performance in a double poling ergometer in junior female cross-country skiers. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
... Provided that RT-SWIM or SWIM-RT orders have not directly tested in competitive swimmers, there is no supportive evidence of one over the other. Considering other sports paradigms (running, cycling, skiing) that compared RT-endurance or endurance-RT orders, there is evidence to suggest similar improvements in power output during high-intensity tests after 6-25 weeks [54][55][56]60]. In addition, similar maximal strength gains with both training orders after 8-14 weeks of training were observed [54][55][56]60,61]. ...
... Considering other sports paradigms (running, cycling, skiing) that compared RT-endurance or endurance-RT orders, there is evidence to suggest similar improvements in power output during high-intensity tests after 6-25 weeks [54][55][56]60]. In addition, similar maximal strength gains with both training orders after 8-14 weeks of training were observed [54][55][56]60,61]. Possibly, competitive swimmers will benefit from increased 1-RM strength in dry-land-based exercises (i.e., bench press) [8], or in-water-based tests [4], either with RT-SWIM or SWIM-RT orders. ...
Article
Full-text available
Dry-land resistance exercise (RT) is routinely applied concurrent to swimming (SWIM) training sessions in a year-round training plan. To date, the impact of the acute effect of RT on SWIM or SWIM on RT performance and the long-term RT-SWIM or SWIM-RT training outcome has received limited attention. The existing studies indicate that acute RT or SWIM training may temporarily decrease subsequent muscle function. Concurrent application of RT-SWIM or SWIM-RT may induce similar physiological alterations. Such alterations are dependent on the recovery duration between sessions. Considering the long-term effects of RT-SWIM, the limited existing data present improvements in front crawl swimming performance, dry-land upper and lower body maximum strength, and peak power in swim turn. Accordingly, SWIM-RT training order induces swimming performance improvements in front crawl and increments in maximum dry-land upper and lower body strength. Concurrent application of RT-SWIM or SWIM-RT training applied within a training day leads in similar performance gains after six to twelve weeks of training. The current review suggests that recovery duration between RT and SWIM is a predisposing factor that may determine the training outcome. Competitive swimmers may benefit after concurrent application with both training order scenarios during a training cycle.
... Traditionally, this is achieved by means of training programs composed by an adequate exercise stint and workload [1]. These programs require remarkable compliance from the subject and long-lasting training application for enhancing force, motor endurance or ability [1,2]. Moreover, intervention based on exercise execution could not fit with a subject's eventual status, because of a muscular frailty or exercise intolerance (e.g., elderly, post trauma subjects). ...
... The outcome values at the end of the follow-up are reported (* p < 0.01; ** p < 0.001). 1 Fatigue index: fatigue evaluation computed as muscle fiber velocity conduction. 2 Postural Sway Area: the area which encloses the data points relative to oscillations in the horizontal plane of the center of gravity even when a person is standing. 3 Velocity of Sway: velocity of the center of gravity oscillations. ...
Article
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Mechanical vibration, applied to single or few muscles, can be a selective stimulus for muscle spindles, able to modify neuromuscular management, inducing short and long-term effects, are now mainly employed in clinic studies. Several studies reported as treatments with focal vibratory (FVT) can influence neuromuscular parameters also in healthy people. However, the application modalities and the consequent effects are remarkably fragmented. This paper aims to review these studies and to characterize the FVT effectiveness on long-term conditional capacities in relation to FVT characteristics. A systematic search of studies published from 1985 to 2020 in English on healthcare databases was performed. Articles had to meet the following criteria: (1) treatment based on a locally applied vibration on muscle belly or tendon; (2) healthy adults involved; (3) outcomes time analysis enduring for more than 24 h. Twelve studies were found, all of them presented an excellent quality score of ≥75%. All selected papers reported positive changes, comparable with traditional long-lasting training effects. Muscle force and power were the most investigated parameters. The after-effects persisted for up to several months. Among the different FV administration modalities, the most effective seems to show a stimulus frequency of ≈100 Hz, repeated more times within three-five days on a voluntary contracted muscle.
... However, combining these training forms may lead to improvements in both endurance and strength performances. Several studies have recently shown that it is possible to improve muscular strength and power by combining endurance and strength training without losing aerobic fitness [14,15]. This is also true in the military environment, where it has been reported that the addition of strength training during the BT period did not interfere with the development of improved aerobic fitness [24,25]. ...
... Endurance training has previously been considered to interfere with explosive strength development by limiting the training induced changes in rapid neural activation [5]. More recently there have been several studies among endurance athletes [14,15,21] as well in untrained subjects [13] showing that endurance and strength training programmes can be combined without limitation of strength development. This may suggest that strength development in combined training may not be so strongly related to training history. ...
Article
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Study aim : The purpose of this study was to evaluate neuromuscular adaptations in conscripts with different fitness levels (VO 2max ) during 8 weeks of military basic training (BT). Material and methods : Twenty-four male conscripts (18–21 years) were divided into two groups (Good Fitness [GF] and Low fitness [LF]) based on their VO 2max at the beginning of BT. Body mass (BM), fat free mass (FFM) and Fat% were measured after 2, 4, and 7 weeks of training. VO 2max , maximal isometric leg press force (MVC), H-reflex (H max /M max ) at rest and V-wave (V/M max ) during maximal isometric plantarflexion were measured from the soleus muscle at the beginning, after 5, and after 8 weeks of training. Results : FFM decreased significantly in LF after 7 weeks of training (–3.0 ± 1.7%, p < 0.001), which was not observed in GF. Both GF (6.9 ± 4.6%, p < 0.01) and LF (5.7 ± 4.6%, p < 0.01) showed improved VO 2max after 5 weeks, with no changes during the last 3 weeks. A main effect of training was observed in decreased leg press MVC (–7.3 ± 9.3%, F = 4.899, p < 0.05), with no between-group differences. V-wave was significantly lower in LF during 5 (–37.9%, p < 0.05) and 8 (–44.9%, p < 0.05) weeks. Conclusion : Poor development of the neuromuscular system during BT suggests that explosive and/or maximal strength training should be added to the BT protocol for all conscripts regardless of fitness level. In addition, individualized training periodization should be considered to optimize the training load.
... Another important point to consider is the amount of sportspecific training volume that is completed by both the experimental and control groups. In the current review we excluded studies in which individuals in the control and experimental groups did not perform the same volume of sport-specific training (Bastiaans, van Diemen, Veneberg, & Jeukendrup, 2001;Mikkola, Rusko, Nummela, Paavolainen, & Häkkinen, 2007;Mikkola, Rusko, Nummela, Pollari, & Häkkinen, 2007;Paavolainen, Häkkinen, Hämäläinen, Nummela, & Rusko, 1999), as it is possible that reducing the volume of sport-specific training in itself may benefit time trial performance (Houmard, 1991). Notably, all of these studies (Bastiaans et al., 2001;Mikkola, Rusko, Nummela, Paavolainen, et al., 2007;Mikkola, Rusko, Nummela, Pollari, et al., 2007;Paavolainen et al., 1999) replaced some sport-specific training with resistance training, so that the resistance training group performed a lower volume of sport-specific training. ...
... In the current review we excluded studies in which individuals in the control and experimental groups did not perform the same volume of sport-specific training (Bastiaans, van Diemen, Veneberg, & Jeukendrup, 2001;Mikkola, Rusko, Nummela, Paavolainen, & Häkkinen, 2007;Mikkola, Rusko, Nummela, Pollari, & Häkkinen, 2007;Paavolainen, Häkkinen, Hämäläinen, Nummela, & Rusko, 1999), as it is possible that reducing the volume of sport-specific training in itself may benefit time trial performance (Houmard, 1991). Notably, all of these studies (Bastiaans et al., 2001;Mikkola, Rusko, Nummela, Paavolainen, et al., 2007;Mikkola, Rusko, Nummela, Pollari, et al., 2007;Paavolainen et al., 1999) replaced some sport-specific training with resistance training, so that the resistance training group performed a lower volume of sport-specific training. Of these studies, which were again excluded from our analyses but have been included in other reviews (Bazyler et al., 2015;Beattie et al., 2014Beattie et al., , 2010Yamamoto et al., 2008), only one (Paavolainen et al., 1999) demonstrated a beneficial effect of resistance training on improving an actual running performance measure. ...
Article
A number of reviews have concluded that resistance training is beneficial for improving sports performance despite the inclusion of studies which do not actually measure a performance outcome (i.e. a timed trial). The purpose of this review was to examine only those studies which would allow us to infer the benefits of resistance training on improving time trial performance. Of the nine studies meeting all inclusion criteria only three demonstrated an additive effect of adding resistance training to the current activity-specific training being performed. These three studies demonstrated improvements in either 5 or 10 km time trial among recreationally skilled athletes (i.e. non-elite level time). Previous reviews have included studies which did not include: (1) performance outcomes; (2) control groups; and/or (3) equal volumes of activity-specific exercise among the resistance training and control groups. Presently, there is little evidence that adding resistance exercise to a sport-specific training program will augment time trial performance. While it is difficult to perform such long-term studies assessing the effects of resistance training among time trial athletes, the statement that resistance training is efficacious for improving time trial performance should be tempered until sufficient evidence is presented to support such claims.
... Legs have higher capillary density, lower lactate onset and higher aerobic capacity than the arms ( Holmberg, 2015;Monahan 2016). The potential association between strength capacities and performance has been investigated in the past studies ( Mikkola et al. 2007;Sandbakk 2010). Stöggl et al. (2011 determined the relationships between general strength, maximal skiing speeds, pole and leg kinetic and kinematics of a group of elite male skiers. ...
... Stöggl et al. (2011) analyzed the relationships between general strength, maximal skiing speeds, pole and leg kinetic and kinematics of a group of elite male skiers, revealing that the general strength and power per se seem not to be major determinants of performance in elite skiers. Mikkola et al. (2007) showed that in male cross-country skiers, concurrent explosive strength and endurance training led to improvements in explosive force associated with increased rapid activation of trained leg muscles. And they also observed an increase in 30-m double poling test performance. ...
Article
Full-text available
The purpose of this study was to examine the effect of roller-ski aerobic high-intensity interval training on leg muscle strength and time-trial performance after 8-week of roller-ski uphill training. The sample comprised of 10 males (age, 18.8±2.1 years) and 8 females (age, 16.1±0.3 years) junior cross-country skiers, who performed 8-week intervention training periods three times a week in addition to their normal seasonal training. All skiers performed all-out uphill interval training, 2 sets as long duration (10-15 minutes), at 85-92 percent of HRmax with total duration of 40-45 minutes (height difference is 144 MT and 2-km distance). Before and after the intervention period all athletes were tested for hamstring and quadriceps isokinetic strength at 600 /sec and 2-km time-trial performance. Both group improved leg muscle strength and time-trial performance between pre- and post-test (all p<0.05). In conclusion, 8-week of supplemental aerobic high-intensity interval training promotes increases in isokinetic strength and time-trial performance.
... The most common concept of whole body efficiency is GE, defined as the amount of metabolic energy transferred to external work (van Ingen Schenau & Cavanagh, 1990). An alternative to GE is an expression of economy (Saunders et al., 2004) and several earlier studies on c.c. skiing have used this concept (Hoff et al., 1999;Hoffman, 1992;Hoffman et al., 1994;Losnegard et al., 2013;Mahood et al., 2001;Mikkola et al., 2007;Millet et al., 1998a;Millet et al., 2003;Østerås et al., 2002). Movement economy is usually expressed as the V̇O2 at a given submaximal velocity or, alternatively, as the VO2 per distance covered (mL/kg/m); i.e., the O2 cost. ...
... Therefore, training to enhance Vmax should probably focus on a combination of maximal strength, power and speed training exercises, together with a particular focus on technique development. Such improvements may also enhance skiing economy as demonstrated previously (Hoff et al., 1999;Mikkola et al., 2007;Østerås et al., 2002;Helgerud et al., 2001). ...
Thesis
Full-text available
Cross-country (c.c.) skiing is a complex sport discipline from both physiological and biomechanical perspectives, with varying course topographies that require different proportions of the involved sub-techniques to be utilised. A relatively new event in c.c. skiing is the sprint race, involving four separate heats, each lasting 2-4 min, with diverse demands from distance races associated with longer durations. Therefore, the overall aim of the current thesis has been to examine the biomechanical and physiological factors associated with sprint c.c. skiing performance through novel measurements conducted both in the field (Studies I-III) and the laboratory (Studies IV and V). In Study I sprint skiing velocities and sub-techniques were analysed with a differential global navigation satellite system in combination with video recording. In Studies II and III the effects of an increasing velocity (moderate, high and maximal) on the biomechanics of uphill classical skiing with the diagonal stride (DS) (Study II) and herringbone (HB) (Study III) sub-techniques were examined. In Study I the skiers completed the 1,425 m (2 x 712 m) sprint time trial (STT) in 207 s, at an average velocity of 24.8 km/h, with multiple technique transitions (range: 21-34) between skiing techniques (i.e., the different gears [G2-7]). A pacing strategy involving a fast start followed by a gradual slowing down (i.e., positive pacing) was employed as indicated by the 2.9% faster first than second lap. The slower second lap was primarily related to a slower (12.9%) uphill velocity with a shift from G3 towards a greater use of G2. The maximal oxygen uptake (V̇O2max) was related to the ability to maintain uphill skiing velocity and the fastest skiers used G3 to a greater extent than G2. In addition, maximal speed over short distances (50 and 20 m) with the G3 and double poling (DP) sub-techniques exerted an important impact on STT performance. Study II demonstrated that during uphill skiing (7.5°) with DS, skiers increased cycle rate and cycle length from moderate to high velocity, while cycle rate increased and cycle length decreased at maximal velocity. Absolute poling, gliding and kick times became gradually shorter with an elevated velocity. The rate of pole and leg force development increased with elevated velocity and the development of leg force in the normal direction was substantially faster during skiing on snow than previous findings for roller skiing, although the peak force was similar in both cases. The fastest skiers applied greater peak leg forces over shorter durations. iv Study III revealed that when employing the HB technique on a steep uphill slope (15°), the skiers positioned their skis laterally (“V” between 25 to 30°) and planted their poles at a slight lateral angle (8 to 12°), with most of the propulsive force being exerted on the inside forefoot. Of the total propulsive force, 77% was generated by the legs. The cycle rate increased across all three velocities (from 1.20 to 1.60 Hz), while cycle length only increased from moderate to high velocity (from 2.0 to 2.3 m). Finally, the magnitude and rate of leg force generation are important determinants of both DS and HB skiing performance, although the rate is more important in connection with DS, since this sub-technique involves gliding. In Studies IV and V skiers performed pre-tests for determination of gross efficiency (GE), V̇O2max, and Vmax on a treadmill. The main performance test involved four self-paced STTs on a treadmill over a 1,300-m simulated course including three flat (1°) DP sections interspersed with two uphill (7°) DS sections. The modified GE method for estimating anaerobic energy production during skiing on varying terrain employed in Study IV revealed that the relative aerobic and anaerobic energy contributions were 82% and 18%, respectively, during the 232 s of skiing, with an accumulated oxygen (O2) deficit of 45 mL/kg. The STT performance time was largely explained by the GE (53%), followed by V̇O2 (30%) and O2 deficit (15%). Therefore, training strategies designed to reduce energetic cost and improve GE should be examined in greater detail. In Study V metabolic responses and pacing strategies during the four successive STTs were investigated. The first and the last trials were the fastest (both 228 s) and were associated with both a substantially larger and a more rapid anaerobic energy supply, while the average V̇O2 during all four STTs was similar. The individual variation in STT performance was explained primarily (69%) by the variation in O2 deficit. Furthermore, positive pacing was employed throughout all the STTs, but the pacing strategy became more even after the first trial. In addition, considerably higher (~ 30%) metabolic rates were generated on the uphill than on the flat sections of the course, reflecting an irregular production of anaerobic energy. Altogether, a fast start appears important for STT performance and high work rates during uphill skiing may exert a more pronounced impact on skiing performance outdoors, due to the reduction in velocity fluctuations and thereby overall air-drag. Keywords: cycle characteristics, energy cost, energy yield, incline, joint angles, kinematics, kinetics, mechanics, Nordic skiing, oxygen deficit, oxygen demand, technique transitions, total metabolic rate.
... In turn, this has led researchers to explore the role of strength training in connection to XC racing in greater detail. Notably, Mikkola, Rusko, Nummela, Paavolainen, and Häkkinen (2007) observed improved performance in 30 m sprint performance after explosive-type strength training. Similarly, others have reported correlations between greater strength levels and maximal speed or performances over short distances (Stöggl, Lindinger, & Müller, 2007;Stöggl et al., 2011). ...
... Similarly, others have reported correlations between greater strength levels and maximal speed or performances over short distances (Stöggl, Lindinger, & Müller, 2007;Stöggl et al., 2011). XC skiing researchers have examined the relationships between maximal velocity, force production characteristics and racing performance (Mikkola et al., 2007;Stöggl et al., 2007;Stöggl et al., 2011), but few have examined the start phase. Hansen and Losnegard (2010) did investigate performance over 80 m from a standing start and found longer poles led to better performances, particularly over the first 20 m. ...
Article
The present study was designed to analyse and compare the kinetics and kinematics associated with three different starting strategies during classic cross-country ski racing. Inside a ski tunnel, 12 elite male skiers performed three sets of three 38 m starts. Each set included one start using: double poling only (DP), diagonal stride only (DIA) and freely chosen (FREE) (i.e. where subjects used the strategy or combination of strategies they felt was fastest) in random order. The first 18 m was performed on a series of force plates that measured horizontal and vertical forces followed by 20 m of a standard snow track. Additionally, cycle characteristics and joint angles were measured. DIA and FREE were faster over 38 m than DP (P < .01). Net horizontal impulse (taking into account both positive and negative impulses) 5-10 m after the start was lower during DP than during DIA and FREE (both P < .05). All subjects skied faster when using only DIA for the entire 38 m. Furthermore, the sum duration and frequency of propulsive contacts over the first 18 m was less in DP than DIA and FREE (P < .01). In conclusion, differences between the starting strategies examined was especially pronounced during the initial cycles. Transition from DIA to DP during the start also slowed the skiers, but optimal timing for such a transition was not elucidated.
... A considerable number of studies have examined the O 2 -cost in XC skiing (, Mikkola et al. 2007). In general, these studies indicate that the level of the skier and the skiing technique affects O 2 -cost. ...
... In addition, not only the VO 2max is expected to change due to a large amount of endurance training, but also the fractional utilization of VO 2max , anaerobic capacity and the O 2 -cost of the skier. Recent studies have demonstrated that systematic heavy strength training (and subsequent strength gains) reduce O 2 -cost during DP on ergometers or rollerskis in highly trained skiers (Hoff et al. 1999; , Østerås et al. 2002 , Mikkola et al. 2007) albeit not all studies have confirmed such a mechanism during rollerski skating (Losnegard et al. , Rønnestad et al. 2012). However, to date limited information exists on longitudinal changes (i.e., > 12 weeks) and effects of training on O 2 -cost during skiing. ...
Thesis
This thesis consists of four studies with additional unpublished results, in which the main objective was to examine factors that determine performance in modern elite cross-country (XC) skiing. Thirty-two elite male XC skiers volunteered to participate, with some subjects participating in several studies. Maximal aerobic power, maximal anaerobic capacity, O2-cost and performance was measured during rollerski skating on a treadmill to investigate differences between techniques (V1 and V2), differences between skiers, and changes in these variables during an annual training season. In addition, a novel approach involving PET/MRI scanning was used to investigate muscle use at low- and high-intensity exercise in double poling (DP). The studies together demonstrate that performance in elite male distance skiing (> 15 km) is highly related to VO2max, exemplified by the findings that the best skiers reached values of 83 ± 3 mL·kg- 1·min-1. Sprint skiing (< 1.8 km) performance has somewhat different physical and physiological demands, as sprint skiers have a larger body-mass index and a significantly higher anaerobic capacity compared to distance skiers. With systematic testing of elite skiers during an annual training year VO2max was unchanged and the increased performance was related to enhanced O2- cost and anaerobic capacity. The observed constant VO2max across the yearly training cycle, and the finding that VO2max is not related to increased performance during an annual training season, seems contradictory to results obtained during the 1980s and is likely related to changes in training habits of elite skiers in recent decades. With respect to propulsion technique, there were no differences between V1 and V2 in O2-cost or performance, but individual differences occurred and therefore, choice of skiing technique is likely important for the individual skier. The present results further suggest that with increasing intensity during DP, the legs contribute significantly to the total increased energy turnover. Hence, specific training is not only related to exercise modes but also to the intensity of exercise performed by the skier. FULLTEXT: http://www.nb.no/idtjeneste/URN:NBN:no-bibsys_brage_38606
... A treadmill test was performed to assess physiological variables associated with aerobic capacity using a standard incremental protocol (Mikkola et al., 2007). A resting fingertip blood sample was taken for the analysis of resting Bla (EKF diagnostic, C-line system, Biosen, Germany). ...
Article
Full-text available
Purpose: To examine the influence of menstrual cycle (MC) and hormonal contraceptive (HC) cycle phases on physiological variables monitored during incremental treadmill testing in physically active women (eumenorrheic, EUM = 16 and monophasic HC-users, CHC = 12). Methods: Four running tests to exhaustion were performed at bleeding, mid follicular (mid FOL)/active 1, ovulation/active 2, and mid luteal (mid LUT)/inactive. HC and MC phases were confirmed from serum hormones. Heart rate (HR), blood lactate (Bla), and V ˙ O 2 were monitored, while aerobic (AerT) and anaerobic (AnaT) thresholds were determined. V ˙ O 2peak , maximal running speed (RUN peak ), and total running time (RUN total ) were recorded. Results: No significant changes were observed in V ˙ O 2 or Bla at AerT or AnaT across phases in either group. At maximal effort, absolute and relative V ˙ O 2peak , RUN peak , and RUN total remained stable across phases in both groups. No significant fluctuations in HR max were observed across phases, but HR at both AerT and AnaT tended to be lower in EUM than in CHC across phases. Conclusion: Hormonal fluctuations over the MC and HC do not systematically influence physiological variables monitored during incremental treadmill testing. Between group differences in HR at AerT and AnaT underline why HR-based training should be prescribed individually, while recording of MC or HC use when testing should be encouraged as phase may explain minor, but possibly meaningful, changes in, e.g., Bla concentrations or differences in HR response.
... In sports such as sprinting, jumping and boxing and in situations where rapid joint stabilization is needed to avoid movement damage, the human ability to generate explosive force is considered important [25,26]. After 8 weeks of explosive training, the 30 m sprint time of young long-distance runners was significantly improved [27]. After explosive training is added to regular football training, the jumping ability of young football players has also been greatly improved [28]. ...
Article
Full-text available
Acupuncture can improve explosive force production and affect joint stiffness by affecting muscle activation levels. This study aims to explore the effects of true acupuncture (TA) compared with sham acupuncture (SA) on the explosive force production and stiffness of the knee joint in healthy male subjects. Twenty subjects were randomly divided into the TA group (n = 10) and SA group (n = 10) to complete isokinetic movement of the right knee joint at a speed of 240°/s before and after acupuncture. Futu (ST32), Liangqiu (ST34), Zusanli (ST36), Xuehai (SP10), and Chengshan (BL57) were selected for acupuncture. The intervention of SA is that needles with a blunt tip were pushed against the skin, giving an illusion of insertion. The results showed that acupuncture and the intervention time had a significant interaction effect on knee joint explosive force and joint stiffness (p < 0.05). The average maximum (max) torque, average work, average power, average peak power and total work of the TA group increased significantly after acupuncture (p < 0.05), while the SA group did not (p > 0.05). Therefore, true acupuncture can immediately improve the explosive force and joint stiffness of the male knee joint by inducing post-activation potentiation (PAP) and/or De-Qi.
... 1,6 However, a complexity of factors determine DP performance, and due to inconsistent findings in the literature, it is debated how important maximal strength is for performance in cross-country skiing. 11,22,[24][25][26][27] This may have jeopardized the chance for the skiers in the present study to take advantage of a Abbreviations: ES, effect size; NoEx, no exercise; RES, resistance exercise session; TTE, time to exhaustion. Note: Data are represented as mean (SD), n = 6. a Trivial (ES < 0.2). ...
Purpose: We tested whether a single session of heavy-load resistance priming conducted in the morning improved double-poling (DP) performance in the afternoon. Methods: Eight national-level male cross-country skiers (mean [SD]: 23 [3] y, 184 [6] cm, 73 [7] kg, maximum oxygen consumption = 69 [6] mL·kg-1·min-1) carried out 2 days of afternoon performance tests. In the morning, 5 hours before tests, subjects were counterbalanced to either a session of 3 × 3 repetitions (approximately 85%-90% 1-repetition maximum) of squat and sitting pullover exercises or no exercise. The performance was evaluated in DP as time to exhaustion (TTE) (approximately 3 min) on a treadmill and 30-m indoor sprints before and after TTE (30-m DP pre/post). Furthermore, submaximal DP oxygen cost, countermovement jump, and isometric knee-extension force during electrical stimulation were conducted. Participants reported perceived readiness on test days. Results: Resistance exercise session versus no exercise did not differ for TTE (approximately 3 min above) (mean ± 95% confidence interval = 3.6% ± 6.0%; P = .29; effect size [ES], Cohen d = 0.27), 30-m DP pre (-0.56% ± 0.80%; P = .21; ES = 0.20), 30-m DP post (-0.18% ± 1.13%; P = .76; ES = 0.03), countermovement jump (-2.0% ± 2.8%; P = .21; ES = 0.12), DP oxygen cost (-0.13% ± 2.04%; P = .91; ES = 0.02), or perceived readiness (P ≥ .11). Electrical stimulation force was not different in contraction or relaxation time but revealed low-frequency fatigue in the afternoon for the resistance exercise session only (-12% [7%]; P = .01; ES = 1.3). Conclusion: A single session of heavy-load, low-volume resistance exercise in the morning did not increase afternoon DP performance of short duration in high-level skiers. However, leg low-frequency fatigue after resistance priming, together with the presence of small positive effects in 2 out of 3 DP tests, may indicate that the preconditioning was too strenuous.
... A running test of this duration in a recreationally trained population correlates significantly with laboratorydetermined oxygen-consumption data and this relationship makes it possible to estimate aerobic capacity with reasonable accuracy in field conditions (Cooper, 1968). Maximal aerobic capacity was recorded using a standard protocol (Mikkola et al., 2007). Briefly, treadmill incline remained a constant 0.5 degrees while running velocity began at 7-9 km · h −1 and was increased by 1 km · h −1 every third min until volitional exhaustion. ...
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Purpose: To examine the potential sex differences in adaptations to combined endurance and strength training in recreationally endurance trained (eumenorrheic) women (n = 9) and men (n = 10). Methods: Isometric (ISOMmax) and dynamic bilateral leg press (1RM), countermovement jump (CMJ), running performance (3,000 m time trial), lean mass and body fat % (LEAN and FAT% determined by dual X-ray absorptiometry) as well as serum testosterone and cortisol (TES and COR, respectively, measured using hormone-specific immunoassay kits) were examined before a control period and pre, mid, and post a supervised 10-week combined high-intensity interval endurance training (4 × 4 min intervals and 3 × 3 × 100 m repeated sprints) and mixed maximal and explosive strength training. No more than 2 weeks separated training and testing for either women or men and all women were tested in the early follicular phase of the menstrual cycle to minimize the possible influence of menstrual cycle phase on performance measures. Results: Absolute and relative changes in 1RM, CMJ, 3,000 m, LEAN, and FAT% were similar between groups. The only statistically significant differences observed between groups were observed at post and included a larger Δ% increase in ISOMmax force in men and a relatively greater Δ% decrease in serum TES in women. Conclusion: Women and men can achieve similar relative adaptations in dynamic maximal strength and CMJ as well as endurance performance gains and body composition over the same high-intensity 10-week combined program, although relative adaptations in TES may differ.
... Breath-by-breath gas exchange was recorded with a Vmax Encore 29 metabolic cart (VIASYS Respiratory Care Inc., Palm Springs, CA, United States), which was calibrated according to the manufacturer's instructions before each measurement. Maximal oxygen uptake (VO 2max ) was determined as the highest VO 2 averaged over 60 s (Mikkola et al., 2007). Maximal aerobic cycling power (Pmax) was calculated as Pmax = Pcom + (t/180) P in which Pcom is the last cycling FIGURE 1 | Schematic illustration of the study setup. ...
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Background To date, microRNAs (miRs) carried in extracellular vesicles (EVs) in response to exercise have been studied in blood but not in non-invasively collectable body fluids. In the present study, we examined whether six exercise–responsive miRs, miRs-21, -26, -126, -146, -221, and -222, respond to acute endurance exercise stimuli of different intensities in sweat.Methods We investigated the response of miRs isolated from sweat and serum EVs to three endurance exercise protocols: (1) maximal aerobic capacity (VO2max), (2) anaerobic threshold (AnaT), and (3) aerobic threshold (AerT) tests. Sauna bathing was used as a control test to induce sweating through increased body temperature in the absence of exercise. All protocols were performed by the same subjects (n = 8, three males and five females). The occurrence of different miR carriers in sweat and serum was investigated via EV markers (CD9, CD63, and TSG101), an miR-carrier protein (AGO2), and an HDL-particle marker (APOA1) with Western blot. Correlations between miRs in sweat and serum (post-sample) were examined.ResultsOf the studied miR carrier markers, sweat EV fractions expressed CD63 and, very weakly, APOA1, while the serum EV fraction expressed all the studied markers. In sweat EVs, miR-21 level increased after AerT and miR-26 after all the endurance exercise tests compared with the Sauna (p < 0.050). miR-146 after AnaT correlated to sweat and serum EV samples (r = 0.881, p = 0.004).Conclusion Our preliminary study is the first to show that, in addition to serum, sweat EVs carry miRs. Interestingly, we observed that miRs-21 and -26 in sweat EVs respond to endurance exercise of different intensities. Our data further confirmed that miR responses to endurance exercise in sweat and serum were triggered by exercise and not by increased body temperature. Our results highlight that sweat possesses a unique miR carrier content that should be taken into account when planning analyses from sweat as a substitute for serum.
... Contemporary skiing races are characterized by higher skiing speed and performance, with higher and lower body capacities being higher (Saltin, 1997), the development of neuromuscular and technical skills. The majority of cross-country (XC) skiing techniques have undergone significant changes over the past decade (Holmberg, 2005;Holmberg et al., 2005;Mikkola et al., 2007, Stöggl et al., 2008Lindinger et al., 2009a). Kick double poling is characterized by a propulsive leg push between double poling actions for momentum conservation in light uphill conditions (Smith, 2002) and leg push is similar to diagonal skiing (Lindinger et al., 2009b). ...
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The purpose of this study was to examine the effect of fatigue due to uphill on the kick double pole technique. Ten young male subjects volunteered to study. Subjects' cross country sprint times were taken using a kick double pole technique with maximum effort for 1 km in a climbing course with an average slope of 4%. In accordance with these measured times, a separate average speed for each subject was modified, and the subjects were tested on the treadmill at these specified speeds, with the same duration, slope, and technique. Each participant was asked to perform three trials with half an hour between them. Kinematic data were obtained using a three-dimensional motion capture system (Vicon Peak, Oxford, UK). Statistical analysis was performed by separating the variables into 3 separate groups: a) periods of time b) distance data c) joint angles. In conclusion, in kinematic data analyzed according to the fatigue of climb, there was a significant difference between the duration of the poling times, duration of the first cycles with the left leg propulsion and the last cycles, and the duration of the first cycles with the right leg propulsion and left leg propulsion. Significant differences were found in the hip, shoulder, elbow and trunk angles. Significant differences were also found among all the identified distances.
... This interference phenomenon (13) seems to be associated with a greater inhibitory effect on strength development than on aerobic capacity when CT is conducted (22). Nevertheless, some studies have shown no antagonistic effects on strength (30) or aerobic performance (33) after CT compared with performance after either form of stand-alone training. This fact could be due to the physiological adaptations induced by CT, which seem to be dependent on the order, volume, and intensity of the stimulus applied during the training session (28). ...
Article
The aim of this study was to verify the effects of different aerobic training intensities combined with the same resistance training on neuromuscular and aerobic performances. Thirty-nine males were randomly assigned to a low-intensity group (LIG, n=10), a moderate-intensity group (MIG, n=10), a high-intensity group (HIG, n=10), and a control group (CG, n=6). The training program consisted on full squat (FS) with 70–85% of 1 repetition-maximum (1RMest) combined with jump and sprint exercises, followed by running at 80% (LIG), 90% (MIG), or 100% (HIG) of the maximal aerobic speed for 16–20 min. The training period lasted for 8-weeks, followed by 4-weeks of detraining (DT). Pre-training, post-training, and post-DT evaluations included 20-m sprints (0–10 m: T10; 0–20 m: T20), shuttle run (oxygen uptake: VO2max), countermovement vertical jump (CMJ), and maximal strength (1RMest) in FS. All the experimental groups showed significant improvements from pre to post-training (p<0.05) in T10 (LIG:4%; MIG:5%; HIG:2%), T20 (LIG:3%; MIG:4%; HIG:2%), CMJ (LIG:9%; MIG:10%; HIG:7%), 1RMest (LIG:13%; MIG:7%; HIG:8%), and in VO2max (LIG:10%, MIG:11%; HIG:10%). Comparing the changes between experimental groups, only 1RMest gains were higher in the LIG than HIG (p=0.04) and MIG (p=0.01). DT resulted in performance decrements, with minimal losses of VO2max for the LIG. It seems that performing concurrent training is beneficial for strength and aerobic development in healthy adults regardless of the aerobic training intensity. However, choosing lower intensities can lead to increased strength and are also recommended when the cardiorespiratory gains should be maintained for longer.
... The ability to produce force rapidly could also have contributed to enhanced performance. Previous results suggest that the capacity to develop rapid force is a critical determinant of cross-country skiing performance (13,17,18). One previous study pointed out that there is a positive relationship between maximal skating speed and the rate of force development during the leg push-off (21). ...
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Kurz, A, Lauber, B, Franke, S, and Leukel, C. Balance training reduces postural sway and improves sport-specific performance in visually impaired cross-country skiers. J Strength Cond Res XX(X): 000-000, 2018-Balance training is highly effective in reducing sport injuries and causes improvements in postural stability and rapid force production. So far, the positive effects of balance training have been described for healthy athletes. In the present experiments, we questioned whether athletes with disabilities of the visual system can also benefit from balance training. Fourteen visually impaired cross-country skiers participated in this randomized controlled study. The intervention group (N = 7) completed 8 sessions of balance training over a period of 4 weeks (2 times per week), whereas a waiting control group (N = 7) received no training during that time. After training, postural sway was significantly reduced in the intervention group but not in the waiting control group. In addition, sport-specific performance, which was assessed by a standardized Cooper's 12-minute test on roller skis or rollerblades, increased in the intervention group. The change in postural sway from the premeasurement to the postmeasurement correlated with the change in sport-specific performance in all participants. Our results indicate that balance training is useful for improving postural stability and sport-specific performance in visually impaired cross-country skiers. We propose that balance training should therefore be implemented as part of the training routine in athletes with disabilities of the visual system.
... Se han observado incrementos en el VO2máx y en la fuerza máxima con entrenamientos combinados (izquierdo, 2005). En otros trabajos se ha descrito lo contrario (Mikkola, 2007). Las causas de este tipo de procesos negativos sobre la fuerza muscular podrían ser las siguientes: ...
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En el presente trabajo se describen las adaptaciones estructurales y funcionales en los principales órganos y sistemas que intervienen en la realización de ejercicio físico. Palabras clave: Entrenamiento. Fuerza muscular. Ejercicio físico. Abstract In this paper the structural and functional adaptations in the main organ and systems involved in physical exercise are described. Un entrenamiento de fuerza planificado y sistematizado produce una serie de adaptaciones sobre los distintos sistemas y órganos del cuerpo humano. En el presente trabajo se describen las adaptaciones que se producen en los elementos estructurales (tejido conjuntivo, óseo y, sobre todo, muscular), sistema nervioso (adaptaciones neuronales), sistema hormonal (secreción de hormonas como testosterona, hormona del crecimiento y cortisol), y sistema cardiorrespiratorio (consumo máximo de oxígeno, VO2máx). 2. Tipos de fibra muscular y ejercicio físico A. La célula muscular El músculo esquelético es el órgano del sistema muscular. Su carácter voluntario y sus propiedades mecánicas y eléctricas (contractilidad, elasticidad, excitabilidad y extensibilidad) le facilitan realizar diversas funciones: almacenar y movilizar sustancias, mantener la postura, movimiento corporal y producción de calor. La unidad estructural y funcional básica del músculo esquelético se denomina fibra muscular. Es alargada, polinucleada, la situación del núcleo es periférica y su estructura es sincital. B. Tipos de fibra muscular En función de sus características estructurales, funcionales y metabólicas, las fibras musculares se clasifican en:
... Contemporary skiing races are characterized by higher skiing speed and performance, with higher and lower body capacities being higher (Saltin, 1997), the development of neuromuscular and technical skills. The majority of cross-country (XC) skiing techniques have undergone significant changes over the past decade (Holmberg, 2005;Holmberg et al., 2005;Mikkola et al., 2007, Stöggl et al., 2008Lindinger et al., 2009a). Kick double poling is characterized by a propulsive leg push between double poling actions for momentum conservation in light uphill conditions (Smith, 2002) and leg push is similar to diagonal skiing (Lindinger et al., 2009b). ...
... The effect of concurrent training has been reported mostly in untrained or moderately trained subjects, showing a greater improvement in cardiovascular and neuromuscular parameters (Häkkinen et al., 2003;Mikkola et al., 2012), or similar improvements compared with strength or endurance training alone (Izquierdo et al., 2005). However, especially during the last decades the effect of concurrent training in welltrained and highly-trained endurance athletes, such as runners, has been reported and indicated no trivial effect on VO2max (Sedano et al., 2013;Paavolainen et al., 1999a), a possible improvement in running economy (Paavolainen et al., 1999a;Millet, Jaouen et al., 2002;Storen et al., 2002), improvements in velocity at the lactate threshold (Mikkola et al., 2007;Taipale et al., 2013) and in the actual endurance running performance (Paavolainen et al., 1999a). However, the influence of strength training in cycling remains somewhat unclear, with some studies showing an improvement in maximal aerobic power (Wmax) (Rønnestad et al., 2010a(Rønnestad et al., , 2010bSunde et al., 2010) or no beneficial effects of the added strength training (Bishop et al., 1999;Jackson et al., 2007;Levin et al., 2009). ...
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This study investigated the effects of adding a traditional strength training approach (endurance-strength = ES) during the pre-season versus a non-traditional approach where strength training is further maintained throughout the season (maximal-strength = MS), on aerobic and anaerobic parameters of off-road cyclists. Eleven off-road cyclists were divided into two groups. The ES group (n=6) performed during the first 8 weeks endurance-strength training, while the MS group (n=5) performed maximal-strength training, both together with their usual endurance training. During the following 8 weeks, only MS group maintained 1 session of strength training per week. 1RM, VO2max, Maximal aerobic power (Wmax), Power at 4-mmol·L-1 (LT4.0), Peak Power (PP), Mean Power (MP), Power best 5s (PB5), Power last 5s (PL5) and Fatigue Index (FI) were assessed. Results showed that there were significant (P < 0.05) increases for MS group in PP (+ 4.8%) from PRE to MID, in 1RM (+ 15.8%) from PRE to POST, while in the ES group there was a decrease in 1RM (- 16.1%), PL5 (-4.3%) with an increase in FI (+ 9.5) from MID to POST. Effect size calculations showed small and moderate improvements in PP (+ 3.6%), MP (+ 2.8%), PB5 (+ 4.3%) from PRE to POST for MS group, while ES group showed a small improvement in VO2max (+ 4.1%), LT4.0 (+ 4.3%) and PB5 (+ 2.7%) from PRE to MID, and a small decrease between MID to POST in Wmax (- 4.1%) and MP (- 2.6%). These results suggest that by including a non-traditional strength training approach it is possible to maintain aerobic levels and possibly increase anaerobic parameters throughout the off-road cycling season
... จากการรวบรวมงานวิ จั ยที ผ่ านมาแสดงให้ เห็ นถึ งผลของโปรแกรมการฝึ กแบบควบคู ่ ที สามารถ ยกระดั บสมรรถนะของนั กกี ฬาประเภทความอดทน เช่ น ประสิ ทธิ ภาพของการวิ ง การเพิ มขึ นของความเร็ วที จุ ด เริ มล้ า หรื อความสามารถของการกระโดด (Johnston et al., 1997;Mikkola, Rusko & Nummela, 2007;Rønnestad, Hansen & Raastad, 2010;Balabinis et al., 2003;Millet et al., 2002;Paavolainen et al., 1999;Saunders et al., 2006;Spurrs, Murphy & Watsford, 2003) หรื อในนั กกี ฬาเรื อพาย (Izquierdo-Gabarren et al., 2010) แม้ ว่ าบางการศึ กษา พบว่ า มี การลดลงของความแข็ งแรง (Hakkinen et al., 2003;Hickson, 1980;Kraemer et al., 1995) ขนาดของกล้ ามเนื อ (Hickson, 1980;Kraemer et al., 1995 (Leveritt et al., 1999;Sale et al., 1990) (Hickson, 1980;Dudley & Djamil, 1985;Craig et al., 1991;Hennessy & Watson, 1994;Kraemer et al., 1995;Hunter, Demment & Miller, 1987;Thomas & Nelson, 1990;Dudley & Fleck, 1987;Chromiak & Mulvaney, 1990) อย่ างไร ก็ ตาม จากรายงานการศึ กษาของ (Smaros, 1980;Wisløff ,Helgerud & Hoff, 1998;Green, 1992;Balsom, 1994 (Kraemer et al., 1995;Chromiac & Mulvaney, 1990) มี การศึ กษาผลของการฝึ กเพื อพั ฒนาความ แข็ งแรงที มี ต่ อความสามารถด้ านความอดทน (Hickson et al., 1988 ...
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Intermittent sport athletes do necessarily have a capacity in any of the areas of physical performance. Strength, muscle power and endurance as physical fitness are important. The coaches will be training athletes to develop the capability to move up and ready for the competition. Concurrent strength and endurance training is another form that is important which affect sports performance of intermittent sport athletes. Understanding the adaptation of the cardiovascular system and endurance performance as well as nerve and muscle adaptations to training and performance have given rise to more effective training interventions. Endurance interval training using an intensity at 90–95% of maximal heart rate in 3- to 8-minute bouts have proved to be effective in the development of endurance and other aspects related to sports. While studies on training to develop strength show using high loads, few repetitions and maximal mobilization of force in the concentric mode have proved to be effective in the development of strength, sprint and jump performance of athletes. It also enhances endurance capabilities through the development of efficient movement. Application form to apply this training to the development of athletes that have considered the challenge. Therefore, understanding and accuracy to guide for coaches and athletes use in the training of Concurrent Training between strength and endurance are important. In order to get the proper training and effective to avoid the negative aspects of the training that can occur in intermittent sport athletes.
... Furthermore, strength training has been shown to positively influence both LIEE and HIEE across a spectrum of endurance events with greater effects observed in HIEE (34,46,50,58,82,83). ...
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THE PURPOSE OF THIS REVIEW IS TWOFOLD: TO ELUCIDATE THE UTILITY OF RESISTANCE TRAINING FOR ENDURANCE ATHLETES, AND PROVIDE THE PRACTITIONER WITH EVIDENCED-BASED PERIODIZATION STRATEGIES FOR CONCURRENT STRENGTH AND ENDURANCE TRAINING IN ATHLETIC POPULATIONS. BOTH LOW-INTENSITY EXERCISE ENDURANCE (LIEE) AND HIGH-INTENSITY EXERCISE ENDURANCE (HIEE) HAVE BEEN SHOWN TO IMPROVE AS A RESULT OF MAXIMAL, HIGH FORCE, LOW VELOCITY (HFLV) AND EXPLOSIVE, LOW-FORCE, HIGH-VELOCITY STRENGTH TRAINING. HFLV STRENGTH TRAINING IS RECOMMENDED INITIALLY TO DEVELOP A NEUROMUSCULAR BASE FOR ENDURANCE ATHLETES WITH LIMITED STRENGTH TRAINING EXPERIENCE. A SEQUENCED APPROACH TO STRENGTH TRAINING INVOLVING PHASES OF STRENGTH-ENDURANCE, BASIC STRENGTH, STRENGTH, AND POWER WILL PROVIDE FURTHER ENHANCEMENTS IN LIEE AND HIEE FOR HIGH-LEVEL ENDURANCE ATHLETES.
... Furthermore, strength training has been shown to positively influence both LIEE and HIEE across a spectrum of endurance events with greater effects observed in HIEE (34,46,50,58,82,83). ...
Article
ABSTRACT: THE PURPOSE OF THIS REVIEW IS TWOFOLD: TO ELUCIDATE THE UTILITY OF RESISTANCE TRAINING FOR ENDURANCE ATHLETES, AND PROVIDE THE PRACTITIONER WITH EVIDENCED-BASED PERIODIZATION STRATEGIES FOR CONCURRENT STRENGTH AND ENDURANCE TRAINING IN ATHLETIC POPULATIONS. BOTH LOW-INTENSITY EXERCISE ENDURANCE (LIEE) AND HIGH-INTENSITY EXERCISE ENDURANCE (HIEE) HAVE BEEN SHOWN TO IMPROVE AS A RESULT OF MAXIMAL, HIGH FORCE, LOW VELOCITY (HFLV) AND EXPLOSIVE, LOW-FORCE, HIGH-VELOCITY STRENGTH TRAINING. HFLV STRENGTH TRAINING IS RECOMMENDED INITIALLY TO DEVELOP A NEUROMUSCULAR BASE FOR ENDURANCE ATHLETES WITH LIMITED STRENGTH TRAINING EXPERIENCE. A SEQUENCED APPROACH TO STRENGTH TRAINING INVOLVING PHASES OF STRENGTH-ENDURANCE, BASIC STRENGTH, STRENGTH, AND POWER WILL PROVIDE FURTHER ENHANCEMENTS IN LIEE AND HIEE FOR HIGH-LEVEL ENDURANCE ATHLETES.
... Concurrent strength and endurance training is considered an optimal stimulus to promote both neuromuscular and cardiovascular gains Izquierdo et al., 2001;Mikkola et al., 2007;Silva et al., 2012). However, some studies have shown that concurrent training may result in lower strength gains compared with strength training alone, and this phenomenon is called the "interference effect" (Bell et al., 2000;Leveritt et al., 2003;McCarthy et al., 2002). ...
Article
This study aimed to investigate the acute effects of two strength-training protocols on the neuromuscular and cardiorespiratory responses during endurance exercise. Thirteen young males (23.2 ± 1.6 years old) participated in this study. The hypertrophic strength-training protocol was composed of 6 sets of 8 squats at 75% of maximal dynamic strength. The plyometric strength-training protocol was composed of 6 sets of 8 jumps performed with the body weight as the workload. Endurance exercise was performed on a cycle ergometer at a power corresponding to the second ventilatory threshold until exhaustion. Before and after each protocol, a maximal voluntary contraction was performed, and the rate of force development and electromyographic parameters were assessed. After the hypertrophic strength-training and plyometric strength-training protocol, significant decreases were observed in the maximal voluntary contraction and rate of force development, whereas no changes were observed in the electromyographic parameters. Oxygen uptake and a heart rate during endurance exercise were not significantly different among the protocols. However, the time-to-exhaustion was significantly higher during endurance exercise alone than when performed after hypertrophic strength-training or plyometric strength-training (p <0.05). These results suggest that endurance performance may be impaired when preceded by strength-training, with no oxygen uptake or heart rate changes during the exercise.
... It is important to emphasize that our sample comprised national and international competitors and, even in the group of endurance athletes, the efficiency of the stretch-shortening cycle is crucial to sports performance because of the aforementioned factors. Nowadays, most coaches and athletes are aware of the effectiveness of concurrent endurance and explosive type strength training on neuromuscular and endurance performance (21). For instance, in a study by Ramirez-Campillo et al. (25), highly competitive middle-and long-distance runners improved their 2.4-km time trial, sprinting ability and performance in CMJs and drop jumps after explosive type training, although the control group did not demonstrate any improvement. ...
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The aim of this study was to compare muscle mechanical properties (using tensiomyography - TMG) and jumping performance of endurance and power athletes, and to quantify the associations between TMG parameters and jumping performance indices. Forty-one high-level track and field athletes from power (n=22; mean ± SD age, height, and weight were 27.2 ± 3.6 years; 180.2 ± 5.4 cm; 79.4 ± 8.6 kg) and endurance (endurance runners and triathletes; n=19; mean ± SD age, height, and weight were 27.1 ± 6.9 years; 169.6 ± 9.8 cm; 62.2 ± 13.1 kg) specialties had the mechanical properties of their rectus femoris (RF) and biceps femoris (BF) assessed by TMG. Muscle displacement (Dm), contraction time (Tc), and delay time (Td) were retained for analyses. Furthermore, they performed squat jumps (SJ), countermovement jumps (CMJ) and drop jumps to assess reactive strength index (RSI), using a contact platform. Comparisons between groups were performed using differences based on magnitudes and associations were quantified by the Spearman's ρ correlation. Power athletes showed almost certain higher performance in all jumping performance indices when compared with endurance athletes (SJ = 44.9 ± 4.1 vs. 30.7 ± 6.8 cm; CMJ = 48.9 ± 4.5 vs. 33.6 ± 7.2 cm; RSI = 2.19 ± 0.58 vs. 0.84 ± 0.39, for power and endurance athletes, mean ± SD, respectively; 00/00/100, almost certain, P< 0.05), along with better contractile indices reflected by lower Dm, Tc and Td (Tc BF = 14.3 ± 2.3 vs. 19.4 ± 3.3 ms; Dm BF = 1.67 ± 1.05 vs. 4.23 ± 1.75 mm; Td BF = 16.8 ± 1.6 vs. 19.6 ± 1.3 ms; Tc RF = 18.3 ± 2.8 vs. 22.9 ± 4.0 ms; Dm RF = 4.98 ± 3.71 vs. 8.88 ± 3.45 mm; Td RF = 17.5 ± 1.0 vs. 20.9 ± 1.6 ms, for power and endurance athletes, mean ± SD, respectively; 00/00/100, almost certain, P< 0.05). Moderate correlations (Spearman's ρ between -0.61 and -0.72) were found between TMG and jumping performance. The power group presented better performance in vertical jumps, supporting the validity of these tests to distinguish between endurance and power athletes. Furthermore, TMG can discriminate the "athlete-type" using non-invasive indices moderately correlated with explosive lower-body performance. In summary, both vertical jump and TMG assessments could be useful in identifying and selecting young athletes.
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O desempenho de corredores de longa-distância é estabelecido por uma complexa interação entre variáveis físicas, tais como consumo máximo de oxigênio, economia de corrida e limiares metabólicos. Sabe-se que o treinamento pliométrico e de longa-distância podem modificar a interação entre estas variáveis, porém, investigações adicionais sobre como ocorrem estas adaptações, bem como sua transferência para o desempenho são necessárias. Portanto, o presente estudo teve como objetivo investigar o efeito combinado do treinamento pliométrico e de longa-distância em variáveis constituintes do desempenho de corredores fundistas. A amostra foi composta por 23 corredores do sexo masculino, com idade entre 18 e 50 anos, especialistas em provas de 10-km, e divididos em dois grupos experimentais de treinamento: I) treinamento combinado (TP: pliométrico + longa-distância; n = 11); II) treinamento de longa-distância (TC: longa-distância; n = 12). Todos os atletas foram submetidos a três sessões de avaliações (momento 1 - pré), correspondentes as mensurações de parâmetros antropométricos, neuromusculares, cardiorrespiratórios (sessão 1 e 2), e de desempenho nos 10-km em pista (sessão 3). Após o término das avaliações iniciais, os atletas foram divididos de forma pareada nos grupos de treinamento combinado (TP) ou de longa-distância (TC) a partir do teste de desempenho obtido nos 10-km antes do início do treinamento, e em seguida, iniciaram as 8 semanas de treinamento. Ao final do protocolo experimental, os atletas foram reavaliados (momento 2 - pós), e os testes aplicados foram os mesmos da avaliação inicial. Os resultados do presente estudo demonstraram que não houve alterações nas variáveis antropométricas e de flexibilidade, com exceção do ângulo de fase. Em relação aos testes neuromusculares, foi encontrado aumento significativo nos saltos counter movement jump, squat jump e drop jump após o treinamento, independente do grupo analisado. A altura do drop jump 50cm foi menor no grupo pliométrico, quando comparado ao grupo de treinamento de longa-distância, independente do momento de avaliação. Quando analisado as variáveis biomecânicas, encontramos aumento do tempo de contato com o solo e da oscilação vertical (apenas 18 km.h-1), além de diminuição da frequência de passada (12, 16 e 18 km.h-1) e da rigidez da perna (10 a 18 km.h-1) após o treinamento, independente do grupo analisado. O grupo pliométrico apresentou aumento do tempo de contato com o solo (14 km.h-1), porém, apresentou reduções significativas na força relativa máxima (16 km.h-1) e na rigidez da perna (14 km.h-1). Nas variáveis fisiológicas, houve aumento da economia de corrida, do ponto de compensação respiratória e do pico de velocidade em esteira, porém, o consumo máximo de oxigênio manteve-se estável, nos dois grupos de treinamento investigados. O desempenho final e a percepção subjetiva de esforço no teste de 10-km também não foram alterados significativamente, porém, a estratégia de prova (trecho inicial e parciais) e pico de velocidade nos 10-km aumentaram após o período experimental. Em resumo, após o protocolo experimental, o grupo de treinamento combinado apresentou alterações semelhantes em variáveis constituintes do desempenho em corredores de 10-km, quando comparado ao grupo de treinamento de longa-distância.
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The purpose of the present study was to compare time results from a roller-skiing double poling (DP) time trial with different physiological variables, muscular strength variables, and DP characteristics in both male and female young competitive skiers with the same relative training background. In order to do this, 28 (16 women and 12 men) well-trained 16–25-year-old cross-country skiers from three Norwegian high schools for skiers, as well as local high performance competitive skiers from the South-East of Norway were recruited to participate in the study. All participants were tested for; maximal oxygen uptake in running, Peak oxygen uptake in DP, lactate threshold in DP, DP economy, time to voluntary exhaustion in DP, force analyses in DP, one repetition maximum and power output in pulldown, and leg press and a time trial during DP roller skiing. The results expressed strong correlations between roller skiing time trial performance and maximal strength in pull-down, both independent (rxy = −0.83, p < 0.01) and dependent (rxy–z = −0.50, p < 0.02) of sex. Higher maximal upper body strength was related to higher DP peak forces (PF) (rxy = 0.78, p < 0.02), lower DP frequency (rxy = −0.71, p < 0.01), and shorter DP contact time (CT) (rxy = −0.48, p < 0.02). The practical implications of the present study is to acknowledge maximal upper body strength as a performance determining factor in DP. This point at the importance of including maximal strength training in cross-country skiers training programs.
Article
A number of factors determine neuromuscular economy (NE) and running economy (RE) in endurance-trained runners. The purpose of this investigation was to examine the relationship between aerobic fitness and NE in endurance-trained runners. Twenty-seven endurance-trained runners (25.1 ± 10.2 y) completed a maximal voluntary isometric contraction of the leg extensors to measure maximal electromyography (EMGmax) amplitude of the vastus lateralis (VL) and rectus femoris (RF), a steady-state treadmill run at 9.66, 11.27, and 12.87 km∙hr-1 and a maximal graded exercise test. Participants were outfitted with surface electrodes over the VL and RF muscles to record EMG amplitude throughout each test. During the steady-state test, the EMG (as a percentage of EMGmax) and oxygen consumption (VO2) over the final minute of each stage were established and considered NE and RE, respectively. Pearson product moment correlations were used to determine the relationships between VO2max and velocity at VO2max (vVO2max) and NE and RE. The results revealed significant negative correlations between VO2max and vVO2max and relative NE and RE at all three speeds. In addition, there were significant correlations between relative RE and NE at all three speeds. These results indicate that faster runners have improved NE and RE when expressed as a relative measure.
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El objetivo de este trabajo es profundizar en una línea de investigación emergente en el contexto de la psicología del deporte como es el optimismo. A través de la teoría de los estilos explicativos y las dimensiones de permanencia, amplitud y personalización, se llega a dos trabajos específicos que relacionan por un lado el optimismo con el rendimiento y por otro la posible influencia de los estilos explicativos del entrenador en el análisis de la competición sobre los jugadores de un equipo. A partir de los resultados de ambos trabajos se establece la reflexión sobre la importancia del constructo optimismo en todos los aspectos de la competición deportiva así las posibilidades de modificar los estilos explicativos y trabajar en este sentido desde la disciplina de la psicología del deporte.
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O objetivo deste estudo foi revisar trabalhos que investigaram os efeitos do treinamento de força (TF) para o desempenho de endurance. Os principais fatores fisiológicos determinantes das provas de endurance (PE) são o consumo máximo de oxigênio (VO2max), o limiar anaeróbio (LAn) e a economia de movimento (EM). Ambos VO2max e LAn são bem estimulados com meios e métodos tradicionais de treinamento e essas duas variáveis parecem ser pouco sensíveis ao TF em pessoas treinadas. Por outro lado, a EM pode ser aperfeiçoada com o TF, mesmo em indivíduos bem treinados em endurance. Portanto, concluímos que o TF colabora para a melhora na endurance, por meio do incremento da EM, e esses resultados sugerem mudança de paradigma na periodização do treinamento de PE. The aim of this study was to review studies that analyzed the effects of resistance training (RT) on endurance performance. The main physiological determinants of endurance events is the maximal oxygen uptake (VO2max), anaerobic threshold (AT) and economy of movement (EM). Both, VO2max and AT, are very encouraged with the means and traditional methods of training and these two variables appear to be few sensitive to people already trained in RT. On the other hand, EM can be improved with the RT even in endurance-trained individuals. Therefore, we conclude that RT contributes to the improvement in endurance, through the increase in EM, and these results suggest a paradigm shift in periodization training of endurance events.
Chapter
All the countries that compete in Nordic skiing spend considerable time and effort on equipment testing. Field tests are used by everyone, but also scientific research methods using inertial measurement units and a special ski tester have been developed and published, in particular to study the gliding properties of the skis. Standing Paralympic skiers with visual impairment have been reported to have higher maximal VO2, heart rate, and volume of expired air values than sit-ski athletes. This chapter discusses scientific information addressing sit-skiing, and describes how the classification process is conducted in this sport. One difference in double poling between standing and sitting skiers is that in sit-skiing the use of leg muscles is restricted. According to a study, it has been suggested that the poling cycle for the sit-skiers should be divided into three phases: poling phase, transition phase, and recovery phase.
Research
Abstract Intermittent sport athletes do necessarily have a capacity in any of the areas of physical performance. Strength, muscle power and endurance as physical fitness are important. The coaches will be training athletes to develop the capability to move up and ready for the competition. Concurrent strength and endurance training is another form that is important which affect sports performance of intermittent sport athletes. Understanding the adaptation of the cardiovascular system and endurance performance as well as nerve and muscle adaptations to training and performance have given rise to more effective training interventions. Endurance interval training using an intensity at 90–95% of maximal heart rate in 3- to 8-minute bouts have proved to be effective in the development of endurance and other aspects related to sports. While studies on training to develop strength show using high loads, few repetitions and maximal mobilisation of force in the concentric mode have proved to be effective in the development of strength, sprint and jump performance of athletes. It also enhances endurance capabilities through the development of efficient movement. Application form to apply this training to the development of athletes that have considered the challenge. Therefore, understanding and accuracy to guide for coaches and athletes use in the training of Concurrent Training between strength and endurance are important. In order to get the proper training and effective to avoid the negative aspects of the training that can occur in intermittent sport athletes. Keywords: Concurrent Training / Strength and Endurance / Intermittent Sport
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In het eerste deel 1 van dit artikel is toegelicht dat stijgtijd bij explosieve bewegingen een belangrijke prestatiebeperkende factor is. Tevens is uitgelegd hoe deze stijgtijd kan worden beïnvloed. In dit tweede deel wordt beschreven hoe de bewegingscontext de mate van transfer van de (trainings- of test-) oefening naar de doelbeweging bepaalt. Ook worden enkele praktische aanbevelingen voor het trainen van de explosieve prestatie gegeven.
Article
Purpose - This study sought to determine the relationship among running economy (RE), anaerobic threshold (AT), maximal aerobic capacity (VO2max), ventilatory threshold (VT) and distance-running performance in collegiate distance-runners. Methods - Fourteen (7 male, 7 female) well-trained, collegiate distance-runners were tested during treadmill running at progressively increasing velocities (190 m×min-1 – 290 m×min-1) to determine RE, AT and VT on one occasion, and VO2max was measured on a second occasion. Distance-running performance was assessed as the time to complete the NCAA Division II South-eastern Regional cross-country championship race (10-km for men, 6-km for women), and was normalized to distance to yield running pace velocity. Results - Performance pace velocity and RE were not strongly related across the 3 common economy velocities of 230, 240, and 250 m×min-1 (r2 = 0.01, 0.31, and 0.35 respectively, p < 0.05). Running pace at AT was a very strong predictor (r2 = 0.95, p < 0.05) of performance pace velocity, and so was pace at VT (r2 = 0.87, p < 0.05). VO2max was a strong predictor of performance pace (r2 = 0.88, p < 0.05), but only when the men and women were compared together. Conclusions - Running pace at AT accounted for 95% of the variation observed in race performance, confirming that among trained distance-runners, pace at AT was the strongest predictor of performance.
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MILLET, G. P., B. JAOUEN, F. BORRANI, and R. CANDAU. Effects of concurrent endurance and strength training on running economy and V̇O2 kinetics. Med. Sci. Sports Exerc., Vol. 34, No. 8, pp. 1351-1359, 2002. Purpose: It has been suggested that endurance training influences the running economy (CR) and the oxygen uptake (V̇O2) kinetics in heavy exercise by accelerating the primary phase and attenuating the V̇O2 slow component. However, the effects of heavy weight training (HWT) in combination with endurance training remain unclear. The purpose of this study was to examine the influence of a concurrent HWT+endurance training on CR and the V̇O2 kinetics in endurance athletes. Methods: Fifteen triathletes were assigned to endurance+strength (ES) or endurance-only (E) training for 14 wk. The training program was similar, except ES performed two HWT sessions a week. Before and after the training period, the subjects performed 1) an incremental field running test for determination of V̇O2max and the velocity associated (VV̇O2max), the second ventilatory threshold (VT2); 2) a 3000-m run at constant velocity, calculated to require 25% of the difference between V̇O2max and VT2, to determine CR and the characteristics of the V̇O2 kinetics; 3) maximal hopping tests to determine maximal mechanical power and lower-limb stiffness; 4) maximal concentric lower-limb strength measurements. Results: After the training period, maximal strength were increased (P < 0.01) in ES but remained unchanged in E. Hopping power decreased in E (P < 0.05). After training, economy (P < 0.05) and hopping power (P < 0.001) were greater in ES than in E. V̇O2max, leg hopping stiffness and the V̇O2 kinetics were not significantly affected by training either in ES or E. Conclusion: Additional HWT led to improved maximal strength and running economy with no significant effects on the V̇O2 kinetics pattern in heavy exercise.
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Forty-two healthy men and women in two age groups (40 and 70 years) were examined for muscle cross-sectional area (CSA), maximal voluntary bilateral isometric force, force-time characteristics, maximal concentric 1 RM, and power performance of the leg extensors in a sitting position, squat jump, and standing long-jump. The results suggested that the decline in maximal strength with increasing age is related to the decline in muscle CSA; however, particularly in older women, the force/CSA ratio may also be lowered. Explosive force seems to decrease with increasing age even more than maximal strength, suggesting that muscle atrophy with aging is greater in fast-twitch fibers. The voluntary activation of the agonist and antagonist muscles seems to vary depending on the type of muscle action and/or velocity and time duration of the action in both age groups but to a greater extent in older people. There appears to be an age-related increase in antagonist coactivation, especially in dynamic explosive movements.
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Twelve experienced male weight lifters performed a rebound bench press and a purely concentric bench press lift. Data were obtained pertaining to 1) the benefits to concentric motion derived from a prior stretch and 2) the movement frequency adopted during performance of the stretch-shorten cycle (SSC) portion of the rebound bench press lift. The subjects also performed a series of quasi-static muscular actions in a position specific to the bench press movement. A brief perturbation was applied to the bar while these isometric efforts were maintained, and the resulting damped oscillations provided data pertaining to each subject's series elastic component (SEC) stiffness and natural frequency of oscillation. A significant correlation (r = -0.718, P less than 0.01) between maximal SEC stiffness and augmentation to concentric motion derived from prior stretch was observed. Subjects were also observed to perform the SSC portion of the rebound bench press movement to coincide with the natural frequency of oscillation of their SEC. These results are interpreted as demonstrating that the optimal stiffness in a rebound bench press lift was a resonant-compliant SEC.
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The impact of adding heavy-resistance training to increase leg-muscle strength was studied in eight cycling- and running-trained subjects who were already at a steady-state level of performance. Strength training was performed 3 days/wk for 10 wk, whereas endurance training remained constant during this phase. After 10 wk, leg strength was increased by an average of 30%, but thigh girth and biopsied vastus lateralis muscle fiber areas (fast and slow twitch) and citrate synthase activities were unchanged. Maximal O2 uptake (VO2max) was also unchanged by heavy-resistance training during cycling (55 ml.kg-1.min-1) and treadmill running (60 ml.kg-1.min-1); however, short-term endurance (4-8 min) was increased by 11 and 13% (P less than 0.05) during cycling and running, respectively. Long-term cycling to exhaustion at 80% VO2max increased from 71 to 85 min (P less than 0.05) after the addition of strength training, whereas long-term running (10 km times) results were inconclusive. These data do not demonstrate any negative performance effects of adding heavy-resistance training to ongoing endurance-training regimens. They indicate that certain types of endurance performance, particularly those requiring fast-twitch fiber recruitment, can be improved by strength-training supplementation.
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The purpose of the study was to determine the relationship between running economy and distance running performance in highly trained and experienced distance runners of comparable ability. Oxygen uptake (Vo2) during steady-state and maximal aerobic power (Vo2max) were measured during treadmill running using the open-circuit method. Distance running performance was determined in a nationally prominent 10 km race; all subjects (12 males) placed among the top 19 finishers. The subjects averaged 32.1 min on the 10 km run, 71.7 ml.kg-1.min-1 for Vo2max, and 44.7, 50.3, and 55.9 ml.kg-1.min-1 for steady-state Vo2 at three running paces (241, 268, and 295 m.min-1). The relationship between Vo2max and distance running performance was r = -0.12 (p = 0.35). The relationship between steady-state Vo2 at 241, 268 and 295 m.min-1 and 10 km time were r = 0.83, 0.82, and 0.79 (p < 0.01), respectively. Within this elite cluster of finishers, 65.4% of the variation observed in race performance time on the 10 km run could be explained by variation in running economy. It was concluded that among highly trained and experienced runners of comparable ability and similar Vo2max, running economy accounts for a large and significant amount of the variation observed in performance on a 10 km race.
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A popular concept in the exercise sciences holds that fatigue develops during exercise of moderate to high intensity, when the capacity of the cardiorespiratory system to provide oxygen to the exercising muscles falls behind their demand inducing "anaerobic" metabolism. But this cardiovascular/anaerobic model is unsatisfactory because (i) a more rigorous analysis indicates that the first organ to be affected by anaerobiosis during maximal exercise would likely be the heart, not the skeletal muscles. This probability was fully appreciated by the pioneering exercise physiologists, A. V Hill, A. Bock and D. B. Dill, but has been systematically ignored by modern exercise physiologists; (ii) no study has yet definitely established the presence of either anaerobiosis, hypoxia or ischaemia in skeletal muscle during maximal exercise; (iii) the model is unable to explain why exercise terminates in a variety of conditions including prolonged exercise, exercise in the heat and at altitude, and in those with chronic diseases of the heart and lungs, without any evidence for skeletal muscle anaerobiosis, hypoxia or ischaemia, and before there is full activation of the total skeletal muscle mass, and (iv) cardiovascular and other measures believed to relate to skeletal muscle anaerobiosis, including the maximum oxygen consumption (VO2 max) and the "anaerobic threshold", are indifferent predictors of exercise capacity in athletes with similar abilities. This review considers four additional models that need to be considered when factors limiting either short duration, maximal or prolonged submaximal exercise are evaluated. These additional models are: (i) the energy supply/energy depletion model; (ii) the muscle power/muscle recruitment model; (iii) the biomechanical model and (iv) the psychological model. By reviewing features of these models, this review provides a broad overview of the physiological, metabolic and biomechanical factors that may limit exercise performance under different exercise conditions. A more complete understanding of fatigue during exercise, and the relevance of the adaptations that develop with training, requires that the potential relevance of each model to fatigue under different conditions of exercise must be considered.
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Maximal strength-training with an emphasis on maximal mobilization during cross-country skiing increases exercise economy when double-poling. The aim of this experiment was to investigate whether the mechanism of this increase is a change in the force-velocity relationship and the mechanical power output. A group of 19 cross-country skiers having an average peak oxygen uptake of 255 ml x kg(-0.67) body mass x min(-1) or 61 ml x kg(-1) x min(-1) were randomly assigned to either a high resistance-training group (n=10) or a control group (n=9). Upper body endurance was tested on a ski ergometer. The high-resistance-training group trained for 15 min on three occasions a week for 9 weeks. Training consisted of three series of five repetitions using 85% of one repetition maximum (1RM), with emphasis on high velocity in the concentric part of the movement. Upper body exercise economy, 1RM and time to exhaustion increased significantly in the high resistance-training group, but was unchanged in the control group. Peak power and the velocities for a given load increased significantly, except for the two lowest loads. We conclude that the increased exercise economy after a period of upper body high resistance-training can be partly explained by a specific change in the force-velocity relationship and the mechanical power output.
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The purpose of this study was to investigate effects of concurrent strength and endurance training (SE) (2 plus 2 days a week) versus strength training only (S) (2 days a week) in men [SE: n=11; 38 (5) years, S: n=16; 37 (5) years] over a training period of 21 weeks. The resistance training program addressed both maximal and explosive strength components. EMG, maximal isometric force, 1 RM strength, and rate of force development (RFD) of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) throughout the lengths of 4/15–12/15 (L f) of the femur, muscle fibre proportion and areas of types I, IIa, and IIb of the vastus lateralis (VL), and maximal oxygen uptake (V̇O2max) were evaluated. No changes occurred in strength during the 1-week control period, while after the 21-week training period increases of 21% (p<0.001) and 22% (p<0.001), and of 22% (p<0.001) and 21% (p<0.001) took place in the 1RM load and maximal isometric force in S and SE, respectively. Increases of 26% (p<0.05) and 29% (p<0.001) occurred in the maximum iEMG of the VL in S and SE, respectively. The CSA of the QF increased throughout the length of the QF (from 4/15 to 12/15 L f) both in S (p<0.05–0.001) and SE (p<0.01–0.001). The mean fibre areas of types I, IIa and IIb increased after the training both in S (p<0.05 and 0.01) and SE (p<0.05 and p<0.01). S showed an increase in RFD (p<0.01), while no change occurred in SE. The average iEMG of the VL during the first 500 ms of the rapid isometric action increased (p<0.05–0.001) only in S. V̇O2max increased by 18.5% (p<0.001) in SE. The present data do not support the concept of the universal nature of the interference effect in strength development and muscle hypertrophy when strength training is performed concurrently with endurance training, and the training volume is diluted by a longer period of time with a low frequency of training. However, the present results suggest that even the low-frequency concurrent strength and endurance training leads to interference in explosive strength development mediated in part by the limitations of rapid voluntary neural activation of the trained muscles.
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To further the understanding of double poling (DP) through biomechanical analysis of upper and lower body movements during DP in cross-country (XC) skiing at racing speed. Eleven elite XC skiers performed DP at 85% of their maximal DP velocity (V85%) during roller skiing at 1 degrees inclination on a treadmill. Pole and plantar ground reaction forces, joint angles (elbow, hip, knee, and ankle), cycle characteristics, and electromyography (EMG) of upper and lower body muscles were analyzed. 1) Pole force pattern with initial impact force peak and the following active force peak (PPF) correlated to V85%, (r = 0.66, P < 0.05); 2) active flexion-extension pattern in elbow, hip, knee, and ankle joints with angle minima occurring around PPF, correlated to hip angle at pole plant (r = -0.89, P < 0.01), minimum elbow angle (r = -0.71), and relative poling time (r = -0.72, P < 0.05); 3) two different DP strategies (A and B), where strategy A (best skiers) was characterized by higher angular elbow- and hip-flexion velocities, smaller minimum elbow (P < 0.01) and hip angles (P < 0.05), and higher PPF (P < 0.05); 4) EMG activity in trunk and hip flexors, shoulder, and elbow extensors, and several lower body muscles followed a specific sequential pattern with changing activation levels; and 5) EMG activity in lower body muscles showed DP requires more than upper body work. DP was found to be a complex movement involving both the upper and lower body showing different strategies concerning several biomechanical aspects. Future research should further investigate the relationship between biomechanical and physiological variables and elaborate training models to improve DP performance.
Article
To investigate the effects of simultaneous explosive-strength and endurance training on physical performance characteristics, 10 experimental (E) and 8 control (C) endurance athletes trained for 9 wk. The total training volume was kept the same in both groups, but 32% of training in E and 3% in C was replaced by explosive-type strength training. A 5-km time trial (5K), running economy (RE), maximal 20-m speed ( V 20 m ), and 5-jump (5J) tests were measured on a track. Maximal anaerobic (MART) and aerobic treadmill running tests were used to determine maximal velocity in the MART ( V MART ) and maximal oxygen uptake (V˙o 2 max ). The 5K time, RE, and V MART improved ( P < 0.05) in E, but no changes were observed in C. V 20 m and 5J increased in E ( P < 0.01) and decreased in C ( P < 0.05).V˙o 2 max increased in C ( P < 0.05), but no changes were observed in E. In the pooled data, the changes in the 5K velocity during 9 wk of training correlated ( P< 0.05) with the changes in RE [O 2 uptake ( r = −0.54)] and V MART ( r = 0.55). In conclusion, the present simultaneous explosive-strength and endurance training improved the 5K time in well-trained endurance athletes without changes in theirV˙o 2 max . This improvement was due to improved neuromuscular characteristics that were transferred into improved V MART and running economy.
Article
The aim of ski mechanics is to reduce the normal pressure and friction between man and snow. This investigation is intended to express, in biomechanical terms, the diagonal stride and double-poling in cross-country skiing. Tradition and long experience have led to changes in ski length, width, camber and weight, and with respect to the skier weight, height and skill. All types of skis have varying cross-sections, longitudinal and transverse flexibility, and a chamber designed to distribute the skier's weight and maneuvering forces suitably along the ski track. The bottom surface of a ski functions in three zones - two gliding zones and one gripping zone under the foot. To aid the measurement of force interplay between the skier, ski and snow, the following equipment has been developed and used with cross-country skis and ski poles: a camber control, adjustable 14- to 35-mm camber height and stiffness which allows comparative tests of the bottom surface; a measuring platform, including five force measuring cells for vertical and horizontal directions; strain gauges, attached to ski poles for measuring propulsion; a telemetry amplifier, for signal transmission, 3 channels; calibration equipment, to analyze pressure distribution of static and dynamic force; and portable glide testing equipment, consisting of an adjustable angle measuring device for measuring the flat surface of snow-covered ski tracks. The results showed the vertical and horizontal forces between the skier, the skis, and the ski poles in diagonal stride and double-poling in cross-country skiing. Similarities exist between running and skiing in regard to vertical force and the position of the resultant force. Measuring the static and dynamic pressure distribution for a normal ski and a test ski with camber control makes it possible to determine which zones of the ski are active, a factor especially important from the aspect of waxing. Starting and gilding friction occurs within the stationary pause in each diagonal stride with the ski. An investigation into starting and gilding friction has been conducted with glide measuring equipment and field test equipment.
Article
The time course of strength gain with respect to the contributions of neural factors and hypertrophy was studied in seven young males and eight females during the course of an 8 week regimen of isotonic strength training. The results indicated that neural factors accounted for the larger proportion of the initial strength increment and thereafter both neural factors and hypertrophy took part in the further increase in strength, with hypertrophy becoming the dominant factor after the first 3 to 5 weeks. Our data regarding the untrained contralateral arm flexors provide further support for the concept of cross education. It was suggested that the nature of this cross education effect may entirely rest on the neural factors presumably acting at various levels of the nervous system which could result in increasing the maximal level of muscle activation.
To investigate the effects of a combination of simultaneous strength and endurance training on selected neuromuscular and aerobic performance characteristics seven male cross-country skiers underwent training for a period of 6 weeks. The experimental group trained 6-9 times per week with a programme consisting of 34% explosive type strength training and 66% endurance training during the first 3 weeks of the experiment and 42% and 58% respectively during the last 3 weeks of the experiment. The total volume of training of the control group (eight skiers) was of the same magnitude but consisted of 85% pure endurance training and 15% endurance type strength training. The experimental training regime resulted in specific changes in neuromuscular performance. This was demonstrated by improvements (P less than 0.01) in the maximal heights of rise of the centre of gravity in the squat and countermovement jumps. A significant decrease (P less than 0.05) took place also in the time of rapid isometric force production during experimental training, while no changes occurred in the maximal force of the trained muscles. Aerobic performance characteristics of the experimental group did not change during the experimental training period. No significant changes occurred in neuromuscular or aerobic performance characteristics in the control group. These findings indicated that training-induced improvements in explosive force production may not be fully inhibited by this kind of aerobic training. They also suggested that endurance athletes could undertake explosive type strength training programmes without a concomitant reduction in aerobic capacity, if the overall loading of training were within predefined limits.
Article
To investigate the influence of explosive type strength training on isometric force- and relaxation-time and on electromyographic and muscle fibre characteristics of human skeletal muscle, 10 male subjects went through progressive training which included primarily jumping exercises without extra load and with light extra weights three times a week for 24 weeks. Specific training-induced changes in force-time curve were observed and demonstrated by great (P less than 0.05-0.01) improvements in in parameters of fast force production and by a minor (P less than 0.05) increase in maximal force. The continuous increases in fast force production during the entire training were accompanied by and correlated with the increases (P less than 0.05) in average IEMG-time curve and with the increase (P less than 0.05) in the FT:ST muscle fibre area ratio. The percentage of FT fibres of the muscle correlated (P less than 0.05) with the improvement of average force-time curve during the training. The increase in maximal force was accompanied by significant (P less than 0.05) increases in maximum IEMGs of the trained muscles. However, the hypertrophic changes, as judged from the anthropometric and muscle fibre area data, were only slight during the training. It can be concluded that in training for fast force production considerable neural and selective muscular adaptations may occur to explain the improvement in performance, but that genetic factors may determine the ultimate potential of the trainability of this aspect of the neuromuscular performance.
Article
1. Skinfold thicknesses at four sites – biceps, triceps, subscapular and supra-iliac – and total body density (by underwater weighing) were measured on 209 males and 272 females aged from 16 to 72 years. The fat content varied from 5 to 50% of body-weight in the men and from 10 to 61% in the women.2. When the results were plotted it was found necessary to use the logarithm of skinfold measurements in order to achieve a linear relationship with body density.3. Linear regression equations were calculated for the estimation of body density, and hence body fat, using single skinfolds and all possible sums of two or more skinfolds. Separate equations for the different age-groupings are given. A table is derived where percentage body fat can be read off corresponding to differing values for the total of the four standard skinfolds. This table is subdivided for sex and for age.4. The possible reasons for the altered position of the regression lines with sex and age, and the validation of the use of body density measurements, are discussed.
The purpose of this study was to determine how individuals adapt to a combination of strength and endurance training as compared to the adaptations produced by either strength or endurance training separately. There were three exercise groups: a strength group (S) that exercised 30--40 min . day-1, 5 days . week-1, and endurance group (E) that exercised 40 min . day-1, 6 days . week-1; and an S and E group that performed the same daily exercise regimens as the S and E groups. After 10 weeks of training, VO2max increased approx. 25% when measured during bicycle exercise and 20% when measured during treadmill exercise in both E, and S and E groups. No increase in VO2max was observed in the S group. There was a consistent rate of development of leg-strength by the S group throughout the training, whereas the E group did not show any appreciable gains in strength. The rate of strength improvement by the S and E group was similar to the S group for the first 7 weeks of training, but subsequently leveled off and declined during the 9th and 10th weeks. These findings demonstrate that simultaneously training for S and E will result in a reduced capacity to develop strength, but will not affect the magnitude of increase in VO2max.
The aim of this study was to illustrate the influence of different levels of the fulcrum (the axis of sagittal rotation) on measured trunk flexion and extension strength and compare force and torque as a unit of measure. The isometric trunk strength was measured in 16 healthy female subjects. The dynamometer was kept at the shoulder level and the moment arm was lengthened step by step by moving the fulcrum caudally from the level of the posterior superior iliac spine to the level of the gluteal fold. The moment of force (torque) increased from 117.0 to 208.5 N.m in flexion and from 182.2 to 292.5 N.m in extension, P < 0.0001. An attempt to quantify this change was made. Paradoxically, the measured force remained at a constant level (in flexion) or slightly decreased (in extension). We concluded that torque as a measure of trunk flexion and extension strength is highly dependent on the level of the rotation axis and force appears to be less sensitive for variations with the height of the fulcrum. We would suggest that the observed increase in torque is physiological and reflects to what extent hip flexor or extensor muscles are recruited. The force, on the other hand, may better characterize a person's capability to perform functional tasks. Force and torque should strictly be distinguished from one another.
A new maximal anaerobic running power (MARP) test was developed. It consisted of n.20-s runs on a treadmill with a 100-s recovery between the runs. During the first run the treadmill speed was 3.97 m.s-1 and the gradient 5 degrees. The speed of the treadmill was increased by 0.35 m.s-1 for each consecutive run until exhaustion. The height of counter-movement jumps and blood lactate concentration ([la-]b) were measured after each run. Submaximal ([la-]b = 3 mmol.l-1 and 10 mmol.l-1) and maximal speed and power (W3mmol, W10mmol and Wmax, respectively) were calculated and W was expressed in oxygen equivalents according to the American College of Sports Medicine equation. Thirteen male athletes whose times over 400 m ranged from 47.98 s to 54.70 s served as subjects. In the MARP-test the speed at exhaustion was 6.89 (SD 0.28) m.s-1 corresponding to a Wmax of 118 (SD 5) ml.kg-1 x min-1. The peak [la-]b after exhaustion was 17.0 (SD 1.6) mmol.l-1. A significant correlation (r = 0.89, P < 0.001) was observed between the Wmax and the average speed in the 400-m sprint. The maximal 20-m sprinting speed on a track and W10mmol correlated with both the Wmax and the 400-m speed. It was concluded that the new method allows the evaluation of several determinants of maximal anaerobic performance including changes in the force-generating capacity of leg muscles and [la-]b relative to the speed of the sprint running. the [la-]b at submaximal sprinting speed was suggested as describing the anaerobic sprinting economy.
Article
1. The adaptations of the ankle dorsiflexor muscles and the behaviour of single motor units in the tibialis anterior in response to 12 weeks of dynamic training were studied in five human subjects. In each training session ten series of ten fast dorsiflexions were performed 5 days a week, against a load of 30-40% of the maximal muscle strength. 2. Training led to an enhancement of maximal voluntary muscle contraction (MVC) and the speed of voluntary ballistic contraction. This last enhancement was mainly related to neural adaptations since the time course of the muscle twitch induced by electrical stimulation remained unaffected. 3. The motor unit torque, recorded by the spike-triggered averaging method, increased without any change in its time to peak. The orderly motor unit recruitment (size principle) was preserved during slow ramp contraction after training but the units were activated earlier and had a greater maximal firing frequency during voluntary ballistic contractions. In addition, the high frequency firing rate observed at the onset of the contractions was maintained during the subsequent spikes after training. 4. Dynamic training induced brief (2-5 ms) motor unit interspike intervals, or 'doublets'. These doublets appeared to be different from the closely spaced (+/-10 ms) discharges usually observed at the onset of the ballistic contractions. Motor units with different recruitment thresholds showed doublet discharges and the percentage of the sample of units firing doublets was increased by training from 5.2 to 32.7%. The presence of these discharges was observed not only at the onset of the series of spikes but also later in the electromyographic (EMG) burst. 5. It is likely that earlier motor unit activation, extra doublets and enhanced maximal firing rate contribute to the increase in the speed of voluntary muscle contraction after dynamic training.
Article
The present study examines the hypothesis that maximal strength training improves work economy and anaerobic threshold in trained female cross-country skiers while working on a ski ergometer. Fifteen female cross-country skiers (17.9 +/- 0.3 yr, 166.7 +/- 1.3 cm, 60.1 +/- 1.9 kg, and 55.3 +/- 1.3 mL x kg(-1) x min(-1)) participated in the study. Eight skiers made up the high-intensity strength-trained group, and seven served as the control group. Endurance performance was tested on a specially instrumented ski ergometer. Strength training and testing simulated double poling in cross-country skiing. A significant (P < 0.001) improvement in double-poling economy on the ski ergometer was observed among the strength-trained group. Anaerobic threshold did not change during the experimental period for either group. After a 9-wk training period, time to exhaustion increased from 5.2 (+/-0.9) to 12.3 (+/-1.6) min (P < 0.001) and from 4.0 (+/-0.9) to 6.3 (+/-0.9) min (P < 0.01) for the strength and control group, respectively. Time to exhaustion was significantly higher (P < 0.001) for the strength group compared with the control group after training. One repetition maximum increased 14.5% (1.8) (P < 0.001) in the strength group but was unchanged in the control group. Expressed in relation to peak force at one repetition maximum, strength training resulted in a significant reduction in the relative available force employed working on the ski ergometer (P < 0.01). Time to peak force at maximal aerobic velocity on the ski ergometer was significantly reduced in the strength-training group (P < 0.01). It is concluded that maximal strength training in the upper-body improved the double-poling performance by improved work economy. Work economy was improved by a reduction in relative workload and time to peak force while double poling.
Article
In the exercising human, maximal oxygen uptake (VO2max) is limited by the ability of the cardiorespiratory system to deliver oxygen to the exercising muscles. This is shown by three major lines of evidence: 1) when oxygen delivery is altered (by blood doping, hypoxia, or beta-blockade), VO2max changes accordingly; 2) the increase in VO2max with training results primarily from an increase in maximal cardiac output (not an increase in the a-v O2 difference); and 3) when a small muscle mass is overperfused during exercise, it has an extremely high capacity for consuming oxygen. Thus, O2 delivery, not skeletal muscle O2 extraction, is viewed as the primary limiting factor for VO2max in exercising humans. Metabolic adaptations in skeletal muscle are, however, critical for improving submaximal endurance performance. Endurance training causes an increase in mitochondrial enzyme activities, which improves performance by enhancing fat oxidation and decreasing lactic acid accumulation at a given VO2. VO2max is an important variable that sets the upper limit for endurance performance (an athlete cannot operate above 100% VO2max, for extended periods). Running economy and fractional utilization of VO2max also affect endurance performance. The speed at lactate threshold (LT) integrates all three of these variables and is the best physiological predictor of distance running performance.
Article
It has been suggested that endurance training influences the running economy (CR) and the oxygen uptake (.VO(2)) kinetics in heavy exercise by accelerating the primary phase and attenuating the .VO(2) slow component. However, the effects of heavy weight training (HWT) in combination with endurance training remain unclear. The purpose of this study was to examine the influence of a concurrent HWT+endurance training on CR and the .VO(2) kinetics in endurance athletes. Fifteen triathletes were assigned to endurance+strength (ES) or endurance-only (E) training for 14 wk. The training program was similar, except ES performed two HWT sessions a week. Before and after the training period, the subjects performed 1) an incremental field running test for determination of .VO(2max) and the velocity associated (V(.VO2max)), the second ventilatory threshold (VT(2)); 2) a 3000-m run at constant velocity, calculated to require 25% of the difference between .VO(2max) and VT(2), to determine CR and the characteristics of the VO(2) kinetics; 3) maximal hopping tests to determine maximal mechanical power and lower-limb stiffness; 4) maximal concentric lower-limb strength measurements. After the training period, maximal strength were increased (P < 0.01) in ES but remained unchanged in E. Hopping power decreased in E (P < 0.05). After training, economy (P < 0.05) and hopping power (P < 0.001) were greater in ES than in E. .VO(2max), leg hopping stiffness and the .VO(2) kinetics were not significantly affected by training either in ES or E. Additional HWT led to improved maximal strength and running economy with no significant effects on the .VO(2) kinetics pattern in heavy exercise.
Article
This study determined whether a 6-week regimen of plyometric training would improve running economy (i.e., the oxygen cost of submaximal running). Eighteen regular but not highly trained distance runners (age = 29 +/- 7 [mean +/- SD] years) were randomly assigned to experimental and control groups. All subjects continued regular running training for 6 weeks; experimental subjects also did plyometric training. Dependent variables measured before and after the 6-week period were economy of running on a level treadmill at 3 velocities (women: 2.23, 2.68, and 3.13 m.s(-1); men: 2.68, 3.13, and 3.58 m.s(-1)),VO(2)max, and indirect indicators of ability of muscles of lower limbs to store and return elastic energy. The last were measurements during jumping tests on an inclined (20 degrees ) sled: maximal jump height with and without countermovement and efficiencies of series of 40 submaximal countermovement and static jumps. The plyometric training improved economy (p < 0.05). Averaged values (m.ml(-1).kg(-1)) for the 3 running speeds were: (a). experimental subjects-5.14 +/- 0.39 pretraining, 5.26 +/- 0.39 posttraining; and (b). control subjects-5.10 +/- 0.36 pretraining, 5.06 +/- 0.36 posttraining. The VO(2)max did not change with training. Plyometric training did not result in changes in jump height or efficiency variables that would have indicated improved ability to store and return elastic energy. We conclude that 6 weeks of plyometric training improves running economy in regular but not highly trained distance runners; the mechanism must still be determined.
Article
Previous research has reported that plyometric training improves running economy (RE) and ultimately distance-running performance, although the exact mechanism by which this occurs remains unclear. This study examined whether changes in running performance resulting from plyometric training were related to alterations in lower leg musculotendinous stiffness (MTS). Seventeen male runners were pre- and post-tested for lower leg MTS, maximum isometric force, rate of force development, 5-bound distance test (5BT), counter movement jump (CMJ) height, RE, VO(2max), lactate threshold (Th(la)), and 3-km time. Subjects were randomly split into an experimental (E) group which completed 6 weeks of plyometric training in conjunction with their normal running training, and a control (C) group which trained as normal. Following the training period, the E group significantly improved 3-km performance (2.7%) and RE at each of the tested velocities, while no changes in VO(2max) or Th(la) were recorded. CMJ height, 5BT, and MTS also increased significantly. No significant changes were observed in any measures for the C group. The results clearly demonstrated that a 6-week plyometric programme led to improvements in 3-km running performance. It is postulated that the increase in MTS resulted in improved RE. We speculate that the improved RE led to changes in 3-km running performance, as there were no corresponding alterations in VO(2max) or Th(la).
Neuromuscular adaptation during strength training, aging, detraining, and immobilization
  • K Hä Kkinen
HÄ KKINEN, K. Neuromuscular adaptation during strength training, aging, detraining, and immobilization. Crit Rev. Phys. Rehab. Med. 6:161-198. 1994.
Concurrent strength and endurance training: A review
  • M Leveritt
  • P Abernethy
  • B Barry
  • And P Logan
LEVERITT, M., P. ABERNETHY, B. BARRY, AND P. LOGAN. Concurrent strength and endurance training: A review. Sports Med. 28:413-427. 1999.
Neural adaptation to resistance training
  • D G Sale
SALE, D.G. Neural adaptation to resistance training. Med. Sci. Sports Exerc. 20(5 Suppl.):S135-S145. 1988.