No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
V˙O2 Kinetics and Performance in Soccer Players after Intense Training and Inactivity
Abstract
The study's purpose was to examine the effects of a short-term period with intensified training or training cessation of trained soccer players on VO(2) kinetics at 75% maximal aerobic speed, oxidative enzymes, and performance in repeated high-intensity exercise.
After the last match of the season, 18 elite soccer players were, for a 2-wk period, assigned to a high-intensity training group (n = 7) performing 10 training sessions mainly consisting of aerobic high-intensity training (8 × 2 min) and speed endurance training (10-12 × 30-s sprints) or a training cessation group (n = 11) that refrained from training.
For the training cessation group, VO(2) kinetics became slower (P < 0.05) with a larger time constant (τ = 21.5 ± 2.9 vs 23.8 ± 3.2 s (mean ± SD, before vs after)) and a larger mean response time (time delay + τ = 45.0 ± 1.8 vs 46.8 ± 2.2 s). The amount of muscle pyruvate dehydrogenase (17%, P < 0.01) and maximal activity of citrate synthase (12%) and 3-hydroxyacyl-CoA (18%, P < 0.05) were lowered. In addition, the fraction of slow twitch fibers (56% ± 18% vs 47% ± 15%, P < 0.05), Yo-Yo intermittent recovery level 2 test (845 ± 160 vs 654 ± 99 m), and the repeated sprint performance (33.41 ± 0.96 vs 34.11 ± 0.92 s, P < 0.01) were reduced. For the high-intensity training group, running economy was improved (P < 0.05), and the amount of pyruvate dehydrogenase (17%) and repeated sprint performance (33.44 ± 1.17 vs 32.81 ± 1.01 s) were enhanced (P < 0.05).
Inactivity slows VO(2) kinetics in association with a reduction of muscle oxidative capacity and repeated high-intensity running performance. In addition, intensified training of already well-trained athletes can improve mechanical efficiency and repeated sprint performance.
... SET induces numerous adaptations of importance for performance during high-intensity exercise [21,27]. But unlike aerobic training, performance enhancements in athletes exposed to a period of SET seldom reflect adaptations in V O 2 max , capillarization, and muscle oxidative capacity as these factors remain unaltered or even lowered [21,114,[119][120][121][122][123][124]. Instead, studies show that SET augments the capacity of ion transport systems in the trained muscle [21,[125][126][127]. ...
... Similar effects have been observed in semi-professional players during 2 weeks of intensified training with ten sessions of aerobic high-intensity training (8 × 2 min with 1 min recovery) and SET-P (10-12 × 25-to 30-s sprints with 3 min recovery) concomitant with a 30% reduction in weekly training time at the end of the competitive season [124,126]. Though the training did not significantly increase Yo-Yo IR level 2 performance (937 m before vs. 994 m after the training), it enhanced mean repeated sprint time 2.6% and running economy at 75% maximal aerobic speed (from 198 to 193 mL × kg -1 × km -1 ) [124]. ...
... Similar effects have been observed in semi-professional players during 2 weeks of intensified training with ten sessions of aerobic high-intensity training (8 × 2 min with 1 min recovery) and SET-P (10-12 × 25-to 30-s sprints with 3 min recovery) concomitant with a 30% reduction in weekly training time at the end of the competitive season [124,126]. Though the training did not significantly increase Yo-Yo IR level 2 performance (937 m before vs. 994 m after the training), it enhanced mean repeated sprint time 2.6% and running economy at 75% maximal aerobic speed (from 198 to 193 mL × kg -1 × km -1 ) [124]. ...
Because physical demands are surging in football (soccer, USA), clubs are more and more seeking players who have a high capacity to perform repeated intense exercise. High-intensity interval training (HIIT), comprising exercise performed at intensities near or exceeding the capacity of aerobic energy systems, effectively enhances the physical conditioning of players. But given that HIIT imposes high loads, it increases the risk of overload-associated match performance decline and injury. This makes some coaches inclined to conduct HIIT in the weeks leading up to the season and during the season. Therefore, the challenge is how to optimize and dose HIIT during these phases, as they can be decisive. Studies have highlighted the utility of conducting periods of intensified training to overcome the risk of overload while at the same time enhancing performance. During intensified training periods of typically a few weeks, intensity is increased by enlarging the amount of HIIT, for example, aerobic high-intensity training or speed endurance training, while volume at low-to-moderate intensity is significantly reduced. The outcome depends on training composition and prescription—most notably, intensity and duration of bouts and recovery. When work intervals are prescribed for a few minutes at intensities > 90% heart rate max (i.e., aerobic high-intensity training), then beneficial adaptations pertaining to aerobic power and capacity are apparent. But when work intervals are conducted at much higher intensities, as all-out efforts or sprinting of typically 10- to 40-s duration with longer recovery periods (i.e., speed endurance training), beneficial adaptations pertaining to anaerobic energy systems, ion handling, and fatigue resilience are commonly observed. In this review, we discuss the utility of conducting intensified training periods to enhance performance in elite football players during the late preparation phase and competitive season.
... Generally, the common factors between modes are the high degree of physiological stress and the sharing of some similar physiological and functional training-induced adaptations imposed by the acute and chronic effects of the high-intensity bouts. HIT is a useful training method, providing a high training stimulus Buchheit & Laursen, 2013a;Christensen et al., 2011;Iaia & Bangsbo, 2010;Iaia et al., 2009a) on both the cardiopulmonary (Buchheit & Laursen, 2013a) and neuromuscular levels (Buchheit & Laursen, 2013b), thereby promoting physiological and performance adaptations that allow players to more successfully cope with the match and training demands (Castagna et al., 2009;Girard, Mendez-Villanueva & Bishop, 2011;Gunnarsson et al., 2012;Helgerud et al., 2001;Iaia, Rampinini & Bangsbo, 2009;Impellizzeri et al., 2006;Ingebrigtsen et al., 2013b;Krustrup et al., 2005;Mohr, Krustrup & Bangsbo, 2003;Rampinini et al., 2007a). ...
... This undesirable dynamic in certain physiological determinants and endurance-related performance measures could be explained by the tight in-season schedule, with most of the time dedicate to recover from the previous match and prepare the strategy for the next opponent. In this regard, if a "window of opportunity" occurs (e.g., player ban as result of a red card and players not selected for national team breaks) further in-season improvements in aerobic and anaerobic qualities determinant for the running capacity and sub-maximal and maximal soccer-running performances than can be achieved through normal training routines may be obtained by incorporation of short duration HIT blocks (Christensen et al., 2011;Wahl, Guldner & Mester, 2014). As an example, although positive adaptations in running economy have mainly been reported and investigated during the pre-season, there are recent reports of increased running economy (75% of MAS) in players after performing 2 weeks of intense HIT executed just after the competitive season ended (Christensen et al., 2011); this result suggests that players still have significant physiological and performance adaptation potential to be explored. ...
... In this regard, if a "window of opportunity" occurs (e.g., player ban as result of a red card and players not selected for national team breaks) further in-season improvements in aerobic and anaerobic qualities determinant for the running capacity and sub-maximal and maximal soccer-running performances than can be achieved through normal training routines may be obtained by incorporation of short duration HIT blocks (Christensen et al., 2011;Wahl, Guldner & Mester, 2014). As an example, although positive adaptations in running economy have mainly been reported and investigated during the pre-season, there are recent reports of increased running economy (75% of MAS) in players after performing 2 weeks of intense HIT executed just after the competitive season ended (Christensen et al., 2011); this result suggests that players still have significant physiological and performance adaptation potential to be explored. Nevertheless, caution is needed when extrapolating these findings for professional players as these experimental studies were performed by amateur and semi-professional players (Christensen et al., 2011;Wahl, Guldner & Mester, 2014). ...
The physiological demands of soccer challenge the entire spectrum of the response capacity of the biological systems and fitness requirements of the players. In this review we examined variations and evolutionary trends in body composition, neuromuscular and endurance-related parameters, as well as in game-related physical parameters of professional players. Further, we explore aspects relevant for training monitoring and we reference how different training stimulus and situational variables (e.g., competition exposure) affect the physiological and performance parameters of players. Generally, improvements of small magnitude in non- (non-CMJ) and countermovement-based jumps (CMJBased) and in the sprint acceleration (ACCPhase) and maximal velocity phase (MVPhase) are observed from start of preparation phase (PPS) to beginning of competition phase (BCP). A greater magnitude of increases is observed in physiological and endurance performance measures within this period; moderate magnitude in sub-maximal intensity exercise (velocity at fixed blood lactate concentrations; V2–4mmol/l) and large magnitude in VO2max, maximal aerobic speed (MAS) and intense intermittent exercise performance (IE). In the middle of competition phase (MCP), small (CMJBased and ACCPhase), moderate (non-CMJ; MVPhase; VO2max; sub-maximal exercise) and large (MAS and IE) improvements were observed compared to PPS. In the end of competition period (ECP), CMJBased and MVPhase improve to a small extent with non-CMJ, and ACCPhase, VO2max, MAS, sub-maximal intensity exercise and IE revealing moderate increments compared to PPS. Although less investigated, there are generally observed alterations of trivial magnitude in neuromuscular and endurance-related parameters between in-season assessments; only substantial alterations are examined for IE and sub-maximal exercise performance (decrease and increase of small magnitude, respectively) from BCP to MCP and in VO2max and IE (decrements of small magnitude) from MCP to ECP. Match performance may vary during the season. Although, the variability between studies is clear for TD, VHSR and sprint, all the studies observed substantial increments in HSR between MCP and ECP. Finally, studies examining evolutionary trends by means of exercise and competition performance measures suggests of a heightened importance of neuromuscular factors. In conclusion, during the preseason players “recover” body composition profile and neuromuscular and endurance competitive capacity. Within in-season, and more robustly towards ECP, alterations in neuromuscular performance seem to be force-velocity dependent, and in some cases, physiological determinants and endurance performance may be compromised when considering other in-season moments. Importantly, there is a substantial variability in team responses that can be observed during in-season. Consequently, this informs on the need to both provide a regular training stimulus and adequate monitorization throughout the season.
... More specifically, it is noticed [3] that a prolonged period of rest after the competitive season causes the partial or complete loss of training-induced physiological and performance adaptations, in response to an insufficient training stimulus, which is defined as detraining. Decreases in physical fitness are inevitable after two to six week period of detraining in athletes [4][5][6][7][8]. The detraining can impair cardiovascular and neuromuscular performance [6]. ...
... However, studies investigating the effect of a SM on soccer players are limited [4,11,13] while none have been performed on high-level soccer players. Therefore, the aim of our study was to apply a shock-microcycle (SM) after the lockdown period and return to training and assess its effect on elite professional soccer players' performance. ...
... The improvement percentage in these studies is greater than 20%. However, one study reported an improvement of 0.75% [4]. One possible explanation given by the researchers for this slight improvement is that the interventional program was implemented just after the end of the season and the aerobic level of the players was at high level. ...
Objectives: Decreases in physical fitness are inevitable after two to six week period of detraining in athletes. Lockdown period changed the characteristics of soccer players’ training.
Aim of the study: The aim of our study was to apply a HIIT shock-microcycle (SM) after return to training and assess its effect on players’ performance.
Equipment and methods: Nineteen elite professional soccer players during the lockdown period (LP) from March to May 2020 (8 weeks) performed 3-4 individual training sessions per week. The training sessions included running boots of anaerobic short and aerobic prolonged duration intervals. Intensity was determined according to lab ergospirometry test 2 weeks before LP. All the players followed an indoor program, 3-6 sessions per week consisted of core, balance and flexibility exercises (∼45 minutes). SM training content was same for both groups and took place the first two weeks after LP, consisted by eight high intensity interval training sessions (HIIT), two technique, two tactical sessions and two days off.
Results: Repeated sprint ability mean time (RSAMeanTime) and Repeated sprint ability performance – sprint no 4,5,6 (RSA4,5,6S) improved after SM (p=0.025, Effect size:r²=0.331, p=0.010, Effect size:r²=0.411, p=0.009, Effect size:r²=0.418, p=0.037, Effect size:r²=0.293, respectively. Yo-Yo intermitted recovery test level 2 (YYIR2TotalDistance) that covered by players during the 2nd measurement was 10.8% longer (p=0.004, Effect size:r²=0.483). Also, the YYIR2HeartRateRecovery percentage was lower during the 2nd measurement (p=0.014, Effect size:r²=0.107).
Conclusions: These results indicate that SM can improve YYIR2 and RSA performance thus it is a useful tool to regain physical attributes in a short period.
... Although the literature that examines how the training process produces physical adaptations in CP footballers is scarce, the training process in CP athletes seems to be crucial to maintain their physical fitness values as the CP disability causes an early decline in motor function, and poor coordination and muscle weakness are the main limitations of CP population (Cans, 2000), as well as of CP football population (Reina et al., 2016) who have lower levels of impairment compared to general population with CP (Palisano et al., 2008). For CP football players, who follow systematic training processes, the effects of a detraining period (e.g., a lockdown) are not known, but the same as in regular football, negative consequences in their physical fitness can be expected (Christensen et al., 2011;Joo, 2018). Due to these expectations of a possible physical fitness detriment during the lockdown period, the main aim of the athletes worldwide during this period was to maintain their general fitness and health (Washif et al., 2021). ...
... The CP football players' physical fitness in the 5, 10 and 20-m sprint, change of direction and dribbling was maintained after the self-training program of this study. A physical fitness decrement after a detraining period has been widely studied in football (Christensen et al., 2011;Joo, 2018;Koundourakis et al., 2014), but in this study, the "detraining" period was a mandatory lockdown in which the technical staff tried to maintain the players' physical fitness through a self-training at home. A previous study by Nakamura et al. (2012) showed no differences in football players' physical fitness after a detraining period between players who did not train, players who performed an endurance training program twice a week and players who performed a plyometric program twice a week (Nakamura et al., 2012). ...
... A previous study by Nakamura et al. (2012) showed no differences in football players' physical fitness after a detraining period between players who did not train, players who performed an endurance training program twice a week and players who performed a plyometric program twice a week (Nakamura et al., 2012). In contrast, Christensen et al. (2011) showed physical fitness maintenance after a 2-week period in which football players performed a high-intensity training program while players who stopped their activity reduced their values in the same variables. However, we cannot compare our results with the mentioned study because in their training program, players performed football-specific tasks (i.e., small-sided games), which the participants of the present study were not allowed to carry out due to the mandatory lockdown. ...
Background The COVID-19 global pandemic caused a complete stop in sport participation which meant a detraining period for athletes. High-level athletes had to train at home guided by their coaches and conditioning trainers in an effort to maintain their physical fitness. The aim of maintaining the training adaptations and physical fitness during the COVID-19 mandatory lockdown was especially important for CP athletes, in which the detraining period was expected to cause early declines in motor function, poor coordination and muscle weakness due to their disability. Methods The present study assessed the effect of a guided self-training program on international CP football players’ physical fitness during the COVID-19 mandatory lockdown. Fifteen CP football players from the Spanish National Team participated in the study. An experimental design with a pre- (T1) and a post-intervention (T2) assessment was carried out, with a 12-week period of players’ self-training (divided in two periods of 6 weeks) which combined strength and endurance training. Physical performance assessment consisted in the free countermovement jump (CMJ), 5, 10 and 20-m sprint, the modified agility T-test (MAT) and a dribbling test. The Kruskal–Wallis test was used for between-group comparisons, while the Student’s paired t test or the Fisher Pitman permutation test, based on the normality of the data, were used for within-group comparisons. Results The results showed no differences between sport classes (FT1, FT2 and FT3) in physical fitness change after the training program (Chi2 = 0.16 to 1.73; p = 0.42 to 0.92). Within-group comparisons showed an increase of jump height in the CMJ (4.19 cm [2.46, 5.93]; p < 0.001) and a maintenance of the 5, 10 and 20-m sprint, MAT and dribbling ability (
... Seven studies were conducted in professional players, three studies were conducted in semi-professional levels, and two in young/youth. Two of the included studies [43,44] applied an intense intervention consisting of five high-intensity sessions per week for two weeks. Both were included as OTP. ...
... The systematic review and meta-analysis revealed significant decreases in YYIRT (Level 1 and 2) distance after training cessation (− 5.2 to − 14.8%) but not after OTPs (Table 6; Fig. 4). The high-intensity nature of the OTP analyzed in this systematic review and meta-analysis [43,44,51] may have helped to avoid a detrimental effect on YYIRT performance. In fact, in several OTPs [43,44,51], meaningful improvements (3.4-6.1%) in YYIRT distance were observed. ...
... The high-intensity nature of the OTP analyzed in this systematic review and meta-analysis [43,44,51] may have helped to avoid a detrimental effect on YYIRT performance. In fact, in several OTPs [43,44,51], meaningful improvements (3.4-6.1%) in YYIRT distance were observed. Such OTPs applied three to five sessions week, with regimens of 3 × 12 min (80-90%HRmax) [51] and 8 × 2 min small-sided games/10-12/25-30 s all-out sprinting (~ 88% HRmax) [43,44]. ...
Background
The off-season period in soccer leads necessarily to changes in fitness status. However, there is a lack of systematization that allows identifying the magnitude of these changes in groups participating in off-season training programs compared with those subjected to training cessation.
Objective
This systematic review with meta-analysis was conducted to assess the effects of training cessation in off-season training programs on men soccer players’ body fat, maximal oxygen uptake (VO2max), yo–yo intermittent recovery test (YYIRT), vertical jump, sprinting time, and repeated-sprint ability.
Methods
To qualify for inclusion in the systematic review, studies must have included: (1) a detraining period of ≥ 2 weeks; (2) controlled trials or cohorts of healthy men soccer players with no restriction on age; and (3) a pre–post training cessation or off-season training programs measure of body fat (%), VO2max (mL kg⁻¹ min⁻¹), YYIRT performance (meters), vertical jump (height), sprinting (time), and repeated-sprint ability (total time).
Results
The electronic search yielded 563 articles, and 12 were subsequently included. Significant (all p < 0.05) detrimental training cessation effects were noted for body fat (ES = 0.26), VO2max (ES = − 1.48), YYIRT (ES = − 0.46), vertical jump (ES = − 0.81), and repeated-sprint ability (ES = 0.68). Similarly, significant (all p < 0.05) detrimental off-season training programs effects were noted for body fat (ES = 0.26), VO2max (ES = − 0.48), vertical jump (ES = − 0.51), and sprinting time (ES = 0.86). When training cessation and off-season training programs effects were compared, greater detrimental effects were noted after training cessation for VO2max (p = 0.002) and repeated-sprint ability (p < 0.001).
Conclusions
Detrimental effects on body composition and physical fitness were observed after both training cessation and off-season training programs. However, off-season training programs seem to ameliorate such detrimental effects on VO2max and repeated-sprint ability to some extent. The results presented here call for the implementation of more effective off-season training programs among male soccer players.
... Similarly, a 4-week periodized HIT program demonstrated greater power and enhanced on-ice performance in male collegiate ice hockey players compared with control intervention (29). However, with congested schedules, shorter block periodization such as shock microcycles may be a promising alternative to improve sport-specific performance in a short-term perspective (3,9,18,39). ...
... However, the absence of a control group precludes to draw strong conclusions regarding the interpretation of the results. In other team sports, such as soccer, a 2-week period including HIT (10 sessions consisting of 8 3 2 minutes aerobic high-intensity exercise) and speed endurance (10-12 3 30-second sprints) vs. a training cessation group improved work efficiency during submaximal running and repeated-sprint ability (RSA) performance in Danish second division male soccer players (9). Similarly, 12 sessions of HIT (4 3 4 minutes interval running on a dribbling track or as small-sided games) disseminated over a 2-week period largely improved RSA-related parameters and Yo-Yo intermittent recovery test level 2 (YYIR2) performance in soccer players (39). ...
... Several studies have shown that shock microcycles, including additional HIT sessions, provide a time-efficient way to enhance fitness level in intermittent, high-intensity sports (3,9,18,25,39). To the best of our knowledge, previous ice hockey studies focusing on block periodization used protocols of 4-to 6-week duration (29,33) with the exception of Kinnunen et al. (25) who used an HIT program of 2.5 weeks in elite female ice hockey players. In this latter study, the authors showed positive changes in maximal voluntary plantar flexor torque (111.6%), ...
Elite athletes face congested schedules with increased competition frequency and restricted time for training periods. Therefore, time is lacking to design long-term sport-specific block periodization. This study aimed to investigate the effects of adding a 14-day off-ice high-intensity training (HIT) shock microcycle to the usual training content of the pre-season preparation of high-level male ice hockey players' fitness. Fourteen players were randomly assigned to off-ice HIT (n = 7) or usual pre-season training (control, n = 7). For the HIT group, additional off-ice training content included 2 sessions of repeated-maximal resistance training, 2 sessions of repeated-sprint training, and 2 sessions of high-intensity intermittent training. Control group performed equal number of off-ice sessions using traditional strength and conditioning training. Off-ice Yo-Yo intermittent recovery test level 2 (YYIR2) and on-ice repeated-sprint ability test (RSA) were conducted before (pre-test) and 3 days after the intervention (post-test). Statistical significance was set at p < 0.05. Significant group × time interactions were found for off-ice YYIR2 performance (p < 0.05) and on-ice RSA-cumulated skating time (RSATT; p < 0.05). Compared with pre-test, off-ice YYIR2 distance covered significantly increased (from 708.6 ± 97.2 to 885.7 ± 118.7 m, p < 0.01; +25.8 ± 16.9%, p < 0.05) and on-ice RSATT significantly decreased (from 28.35 ± 0.87 to 28.14 ± 0.84 seconds; -1.7 ± 2.1%, both p < 0.05)] for HIT group. No significant pre-test to post-test changes were found for the control group (+2.7 ± 20.0% for YYIR2 and +0.9 ± 2.2% for RSATT). The implementation of a 14-day shock microcycle (including 6 HIT sessions) significantly improved fitness performance in high-level male ice hockey players. Such HIT block periodization offers a promising way to deal with congested schedules.
... In this sense, it has been highlighted the importance that off-season training has to avoid soccer players' deconditioning (6). The effects of short-term detraining on exercise performance during this period have previously been studied (7,29). These studies have shown a significant reduction on RSA performance after a 2-week training cessation in well-trained soccer players (7,29). ...
... The effects of short-term detraining on exercise performance during this period have previously been studied (7,29). These studies have shown a significant reduction on RSA performance after a 2-week training cessation in well-trained soccer players (7,29). However, these studies have reported that a short-term intensified training program at the end of the competitive season might counteract this negative effect (7,29). ...
... These studies have shown a significant reduction on RSA performance after a 2-week training cessation in well-trained soccer players (7,29). However, these studies have reported that a short-term intensified training program at the end of the competitive season might counteract this negative effect (7,29). To the best of our knowledge, no study has analyzed the effects of training cessation during the regular season, nor has this been performed with youth soccer players. ...
The aim of this study was to analyse the effects of two short-term training programs to prevent the negative effect of detraining on repeated sprint ability (RSA) performance. The study was carried out during a 2-wk midseason break without official matches. Forty-five youth soccer players (17.7 ± 0.8 yr, 175.4 ± 5.5 cm and 67.2 ± 5.1 kg) were split into three groups during the intervention period: inactivity group (IN; N = 16), generic high-intensity training group (GG; N = 15) and specific training group (SG; N = 14). IN was instructed to avoid performing physical activity during the 2-wk training intervention. However, GG and SG performed 8 training sessions. GG performed a generic aerobic interval training consisting of 4 repetitions of 4-min of exercise at 90-95% of maximal heart rate. SG performed a specific conditioning through small-sided games (4 vs. 4, 4 × 4-min) and repeated sprints (6 × 30-m). Testing sessions included a RSA test and a Yo-Yo intermittent recovery test level 1 (YYIR1). RSA performance only improved after the training intervention in SG (~2%, P < 0.01, ηp2= 0.23 - 0.25). Both GG and IN declined their performance in post-test (~2%, P < 0.01, ηp2= 0.19 - 0.22). No significant effect, group × time, was analysed for YYIR1 performance. This study suggests that only specific training, based on small-sided games and repeated sprints, leads to short-term improvements on RSA performance in youth soccer players.
... Where reported, there was an almost equal use of active or passive recovery (n 5 19 vs. 18 studies). Limited details were provided on the distance or intensity of active recoveries; 8 studies stated that subjects jogged during the active recovery (13,27,47,125,150,163,179,180) and 3 reported that subjects walked (110,142,146). Regarding the mean results, mean sprint distance was 28. ...
... Data from match-play in team sports would support the use of active recovery, such as jogging, walking, or shuffling (104,170), but this is often not incorporated into RSA test design. As highlighted in the results section, limited information was provided on the distance or intensity of active recoveries; 8 studies stated that subjects jogged during the active recovery (13,27,47,125,150,163,179,180) and 3 reported that subjects walked (110,142,146). Even where passive recovery is stated, this seems unlikely given that subjects will have to decelerate at the end of each sprint effort and return back to the start line. ...
Kyles, A, Oliver, JL, Cahill, MJ, Lloyd, RS, and Pedley, J. Linear and change of direction repeated sprint ability tests: a systematic review. J Strength Cond Res 37(8): 1703-1717, 2023-The ability to repeatedly sprint is important in many sports, but there is no established protocol for measuring repeated sprint ability (RSA). The purpose of this review was to identify overground RSA protocols previously reported in the literature and to recommend standardized protocols. A systematic review of the literature was used to identify studies that have used an RSA test, with data describing protocol design extracted. One hundred eight studies were included in the review, across which 47 unique protocols were identified. Eighteen protocols included at least one change of direction (COD), and this increased mean sprint time compared with linear RSA tests (7.26 ± 1.84 vs. 4.48 ± 1.02 seconds). There was considerable variability across protocols regarding sprint distance (20-40 m), sprint repetitions (3-15), recovery duration (10-60 seconds), recovery type (active vs. passive), and work-to-rest ratio (≤1:1.4-19.2). Separate protocols are needed for linear and COD tests, and these should reflect the brief nature of intense periods of competition and stress the ability to recover. Based on data across studies for protocol design and to ensure a demanding work-to-rest ratio, it is suggested that a linear RSA should comprise 6 × 30 m sprints separated by 15 seconds of active recovery. To provide some parity to linear tests, to keep work duration brief and to maintain a demanding work-to-rest ratio, a COD RSA should comprise 6 × 30 m shuttle sprints (15 + 15 m), providing one change of direction (180° COD), and maintaining a 15-second active recovery.
... It is also possible that RSA mean related to anaerobic aspects 17 is more affected by a short-time of inactivity, while RSA best requires more time to decrease performance, as 28 days of inactivity show beneficial minor effects (ES = 0.42) in 25 m sprints in female pole-vaulters. 36 In agreement with our results, Christensen et al. 37 observed no significant changes in RSA best (3.14 ± 0.08 s and 3.15 ± 0.14 s) but the performance was significantly reduced in RSA total (33.41 ± 0.96 s vs. 34.11 ± 0.92 s) in 10 × 20 m Figure 3. Number of accelerations in each set of small sided games before (BD) and after (AD) detraining period in day 1 (d1) and day 2 (d2) in female soccer players. ...
... This absence of changes may be due to the fact that a 2-week in-season break is a short period of time, although previous studies have shown that it is sufficient to impair performance. 2,37 Previous studies 39 have also shown that SSGs locomotor performance does not serve as a valid and reliable fitness indicator for individual players. The high variability in individual response and the 'ceiling effect' (highly fit or skilled players not achieving high-exercise intensities) in the SSGs may explain these results. ...
The current study aimed to analyse the effects of an in-season break period (2-week) on specific performance in amateur young female soccer players. Twelve female soccer players completed four assessment sessions, two before (BD-d1 and BD-d2) and two after (AD-d1 and AD-d2) a 2-week in-season break detraining period (both separated by 24 h). In each session, players completed a repeated sprint ability test (repeated sprint ability = 8 sprints of 30 m with 25 s of recovery), a countermovement jump test and locomotor performance in small-sided games (small-sided games = 3 sets of 5 min in a 5 vs. 5). Players exhibited a significant decrease in mean of repeated sprint ability (mean time of 8 sprints, p = 0.000, effect size = 2.04) and countermovement jump ( p = 0.009, effect size = 1.39) performance between BD-d1 and AD-d1. The percentage of change between BD-d1 and BD-d2 from AD-d1 and AD-d2 shows significant differences ( p = 0.05, effect size = 1.12) in best of repeated sprint ability (best time of 8 sprints) but not ( p = 0.517, effect size = 0.31) in mean of repeated sprint ability. Significantly less high-intensity acceleration was performed in BD-d2 and AD-d2 from BD-d1 ( p = 0.003, effect size = 3.21 and p = 0.002, effect size = 3.25, respectively). Only a 2-week in-season break inactivity was sufficient to decrease mean of repeated sprint ability and countermovement jump performance but not the best of repeated sprint ability. Therefore, it is necessary to apply specific training strategies to prevent decreases in performance in female soccer players in specific periods of the season.
... In the study from Beard et al., the authors found that four sessions of RSH spread over 2 weeks enhanced repeated sprint ability (i.e., both maximal and mean power) in world-level male rugby union players [19]. Other studies also highlighted that intensified training over 2 weeks or RSH over 10 days can improve physical performance in soccer players and a professional cyclist, respectively [20,21]. Finally, another investigation demonstrated that six sessions of RSH spread over 2 weeks improved repeated sprint ability of upper body muscles in cross-country skiers [22]. ...
... Of note, it cannot be ruled out that peak aerobic power from the time trial exercise should be improved through improvement of both maximal accumulated oxygen deficit and accumulated V O 2 . Importantly, it was also recently observed that repeated sprint performance can be improved after only a 2-week RSH protocol in elite soccer players, international rugby union players and cross-country skiers [19,20,22]. Thus, our data are in line with these studies suggesting that 2-week RSH protocols may enhance some parameters of anaerobic performance. ...
This study compared the effects of a brief repeated sprint training (RST) intervention performed with bilateral blood flow restriction (BFR) conditions in normoxia or conducted at high levels of hypoxia on response to exercise. Thirty-nine endurance-trained athletes completed six repeated sprints cycling sessions spread over 2 weeks consisting of four sets of five sprints (10-s maximal sprints with 20-s active recovery). Athletes were assigned to one of the four groups and subjected to a bilateral partial blood flow restriction (45% of arterial occlusion pressure) of the lower limbs during exercise (BFRG), during the recovery (BFRrG), exercised in a hypoxic room simulating hypoxia at FiO 2 ≈ 13% (HG) or were not subjected to additional stress (CG). Peak aerobic power during an incremental test, exercise duration, maximal accumulated oxygen deficit and accumulated oxygen uptake ( VO 2 ) during a supramaximal constant-intensity test were improved thanks to RST ( p < 0.05). No significant differences were observed between the groups ( p > 0.05). No further effect was found on other variables including time-trial performance and parameters of the force-velocity relationship ( p > 0.05). Thus, peak aerobic power, exercise duration, maximal accumulated oxygen deficit, and VO 2 were improved during a supramaximal constant-intensity exercise after six RST sessions. However, combined hypoxic stress or partial BFR did not further increase peak aerobic power.
... In another study on the subject [41] that evaluated the effects of an intensive training program consisting of highintensity aerobic activities (8x2 min) and resistance speed tasks (10-12x30 seconds) with a complete training interruption, it was observed that soccer players who did not participate in the intensive training showed delayed inertia of VO 2 max associated with reduced muscle oxidative capacity. ...
... In the studies previously mentioned, the effects of a detraining period were analyzed based on the evaluation of different physical and physiological capacities associated with aerobic capacity [2, 15, 17 -19, 42], anaerobic capacity [2,5,11,32,44], speed [41], flexibility [8,9] and body composition [15,18]. Considering that soccer is a game of interaction and collective involvement, in which the performance depends on a set of interactions between the variables, it is essential to perceive and investigate how the techniques and behavioral variables influence the individual and collective performance [2]. ...
Competitive breaks in soccer have been revealed to be detrimental to the individual and collective performance of soccer players and teams. Several studies have been carried out, and the evidence suggests the need to apply specific training programs to avoid a decline in soccer players’ performance. However, the elaboration of these specific programs, in many cases, is essentially focused on physical performance, neglecting the technical and behavioral domain.
In this small review, the competitive breaks and their main effects for detraining were critically analyzed. Concurrently, we analyzed the effects of the use of specific training programs to avoid changes in the performance of soccer players and teams.
It is essential to create guidelines for coaches to apply for specific training programs properly during competitive breaks so that soccer players can maintain their individual and collective performance, considering the physiological, technical, and behavioral domains. Applying of these programs will also contribute to enhancing soccer players’ physical condition, increasing their tolerance to the imposed training loads, and, consequently, reducing the appearance of injuries.
... However, in line with our results, Buchheit [50] found no correlations between RSA performance and τ phase II , reporting that stepwise multiple regression analysis showed that mean repeated-sprint time, best sprint time and maximal aerobic speed were the only significant predictors of RSA performance. Accordingly, Christensen and associates [51] also found that τ phase II was not associated with better RSA performance in a group of soccer players, although the changes in τ phase II after a speed-endurance training program were associated with changes in RSA performance. ...
... The studies mentioned above [21,50,51] involved running activities, utilizing a different set of muscle groups, in a different set of participants, exposed to very different training regimens compared to the individuals involved in the present study. However, they allow us to make some assertions regarding the observed results. ...
The present study sought to investigate if faster upper body oxygen uptake (VO2) and hemoglobin/myoglobin deoxygenation ([HHb]) kinetics during heavy intensity exercise were associated with a greater upper body repeated-sprint ability (RSA) performance in a group of judokas and in a group of individuals of heterogenous fitness level. Eight judokas (JT) and seven untrained healthy participants (UT) completed an incremental step test, two heavy intensity square-wave transitions and an upper body RSA test consisting of four 15 s sprints, with 45 s rest, from which the experimental data were obtained. In the JT group, VO2 kinetics, [HHb] kinetics and the parameters determined in the incremental test were not associated with RSA. However, when the two groups were combined, the amplitude of the primary phase VO2 and [HHb] was positively associated with the accumulated work in the four sprints (ΣWork). Additionally, maximal aerobic power (MAP), peak VO2 and the first ventilatory threshold (VT1) showed a positive correlation with ΣWork and an inverse correlation with the decrease in peak power output (Dec-PPO) between the first and fourth sprints. Faster VO2 and [HHb] kinetics do not seem to be associated with an increased upper body RSA in JT. However, other variables of aerobic fitness seem to be associated with an increased upper body RSA performance in a group of individuals with heterogeneous fitness level.
... The physical performance decrement after a detraining period has been widely studied in professional football players with different detraining protocols (Christensen et al., 2011;Joo, 2018;Koundourakis et al., 2014). Joo (2018) showed decrements in the players' ability to repeat sprints (RSA) and in the distance covered in an intermittent aerobic test (Yo-YoIR1). ...
... In this regard, a previous study by Nakamura et al., (2012) showed no differences in aerobic and anaerobic fitness after a detraining period among players who did not train, players who performed 30-min of running at 70-80% HRmax twice a week, and players who performed a plyometric program twice a week (Nakamura et al., 2012). In contrast, Christensen et al., (2011) showed physical and physiological maintenance after a 2-week period in which football players performed a high-intensity program while players who stopped their activity reduced their values in the same variables. However, the results of the current study cannot be compared with the mentioned study because in their high-intensity program, players performed footballspecific tasks (i.e., small-sided games), which the participants of the present study were not able to perform due to the mandatory lockdown. ...
COVID-19 caused a total halt in sport competition during 2020. The purpose of this study was to analyze the changes between pre- and post-lockdown competitive periods in the players’ workload variables in competition. Seventeen professional football players were monitored using a WIMU PRO® inertial device throughout the 2019-20 season. Anthropometric and physical fitness were assessed with the aim to relate possible associations between these characteristics and the workload changes in the pre- and post-lockdown periods. During the lockdown, players carried out an 8-week guided self-training. There was a general decrement in the players’ physical workload demands in competition, and the parameters related to high-intensity actions as accelerations and decelerations (-8.96% [ES: 0.64] and -11.04% [ES: 0.77] respectively; p < .05), Ind HSR (-35.57% [ES: 0.92]; p = .002), HMLD (-8.58% [ES: 0.66]; p = .016), PLOAD (-7.03% [ES: 0.54]; p = .047) and Vmax (-3.80% [ES: 0.65]; p = .016) can be highlighted. The results showed high negative correlations between match workload variables prior to the lockdown and the percentage of change in these variables after the lockdown period. Individual percentages of change showed high variability in players’ changes. Individual self-training programs should be reviewed to minimize the impact of a “detraining” period in players’ physical performance during possible new lockdown periods.
... Detraining in team sport players after an offseason (≥4 weeks) causes reductions in maximal oxygen uptake ( _ VO 2max ; 0.8% to 21.2%; Caldwell and Peters 2009;Sotiropoulos et al. 2009;Koundourakis et al. 2014;Melchiorri et al. 2014), which are associated with reductions in blood and plasma volume (5-12%), increases in heart rate during submaximal and maximal training (5-10%), and lower stroke volume (10-17%) (Mujika and Padilla 2000;Silva et al. 2016). .6%) in intermittent running capacity have also been reported after short-term (~2 weeks) detraining periods (Thomassen et al. 2010;Christensen et al. 2011;Joo 2018), suggesting study of the effects of longer detraining periods is needed. Likewise, reductions in vertical jumping (2.1-6.3%) and increased sprint times (2.4-3.3%) ...
... Reductions in intermittent endurance performance are likely explained by adaptations such as slower VO 2 kinetics, alterations in oxidative enzymes (e.g. GLUT-4), reduced mitochondrial content and capillary density, higher sub-maximal heart rate, lower stroke volume and a higher respiratory exchange ratio (Mujika and Padilla 2000;Thomassen et al. 2010;Christensen et al. 2011). Increases in body mass (Darrall-Jones et al. 2016) and the impairment in sprint performance over the off-season might also have contributed to the reductions in 30-15 IFT peak speed. ...
Purpose:
To determine the changes in physical qualities of academy rugby union players over a 10-week unsupervised off-season period.
Methods:
Body mass, jump height, sprint performance, and intermittent running (30:15 IFT) of 64 academy rugby union players (age = 17.2 ± 0.4 y) were recorded before and after the off-season.
Results:
Changes in body mass (+1.4 ± 1.3 kg), countermovement jump (-2.2 ± 1.2 cm), squat jump (-1.5 ± 1.8 cm), 10 m sprint (+0.06 ± 0.05 s), 40 m sprint (+0.13 ± 0.11 s) and 30:15 IFT (-0.8 ± 0.8 kmŸh-1) were observed (P < 0.001, d = -1.77 to 0.47). Only changes in body mass were greater in forwards than backs (P = 0.036, d = 0.46). Players with higher end-of-season body mass, squat jump and 30:15 IFT had greater off-season changes (P = < 0.001 to 0.044; d = 0.63 to 0.94), whilst the pre-post difference in body mass influenced CMJ (P = 0.005, d = 0.75) and 10 m momentum change (P < 0.001, d = 1.61).
Conclusion:
Understanding the individuality of the changes in physical qualities of academy rugby union players during the off-season is important to ensure players return safely to pre-season training loads.
... The training of footballers is also focused on this important aspect of faster removal of lactate by using lactate as a potential source of energy. A number of studies [15][16][17][18][19] have concluded that the level of aerobic efficiency determines the limits of the intensity of work. Oxygen insufficiency in working muscle is considered to be a regulatory factor of the metabolic changes that cause the exhaustion of muscle glycogen resources and the inhibition of the activity of glycolytic enzymes. ...
... Like real match play, an efficient physiological response in AST and CST depends on the appropriate training and running economy of the players. The dominant role of the aerobic energy system in football games has been suggested by many researchers [15,17]. High VO 2max allows athletes to run intermittently, with brief pauses, more efficiently than athletes with low aerobic capacity. ...
In this study, the Ajax Shuttle Test (AST) and the Curved Sprint Test (CST) were conducted on semiprofessional football players to evaluate (1) their test performance, (2) the extent of anaerobic glycolysis by measuring blood lactate, (3) performance decrement and onset of fatigue, and (4) the correlation between selected physiological variables and test performance. Thirty-two semiprofessional Polish football players participated in this study. Both AST and CST were conducted on an outdoor football ground and were conducted in two sets; each set had six repetitions. In the case of AST, the total duration for 6 repetitions of the exercise in Sets 1 and 2 were 90.63 ± 3.71 and 91.65 ± 4.24 s, respectively, whereas, in the case of CST, the respective values were 46.8 ± 0.56 and 47.2 ± 0.66 s. Peak blood lactate concentration [La] after Sets 1 and 2 of AST were 14.47 ± 3.77 and 15.00 ± 1.85 mmol/L, and in the case of CST, the values were 8.17 ± 1.32 and 9.78 ± 1.35 mmol/L, respectively. Performance decrement in AST was more than in CST, both after Set 1 (4.32 ± 1.43 and 3.31 ± 0.96 in AST and CST, respectively) and Set 2 (7.95 ± 3.24 and 3.71 ± 1.02 in AST and CST, respectively). Only in a few of the repetitions, pulmonary ventilation (VE) and oxygen uptake (VO2) were found to be significantly correlated with the performance of the volunteers in both AST and CST. Respiratory exchange ratio (RER) was significantly correlated with most of the repetitions of AST, but not with CST. The study concludes that (1) AST shows more dependence on the anaerobic glycolytic system than shorter repetitive sprints (as in CST), (2) there is more performance decrement and fatigue in AST than in CST, and (3) early decrease in performance and fatigue in the semiprofessional football players in AST and CST may be due to the insufficiency of their aerobic energy system.
... In addition, a high number of specific skills are performed with simultaneous cognition efforts such as decision making under high physiological stress. Thus, athletes in complex sports such as football may experience the greatest challenges in relation to maintaining training status during the COVID-19 lockdown (Christensen et al., 2011;Krustrup et al., 2006). Performance in competitive football is governed by different physiological systems. ...
... Depending on the length of the isolation-training period, one may expect a decrease on general fitness that would be related to the lack of high-intensity exercise performed during this period (Christensen et al., 2011;Krustrup et al., 2006;Thomassen et al., 2010). Training contents (i.e. in the single session), sequence (i.e. in the session and across the functional micro-cycle) and progression (i.e. ...
The COVID-19 pandemic has changed the conditions for competitive football around the globe dramatically. Several competitions and leagues have been cancelled or postponed. Players have firstly been forced to training in solitude. In a second stage, players start training in small groups with strict contact restriction and return to competitive play might occur after only few weeks of normal team training preparation. These special circumstances are likely to impact football performance and injury risk in the upcoming competitions. Thus, clubs, coaching and medical staff, as well as players are challenged on the prioritization of fitness and performance, which easily can create several “catch-22-dilemmas”. The present article presents views on fitness training, physical preparation and recovery during these uncommon conditions, and how elite football players can return to the competitive field well-prepared for post-crisis football endeavours around the world. Due to the multifaceted physiological demands in elite football, the long recovery requirements after match-play and an upcoming reality with many games within a short period, elite football players, managers and clubs may face extraordinary challenges associated with return to play under the current circumstances.
... Christensen et al. [48] demonstrated that a high-intensity training program is a feasible intervention to maintain physical fitness after two weeks in football players; however, the participants who interrupted their training completely showed a severe reduction in their physical fitness. Our meta-analysis demonstrated that the COVID-19 pandemic did not negatively affect the fitness level. ...
Sporting events were cancelled, and sports training was banned to prevent the spread of COVID-19. These changes during the COVID-19 pandemic decreased the physical activity levels, increased sedentary time, and also impaired the mental health of elite and sub-elite athletes. The impact on body composition and physical performance is not clear, however, especially considering a systematic review with meta-analysis. Thus, our objective was to conduct a review in accordance with the PRISMA Statement studies published in scientific journals (PubMed, Web of Science, or Scopus databases) that investigated the effect that social distancing during the COVID-19 pandemic had on the physical performance (muscle power, cardiorespiratory capacity, and sprint) or body composition (body weight, percentage of fat, fat mass, and fat-free mass) of athletes. Data from 24 studies indicate that, throughout the global lockdown, the athletes maintained muscle power, cardiorespiratory capacity, and sprint, and prevented significant changes in fat mass and fat-free mass. However, the total body weight (meta-analysis with 18 studies), showed a significant increase (p = 0.006), with a small ES = 0.12; 95% CI = 0.04 to 0.21. Furthermore, the time of follow-up, level of training, and the age of the athletes were possible moderators of these effects. The data reinforce the importance of general strength and endurance exercises sessions to maintain physical fitness during non-competitive periods or due to the mandatory lockdown.
... 14 Previous literature has shown physical performance improvements in sprint, jump, change of direction, and endurance after combined training programs in regular football. 35,36 However, there is no previous literature that has analyzed sport-specific physical performance improvements after a training program in CP football. In the present study, the application of the training program, which included a combination of football-specific training and strength training, showed likely to most likely positive effects (P < .01) ...
Purpose:
Force production is crucial in football, and it is the main limitation of people with cerebral palsy (CP). This study aimed to describe the changes in sprint force-velocity (Fv) profile after a period of 25 weeks of regular training in international football players with CP.
Methods:
The sprint Fv profile and other physical performance variables (ie, linear sprint, vertical jump, change of direction, and intermittent endurance) of 14 international players from the Spanish national team were assessed during 2 consecutive training camps. Pretesting and posttesting sessions were carried out 1 week before and after the 25-week intervention period. The intervention consisted of 2 strength sessions per week added to the usual football training.
Results:
The repeated-measures analysis of variance showed changes in players' physical performance (linear sprint: F = 18.05, P < .01; change of direction: F = 16.71, P < .01; and endurance: F = 31.45, P < .01) and in some variables of the sprint Fv profile (maximal horizontal force, maximal power, slope, maximal ratio of force, and decrease of ratio of force; F = 14.28-37.81; P < .01), whereas players' maximal velocity (theoretical and actual) did not change (F = 0.13 and 0.01; P = .72 and .98, respectively).
Conclusions:
This study showed that the implementation of 2 strength-training sessions per week, for 25 weeks, is effective to improve CP football players' physical performance. The main finding of this study is the improvement of force application in the acceleration phase (sprint Fv profile), which is the main attribute in many physical performance tests and is the main limitation of the CP population.
... Este escenario podría ser similar al periodo transitorio que se da luego de una temporada competitiva donde el nivel de condición física disminuye por falta de preparación específica repercutiendo en múltiples pérdidas, pero sobre todo a nivel cardiovascular (Christensen, et al., 2011). En este sentido, recordando que durante el encuentro los árbitros de fútbol cumplen acciones intensas con esfuerzos de hasta el 90% de la capacidad aeróbica (Bangsbo, 1994), además toman cerca de 137 decisiones durante el juego (Helsen & Bultynck, 2004) indican que una pérdida de condición física disminuiría tanto las adaptaciones alcanzadas durante la temporada de entrenamientos y competencias, como la ejecución de acciones de alta intensidad aspecto determinante en los árbitros de fútbol para tomar buenas decisiones (Cardoso, et al. 2019). ...
El objetivo del presente estudio fue evaluar el efecto de un programa de entrenamiento interválico de alta intensidad (HIIT) sobre la habilidad de esprint repetido (RSA) en árbitros y árbitros asistentes del fútbol profesional ecuatoriano. Se realizó un diseño cuasi experimental de corte longitudinal cuantitativo sin grupo control en 9 árbitros y 11 árbitros asistentes entre los meses de octubre y diciembre del 2020. Se evaluó la habilidad de esprint repetido con el test RSA, previo y posterior a la implementación de un programa de entrenamiento interválico de alta intensidad. Se utilizó la prueba t de datos relacionados para evaluar el efecto de la intervención. Los resultados obtenidos muestran que el programa de entrenamiento no fue efectivo para mejorar la habilidad de esprint repetido. Futuros estudios deberían incluir un programa de entrenamiento para toda la temporada, que individualice los ejercicios y el control para cada tipo de árbitro.
... In terms of performance, however, training at home was useful for improving aerobic fitness, although it did not allow players to maintain the power levels of their competitive period (Rampinini et al., 2021). Players may encounter the greatest challenges in relation to maintaining training status (Christensen et al., 2011), especially during the COVID-19. For this reason, many expect reduced fitness, match fatigue and risk of injury, longer recovery times (Mohr et al., 2020). ...
... Isolated HIIT-SM have been performed between 9 and 21 days, during which 9 to 24 sessions were conducted [9][10][11][12][13][17][18][19]. This concept is discussed to promise a rapid increase in performance, but usually reduces the total training volume during this period of about 30% compared to regular training weeks, especially for elite athletes [20]. Although multiple studies have demonstrated the effectiveness of HIIT-SM to improve endurance performance [9][10][11][12][13] others have been less conclusive [16][17][18][19]. ...
Background
Performing multiple high-intensity interval training (HIIT) sessions in a compressed period of time (approximately 7–14 days) is called a HIIT shock microcycle (SM) and promises a rapid increase in endurance performance. However, the efficacy of HIIT-SM, as well as knowledge about optimal training volumes during a SM in the endurance-trained population have not been adequately investigated. This study aims to examine the effects of two different types of HIIT-SM (with or without additional low-intensity training (LIT)) compared to a control group (CG) on key endurance performance variables. Moreover, participants are closely monitored for stress, fatigue, recovery, and sleep before, during and after the intervention using innovative biomarkers, questionnaires, and wearable devices.
Methods
This is a study protocol of a randomized controlled trial that includes the results of a pilot participant. Thirty-six endurance trained athletes will be recruited and randomly assigned to either a HIIT-SM (HSM) group, HIIT-SM with additional LIT (HSM + LIT) group or a CG. All participants will be monitored before (9 days), during (7 days), and after (14 days) a 7-day intervention, for a total of 30 days. Participants in both intervention groups will complete 10 HIIT sessions over 7 consecutive days, with an additional 30 min of LIT in the HSM + LIT group. HIIT sessions consist of aerobic HIIT, i.e., 5 × 4 min at 90–95% of maximal heart rate interspersed by recovery periods of 2.5 min. To determine the effects of the intervention, physiological exercise testing, and a 5 km time trial will be conducted before and after the intervention.
Results
The feasibility study indicates good adherence and performance improvement of the pilot participant. Load monitoring tools, i.e., biomarkers and questionnaires showed increased values during the intervention period, indicating sensitive variables.
Conclusion
This study will be the first to examine the effects of different total training volumes of HIIT-SM, especially the combination of LIT and HIIT in the HSM + LIT group. In addition, different assessments to monitor the athletes' load during such an exhaustive training period will allow the identification of load monitoring tools such as innovative biomarkers, questionnaires, and wearable technology.
Trial Registration : clinicaltrials.gov, NCT05067426. Registered 05 October 2021—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05067426 . Protocol Version Issue date: 1 Dec 2021. Original protocol. Authors: TLS, NH.
... Es un deporte de habilidades abiertas de colaboración-oposición e invasión, por lo que entrenar con otros es parte esencial de su significado y hacerlo de manera aislada del contexto del juego, no es coherente y además alejado de las exigencias de la competencia real (Martín-Barrero y Martínez-Cabrera, 2019). Para mantener la capacidad de resistencia y de fuerza y reducir el impacto negativo del período de confinamiento, se han dispuesto distintas estrategias tanto de entrenamiento como de recuperación (Domínguez et al., 2020;Christensen et al., 2011). Sin embargo, un período inusual sin entrenamiento o competencia también podría presentar un importante efecto sobre los estados emocionales o mentales de los jugadores (Jukic et al., 2020). ...
Resumen. En respuesta a la aparición del COVID 19 y la pandemia ocasionada, los países tomaron medidas para manejar las curvas de infección. Han obligado a permanecer en confinamiento y esta estrategia afectó a diversos contextos, dentro de los cuales, se encuentra el ámbito deportivo, suspendiendo competiciones, partidos oficiales, entrenamientos en cancha, transmisiones deportivas, etc. Sin embargo, en el caso de los profesionales del fútbol, se mantuvieron en preparación física a través de plataformas tecnológicas. El objetivo de este trabajo es explorar los niveles de ansiedad rasgo, de sensación de bienestar y la relación entre ambas variables en futbolistas profesionales de cuatro clubes de Chile con el fin de contribuir al diagnóstico sobre cómo la crisis de Covid-19 puede haber afectado a la realidad deportiva en cuanto a la salud mental y emocional. Para ello se aplicó el STAI y el PERMA. Como resultados, los futbolistas investigados muestran niveles promedio de ansiedad rasgo y buen nivel de bienestar general. También se encuentra correlación entre ambos. Este estudio permite concluir que si bien la situación actual puede verse como amenazante, mantener las condiciones laborales y en actividad para un deportista parece ser clave para sentir cierto grado de control frente a la incertidumbre, así como estrategias de afrontamiento que permitan tener una alta sensación de bienestar. Palabras clave: Emociones, Coronavirus, Pandemia, Futbolista profesional. Abstract. In response to the emergence of COVID 19 and the resulting pandemic, countries took steps to manage infection curves. They have forced them to remain in confinement and this strategy affected various contexts, within which is the sports field, suspending competitions, official matches, training on the field, sports broadcasts, etc. However, in the case of soccer professionals, they remained in physical preparation through technological platforms. The objective of this work is to explore the levels of trait anxiety, feeling of well-being and the relationship between both variables in professional soccer players from four clubs in Chile in order to contribute to the diagnosis of how the Covid-19 crisis may have affected sports reality in terms of mental and emotional health. For this, the STAI and PERMA were applied. As results, the investigated soccer players show average levels of trait anxiety and a good level of general well-being. There is also a correlation between the two. This study allows us to conclude that although the current situation can be seen as threatening, maintaining working and active conditions for an athlete seems to be key to feeling a certain degree of control in the face of uncertainty, as well as coping strategies that allow having a high sensation of wellness.
... Accordingly, a higher reliance on carbohydrate (i.e., higher RER) may at least in part explain the lower V̇O 2 during post-training submaximal exercise testing because oxidation of 100% carbohydrate (RER 5 1.0) relative to 100% fat oxidation (RER 5 0.7) per se would lead to higher energy turnover (21.1 vs. 19.6 kJ per liter V̇O 2 ) during exercise, as supported by observations in persons ingesting high fat diets before exercise (14). The potential mechanism(s) responsible for the higher RER remains speculative because a higher RER during exercise typically is associated with endurance training cessation (16) or detraining (36). Consequently, the presence of measurement noise could also be a plausible cause for the present gains in RER. ...
Bláfoss, R, Rikardo, J, Andersen, AØ, Hvid, LG, Andersen, LL, Jensen, K, Christensen, PM, Kvorning, T, and Aagaard, P. Effects of resistance training cessation on cycling performance in well-trained cyclists: an exploratory study. J Strength Cond Res 36(3): 796-804, 2022-Supplementary (i.e., concurrent) resistance training can enhance cycling performance among competitive cyclists. However, a lack of knowledge exists about the retention (decay profile) in mechanical muscle function and cycling performance after concurrent resistance and endurance training. The present exploratory intervention study investigated the effect of 6 weeks of resistance training cessation when preceded by 8 weeks of concurrent resistance and endurance training on mechanical muscle function and cycling performance in 9 male well-trained competitive cyclists (V̇o2max = 66 ± 7 ml·min-1·kg-1). Cyclists performed periodized resistance training targeting leg and core muscles for 8 weeks as a supplement to their normal endurance (cycling) training. This was followed by 6 weeks of endurance training only (retention period) leading up to the start of the competitive season. Maximal leg extensor power, isometric leg extensor strength (maximal voluntary contraction [MVC]), rate of force development (RFD), and long-term cycling performance (2-hour submaximal cycling at 55% of Wmax), followed by 5-minute max cycling were evaluated. After 8 weeks of concurrent resistance and endurance training, leg extensor power, MVC, and RFD increased by 12, 15, and 17%, respectively while mean power output (W) during 5-minute max cycling increased by 7% (p < 0.05). Training-induced gains in MVC and 5-minute max cycling power were retained after 6-week cessation of resistance training (p < 0.05). These findings indicate that competitive cyclists can focus on cycling training alone for at least 6 weeks leading up to competition without losing attained gains in maximal muscle strength and cycling performance achieved by preceding periods of concurrent resistance training.
... Desde el punto de vista del rendimiento la evaluación constante de RSA a lo largo de la temporada puede proporcionar información valiosa a los entrenadores y atletas. De manera similar a las pausas fuera y dentro de la temporada, pueden conducir a un desentrenamiento a corto plazo, esto puede inducir un desacondicionamiento cardiovascular y neuromuscular (Christensen et al., 2011;Mujika y Padilla, 2001), que potencialmente puede alterar el RSA, el índice de fatiga o la puntuación de disminución porcentual (Sdec) (Glaister, 2009). El conocimiento del alcance de las respuestas de la fatiga durante un RSA puede ayudar a los preparadores físicos a prever cambios eventuales durante los descansos de la temporada y a implementar estrategias de entrenamiento adecuadas para optimizar los niveles de condición física. ...
Introducción: El desarrollo de dispositivos portátiles de espectroscopia de infrarrojo cercano no invasivo (NIRS) ha permitido que las mediciones de oxígeno muscular se realicen fuera de un entorno de laboratorio para investigar cambios musculares locales en pruebas campo para guiar el entrenamiento. En general, durante el ejercicio los NIRS portátiles utiliza la saturación de oxígeno muscular (SmO2) como parámetro principal para el estudio de la hemodinámica porque proporciona información sobre el rendimiento y el metabolismo muscular durante el ejercicio. Un uso novedoso de NIRS portátil, es la medición de la oxigenación muscular en reposo a través del método de oclusión arterial (AOM). AOM consiste en realizar breves oclusiones arteriales para conocer el consumo de oxígeno muscular en reposo (mVO2). En la actualidad, AOM es una técnica para obtener información de la capacidad oxidativa del músculo en reposo, lo cual significa que el atleta no realiza ningún esfuerzo físico. Sin embargo, existe poca literatura científica de cómo está implicado el mVO2 en el proceso de entrenamiento.
Por otro lado, el monitoreo de la acumulación de fatiga pre y post competencia es importante dentro de la planificación del entrenamiento. Uno de los roles de los científicos del deporte es conocer el perfil de fatiga y recuperación con el fin de optimizar los procesos de entrenamiento para buscar un mejor rendimiento deportivo. Pero existen limitaciones, debido a que el estudio de la fatiga es un fenómeno multifactorial que envuelve diferentes mecanismos fisiológicos. En cuanto a la relación que pueda tener NIRS portátil y la medición de SmO2 con la fatiga dentro de un contexto deportivo se desconoce, debido a que es una variable que no se ha puesto en práctica en el deporte, pero con un gran potencial.
En el contexto de la salud, existen numerosas investigaciones que han asociado la SmO2 a enfermedades cardiovasculares, respiratorias y metabólicas como el sobrepeso y obesidad, que son patologías que afectan la entrega de oxígeno durante la actividad física. Uno de los factores claves para prescribir el ejercicio físico es conocer las zonas de metabólica, es decir la intensidad de ejercicio donde existen cambios metabólicos y que se aplica según el objetivo de la sesión de entrenamiento en personas que realizan actividad física para la salud.
Por último, existen algunos vacíos científicos de la aplicación de NIRS portátil en contextos de fatiga, rendimiento y salud. Por lo tanto, con esta tesis podemos brindar nuevos aportes científicos del metabolismo muscular a través de la medición de la SmO2 en reposo y durante el ejercicio, necesario para conocer estados de condición física de un deportista, fatiga, recuperación y la prescripción de ejercicio de ejercicio físico.
Objetivos: La tesis presenta como objetivo general: Utilizar la saturación de oxígeno muscular y estudiar su implicación en la fatiga, rendimiento y salud.
Para realizar el objetivo general se llevó a cabo los siguientes objetivos específicos: 1. Examinar la relación de la saturación de oxígeno muscular en reposo con marcadores de fatiga en futbolistas femeninos. 2. Interpretar el rol de la saturación de oxígeno muscular como un marcador de rendimiento deportivo durante una prueba de alta intensidad (sprint-repetidos) en futbolistas femeninos. 3. Evaluar los cambios de oxigenación muscular en reposo después de un periodo de entrenamiento y correlacionarlos con la composición corporal y la potencia de salto en futbolistas. 4. Comparar y correlacionar los parámetros fisiológicos en función de la saturación de oxígeno muscular por zonas metabólicas durante una prueba de esfuerzo en personas con sobrepeso/obesidad y normo-peso.
Métodos: Los cuatro objetivos de esta tesis fueron investigados con cuatro estudios científicos. Los participantes fueron futbolistas femeninos y masculinos que competían en segunda y tercera división respectivamente, y mujeres con sobrepeso/obesidad y normo-peso. En todas las pruebas se utilizó un NIRS portátil marca MOXY colocado en el músculo gastrocnemio y músculo vasto lateral. El primer estudio consistió en medir marcadores de fatiga neuromuscular, escalas psicológicas y marcadores sanguíneos utilizados para medir fatiga a nivel biológico. En conjunto se midió la prueba de oxígeno muscular en reposo (mVO2 y SmO2) mediante la técnica AOM. Todas las mediciones se realizaron pre, post y post 24 h tras un partido de futbol femenino. El segundo estudio consistió en que los futbolistas femeninos realizaran una prueba de sprint repetidos, donde se evaluó la frecuencia cardiaca, velocidad y SmO2 en conjunto. El tercer estudio consistió en observar cambios de SmO2 en reposo después de un periodo de pretemporada en jugadores de futbol y relacionarlo con la composición corporal y la potencia de salto. El cuarto estudio consistió en realizar una prueba de esfuerzo incremental con detección de zonas metabólicas: fatmax, umbrales de entrenamiento VT1 y VT2 y potencia aeróbica máxima para compararlo y relacionarlo con la SmO2.
Resultados y Discusión: En base a los objetivos de la tesis: Primero, en las jugadoras de futbol se encontró un aumento de mVO2 y SmO2 en reposo a las 24 h post partido oficial [(mVO2: 0.75 ± 1.8 vs 2.1± 2.7 μM-Hbdiff); (SmO2: 50 ± 9 vs 63 ± 12 %)]. Principalmente, este aumento es resultado de la correlación de la vasodilatación mediada por el flujo sanguíneo y el trasporte de oxígeno muscular que es un mecanismo implicado en los procesos de recuperación de la homeostasis del músculo esquelético y la restauración del equilibrio metabólico. El aumento del consumo de oxígeno se relacionó con la disminución de la potencia de salto (r= −0.63 p <0.05) y el aumento del lactato deshidrogenada (LDH) (r = 0.78 p <0.05) como marcadores de fatiga. Seguidamente en el segundo estudio, encontramos que la disminución del rendimiento durante una prueba de sprint repetidos, comienza con el aumento gradual de la SmO2, debido al cambio de la presión intramuscular y la respuesta hiperémica que conlleva, mostrando una disminución en la respuesta inter-individual [desaturación desde el cuarto sprint (Δ= 32%) y re-saturación después del sexto sprint (Δ= 89%)]. Además, la extracción de oxígeno por parte del músculo tiene una asociación no-lineal con la alta velocidad (r = 0.89 p <0.05) y con la fatiga mostrada el % decremento del sprint (r = 0.93 p <0.05).
En el estudio 3 se encontró que la dinámica de SmO2 en reposo es sensible a cambios después de un periodo de pretemporada (SmO2-Pendiente de recuperación: 15 ± 10 vs. 5 ± 5). Asimismo, se mostró que la SmO2 en reposo está relacionado paralelamente con el porcentaje de grasa del cuerpo (r= 0,64 p <0.05) y una relación inversa con la potencia de salto a una sola pierna (r = -0,82 p<0.01). Esto significa que a través del entrenamiento se mejoró el metabolismo y hemodinámica muscular con un tránsito más rápido del oxígeno muscular, y se asoció a las mejoras del peso corporal, somatotipo, CMJ y SLCMJ.
En el cuarto estudio, basado en los parámetros fisiológicos de una prueba de esfuerzo para prescribir ejercicio: se encontró una relación entre la SmO2 y el VO2max durante la zona fatmax y VT1 (r=0,72; p=0,04) (r=0,77; p=0,02) en mujeres con normo-peso. Sin embargo, en el grupo sobrepeso obesidad no se encontró ninguna correlación ni cambios de SmO2 entre cada zona metabólica.
Conclusión: La investigación de esta tesis ha demostrado avances en la medición de la SmO2. El uso de mVO2 y SmO2 en reposo es una variable de carga de trabajo que se puede utilizar para el estudio de la fatiga después de un partido de futbol femenino. Asimismo, la SmO2 en reposo puede ser interesante tomarlo en cuenta como un parámetro de rendimiento en futbolistas. Siguiendo el contexto, en el rendimiento durante una prueba de sprint repetidos, la SmO2 debe interpretarse basado en la respuesta individual del porcentaje de extracción de oxígeno muscular (∇%SmO2). El aporte de ∇%SmO2 es un factor de rendimiento limitado por la capacidad de velocidad y soporte de la fatiga de los futbolistas femeninos. Respecto a los aspectos de salud y prescripción del ejercicio, proponemos utilizar la SmO2 como un parámetro fisiológico para controlar y guiar el entrenamiento en zonas fatmax y VT1, pero solo en mujeres normo-peso. En patologías metabólicas como el sobrepeso y obesidad se necesitan más estudios. Como conclusión general, esta tesis muestra nuevas aplicaciones prácticas de cómo utilizar la SmO2 y su implicación en la fatiga, en contraste la adaptación al entrenamiento, pruebas de rendimiento y prescripción de la actividad física para la salud.
... En un interesante estudio (Christensen et al., 2011), se valoró los efectos del desentrenamiento comparando un grupo de futbolistas profesionales, que en la postemporada realizaron entrenamientos de alta intensidad y un grupo de cesación del entrenamiento, en este segundo grupo la cinética del VO2 se volvió más lenta, se redujo la cantidad de piruvato deshidrogenasa muscular y la actividad máxima de citrato sintasa y 3-hidroxiacil-CoA, todos factores que pueden explicar los resultados del presente estudio. El DES provoca importantes modificaciones fisiológicas como reducciones significativas en el volumen de plasma (Grivas, (Bangsbo & Michalsik, 2002). ...
The fact that soccer requires an aerobic base verified through a test of maximum oxygen consumption and identification of the appearance of ventilatory thresholds one and two is recognized. The SARCoV- 2 virus pandemic significantly affected professional football, generating a detraining situation in many clubs. The objective of the present study is to describe the effect of total and partial detraining for 11 weeks, on cardirespiratory parameters. The sample consisted of 26 soccer players belonging to a professional first division club in Paraguay. An ergometry with gas analysis was performed before and after the detraining period associated with the confinement of the pandemic. The results showed a 0.4% increase in body weight. -14.9% decrease in oxygen consumption in the first threshold; -17.4% in oxygen consumption in second threshold; -15.4% in maximum oxygen consumption; no significant changes in heart rate in first and second threshold as in maximum oxygen consumption (0.1, -0.2, 0.6 respectively); -4.7% in maximum aerobic speed and 13.5% in muscle efficiency. Detraining induced by quarantine can produce a significant loss of aerobic performance; detraining at the cardiorespiratory level seems to be more relevant than at the muscular level, based on the muscle efficiency parameter presented.
... Therefore an intermediate muscle typology might be expected in these sports. Multiple investigations on the muscle fiber typology in sub-elite soccer players, confirm a rather intermediate average muscle fiber type composition, as the mean percentage of ST fibers ranges between 40 to 62% ST fibers (J.L. Andersen et al., 1994;Christensen et al., 2011;Gunnarsson et al., 2012;Kuzon et al., 1990;Nyberg et al., 2016;Reilly et al., 2000). Nevertheless, data on elite soccer players is still missing. ...
The human skeletal muscle consists of two major cell types, slow-twitch fibers (also called type I fibers) and fast-twitch fibers (or type II fibers). These fibers have distinct characteristics, as fast-twitch fibers are able to generate a large amount of power at high shortening velocities, while slow-twitch fibers have a better energy efficiency, a higher resistance to fatigue and a more robust structural integrity. On average, most humans will dispose of a 50% slow-twitch and a 50% fast-twitch distribution. However a big heterogeneity exists, what results in people with predominantly slow or fast muscle fibers. The typology of a person is mostly genetically determined and is present across most muscles of the body. Taken together, the fact that muscle fibers have distinct characteristics and that muscle typologies range over the whole continuum from predominantly slow to fast in human, will have important implications for sports performance. Nevertheless, these typologies are currently not used in the daily coaching practice. This is probably due to the invasiveness of the current ‘gold’ standard to measure the muscle typology: a muscle biopsy, which is a labor intensive method and harbors a low generalizability. In 2011, our group introduced a non-invasive way to estimate the muscle fiber type composition through the measurement of carnosine – a metabolite which is abundantly available in fast-twitch fibers – using proton magnetic resonance spectroscopy (1H-MRS). The non-invasiveness of this technique enables the use in both the sports practice and science, and renews the interest of the muscle typology in sports. In the first study, the 1H-MRS method to determine the muscle typology was further optimized with the ultimate goal to make it applicable on various scanner systems of multiple vendors. 1H-MRS was found to be a reliable method to quantify carnosine in the muscle. Furthermore, best practices were proposed to prevent often encountered methodological problems and step by step guidelines were developed to allow broader utilization of this technique. Secondly, we investigated if pre-puberty carnosine measurements could give insights in the post-puberty carnosine concentrations, which would allow application of this technique in early specialization sports (study 2). Carnosine was shown to be a trackable metabolite through the disruptive puberty period (R2=0.249-0.670), which confirms the potential of the current technique to scan both future talents and elite athletes. Next to the methodological optimization, the relevance of the muscle typology for talent identification was examined. Before the start of the thesis, the construct validity of our method was already confirmed in athletics, in which clear differences were determined in the muscle typology of either sprint or endurance disciplines. Despite the fact that a comparable distribution of the muscle typologies could be expected in other cyclic sports such as cycling and swimming, this was not yet investigated in elite athletes. Therefore, study 3 established the muscle typologies of 80 world-class cyclists. Clear differences were found in the muscle typology between cycling events. Keirin, bicycle motocross racing (BMX), sprint and 500 m to 1 km time trial cyclists can be considered as fast typology athletes. Time trial, points race, scratch, and omnium consist of intermediate typology athletes, while most individual pursuit, single-stage, cyclo-cross, mountain bike, and multistage cyclists have a slow typology. Nevertheless, this distribution was not present in 73 elite swimmers (study 4), as no clear differences in the muscle typology were detected between short and long distance swimming events in the different strokes. However, there was some evidence to suggest that truly world-class sprint swimmers had a faster muscle fiber type composition when compared to elite swimmers competing at the international level. Moreover, breaststroke swimmers were identified to have a faster muscle typology in comparison to the either freestyle, backstroke or butterfly swimmers. Elite soccer players (n=118) were found to have an on average intermediate typology, which matches with the intermittent nature of this sport (study 6). In contrary to our hypothesis, no differences in the muscle typology were detected between different positions (keeper, defender, midfielder and striker). A big heterogeneity was established over all positions, indicating that the muscle typology is not of major importance for talent identification in soccer. To determine the influence of the muscle typology on individualized training and recovery cycles, we investigated if fatigue and recovery were different when both slow and fast typology subjects were exposed to the same high-intensity training (study 5). Fatigue during three Wingate tests, determined by the power drop, was 20% higher in fast typology athletes. Even though the same work was done during these Wingate tests, also the recovery from these Wingate tests was found to be 15 times slower in fast typology athletes (20 min in slow typology vs. longer than 5 h in fast typology). If a training plan would be composed with a minimum of recovery in between the training sessions, recovery might be insufficient for fast typology athletes, possibly rendering them with a higher risk for muscle strains. In study 6, we studied if the muscle typology is a risk factor for muscle strains in elite soccer players. We discovered that fast typology soccer players had a 5.3 times higher chance to get a hamstring injury, when compared to slow typology soccer players during a prospective longitudinal follow-up study over three seasons. Next to a higher accumulation of fatigue, a higher vulnerability in fast typology players could be expected due to the lower structural integrity in fast fibers. Bringing together, the muscle typology is an important characteristic, which could be non-invasively monitored using 1H-MRS. This technique could help athletes to make a scientific based decision on their ideal discipline during talent orientation. Moreover, it could help coaches tailoring training to enlarge the athletes’ muscle potential and to prevent fatigue accumulation. This endeavor might partly prevent fast typology athletes to be at a higher risk for strain injuries. Consequently, we believe that measuring the muscle fiber typology of athletes should be considered as a valuable procedure to help athletes to fully develop their potential based on the smart use of muscle profiling.
... The "signal" or the usually observed change following a training program in soccer players is also generally greater in the distance-related tests than in the speed-related tests. Namely, the mean change following training programs comprised of different HIIT formats [18] (i.e., long interval HIIT, short interval HIIT, repeated sprint training (RST), sprint interval training (SIT) and small-sided games (SSG)) lasting from 2 to 12 weeks in soccer players averages 2.7% for UMTT or Vam Eval test [80][81][82][83][84][85] (Table 1), 6.7% for 20mSRT [67,68,[86][87][88][89] (Table 2), 18.8% for Yo-YoIRT1 [58,68,74,85, (Table 3), 16.5% for Yo-YoIRT2 [74,77,[111][112][113][114][115][116][117] (Table 4) and 9.1% for 30-15IFT [58,84,[118][119][120][121] (Table 5). Although solid conclusions cannot be made due to the differences in duration and experimental designs of the studies it is interesting to notice that training programs comprised of short interval HIIT offered the greatest improvements in UMTT, 20mSRT and 30-15IFT. ...
A desire to make fitness testing cheaper and easier to conduct in a team-sport setting has led to the development of numerous field aerobic fitness tests. This has contributed to a growing confusion among strength and conditioning coaches about which one to use. The main aim of this narrative review was to examine the reliability, validity, sensitivity and usefulness of the commonly used field aerobic fitness tests and to provide practical guidelines for their use in soccer. The University of Montreal track test (UMTT) and Vam Eval test seem the best options for estimation of maximal oxygen uptake (VO2max) while the highest signal-to-noise ratio of the 30-15 intermittent fitness test (30-15IFT) suggests its superior sensitivity to track changes in fitness. The UMTT and 30-15IFT are the best solutions for prescription of long and short high-intensity interval training sessions, respectively. All field tests mostly present with marginal usefulness, but the smallest worthwhile change for UMTT or Vam Eval test, Yo-YoIRT2 and 30-15IFT are smaller than their stage increment making the improvement of only one stage in the test performance already worthwhile. Strength and conditioning coaches are advised to choose the test based on their specific purpose of testing.
... It is a general observation that a period of intensified training enhances performance during intense exercise in endurance-trained individuals, despite the fact they experience no training-induced changes inVo 2max , aerobic capacity, Vo 2 -kinetics, capillarization, blood volume, hemoglobin mass, and muscle metabolic enzymes (117,119,304,318,(647)(648)(649)(650). In fact, performance enhancements are occasionally observed in these studies despite detriments in muscle oxidative enzymes (117,650) and capillarization (534) during the training period. ...
Exercise causes major shifts in multiple ions (e.g., K+ , Na+ , H+ , lactate- , Ca2+ , and Cl- ) during muscle activity that contributes to development of muscle fatigue. Sarcolemmal processes can be impaired by the trans-sarcolemmal rundown of ion gradients for K+ , Na+ , and Ca2+ during fatiguing exercise, while changes in gradients for Cl- and Cl- conductance may exert either protective or detrimental effects on fatigue. Myocellular H+ accumulation may also contribute to fatigue development by lowering glycolytic rate and has been shown to act synergistically with inorganic phosphate (Pi) to compromise cross-bridge function. In addition, sarcoplasmic reticulum Ca2+ release function is severely affected by fatiguing exercise. Skeletal muscle has a multitude of ion transport systems that counter exercise-related ionic shifts of which the Na+ /K+ -ATPase is of major importance. Metabolic perturbations occurring during exercise can exacerbate trans-sarcolemmal ionic shifts, in particular for K+ and Cl- , respectively via metabolic regulation of the ATP-sensitive K+ channel (KATP ) and the chloride channel isoform 1 (ClC-1). Ion transport systems are highly adaptable to exercise training resulting in an enhanced ability to counter ionic disturbances to delay fatigue and improve exercise performance. In this article, we discuss (i) the ionic shifts occurring during exercise, (ii) the role of ion transport systems in skeletal muscle for ionic regulation, (iii) how ionic disturbances affect sarcolemmal processes and muscle fatigue, (iv) how metabolic perturbations exacerbate ionic shifts during exercise, and (v) how pharmacological manipulation and exercise training regulate ion transport systems to influence exercise performance in humans. © 2021 American Physiological Society. Compr Physiol 11:1895-1959, 2021.
... The fitness level of the players participating in this experiment was lower than that of the professional soccer players that were included in a previous study (Bradley et al., 2013). The Yo-Yo IL 2 results were lower than those of European professional soccer players (Christensen et al., 2011). These differences in fitness levels can be attributed to differences in league levels, measurement timing, and conditions. ...
Exercise performance is reduced in hot environments due to physiological responses caused by increased body temperature. A proper residential environment is important for improving the performance and maintaining physical condition of soccer players in the summer. The purpose of this study was to determine the effect of indoor temperature of the resting space during the summer on the fitness and condition of soccer players. A total of 12 K-3 League semiprofessional players without serious injuries in the last 3 months voluntarily participated in the study. Participants performed speed (10 m, 20 m, and 30 m), soccer-specific coordination skill (dribbling), agility, repeated sprints, Yo-Yo intermittent level 2, vertical jump, and questionnaire (fatigue, sleep quality, muscle soreness, stress, and mood) after staying indoor temperature at 20°C, 26°C, and 30°C for one night, respectively. There was no difference among groups in physical fitness (speed, agility, jump, coordination, Yo-Yo intermittent level 2, and repeated sprints). The differences in fatigue and sleep quality were not statistically significant among groups, but they tended to be different. Muscle soreness was similar among all groups. Significant differences were observed between the 20°C and 30°C groups in stress and mood levels. The present study concluded that, while the physical fitness did not differ among groups, the 30°C residential environment was shown to have a negative psychological effect. Considering that many diseases associated with hot weather occur in low residential temperatures, a room temperature of 26°C is recommended for elite soccer players in hot summer weather.
... Short-term (1 and 2 weeks) detraining appears not to have any significant effects on Yo-Yo intermittent test in professional soccer players (Joo, 2016;Rodríguez-Marroyo et al., 2018). In contrast, other studies found that the short-term detraining period (2 weeks) decreased performance in the Yo-Yo test (Thomassen et al., 2010;Christensen et al., 2011;Joo, 2018). This contradiction may be due to the expertise level of players (Joo, 2018). ...
The present study aimed to verify the quarantine's effects during a serious viral outbreak on the cardiovascular and performance associated with the Yo-Yo test in a sample of professional soccer players. 20 high-level soccer players (n = 20; age: 26 ± 4 years-old; weight: 76.85 ± 6.7 kg; height: 179 ± 6 cm) participated in this study. The intermittent Yo-Yo test was performed pre-and post-COVID-19 quarantine in a random order. During each test, the soccer players' running performance outcomes were monitored using a portable 5-Hz GPS with a 100 Hz accelerometer and a paired t-test was conducted at a p-value of ≤ 0.05. The main results demonstrated significant differences between pre-versus post-COVID-19 quarantine in the following variables: relative distance (161.7 ± 5.9 > 141.1 ± 33.8 m/min), maximal speed (18.7 ± 0.9 > 18.2 ± 0.6 km/h), acceleration (60 ± 20 frequency > 52 ± 16 frequency), deceleration (34 ± 13 frequency > 27 ± 6 frequency), sprints > 19 km/h [0.8 (0.2;3)% >0.5 (0;0.5)%], and in high intensity running distance [16.48 (2.68;41.64)m > 0.827 (0.164;3.0)m]. We concluded that COVID-19-related restrictions and quarantine COVID-19 demonstrated adverse effects on professional soccer players' Yo-Yo tests performance.
... Thus, exploration of training regimes allowing training quality to be upheld while residing at terrestrial altitude, i.e. 'live high-train high', is warranted. In normoxia, various protocols of high-intensity interval training have continuously proven efficient for improving aerobic and anaerobic exercise capacity in both healthy [5,6] and trained [7,8] individuals. Specifically, sprint-interval training (SIT) performed as four to six 30 s Wingate sprints performed in cycle-ergometers interspersed with 2-4 min of passive recovery [9] is a highly efficient training paradigm to improve maximal oxygen uptake ( _ VO 2max ) and anaerobic performance both in healthy and untrained individuals [10][11][12] as well as trained individuals [13,14]. ...
Sprint-interval training (SIT) is efficient at improving maximal aerobic capacity and anaerobic fitness at sea-level and may be a feasible training strategy at altitude. Here, it was evaluated if SIT intensity can be maintained in mild to moderate hypoxia. It was hypothesized that 6 x 30 s Wingate sprint performance with 2 min active rest between sprints can be performed in hypoxic conditions corresponding to ~3,000 m of altitude without reducing mean power output (MPO). In a single-blinded, randomized crossover design, ten highly-trained male endurance athletes with a maximal oxygen uptake ( V ˙ O 2max ) of 68 ± 5 mL O 2 × min ⁻¹ × kg ⁻¹ completed 6 x 30 s all-out Wingate cycling sprints separated by two-minute active recovery on four separate days in a hypobaric chamber. The ambient pressure within the chamber on each experimental day was 772 mmHg (~0 m), 679 mmHg (~915 m), 585 mmHg (~ 2,150 m), and 522 mmHg (~3,050 m), respectively. MPO was not different at sea-level and up to ~2,150 m (~1% and ~3% non-significant decrements at ~915 and ~2,150 m, respectively), whereas MPO was ~5% lower (P<0.05) at ~3,050 m. Temporal differences between altitudes was not different for peak power output (PPO), despite a main effect of altitude. In conclusion, repeated Wingate exercise can be completed by highly-trained athletes at altitudes up to ~2,150 m without compromising MPO or PPO. In contrast, MPO was compromised in hypobaric hypoxia corresponding to ~3,050 m. Thus, SIT may be an efficient strategy for athletes sojourning to moderate altitude and aiming to maintain training quality.
... For this reason, football players have been provided with different strategies, both for training and recovery, to reduce the negative impact of the confinement period on their fitness and endurance capacity. Training sessions combining multi-vector strength exercises involving eccentric contraction with a high speed of execution [4] and High Intensity Interval Training (HIIT) seems to be efficient to maintain physical fitness [5]. Tools such as individual questionnaires could be used to control the rated perceived exertion (RPE) or wellness [6][7][8]. ...
Background
Coronavirus disease 2019 (COVID-19) has restricted freedom of movement with several countries ‘locked down’ worldwide. During this isolation period or quarantine, habits have been modified. This might have had negative effects on physiological variables but also influenced numerous emotional aspects, especially in elite athletes, which can have a negative impact on training and sleep quality, affecting their performance.
Methods
175 Spanish professional and non-professional association football players answered an online survey about demographic and training habits, as well as two validated questionnaires to assess psychological variables (POMS and WLEIS-S).
Results
The results showed that the confinement period reduced the load of training (p < 0.01), and modified the sleeping behaviour (both, sleep time (p < 0.05) and quality (p < 0.001)) across soccer players. Higher emotional intelligence (EI) values were positively related to training variables and strongly correlated with the mood. Interestingly, athletes’ mood was affected differently depending on gender.
Conclusion
We found that confinement period affects both, training load and recovery process and that mood states and EI could predict the training variables and performance of top-level football players.
... 10,31 Indeed, increases in skeletal muscle mitochondrial biogenesis and mitochondrial enzyme activity (e.g., citrate synthase activity) have been observed after 2 weeks of HIIT in normal healthy individuals, 7À10,39 unhealthy populations, 31 and even highly trained athletes. 40 Considering that a single session of HIIT activates adenosine monophosphate-activated protein kinase and p38 mitogen-activated protein kinase, 41 which phosphorylate and activate PGC-1a and turns on mitochondrial biogenesis, 16,41 it will be important to determine if there are increases in mitochondrial biogenesis and mitochondrial enzyme activities even after the second day of 5 days of HIIT-D. ...
High-intensity interval training (HIIT) induces similar or even superior adaptations compared to continuous endurance training. Indeed, just 6 HIIT sessions over 2 weeks significantly improves VO2max, submaximal exercise fat oxidation and endurance performance. Whether even faster adaptations can be achieved with HIIT is not known. Thus, we aimed to determine whether 2 sessions of HIIT per day, separated by 3 h, every other day for 5 days (double HIIT, HIIT-D, n = 15 participants) can increase VO2max, submaximal exercise fat oxidation and endurance capacity as effectively as 6 sessions of HIIT over 2 weeks (single HIIT, HIIT-S, n = 13). Each training session consisted of 10*60 s of cycling at 100% of VO2max interspersed with 75 s of low-intensity cycling at 60 W. Pre- and post-training assessments included VO2max, time to exhaustion at ∼80% of VO2max and 60-min cycling trials at ∼67% of VO2max. Similar increases (p < 0.05) in VO2max (HIIT-D 7.7% vs. HIIT-S 6.0%, p > 0.05) and endurance capacity (HIIT-D 80.1%, HIIT-S 79.2%, p > 0.05) were observed in the 2 groups. Submaximal exercise CHO oxidation was reduced in the 2 groups after exercise training (HIIT-D 9.2%, p = 0.14 vs. HIIT-S 18.8%, p = 0.14) while submaximal exercise fat oxidation was significantly increased in HIIT-D (15.5%; p = 0.048) but not in HIIT-S (9.3%; p = 0.290).
In summary, 6 HIIT sessions over 5 days was as effective in increasing VO2max and endurance capacity and was more effective in improving submaximal exercise fat oxidation than 6 HIIT sessions over 2 weeks.
... Even though HIIT has been widely used in practice, it is seldom used as a testing protocol [13,14], with INC being used to plan the training calendar. Very few studies with small groups of soccer players have used intermittent running tests (e.g., YO-YO intermittent recovery test) to determine changes in performance after the players followed HIIT training [15][16][17][18]. To date, none have considered the relationship between INC and HIIT protocols in evaluating the performance of professional team players. ...
This descriptive study aimed to explore the physiological factors that determine tolerance to exertion during high-intensity interval effort. Forty-seven young women (15–28 years old) were enrolled: 23 athletes from Taiwan national or national reserve teams and 24 moderately active females. Each participant underwent a maximal incremental INC (modified Bruce protocol) cardiopulmonary exercise test on the first day and high-intensity interval testing (HIIT) on the second day, both performed on a treadmill. The HIIT protocol involved alternation between 1-min effort at 120% of the maximal speed, at the same slope reached at the end of the INC, and 1-min rest until volitional exhaustion. Gas exchange, heart rate (HR), and muscle oxygenation at the right vastus lateralis, measured by near-infrared spectroscopy, were continuously recorded. The number of repetitions completed (Rlim) by each participant was considered the HIIT tolerance index. The results showed a large difference in the Rlim (range, 2.6–12.0 repetitions) among the participants. Stepwise linear regression revealed that the variance in the Rlim within the cohort was related to the recovery rates of oxygen consumption (), HR at the second minute after INC, and muscle tissue saturation index at exhaustion (R = 0.644). In addition, age was linearly correlated with Rlim (adjusted R = −0.518, p < 0.0001). In conclusion, the recovery rates for and HR after the incremental test, and muscle saturation index at exhaustion, were the major physiological factors related to HIIT performance. These findings provide insights into the role of the recovery phase after maximal INC exercise testing. Future research investigating a combination of INC and HIIT testing to determine training-induced performance improvement is warranted.
... 13,14 This observation indicates that prolonged reductions in-or loss of voluntary muscle activation can convert the type 1 fibers to type 2 fibers. However, in studies of persons with intact nerve supply, decreased physical activity patterns such as detraining and immobilization have reported both reductions, 15,16 increases 17 and no change 11,12 in the type 1 muscle fiber proportion. Presently, it seems uncertain whether changes in the muscle fiber type 1 proportions occur in response to patterns of reduced physical activity under normal physiological conditions. ...
The main objective of this systematic review was to examine the effect of reduced muscle activity on the relative number of type 1 muscle fibers (%) in the human vastus lateralis muscle. Other objectives were changes in type 2A and 2X percentages and muscle fiber cross‐sectional area. We conducted systematic literature searches in eight databases and included studies assessing type 1 fiber percentage visualized by ATPase‐ or immunohistochemical staining before‐ and after a period (≥ 14 days) of reduced muscle activity. The reduced muscle activity models were detraining, leg unloading and bed rest. Forty‐two studies comprising 451 participants were included. Effect sizes were calculated as the mean difference between baseline and follow‐up and Generic Inverse Variance tests with random effects models was used for the weighted summary effect size. Overall, the mean type 1 muscle fiber percentage was significantly reduced after interventions (‐1.94 %‐points, 95 % CI [‐3.37, ‐0.51], p = 0.008), with no significant differences between intervention models (p = 0.86). Meta‐regression showed no effect of study duration on type 1 fiber percentage (p = 0.98). Conversely, the overall type 2X fiber percentage increased after reduced muscle activity (p < 0.001). The CSA of the muscle fiber types decreased after the study period (all p‐values < 0.001) with greater reductions in type 2 than type 1 fibers (p < 0.001). The result of this meta‐analysis display that the type 1 muscle fiber percentage decrease as a result of reduced muscle activity, although the effect size is relatively small.
Consensus is lacking regarding whether high-intensity interval training (HIIT) effectively improves VO2max (VO2peak) in elite athletes (Athlete must be involved in regular competition at the national level). This meta-analysis compared the effects of HIIT and conventional training methods (continuous training, repeated-sprint training, high volume low-intensity training, high-intensity continuous running, sprint-interval training, moderate-intensity continuous training)on VO2max in elite athletes. Nine studies were included, comprising 176 elite athletes (80 female). Compared to that with conventional training, VO2max was significantly increased after HIIT (overall: 0.58 [0.30, 0.87], I2 = 0.49, P = 0.03; males: 0.41 [0.06, 0.76], I2 = 0%, P = 0.89). VO2max had positive training effects when the HIIT recovery period had an interval time ≥2 min (0.44 [0.03, 0.84], I2 = 0%, P = 0.99) and recovery phase intensity ≤40% (0.38 [0.05, 0.71], I2 = 0%, P = 0.96). Thus, HIIT shows superiority over conventional training methods in improving VO2max, promoting aerobic capacity, in elite athletes.
Humans are unique among terrestrial mammals in our manner of walking and running, reflecting 7 to 8 Ma of musculoskeletal evolution since diverging with the genus Pan. One component of this is a shift in our skeletal muscle biology towards a predominance of myosin heavy chain (MyHC) I isoforms (i.e. slow fibers) across our pelvis and lower limbs, which distinguishes us from chimpanzees. Here, new MyHC data from 35 pelvis and hind limb muscles of a Western gorilla (Gorilla gorilla) are presented. These data are combined with a similar chimpanzee dataset to assess the MyHC I content of humans in comparison to African apes (chimpanzees and gorillas) and other terrestrial mammals. The responsiveness of human skeletal muscle to behavioral interventions is also compared to the human-African ape differential. Humans are distinct from African apes and among a small group of terrestrial mammals whose pelvis and hind/lower limb muscle is slow fiber dominant, on average. Behavioral interventions, including immobilization, bed rest, spaceflight and exercise, can induce modest decreases and increases in human MyHC I content (i.e. -9.3% to 2.3%, n = 2033 subjects), but these shifts are much smaller than the mean human-African ape differential (i.e. 31%). Taken together, these results indicate muscle fiber content is likely an evolvable trait under selection in the hominin lineage. As such, we highlight potential targets of selection in the genome (e.g. regions that regulate MyHC content) that may play an important role in hominin skeletal muscle evolution.
Objective: The use of the aerobic system is especially relevant due to the duration of the soccer game. In fact, the correct development of the aerobic system benefits the soccer player giving greater energy efficiency because the continuous change of energy system due to the intermittent nature of the game causes a high consumption of glycogen. The purpose of the present study was to evaluate oxygen consumption by means of the Yo-Yo intermittent test and anthropometrical measures, and different COD (change of direction) tests in young soccer players and to observe their possible relationship. Methods: A total of forty-seven young male soccer players (age= 15.7 ± 1.2 years; height = 188.8 ± 5.8 cm, and body mass= of 75.7 ± 8.3 kg; 7.6 ± 2.0 years of experience) from the region of Baleares, Spain, performed the Yo-yo test and subsequently, COD was evaluated by tests in the following order (i) V-cut test; (ii) 505-COD test; and (iii) Illinois test.
Results: A correlation analysis between VO2max and BMI revealed a moderate negative correlation, r=-0.35, p=0.01, and between VO2max and 505-COD, showed a large negative correlation, r=-0.55, p=0.001.
Conclusions: The finding of the present study reveals that there is no relationship between VO2max and agility. Therefore, there is no single method to improve VO2max and agility since both are independent variables. The different agents involved should take this into account if they want to improve VO2max and plan some aerobic resistance exercises; and to improve agility they must plan agility exercises separately.
Keywords: Soccer; VO2max; Young soccer players; Change of direction; Agility.
Ice hockey is an intense team sport characterized by repeated bursts of fast‐paced skating, rapid changes in speed and direction and frequent physical encounters, which are performed in on‐ice shifts of ~30‐80 s interspersed with longer sequences of passive recovery, resulting in about 15‐25 min on‐ice time per player. Nearly 50% of the distance is covered at high‐intensity skating speeds and with an accentuated intense activity pattern in forwards compared to defensemen. During ice hockey match‐play both aerobic and anaerobic energy systems are significantly challenged, with the heart rate increasing toward maximum levels during each shift, and with great reliance on both glycolytic and phosphagen ATP provision. The high‐intensity activity pattern favors muscle glycogen as fuel, leading to pronounced reductions despite the relatively brief playing time, including severe depletion of a substantial proportion of individual ‐fast‐ and slow‐twitch fibres. Player‐tracking suggests that the ability to perform high‐intensity skating may be compromised in the final stages of a game, which is supported by post‐game reductions in repeated‐sprint ability. Muscle glycogen degradation, in particular in individual fibres, as well as potential dehydration and hyperthermia, may be prime candidates implicated in exacerbated fatigue during the final stages of a game, whereas multiple factors likely interact to impair exercise tolerance during each shift. This includes pronounced PCr degradation, with potential inadequate resynthesis in a proportion of fast‐twitch fibres in situations of repeated intense actions. Finally, the recovery pattern is inadequately described, but seems less long‐lasting than in other team sports.
Patients with hypertrophic cardiomyopathy (HCM) have historically been restricted from athletic participation because of the perceived risk of sudden cardiac death. More contemporary research has highlighted the relative safety of competitive athletics with HCM. However, lack of published data on reference values for cardiopulmonary exercise testing (CPET) complicates clinical management and counseling on sports participation in the individual athlete. We conducted a single-center, retrospective cohort study to investigate CPET in athletes with HCM and clinical characteristics associated with objective measures of aerobic capacity. We identified 58 athletes with HCM (74% male, mean age 18 ± 3 years, mean left ventricular (LV) wall thickness 20 ± 7 mm). LV outflow tract obstruction was present in 22 (38%). A total of 15 (26%) athletes were taking a β blocker (BB), but only 4 (7%) reported exertional symptoms. Overall, exercise capacity was mildly reduced, with a peak myocardial oxygen consumption (peak VO2) of 37.9 ml/min/kg (83% of predicted peak VO2). Both LV outflow tract obstruction and BB use were associated with reduced exercise capacity. Limited peak heart rate was more common in athletes taking BB (47% vs 9%, p = 0.002). At a mean 5.6 years follow-up, 5 patients underwent myectomy (9%), and 8 (14%) received an implantable cardioverter defibrillator (ICD) for primary prevention. One individual with massive LV hypertrophy experienced recurrent ICD shocks for ventricular fibrillation and underwent myectomy 7 years after initial evaluation and was no longer participating in sports. There were no deaths over the follow-up period. In conclusion, the prognostic role of CPET remains unclear in athletes with HCM. Mildly reduced exercise capacity was common; however, reduced peak VO2 did not correlate with symptom status or clinical outcomes. A significant proportion went on to require myectomy and/or ICD, thus highlighting the need for close follow-up. These data provide some initial insight into the clinical evaluation of "real world" athletes with HCM; however, further study is warranted to help guide shared decision-making, return-to-play discussions, and the potential long-term safety of competitive athletic participation.
Background and Study Aim. The COVID-19 pandemic has caused many athletes to interrupt their regular training programme. The change-of-direction performance is a highly critical parameter for fencing. This study aims to investigate the effects of the detraining process caused by the COVID-19 pandemic on the change-of-direction performance of fencers.
Material and Methods. The study sample comprised 15 fencers (11 males, 4 females) who were competitors in the U17-20 age categories (mean age: 15.75±1.51 years; height: 170.30±7.68 cm; weight: 65.16±10.83 kg) in Turkey. All participants were high school students. Branch-specific change-of-direction tests (4-2-2-4-m shuttle and 7-m repeat lunge ability) were measured in the middle of the competition season and after the detraining period. The detraining period lasted 31 weeks due to the pandemic process.
Results. The results showed that participants were slower in the post 7-m repeat lunge ability test (23.32±2.21 sec.) compared with the pre-test (22.38±1.58 sec.) and participants were slower in the post 4-2-2-4-m shuttle test (6.43±0.54 sec.) compared with the pre-test (5.84±0.33 sec.) (p
Bu çalışmanın amacı Covid-19 nedeniyle ara verilen KKTC Futbol K-Pet Süper Ligine geriye kalan 8 maçın oynanması için ara, hazırlık periyodu ve yarışma periyodu sorunlarının incelenmesidir. Covid-19 nedeniyle 7 Mart 2020 ile 18 Mayıs 2020 tarihleri arasında 72 gün ara verilmiş, 16 takımlı ve 30 maçlı sezonun oynanan 22 maç sonrası geriye kalan 8 maç oynanamamış ve ara verilmek zorunda kalınmıştır. Burada örnek alınan bir lig takımında bu süre içerisinde 17 sporcu üzerinde yapılan sorgulamada 3 oyuncu hiç antrenman yapamamış, 7 oyuncu ev/bahçede core antrenman, 4 oyuncu bisiklet antrenmanı ve 3 oyuncu koşu/kuvvet ve top antrenmanı yapmıştır. Bu süre içerisinde 7 oyuncunun vücut ağırlıkları aynı kalmış, 5 oyuncunun artmış ve 5 oyuncunun ise vücut ağırlıkları azalmıştır. 72 günlük aranın arkasına 18 Mayıs ile 20 Haziran 2020 tarihleri arası 33 günlük bir Hazırlık Periyodu uygulanmıştır. 21 Haziran-22 Temmuz 2020 tarihleri arasında 31 günlük bir Müsabaka Periyodu uygulanmış ve bu süre içerisinde geriye kalan 8 maç oynanmıştır. Normal olarak KKTC K-Pet Süper Ligi 15 Eylül 2019 ile Mayıs 2020 ortalarında 8 ayda sonlanması yerine Temmuz 2020 ortalarına kadar uzamış ve 11 ay sürmüştür. Çok istisna olan Covid-19 nedeniyle uzayan lig ve karşılaşılan sorunlar ulaşılabilen literatür ışığında çözülmeye çalışılmıştır.
This study aimed to evaluate the effect of high-intensity interval training shock microcycles (HIITSM) on endurance, running economy and change of direction economy in female soccer players. Nineteen sub-elite female soccer players were randomised to two groups: HIITSM (10 HIIT sessions over 13 days) or HIITTRAD (4 HIIT sessions over 13 days) interventions. Endurance performance was evaluated through the 30–15 intermittent fitness test (30–15IFT); running economy over a 5-min treadmill run; and change of direction economy over two conditions: (1) 5-min 20m shuttle run, and (2) 5-min 10m shuttle run. HIITSM significantly improved 30–15IFT scores compared to baseline (+4.4%, p=0.009; d=0.96) and 30–15IFT scores relative to HIITTRAD (p=0.002; d=2.01). There was no significant interaction (group×time) for running economy and change of direction economy. Pre- to post- intervention there was a significant main time effect for blood lactate over 20m and 10m shuttle runs (p<0.001 and p=0.037, respectively), with large (d=0.93) and moderate (d=0.53) changes observed for the HIITSM over the two distances, respectively. HIITSM may be more effective than HIITTRAD to improve 30–15IFT over shorter training periods but may not affect running economy and change of direction economy.
Purpose: To describe the effects of COVID-19 lockdown and a subsequent retraining on the training workloads, autonomic responses and performance of a group of elite athletes.
Methods: The training workloads and heart rate variability (HRV, assessed through the LnRMSSD) of seven elite badminton players were registered daily during 4 weeks of normal training (baseline), 7-10 weeks of lockdown, and 6-8 weeks of retraining. Physical performance was assessed at baseline and after each phase by means of a countermovement jump (CMJ) and the estimated squat 1-repetition maximum (1RM).
Results: A reduction in training workloads was observed in all participants during the lockdown (-63.7%), which was accompanied by a reduced HRV in all but one participant (-2.0%). A significant reduction was also observed for CMJ (-6.5%) and 1RM performance (-11.5%), which decreased in all but one participant after the lockdown. However, after the retraining phase all measures returned to similar values to those found at baseline. At the individual level there were divergent responses, as exemplified by one athlete who attenuated the reduction in training workloads and increased her performance during the lockdown, and another one who markedly reduced his workload and performance and got injured during the retraining phase.
Conclusions: Although there seems to be a large inter-individual variability, COVID-19 lockdown is likely to impose negative consequences on elite athletes, but these detrimental effects might be avoided by attenuating reductions in training workloads and seem to be overall recovered after 6-8 weeks of retraining.
In 2020, the world is suffering an unprecedented pandemic (coronavirus or COVID-19) that it is eliciting devastating consequences. This article has gathered the opinions of international soccer experts about the short-term and long-term effects of coronavirus quarantine on physical performance and injury incidence in high-level soccer players, by means of open-ended questions encouraging the expression of unrestricted opinions. In this way, the text aims to provide the reader with a compilation and comparison of knowledge from a practical perspective in order to understand how the coronavirus quarantine may affect the high-level players’ physical performance from the extensive experience and broad career of conditioning area professionals in top-level soccer teams around the world together with the knowledge provided by research.
This study investigated the repeated-sprint ability (RSA) physiological responses to a standardized, high-intensity, intermittent running test (HIT), maximal oxygen uptake (VO(2) (max)) and oxygen uptake (VO(2)) kinetics in male soccer players (professional (N = 12) and amateur (N = 11)) of different playing standards. The relationships between each of these factors and RSA performance were determined. Mean RSA time (RSA(mean)) and RSA decrement were related to the physiological responses to HIT (blood lactate concentration ([La(-)]), r = 0.66 and 0.77; blood bicarbonate concentration ([HCO(3)-]), r = -0.71 and -0.75; and blood hydrogen ion concentration ([H(+)]), r = 0.61 and 0.73; all p < 0.05), VO(2) (max) (r = -0.45 and -0.65, p < 0.05), and time constant (tau) in VO(2) kinetics (r = 0.62 and 0.62, p < 0.05). VO(2) (max) was not different between playing standards (58.5 +/- 4.0 vs. 56.3 +/- 4.5 mL.kg(-1).min(-1); p = 0.227); however, the professional players demonstrated better RSA(mean) (7.17 +/- 0.09 vs. 7.41 +/- 0.19 s; p = 0.001), lower [La-] (5.7 +/- 1.5 vs. 8.2 +/- 2.2 mmol.L(-1); p = 0.004), lower [H+] (46.5 +/- 5.3 vs. 52.2 +/- 3.4 mmol.L(-1); p = 0.007), and higher [HCO3-] (20.1 +/- 2.1 vs. 17.7 +/- 1.7 mmol.L(-1); p = 0.006) after the HIT, and a shorter in VO2 kinetics (27.2 +/- 3.5 vs. 32.3 +/- 6.0 s; p = 0.019). These results show that RSA performance, the physiological response to the HIT, and differentiate between professional- and amateur-standard soccer players. Our results also show that RSA performance is related to VO(2) max, tau, and selected physiological responses to a standardized, high-intensity, intermittent exercise.
The physiological determinants of performance in two Yo-Yo intermittent recovery tests (Yo-YoIR1 and Yo-YoIR2) were examined in 25 professional (n = 13) and amateur (n = 12) soccer players. The aims of the study were (1) to examine the differences in physiological responses to Yo-YoIR1 and Yo-YoIR2, (2) to determine the relationship between the aerobic and physiological responses to standardized high-intensity intermittent exercise (HIT) and Yo-Yo performance, and (3) to investigate the differences between professional and amateur players in performance and responses to these tests. All players performed six tests: two versions of the Yo-Yo tests, a test for the determination of maximum oxygen uptake (V(O)(2)(max)), a double test to determine V(O)(2) kinetics and a HIT evaluation during which several physiological responses were measured. The anaerobic contribution was greatest during Yo-YoIR2. V(O)(2)(max) was strongly correlated with Yo-YoIR1 (r = 0.74) but only moderately related to Yo-YoIR2 (r = 0.47). The time constant (tau) of V(O)(2) kinetics was largely related to both Yo-Yo tests (Yo-YoIR1: r = 0.60 and Yo-YoIR2: r = 0.65). The relationships between physiological variables measured during HIT (blood La(-), H(+), HCO(3) (-) and the rate of La(-) accumulation) and Yo-Yo performance (in both versions) were very large (r > 0.70). The physiological responses to HIT and the tau of the V(O)(2) kinetics were significantly different between professional and amateur soccer players, whilst V(O)(2)(max) was not significantly different between the two groups. In conclusion, V(O)(2)(max) is more important for Yo-YoIR1 performance, whilst tau of the V(O)(2) kinetics and the ability to maintain acid-base balance are important physiological factors for both Yo-Yo tests.
The present study examined muscle adaptations and alterations in work capacity in endurance-trained runners as a result of a reduced amount of training combined with speed endurance training. For a 6- to 9-wk period, 17 runners were assigned to either a speed endurance group with a 25% reduction in the amount of training but including speed endurance training consisting of six to twelve 30-s sprint runs 3-4 times/wk (SET group n = 12) or a control group (n = 5), which continued the endurance training ( approximately 55 km/wk). For the SET group, the expression of the muscle Na(+)-K(+) pump alpha(2)-subunit was 68% higher (P < 0.05) and the plasma K(+) level was reduced (P < 0.05) during repeated intense running after 9 wk. Performance in a 30-s sprint test and the first of the supramaximal exhaustive runs was improved (P < 0.05) by 7% and 36%, respectively, after the speed endurance training period. In the SET group, maximal O(2) uptake was unaltered, but the 3-km (3,000-m) time was reduced (P < 0.05) from 10.4 +/- 0.1 to 10.1 +/- 0.1 min and the 10-km (10,000-m) time was improved from 37.3 +/- 0.4 to 36.3 +/- 0.4 min (means +/- SE). Muscle protein expression and performance remained unaltered in the control group. The present data suggest that both short- and long-term exercise performances can be improved with a reduction in training volume if speed endurance training is performed and that the Na(+)-K(+) pump plays a role in the control of K(+) homeostasis and in the development of fatigue during repeated high-intensity exercise.
Beat-by-beat \( \dot{Q} \)
aO2 and breath-by-breath \( \dot{V} \)O2 were assessed in ten male subjects (24 ± 3.5 years; 78 ± 7.7 kg; 182 ± 5.6 cm) during cycling exercise at 50 W before and after a 14-day period of head-down tilt-bed rest (HDTBR). O2 deficit (DefO2) was calculated as the difference between the volume of O2 that would have been consumed if a steady state had been immediately attained minus that actually taken up during exercise. \( \dot{Q} \)
aO2 kinetics was described fitting the data with a non-linear mono-exponential model with time delay. Mean response times (MRT) of \( \dot{V} \)O2 and \( \dot{Q} \)
aO2 kinetics were then calculated. DefO2 and MRT of \( \dot{V} \)O2 response did not change after HDTBR, whereas MRT of \( \dot{Q} \)
aO2 kinetics increased. The invariance of \( \dot{V} \)O2 kinetics after HDTBR suggests that, although \( \dot{Q} \)
aO2 response became slower after HDTBR, it did not affect the kinetics of peripheral gas exchange, which probably remained under the control of local muscular mechanisms.
The physical demands in soccer have been studied intensively, and the aim of the present review is to provide an overview of metabolic changes during a game and their relation to the development of fatigue. Heart-rate and body-temperature measurements suggest that for elite soccer players the average oxygen uptake during a match is around 70% of maximum oxygen uptake (VO2max). A top-class player has 150 to 250 brief intense actions during a game, indicating that the rates of creatine-phosphate (CP) utilization and glycolysis are frequently high during a game, which is supported by findings of reduced muscle CP levels and severalfold increases in blood and muscle lactate concentrations. Likewise, muscle pH is lowered and muscle inosine monophosphate (IMP) elevated during a soccer game. Fatigue appears to occur temporarily during a game, but it is not likely to be caused by elevated muscle lactate, lowered muscle pH, or change in muscle-energy status. It is unclear what causes the transient reduced ability of players to perform maximally. Muscle glycogen is reduced by 40% to 90% during a game and is probably the most important substrate for energy production, and fatigue toward the end of a game might be related to depletion of glycogen in some muscle fibers. Blood glucose and catecholamines are elevated and insulin lowered during a game. The blood free-fatty-acid levels increase progressively during a game, probably reflecting an increasing fat oxidation compensating for the lowering of muscle glycogen. Thus, elite soccer players have high aerobic requirements throughout a game and extensive anaerobic demands during periods of a match leading to major metabolic changes, which might contribute to the observed development of fatigue during and toward the end of a game.
We studied the effect of an alteration from regular endurance to speed endurance training on muscle oxidative capacity, capillarization, as well as energy expenditure during submaximal exercise and its relationship to mitochondrial uncoupling protein 3 (UCP3) in humans. Seventeen endurance-trained runners were assigned to either a speed endurance training (SET; n = 9) or a control (Con; n = 8) group. For a 4-wk intervention (IT) period, SET replaced the ordinary training ( approximately 45 km/wk) with frequent high-intensity sessions each consisting of 8-12 30-s sprint runs separated by 3 min of rest (5.7 +/- 0.1 km/wk) with additional 9.9 +/- 0.3 km/wk at low running speed, whereas Con continued the endurance training. After the IT period, oxygen uptake was 6.6, 7.6, 5.7, and 6.4% lower (P < 0.05) at running speeds of 11, 13, 14.5, and 16 km/h, respectively, in SET, whereas remained the same in Con. No changes in blood lactate during submaximal running were observed. After the IT period, the protein expression of skeletal muscle UCP3 tended to be higher in SET (34 +/- 6 vs. 47 +/- 7 arbitrary units; P = 0.06). Activity of muscle citrate synthase and 3-hydroxyacyl-CoA dehydrogenase, as well as maximal oxygen uptake and 10-km performance time, remained unaltered in both groups. In SET, the capillary-to-fiber ratio was the same before and after the IT period. The present study showed that speed endurance training reduces energy expenditure during submaximal exercise, which is not mediated by lowered mitochondrial UCP3 expression. Furthermore, speed endurance training can maintain muscle oxidative capacity, capillarization, and endurance performance in already trained individuals despite significant reduction in the amount of training.
The rates of increase in O2 uptake (VO2) after step changes in work rate from 25 W to 60% of pretraining peak VO2 (VO2 peak) were measured at various times during an endurance training program (2 h/day at 60% pretraining VO2 peak). Seven untrained males [23 +/- 1 (SE) yr] performed a series of repeated step changes in work rate before training (PRE) and after 4 days (4D), 9 days (9D), and 30 days (30D) of training. VO2 kinetic responses were determined from breath-by-breath data averaged across four repetitions and analyzed using a two-component exponential model. Mean response time (time taken to reach 63% of steady-state VO2) was faster (P < 0.01) than PRE (38.1 +/- 2.6 s) at both 4D (34.9 +/- 2.4 s) and 9D (32.5 +/- 1.8 s) and was faster (P < 0.01) at 30D than at all other times (28.3 +/- 1.0 s). Blood lactate concentrations (after 6 min of cycling) were also lower at 4D and 9D than PRE (P < 0.01) and were lower at 30D than at all other times (P < 0.01). VO2 peak was unchanged from PRE (3.52 +/- 0.20 l/min) at 8D (3.55 +/- 0.20 l/min) but was increased (P < 0.01) at 30D (3.89 +/- 0.18 l/min). Muscle oxidative capacity (maximal citrate synthase activity) was not significantly increased until 30D (P < 0.01). It is concluded that at least part of the acceleration of whole body VO2 kinetics with endurance training is a rapid phenomenon, occurring before changes in VO2 peak and/or muscle oxidative potential.
This study examined the contribution of phosphocreatine (PCr) and aerobic metabolism during repeated bouts of sprint exercise. Eight male subjects performed two cycle ergometer sprints separated by 4 min of recovery during two separate main trials. Sprint 1 lasted 30 s during both main trials, whereas sprint 2 lasted either 10 or 30 s. Muscle biopsies were obtained at rest, immediately after the first 30-s sprint, after 3.8 min of recovery, and after the second 10-and 30-s sprints. At the end of sprint 1, PCr was 16.9 ± 1.4% of the resting value, and muscle pH dropped to 6.69 ± 0.02. After 3.8 min of recovery, muscle pH remained unchanged (6.80 ± 0.03), but PCr was resynthesized to 78.7 ± 3.3% of the resting value. PCr during sprint 2 was almost completely utilized in the first 10 s and remained unchanged thereafter. High correlations were found between the percentage of PCr resynthesis and the percentage recovery of power output and pedaling speed during the initial 10 s of sprint 2 (r = 0.84, P < 0.05 and r = 0.91, P < 0.01). The anaerobic ATP turnover, as calculated from changes in ATP, PCr, and lactate, was 235 ± 9 mmol/kg dry muscle during the first sprint but was decreased to 139 ± 7 mmol/kg dry muscle during the second 30-s sprint, mainly as a result of a ~45% decrease in glycolysis. Despite this ~41% reduction in anaerobic energy, the total work done during the second 30-s sprint was reduced by only ~18%. This mismatch between anaerobic energy release and power output during sprint 2 was partly compensated for by an increased contribution of aerobic metabolism, as calculated from the increase in oxygen uptake during sprint 2 (2.68 ± 0.10 vs. 3.17 ± 0.13 l/min; sprint 1 vs. sprint 2; P < 0.01). These data suggest that aerobic metabolism provides a significant part (~49%) of the energy during the second sprint, whereas PCr availability is important for high power output during the initial 10 s.
1. Changes in muscle strength, vastus lateralis fibre characteristics and myosin heavy-chain (MyoHC) gene expression were examined in 48 men and women following 3 weeks of knee immobilization and after 12 weeks of retraining with 1866 eccentric, concentric or mixed contractions. 2. Immobilization reduced eccentric, concentric and isometric strength by 47 %. After 2 weeks of spontaneous recovery there still was an average strength deficit of 11 %. With eccentric and mixed compared with concentric retraining the rate of strength recovery was faster and the eccentric and isometric strength gains greater. 3. Immobilization reduced type I, IIa and IIx muscle fibre areas by 13, 10 and 10 %, respectively and after 2 weeks of spontaneous recovery from immobilization these fibres were 5 % smaller than at baseline. Hypertrophy of type I, IIa and IIx fibres relative to baseline was 10, 16 and 16 % after eccentric and 11, 9 and 10 % after mixed training (all P < 0.05), exceeding the 4, 5 and 5 % gains after concentric training. Type IIa and IIx fibre enlargements were greatest after eccentric training. 4. Total RNA/wet muscle weight and ty I, IIa and IIx MyoHC mRNA levels did not change differently after immobilization and retraining. Immobilization downregulated the expression of type I MyoHC mRNA to 0.72-fold of baseline and exercise training upregulated it to 0.95 of baseline. No changes occurred in type IIa MyoHC mRNA. Immobilization and exercise training upregulated type IIx MyoHC mRNA 2.9-fold and 1.2-fold, respectively. For the immobilization segment, type I, IIa and IIx fibre area and type I, IIa and IIx MyoHC mRNA correlated (r = 0.66, r = 0.07 and r = -0.71, respectively). 5. The present data underscore the role muscle lengthening plays in human neuromuscular function and adaptation.
The main purpose of this study was to investigate the effects of an 8-wk severe interval training program on the parameters of oxygen uptake kinetics, such as the oxygen deficit and the slow component, and their potential consequences on the time until exhaustion in a severe run performed at the same absolute velocity before and after training. Six endurance-trained runners performed, on a 400-m synthetic track, an incremental test and an all-out test, at 93% of the velocity at maximal oxygen consumption, to assess the time until exhaustion. These tests were carried out before and after 8 wk of a severe interval training program, which was composed of two sessions of interval training at 93% of the velocity at maximal oxygen consumption and three recovery sessions of continuous training at 60--70% of the velocity at maximal oxygen consumption per week. Neither the oxygen deficit nor the slow component were correlated with the time until exhaustion (r = -0.300, P = 0.24, n = 18 vs. r = -0.420, P = 0.09, n = 18, respectively). After training, the oxygen deficit significantly decreased (P = 0.02), and the slow component did not change (P = 0.44). Only three subjects greatly improved their time until exhaustion (by 10, 24, and 101%). The changes of oxygen deficit were significantly correlated with the changes of time until exhaustion (r = -0.911, P = 0.01, n = 6). It was concluded that the decrease of oxygen deficit was a potential factor for the increase of time until exhaustion in a severe run performed after a specific endurance-training program.
The purpose of this study was to examine oxygen consumption (VO2) and heart rate kinetics during moderate and repeated bouts of heavy square-wave cycling from an exercising baseline. Eight healthy, male volunteers performed square-wave bouts of leg ergometry above and below the gas exchange threshold separated by recovery cycling at 35% VO2 peak. VO2 and heart rate kinetics were modeled, after removal of phase I data by use of a biphasic on-kinetics and monoexponential off-kinetics model. Fingertip capillary blood was sampled 45 s before each transition for base excess, HCO and lactate concentration, and pH. Base excess and HCO concentration were significantly lower, whereas lactate concentration and pH were not different before the second bout. The results confirm earlier reports of a smaller mean response time in the second heavy bout. This was the result of a significantly greater fast-component amplitude and smaller slow-component amplitude with invariant fast-component time constant. A role for local oxygen delivery limitation in heavy exercise transitions with unloaded but not moderate baselines is presented.
The purpose of this study was to examine the effect of 4 weeks of intense interval-training on the pulmonary off-transient oxygen uptake (V*O2) after running until exhaustion at the same absolute speed. Seven physical education students ran as follows in three maximal tests on a synthetic track (400 m) whilst breathing through a portable, telemetric metabolic analyser: firstly, in an incremental test which determined maximal oxygen uptake (V*O2max), the minimal speed associated with V*O2max (vV*O2max) and the speed at the lactate threshold ( v(LT)). Secondly, in two continuous severe intensity runs at 90% (R90) and 95% (R95) of vV*O2max. After training, the times to exhaustion ( t(lim)) at these two speeds (i.e. the time limits t(lim90) and t(lim95), respectively), were significantly increased at both speeds (+37% and +66% for t(lim90) and t(lim95), P=0.04 and 0.01, respectively) and v(LT) and vV*O2max were increased by 8% and 5%, respectively ( P<0.02). The time constants of the cardio-dynamic added to the metabolic phase (phases I+II) and of the slow phase (phase III) of oxygen kinetics in the on-transient phase decreased significantly after training ( P=0.05). However, the decrease in the time constants of oxygen kinetics in the on-transient phases II and III were not correlated with the improvement in performance (i.e. increase in t(lim)). After training the V*O2 off-transient phase was significantly faster [off-time constant (tau(off)) decreased significantly both after R90 and R95, P=0.03]. This decrease in tau(off) was correlated with the increase in t(lim90) ( r=0.795, P=0.03). The physiological factors best correlated with the increased performance after training were v(LT) for t(lim90) and vV*O2max for t(lim95).
The aim of this study was to assess physical fitness, match performance and development of fatigue during competitive matches at two high standards of professional soccer. Computerized time-motion analyses were performed 2-7 times during the competitive season on 18 top-class and 24 moderate professional soccer players. In addition, the players performed the Yo-Yo intermittent recovery test. The top-class players performed 28 and 58% more (P < 0.05) high-intensity running and sprinting, respectively, than the moderate players (2.43 +/- 0.14 vs 1.90 +/- 0.12 km and 0.65 +/- 0.06 vs 0.41 +/- 0.03 km, respectively). The top-class players were better (11%; P < 0.05) on the Yo-Yo intermittent recovery test than the moderate players (2.26 +/- 0.08 vs 2.04 +/- 0.06 km, respectively). The amount of high-intensity running, independent of competitive standard and playing position, was lower (35-45%; P < 0.05) in the last than in the first 15 min of the game. After the 5-min period during which the amount of high-intensity running peaked, performance was reduced (P < 0.05) by 12% in the following 5 min compared with the game average. Substitute players (n = 13) covered 25% more (P < 0.05) ground during the final 15 min of high-intensity running than the other players. The coefficient of variation in high-intensity running was 9.2% between successive matches, whereas it was 24.8% between different stages of the season. Total distance covered and the distance covered in high-intensity running were higher (P < 0.05) for midfield players, full-backs and attackers than for defenders. Attackers and full-backs covered a greater (P < 0.05) distance in sprinting than midfield players and defenders. The midfield players and full-backs covered a greater (P < 0.05) distance than attackers and defenders in the Yo-Yo intermittent recovery test (2.23 +/- 0.10 and 2.21 +/- 0.04 vs 1.99 +/- 0.11 and 1.91 +/- 0.12 km, respectively). The results show that: (1) top-class soccer players performed more high-intensity running during a game and were better at the Yo-Yo test than moderate professional players; (2) fatigue occurred towards the end of matches as well as temporarily during the game, independently of competitive standard and of team position; (3) defenders covered a shorter distance in high-intensity running than players in other playing positions; (4) defenders and attackers had a poorer Yo-Yo intermittent recovery test performance than midfielders and full-backs; and (5) large seasonal changes were observed in physical performance during matches.
It has frequently been demonstrated that prior heavy cycling exercise facilitates pulmonary O(2) kinetics at the onset of subsequent heavy exercise. This might be due to improved muscle perfusion via acidosis-induced vasodilating effects. However, it is difficult to measure the blood flow (BF) to the working muscles (via the femoral artery) during cycling exercise. We therefore selected supine knee extension (KE) exercise as an alternative, and investigated whether the faster O(2) kinetics in the 2nd bout was matched by proportionally faster BF kinetics to the exercising muscle. Nine healthy subjects (aged 21-44 years) volunteered to participate in this study. The protocol consisted of two consecutive 6-min KE exercise bouts in a supine position (work rate: 70-75% of peak power) separated by a 6-min baseline rest (EX1 to EX2). During the protocol, a pulsed Doppler ultrasound technique was utilized to continuously measure the BF in the right femoral artery. The protocol was repeated at least 6 times to characterize the precise kinetics. In agreement with previous studies using cycling exercise, the O(2) kinetics in the 2nd bout were facilitated compared with that in the 1st bout [mean +/-s.d. of the 'effective' time constant (tau): EX1, 68.6 +/- 15.9, versus EX2, 58.0 +/- 14.4 s. Phase II-tau: EX1, 48.7 +/- 9.0, versus EX2, 41.2 +/- 13.3 s. Empirical index of the slow component (Delta O(2(6-3))): EX1, 78 +/- 44, versus EX2, 57 +/- 36 ml min(-1) (P < 0.05)]. However, no substantial difference was observed for the facilitation of the femoral artery BF response to the 1st and 2nd exercise bouts [i.e. the 'effective'tau of the femoral artery BF: EX1, 40.8 +/- 16.9, versus EX2, 39.0 +/- 17.1 s (P > 0.05)]. It was concluded that the faster pulmonary O(2) kinetics during heavy KE exercise following prior heavy exercise was not associated with a similar modulation in the BF to the working muscles.
The purpose of this study was to test the hypothesis that subjects having a shorter time constant for the fast component of VO2 kinetics in a transition from rest to constant exercise would maintain their speed for a longer time during repeated sprint exercise (RSE). Eleven male soccer players completed a graded test, two constant exercises at 60% maximal aerobic speed and RSE, consisting of fifteen 40-m sprints alternated with 25 s of active recovery. All the tests were performed on the field (200 m indoor track). The parameters of the VO2 kinetics (time delay, time constant, and amplitude of the primary phase) during the two constant exercises were modeled. All subjects elicited VO2 during the RSE. A significant correlation was found between VO2 and the relative decrease in speed during the 15 sprints (r=0.71; p < 0.05), but not between VO2 and the cumulated time for the 15 sprints (r=0.48; p > 0.05). There were significant correlations between the time constant of the primary phase and the relative decrease in speed during the 15 sprints (r=0.80; p < 0.01) and the cumulated time for the 15 sprints (r=0.80; p < 0.01). These results suggest that individuals with faster VO2 kinetics during constant load exercise might also have a faster adjustment of VO2 during RSE leading to a shorter cumulated time and a lower relative decrease in speed during the 15 sprints.
The purpose of the present study was to examine the effect of unilateral lower limb suspension (ULLS) deconditioning on oxygen uptake kinetics. Eight healthy males underwent ULLS for 20 days and performed a series of 6-min square-wave transitions from rest to 60-W single-leg cycling exercises just before and after ULLS. To characterize the kinetics of the oxygen uptake response, a single exponential model was applied to the data until the end of the fast component omitted the first 15 s of the on-transit using a nonlinear least-squares fitting procedure. The following results were found: (i) the time constant of oxygen uptake was unchanged before and after ULLS; (ii) although there was no significant difference in the baseline and the asymptotic amplitude of the fast component, the asymptote, i.e., the absolute asymptotic amplitude of the fast component (the sum of the baseline and the asymptotic amplitude), and the end exercise oxygen uptake were decreased after ULLS; (iii) the contribution of the slow component to the total response of oxygen uptake was unchanged at pre- and post-ULLS. In conclusion, the asymptote in the fast component and the end exercise oxygen uptake were decreased after 20-d ULLS, though the response speed and the amplitude of the slow component of oxygen uptake were not changed. It is suggested that deconditioning as a result of limb disuse affects oxygen uptake response.
To investigate pyruvate dehydrogenase (PDH)-E1alpha subunit phosphorylation and whether free fatty acids (FFAs) regulate PDH activity, seven subjects completed two trials: saline (control) and intralipid/heparin (intralipid). Each infusion trial consisted of a 4-h rest followed by a 3-h two-legged knee extensor exercise at moderate intensity. During the 4-h resting period, activity of PDH in the active form (PDHa) did not change in either trial, yet phosphorylation of PDH-E1alpha site 1 (PDH-P1) and site 2 (PDH-P2) was elevated in the intralipid compared with the control trial. PDHa activity increased during exercise similarly in the two trials. After 3 h of exercise, PDHa activity remained elevated in the intralipid trial but returned to resting levels in the control trial. Accordingly, in both trials PDH-P1 and PDH-P2 decreased during exercise, and the decrease was more marked during intralipid infusion. Phosphorylation had returned to resting levels at 3 h of exercise only in the control trial. Thus, an inverse association between PDH-E1alpha phosphorylation and PDHa activity exists. Short-term elevation in plasma FFA at rest increases PDH-E1alpha phosphorylation, but exercise overrules this effect of FFA on PDH-E1alpha phosphorylation leading to even greater dephosphorylation during exercise with intralipid infusion than with saline.
The two Yo-Yo intermittent recovery (IR) tests evaluate an individual's ability to repeatedly perform intense exercise. The Yo-Yo IR level 1 (Yo-Yo IR1) test focuses on the capacity to carry out intermittent exercise leading to a maximal activation of the aerobic system, whereas Yo-Yo IR level 2 (Yo-Yo IR2) determines an individual's ability to recover from repeated exercise with a high contribution from the anaerobic system. Evaluations of elite athletes in various sports involving intermittent exercise showed that the higher the level of competition the better an athlete performs in the Yo-Yo IR tests. Performance in the Yo-Yo IR tests for young athletes increases with rising age. The Yo-Yo IR tests have shown to be a more sensitive measure of changes in performance than maximum oxygen uptake. The Yo-Yo IR tests provide a simple and valid way to obtain important information of an individual's capacity to perform repeated intense exercise and to examine changes in performance.
The present study examined muscle adaptations and alterations in work capacity in endurance-trained runners after a change from endurance to sprint training. Fifteen runners were assigned to either a sprint training (ST, n = 8) or a control (CON, n = 7) group. ST replaced their normal training by 30-s sprint runs three to four times a week, whereas CON continued the endurance training (approximately 45 km/wk). After the 4-wk sprint period, the expression of the muscle Na+-K+ pump alpha1-subunit and Na+/H+-exchanger isoform 1 was 29 and 30% higher (P < 0.05), respectively. Furthermore, plasma K+ concentration was reduced (P < 0.05) during repeated intense running. In ST, performance in a 30-s sprint test, Yo-Yo intermittent recovery test, and two supramaximal exhaustive runs was improved (P < 0.05) by 7, 19, 27, and 19%, respectively, after the sprint training period, whereas pulmonary maximum oxygen uptake and 10-k time were unchanged. No changes in CON were observed. The present data suggest a role of the Na+-K+ pump in the control of K+ homeostasis and in the development of fatigue during repeated high-intensity exercise. Furthermore, performance during intense exercise can be improved and endurance performance maintained even with a reduction in training volume if the intensity of training is very high.
The two Yo-Yo intermittent recovery (IR) tests evaluate an individual’s ability to repeatedly perform intense exercise. The Yo-Yo IR level 1 (Yo-Yo IR1) test focuses on the capacity to carry out intermittent exercise leading to a maximal activation of the aerobic system, whereas Yo-Yo IR level 2 (Yo-Yo IR2) determines an individual’s ability to recover from repeated exercise with a high contribution from the anaerobic system. Evaluations of elite athletes in various sports involving intermittent exercise showed that the higher the level of competition the better an athlete performs in the Yo-Yo IR tests. Performance in the Yo- Yo IR tests for young athletes increases with rising age. The Yo-Yo IR tests have shown to be a more sensitive measure of changes in performance than maximum oxygen uptake. The Yo-Yo IR tests provide a simple and valid way to obtain important information of an individual’s capacity to perform repeated intense exercise and to examine changes in performance.