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Abstract

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.

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Physical fitness is an important part of overall health and its level does not have a positive trend in the long term. High-intensity interval training (HIIT) is a popular form of exercise that has been repeatedly proven as a functional way of developing cardiorespiratory fitness. Air bike is a widespread cardio machine suitable for HIIT. The aim of this research was to verify the effect of HIIT using air bike on the development of selected physical fitness parameters and compare it to moderate-intensity continuous training (MICT). Twenty active young adults (age 22.1) took part in the research. The participants underwent a complex strength and endurance test, a spiroergometric examination, and a body composition analysis. The experimental group (EG) did HIIT twice a week with work intervals (15-45 seconds), while the control group did MICT in a comparable time period. The results have shown significant improvement in back squat (8.25 %), pulling strength (7.07 %), aerobic endurance (18.74 %), and VO2peak (10.62 %). Comparison of the groups has shown a significant difference in bench press (ES=1.01), back squat (ES=0.68), anaerobic endurance (ES=0.97), aerobic endurance (ES=1.456), and VO2peak (ES=0.92). According to the results, we can conclude that HIIT using air bike is an effective way of developing multiple aspects of physical fitness and is thus suitable for training programs that aim to develop health and sports performance.
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Background: High-intensity interval training (HIIT) is a well-established training modality to improve aerobic and anaerobic capacity. However, sex-specific aspects of different HIIT protocols are incompletely understood. This study aimed to compare two HIIT protocols with different recovery periods in moderately trained females and males and to investigate whether sex affects high-intensity running speed and speed decrement. Methods: Fifty moderately trained participants (30 females and 20 males) performed an exercise field test and were randomized by lactate threshold (LT) to one of two time- and workload-matched training groups. Participants performed a 4-week HIIT intervention with two exercise sessions/week: Group 1 (4 × 30,180 HIIT), 30-s all-out runs, 180-s active recovery and Group 2 (4 × 30,30 HIIT), 30-s all-out runs, 30-s active recovery. High-intensity runs were recorded, and speed per running bout, average speed per session, and speed decrement were determined. Blood lactate measurements were performed at baseline and follow-up at rest and immediately post-exercise. Results: Females and males differed in running speed at LT and maximal running speed determined during exercise field test (speed at LT, females: 10.65 ± 0.84 km h−1, males: 12.41 ± 0.98 km h−1, p < 0.0001; maximal speed, females: 14.55 ± 1.05 km h−1, males: 17.41 ± 0.68 km h−1, p < 0.0001). Estimated maximal oxygen uptake was ~52.5 ml kg−1 min−1 for females and 62.6 ml kg−1 min−1 for males (p < 0.0001). Analysis of HIIT protocols revealed an effect of sex on change in speed decrement (baseline vs. follow-up) in that females showed significant improvements only in the 4 × 30:30 HIIT group (p = 0.0038). Moreover, females performing the 4 × 30:30 protocol presented increased speed per bout and average speed per session at follow-up (all p ≤ 0.0204), while no effect was detected for females performing the 4 × 30:180 protocol. Peak blood lactate levels increased in all HIIT groups (all p < 0.05, baseline vs. follow-up), but males performing the 4 × 30:180 protocol showed no difference in lactate levels. Conclusions: If not matched for physical performance, females, but not males, performing a 4 × 30 HIIT protocol with shorter recovery periods (30 s) present increased average high-intensity running speed and reduced speed decrement compared to longer recovery periods (180 s). We conclude that female- and male-specific HIIT protocols should be established since anthropometric and physiological differences across sexes may affect training performance in real-world settings.
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Dolci, F, Kilding, AE, Chivers, P, Piggott, B, and Hart, NH. High-intensity interval training shock microcycle for enhancing sport performance: A brief review. J Strength Cond Res XX(X): 000-000, 2019-High-intensity interval training (HIIT) is a powerful strategy to develop athletes' fitness and enhance endurance performance. Traditional HIIT interventions involve multiple microcycles (7-10 days long) of 2-3 HIIT sessions each, which have been commonly supported to improve athletic performance after a minimum period of 6 weeks training. Regardless of the efficacy of such an approach, in recent years, a higher frequency of HIIT sessions within a unique microcycle, commonly referred to as an HIIT shock microcycle, has been proposed as an alternative HIIT periodization strategy to induce greater and more efficient endurance adaptation in athletes. This review article provides an insight into this new HIIT periodization strategy by discussing (1) HIIT shock microcycle format and design; (2) the sustainability of this training strategy; (3) effects on performance and physiological parameters of endurance; and (4) potential mechanisms for improvements. Evidence advocates the sustainability and effectiveness of HIIT shock microcycle in different athletes to improve intermittent and continuous running/cycling performance and suggests mitochondria biogenesis as the main acute physiological adaptation following this intervention.
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Background: It is unknown whether a concentrated period of small-sided games and high intensity training is an effective training approach in youth soccer players. The aim of the study was to examine the effect of a concentrated period of soccer specific training on physical fitness in youth players. Methods: Nineteen male soccer players, from two teams, participated (mean ± SD age: 16.2 ± 0.8 years; body mass: 58.2 ± 7.6 kg; height: 170.8 ± 7.7 cm). One team performed 5 days of small-sided games and high intensity training (SSG & HIT; n = 12) and the other team regular soccer training with 1 day of SSG and HIT (REG; n = 7) weekly for 4 weeks. The 30-15 intermittent fitness test (30-15 IFT), countermovement jump (CMJ) and change of direction (COD) performance were measured pre and post intervention. Heart rate (HR) and rating of perceived exertion (RPE) were recorded and session load calculated (RPE x minutes). Results: Average % of maximum HR and session load were 83% and 344 AU for the SSG & HIT vs 73% and 253 AU for the REG (P< 0.05). 30-15 IFT improved for the SSG & HIT (from 17.0 ± 1.1 to 18.4 ± 0.8 km/h; p< 0.05; ES = 0.57) with no difference for the REG group (Pre: 17.9 ± 1.3, Post: 18.2 ± 1.6 km/h, ES= 0.10). CMJ and COD were unchanged in both groups and no injuries were reported. Conclusions: A 4-week concentrated period of daily SSG & HIT is effective for improving endurance performance in youth soccer players. This was without injuries and without negating performance in power and change of direction.
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Objectives This study aimed to conduct the first injury surveillance study in sub-elite football in Australia, using methods from the international football consensus statement. Design Descriptive Epidemiological Study. Methods 1049 sub-elite football players were recruited during the 2016 season. Injury and exposure data was collected by trained Primary Data Collectors (PDCs) who attended every training session and match. Results There were 1041 time loss injuries recorded during 52127 h of exposure resulting in an injury incidence rate of 20 injuries/1000 h (95% Confidence Interval [CI]: 15.9–23.3). The injury burden (days lost to injury relative to exposure) was 228 days lost/1000 h. Muscle and ligament injuries were the most prevalent (41% and 26%) and incurred the highest injury burden (83 and 80 days lost/1000 h, respectively). The most common injuries were observed at the thigh (22%) and ankle (17%), with hamstring (13%) the highest reported muscle injury. The profile of injury severity was: mild − 35%; minor − 29%; moderate − 28% and severe − 8%. Recurrent injuries accounted for 20% of all injuries. Conclusion By addressing issues identified with injury recording in sub-elite football, this study found that the injury incidence was twice that observed in previous research in elite and sub-elite football cohorts. Injury burden was also twice that of the elite setting, with similar injuries associated with the highest burden. The results highlight the need for investment into medical provision, facilities, coach education and injury mitigation programmes to reduce healthcare costs to sub-elite players in Australia.
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Abstract: The purpose of this study was to compare the effects of two types of high-intensity interval training (HIIT) programs on aerobic and anaerobic capacity of female soccer players. Regional-level female athletes were randomly divided into heart rate-based HIIT (n = 8; age 23.4 ± 1.1 year) and speed-based HIIT groups (n = 8; age 23.4 ± 1.3 year). Athletes trained three days per week for six weeks. Before and after training, each athlete’s performance was assessed directly through the Hoff test, 30-15 Intermittent Fitness Test (VIFT), and repeated-sprint ability test (RAST); maximal oxygen consumption (VO2max), power and fatigue were estimated indirectly. Both experimental groups improved power, fatigue index and VO2max after training (p < 0.05). It was noteworthy that the speed-based group had greater gains in minimal power (effect size [ES]: 3.99 vs. 0.75), average power (ES: 2.23 vs. 0.33), and fatigue index (ES: 2.53 vs. 0.17) compared to heart rate-based group (p < 0.05). In conclusion, both heart rate-based and speed-based HIIT induced meaningful improvements in power, VO2max, and fatigue index in female soccer players, although the speed-based HIIT group achieved greater gains in power and fatigue index compared to the heart rate-based group.
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PURPOSE: The aim of this study was to examine the reliability, validity and usefulness of the 30-15IFT in competitive female soccer players. METHODS: Seventeen elite female soccer players participated in the study. A within subject test-retest study design was utilized to assess the reliability of the 30-15 intermittent fitness test (IFT). Seven days prior to 30-15IFT, subjects performed a continuous aerobic running test (CT) under laboratory conditions to assess the criterion validity of the 30-15IFT. End running velocity (VCT and VIFT), peak heart rate (HRpeak) and maximal oxygen consumption (VO2max) were collected and/or estimated for both tests. RESULTS: VIFT (ICC = 0.91; CV = 1.8%), HRpeak (ICC = 0.94; CV = 1.2%), and VO2max (ICC = 0.94; CV = 1.6%) obtained from the 30-15IFT were all deemed highly reliable (p>0.05). Pearson product moment correlations between the CT and 30-15IFT for VO2max, HRpeak and end running velocity were large (r = 0.67, p=0.013), very large (r = 0.77, p=0.02) and large (r = 0.57, p=0.042), respectively. CONCLUSION: Current findings suggest that the 30 -15IFT is a valid and reliable intermittent aerobic fitness test of elite female soccer players. The findings have also provided practitioners with evidence to support the accurate detection of meaningful individual changes in VIFT of 0.5 km/h (1 stage) and HRpeak of 2 bpm. This information may assist coaches in monitoring ‘real’ aerobic fitness changes to better inform training of female intermittent team sport athletes. Lastly, coaches could use the 30-15IFT as a practical alternative to laboratory based assessments to assess and monitor intermittent aerobic fitness changes in their athletes. Keywords: 30-15 intermittent fitness test, aerobic, cardiorespiratory fitness, intermittent activity, soccer, high intensity interval training.
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This study aimed to examine the effect of a five-week HIIT-based running plan on athletic performance, and to compare the physiological and neuromuscular responses during a sprint-distance triathlon before and after the HIIT period. Thirteen triathletes were matched into two groups: the experimental group (EG) and the control group (CG). The CG was asked to maintain their normal training routines while the EG maintained only their swimming and cycling routines and modified their running routine. Participants completed a sprint-distance triathlon before (pre-test) and after (post-test) the intervention period. In both pre- and post-tests, the participants performed four jumping tests: before the race (baseline), post-swim, post-cycling, and post-run. Additionally, heart rate was monitored (HRmean) while RPE and blood lactate accumulation (BLa) were registered after the race. No significant differences (P>=0.05) between groups were found before HIIT intervention (at pre-test). Significant group-by-training interactions were found in vertical jumping ability and athletic performance: the EG improved jumping performance (~6-9%, P<0.05, ES>0.7), swimming performance (P=0.013, ES=0.438) and running time (P=0.001, ES=0.667) during the competition; whereas the CG remained unchanged (P>=0.05, ES<0.4). No changes (P>=0.05, ES<0.4) were observed in RPE, HRmean and BLa. A linear regression analysis showed that [DELTA]CMJ predicted both the [DELTA]Ru_time (R2=0.559; P=0.008) and the [DELTA]Overall_time (R2=0.391; P=0.048). This low-volume, HIIT-based running plan combined with the high training volumes of these triathletes in swimming and cycling improved athletic performance during a sprint-distance triathlon. This improvement may be due to improved neuromuscular characteristics that were transferred into improved muscle power and work economy. Copyright (C) 2016 by the National Strength & Conditioning Association.
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The purpose of this investigation was to determine the reliability of the 30-15 Intermittent Fitness Test (30-15IFT) in semi-professional soccer players. Fourteen male semi-professional soccer players performed the 30-15IFT on two occasions, separated by 7 days. Reliability was assessed by intraclass correlation coefficient (ICC), typical error of measurement (TE) expressed as a coefficient of variation (CV), and smallest worthwhile change (SWC), to determine any significant difference between testing sessions. Maximal intermittent running velocity (VIFT) demonstrated good reliability (ICC = .80) for between session reliability. The CV was 2.5% for between session reliability of the 30-15IFT. As the SWC (0.70 km/h) falls within the range in which the individual's true score is likely to lie (1.0 km/h), the usefulness of the VIFT was rated as 'Marginal'. Despite the usefulness of the 30-15IFT being deemed 'Marginal', a change in performance as small as 1.0 km/h (2 stages) in VIFT could be considered substantial or 'real'. This study demonstrates that VIFT in the 30-15IFT is reliable, resulting in a reliable assessment of team-sport specific cardiorespiratory fitness, with changes as small as 1.0 km/h (2 stages) in VIFT considered meaningful.
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One possible reason for the continued neglect of statistical power analysis in research in the behavioral sciences is the inaccessibility of or difficulty with the standard material. A convenient, although not comprehensive, presentation of required sample sizes is provided. Effect-size indexes and conventional values for these are given for operationally defined small, medium, and large effects. The sample sizes necessary for .80 power to detect effects at these levels are tabled for 8 standard statistical tests: (1) the difference between independent means, (2) the significance of a product-moment correlation, (3) the difference between independent rs, (4) the sign test, (5) the difference between independent proportions, (6) chi-square tests for goodness of fit and contingency tables, (7) 1-way analysis of variance (ANOVA), and (8) the significance of a multiple or multiple partial correlation.
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The aim of this study was to develop and test the practical utility of a perceived recovery status (PRS) scale. Sixteen volunteers (8 men, 8 women) performed 4 bouts of high-intensity intermittent sprint exercise. After completion of the baseline trial, in a repeated-measures design, subjects were given variable counterbalanced recovery periods of 24, 48, and 72 hours whereupon they repeated an identical intermittent exercise protocol. After a warm-up period, but before beginning each subsequent bout of intermittent sprinting, each individual provided their perceived level of recovery with a newly developed PRS scale. Similar to perceived exertion during exercise, PRS was based on subjective feelings. The utility of the PRS scale was assessed by measuring the level of agreement of an individual's perceived recovery relative to their performance during the exercise bout. Perceived recovery status and change (both positive and negative) in sprint performance during multiple bouts of repeated sprint exercise were moderately negative correlated (r = -0.63). Additionally, subjects were able to accurately assess level of recovery using the PRS scale indicated by correspondence with negative and positive changes in total sprint time relative to their previous session. The ability to detect changes in performance using a noninvasive psychobiological tool to identify differences in performance was independent of other psychological and physiological markers measured during testing, because there were no differences (p > 0.05) among ratings of perceived exertion (RPE), heart rate, blood lactate concentration, or session RPE values among any of the performance trials. Although further study is needed, current results indicate a subjective approach may be an effective means for assessing recovery from day to day, at least under similar conditions.
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This article reviews the major physiological and performance effects of aerobic high-intensity and speed-endurance training in football, and provides insight on implementation of individual game-related physical training. Analysis and physiological measurements have revealed that modern football is highly energetically demanding, and the ability to perform repeated high-intensity work is of importance for the players. Furthermore, the most successful teams perform more high-intensity activities during a game when in possession of the ball. Hence, footballers need a high fitness level to cope with the physical demands of the game. Studies on football players have shown that 8 to 12 wk of aerobic high-intensity running training (> 85% HR(max)) leads to VO2(max) enhancement (5% to 11%), increased running economy (3% to 7%), and lower blood lactate accumulation during submaximal exercise, as well as improvements in the yo-yo intermittent recovery (YYIR) test performance (13%). Similar adaptations are observed when performing aerobic high-intensity training with small-sided games. Speed-endurance training has a positive effect on football-specific endurance, as shown by the marked improvements in the YYIR test (22% to 28%) and the ability to perform repeated sprints (approximately 2%). In conclusion, both aerobic and speed-endurance training can be used during the season to improve high-intensity intermittent exercise performance. The type and amount of training should be game related and specific to the technical, tactical, and physical demands imposed on each player.
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Females have often been reported to have a greater muscle fatigue resistance than males, especially during exercise at low-to-moderate intensities. Differences in muscle mass, muscle metabolism and voluntary activation patterns have been the primary explanations for the differences in performance and physiological responses to exercise between sexes. However, while ample data are available for isometric contractions, dynamic activity is a less studied mode of exercise, and there is even less information regarding multiple-sprint exercise (MSE). This is surprising given that MSE places unique demands on metabolic processes in the muscle where energy supply oscillates between fuelling contractile activity and restoring homeostasis. As such, MSE provides a rich area for future applied research. This review examines the limited data available concerning the physiological responses of males and females to sprint exercise, and discusses the methodological confounds arising from non-appropriate comparison methods. Based on original findings, we highlight that sex differences in the absolute mechanical work performed during a given task might explain a significant part of the differences in physiological responses of males and females to sprint exercise. We therefore suggest that future studies using male and female subjects to answer basic physiological questions use mechanical work as a covariate.
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For almost 80 years, physiological studies have attempted to explain endurance performance and to develop ways of improving it by training. Performance for a runner can be represented by the relation of his/her personal power (velocity) to time to exhaustion (time limit).1 There are particular velocities that delineate intensity domains which are determined by oxygen uptake (V̇o2) and blood lactate response versus time.2,3 We are going to use them to define the slow phase of V̇o2 kinetics V̇o2 slow component) which only appears during intense exercise. A high range of work can be identified at which there is a sustained increase in blood lactate and a decrease in arterial pH with time. These responses decline back towards a baseline value. Oxygen uptake increases in a monoexponential way and stabilises at about 80% in high level marathon runners for at least an hour and a half of continuous exercise. After that time, it is possible for oxygen consumption to increase because of thermoregulatory constraints, and this increase is called the “V̇o2 drift”. This intensity of exercise corresponds to the velocity that can be sustained during a marathon and is equal to about 80% of the velocity associated with V̇o2max determined in an incremental test—that is, vV̇o2max.4 During this type of exercise both lipids and carbohydrate are used as fuel. At a higher intensity, the maximal lactate steady state occurs5 when the rate of appearance of blood lactate equals the rate of its disappearance. V̇o2 stabilises after three minutes at about 85% V̇o2max. This corresponds to the highest velocity that an athlete can sustain for an hour (85% vV̇o2max for a well trained …
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To compare aerobic capacity of young and adult elite soccer players using appropriate scaling procedures. Twenty four male adult (mean (SD) age 24 (2) years, weight 75.7 (7.2) kg, VO2max 66.6 (5.2) ml/lbm/min, where lbm is lean body mass in kg) and 21 youth (14 (0.4) years, 60.2 (7.3) kg, 66.5 (5.9) ml/lbm/min) elite soccer players took part in the study. Allometric equations were used to determine the relation between maximal and submaximal oxygen cost of running (running economy) and body mass. Maximal and submaximal oxygen uptake increased in proportion to body mass raised to the power of 0.72 (0.04) and 0.60 (0.06) respectively. The VO2max of adult players was similar to that of the youth players when expressed in direct proportion to body mass--that is, ml/kg/min--but 5% higher (p<0.05) when expressed using appropriate procedures for scaling. Conversely, compared with seniors, youth players had 13% higher (p<0.001) energy cost of running--that is, poorer running economy--when expressed as ml/kg/min but not when expressed according to the scaling procedures. Compared with the youth soccer players, VO2max in the seniors was underestimated and running economy overestimated when expressed traditionally as ml/lbm/min. The study clearly shows the pitfalls in previous studies when aerobic capacity was evaluated in subjects with different body mass. It further shows that the use of scaling procedures can affect the evaluation of, and the resultant training programme to improve, aerobic capacity.
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Bioenergetic interpretations of energy transfer specify that rapid anaerobic, substrate-level adenosine triphosphate (ATP) turnover with lactate production is not appropriately represented by an oxygen uptake measurement. Two types of weight training, 60% of 1 repetition maximum (1RM) with repetitions to exhaustion and 80% of 1RM with limited repetitions, were compared to determine if blood lactate measurements, as an estimate of rapid substrate-level ATP turnover, provide a significant contribution to the interpretation of total energy expenditure as compared with oxygen uptake methods alone. The measurement of total energy expenditure consisted of blood lactate, exercise oxygen uptake, and a modified excess postexercise oxygen consumption (EPOC); oxygen uptake-only measurements consisted of exercise oxygen uptake and EPOC. When data from male and female subjects were pooled, total energy expenditure was significantly higher for reps to exhaustion (arm curl, +27 kJ; bench press, +27 kJ; leg press, +38 kJ; p < 0.03) and limited reps (arm curl, +12 kJ; bench press, +23 kJ; leg press, + 24 kJ; p < 0.05) when a separate measure of blood lactate was part of the interpretation. When the data from men and women were analyzed separately, blood lactate often made a significant contribution to total energy expenditure for reps to exhaustion (endurance-type training), but this trend was not always statistically evident for the limited reps (strength-type training) protocol. It is suggested that the estimation of total energy expenditure for weight training is improved with the inclusion, rather than the omission, of an estimate of rapid anaerobic substrate-level ATP turnover.
Purpose: To evaluate the reliability of new change-of-direction-economy tests (assessing energetic efficiency when performing continuous shuttle runs) compared with common running-economy tests in soccer players Methods: Sixteen subelite, male soccer players were recruited to perform a testing battery involving running economy (RE), 10-m shuttle-running economy (SRE10), and 20-m shuttle-running economy (SRE20) at 8.4 km·h-1 mean speed on 2 different days within 48 hours. SRE10 and SRE20 consisted of continuous shuttle runs interspersed with 180° directional changes. During the RE, SRE20, and SRE10 tests, respiratory exchange ratio and oxygen uptake were collected and used to calculate the movement-economy values over any running condition as oxygen cost and energetic cost. The secondary variables (carbon dioxide production, heart rate, minute ventilation, and blood lactate) were also monitored during all tests. Results: Depending on expression (oxygen cost or energetic cost), reliability was established for RE (CV: 5.5%-5.8%; ICC = .77-.88), SRE10 (CV: 3.5%-3.8%; ICC = .78-.96), and SRE20 (CV: 3.5%-3.8%; ICC = .66-.94). All secondary physiological variables reported good reliability (CV < 10%), except for blood lactate (CV < 35.8). The RE, SRE10, and SRE20 tests show good reliability in soccer players, whereas blood lactate has the highest variability among physiological variables during the economy tests. Conclusion: The assessment of change-of-direction economy through performing 20- and 10-m shuttle runs is reliable and can be applied to evaluate soccer players' energetic movement efficiency under more soccer-specific running conditions.
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Soccer is a complex and exhaustive team-sport requiring a high level of tactical, technical, and physical ability to succeed. During a competitive match, a random combination of explosive and powerful activities, together with technical and tactical gestures, is performed in an intermittent manner over a 90-minute game. This review presents a detailed analysis and up-to-date synthesis of the literature describing activities and energy system contribution during soccer to provide to strength and conditioning coaches a clear understanding of soccer players' physical needs during competition.
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To investigate the effect of a maximal shuttle-run shock microcyle in hypoxia on repeated sprint ability (RSA,6x40-m/20”), Yo-Yo-intermittent-recovery (YYIR) test performance and redox-status. Fourteen players (age:23.9±2.1yr), randomly assigned to hypoxia (~3300m) or normoxia training, performed 8 maximal shuttle-run training sessions within 12 days. YYIR-test performance and RSA fatigue-slope improved independently of the hypoxia stimulus (p<0.05). Training reduced the oxidative stress level (-7.9%, p<0.05), and the reduction was associated with performance improvements (r=0.761,ΔRSA; r=-0.575,ΔYYIR, p<0.05).
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The reliability and accuracy of five portable blood lactate (BLa) analysers (Lactate Pro, Lactate Pro2, Lactate Scout+, Xpress™, and Edge) and one handheld point-of-care analyser (i-STAT) were compared to a criterion (Radiometer ABL90). Two devices of each brand of analyser were assessed using 22 x 6 mL blood samples taken from five subjects at rest and during exercise who generated lactate ranging ~1-23 mM. Each sample was measured simultaneously ~6 times on each device. Reliability was assessed as the within-sample standard deviation (wsSD) of the six replicates; accuracy as the bias compared with the ABL90; and overall error (the root mean squared error (√MSE)) was calculated as the square root of (wsSD(2) and bias(2)). The √MSE indicated that both the Edge and Xpress had low total error (~0-2 mM) for lactate concentrations <15 mM, whereas the Edge and Lactate Pro2 were the better of the portable analysers for concentrations >15 mM. In all cases, bias (negative) was the major contribution to the √MSE. In conclusion, in a clinical setting where BLa is generally <15 mM the Edge and Xpress devices are relevant, but for athlete testing where peak BLa is important for training prescription the Edge and Lactate Pro2 are preferred. Key pointsThe reliability of five common portable blood lactate analysers were generally <0.5 mM for concentrations in the range of ~1.0-10 mM.For all five portable analysers, the analytical error within a brand was much smaller than the biological variation in blood lactate (BLa).Compared with a criterion blood lactate analyser, there was a tendency for all portable analysers to under-read (i.e. a negative bias), which was particularly evident at the highest concentrations (BLa ~15-23 mM).The practical application of these negative biases would overestimate the ability of the athlete and prescribe a training intensity that would be too high.
Article
The purpose of this study was to compare the effect of two different methods of organizing endurance training in elite cross-country skiers approaching the competition period. During the 5-week intervention period, one group performed block periodization (BP; n = 10) with 5 and 3 high-intensity sessions (HIT) during the first and third training week. One HIT was performed during the remaining weeks in BP, while the group performing traditional training organization (TRAD, n = 9) performed two weekly HIT except during the third week where they performed three HIT. HIT were interspersed with low-intensity training (LIT) and both groups performed similar total amount of both HIT and LIT during the intervention. BP achieved a larger relative increase in peak power output and power output at a blood lactate concentration of 4 mmol/L than TRAD (4 ± 4 vs -3 ± 6% and 11 ± 10 vs 2 ± 4%, respectively, both P < 0.01). BP also increased maximal oxygen uptake by 2 ± 2% (P < 0.05), while no changes occurred in TRAD. The effect sizes of the relative improvement in these measurements revealed moderate effects of BP vs TRAD training. The present study suggests that block periodization of endurance training have superior effects on several endurance and performance indices compared with traditional organization. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
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Soccer is characterized as a high-intensity, intermittent, contact team sport that requires a number of proficient physical and physiological capabilities to perform successfully. Apart from the necessary technical and tactical skills required, soccer players must also develop and retain a high level of aerobic and anaerobic conditioning, speed, agility, strength, and power. These are best developed through high-intensity interval training, small-sided games, repeated sprints, coached speed and agility sessions and strength and power-based gym sessions. Soccer coaches and strength and conditioning coaches must work cohesively to ensure a structured and effective program is adhered to.
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The preseason in soccer is a short period of 6-8 weeks where conditional abilities, technical and tactical elements need to be trained. Therefore, time is lacking to perform long term preparation periods for different abilities, especially endurance training. There is evidence that the implementation of high-intensity shock microcycles in preseason training could be one way to improve physical performance in a short period of time. Therefore, the purpose of the present study was to examine the effects and the sustainability of a high-intensity shock microcycle on soccer specific performance. Over 2 weeks, 12 male soccer players (26.1 ± 4.5 years) performed 12 high-intensity training (HIT) sessions in addition to their usual training. Before (pre), 6 days (6d) and 25 days (25d) after training, subjects performed Counter Movement Jump (CMJ), Repeated-Sprint Ability (RSA) test and Yo-Yo Intermittent Recovery Test Level 2 (YYIR2). Mean sprint time (RSAMean) (cohen's d = -1.15), percentage decrement score (RSAIndex) (cohen's d = -1.99) and YYIR2 (cohen's d = +1.92) improved significantly from pre to 6d. 25d after, values showed a significant reduction for YYIR2 (cohen's d = -0.81) and small to moderate but not significant increase for RSAMean (cohen's d = +0.37) and RSAIndex (cohen's d = +0.7) compared to 6d values. Small but no significant increases were found for CMJ (cohen's d = +0.33) and no significant and substantial changes were found for RSABest (cohen's d = -0.07) from pre to 6d. For competitive soccer players, block periodization of HIT offers a promising way to largely improve RSA and YYIR2 in a short period of time. Despite moderate to large decreases in RSAIndex and YYIR2 performance in the 19 day period without HIT, values still remained significantly higher 25d after the last HIT session compared to pre-values. However, it might be necessary to include isolated high-intensity sessions after a HIT training block in order to maintain the higher level of YYIR2 and RSAIndex performance. Key pointsHIT shock microcycle increases performance in semi-professional soccer players in a short period of time.Despite moderate to large decreases in performance in the 19 day period without HIT, values still remained significantly higher 25d after the last HIT session compared to pre-values.This kind of training block increases YYIR2 performance and the ability to repeated sprints, based on the RSAIndex.
Article
Oxygen cost (OC) is commonly employed to assess an athlete's running economy, though the validity of this measure is often overlooked. This study evaluated the validity of OC as a measure of running economy by comparison to the underlying energy cost (EC). Additionally, the most appropriate method of removing the influence of body mass was determined to elucidate a measure of running economy that enables valid inter-individual comparisons. 172 highly trained endurance runners (males, n = 101; females, n = 71) performed a discontinuous submaximal running assessment, consisting of approximately seven 3 min stages (1 km [BULLET OPERATOR] hr increments), to determine the absolute OC (L [BULLET OPERATOR] km) and EC (Kcal [BULLET OPERATOR] km) for the 4 speeds below lactate turnpoint. Comparisons between models revealed linear ratio scaling to be a more suitable method than power function scaling for removing the influence of body mass for both EC (R; males, 0.589 vs 0.588; females, 0.498 vs 0.482) and OC (males, 0.657 vs 0.652; females, 0.532 vs 0.531). There were stepwise increases in EC and RER with increments in running speed (both, P < 0.001). However, no differences were observed for OC across the 4 monitored speeds (P = 0.54). Whilst EC increased with running speed, OC was insensitive to changes in running speed, and therefore does not appear to provide a valid index of the underlying EC of running, likely due to the inability of OC to account for variations in substrate utilisation. Therefore, EC should be employed as the primary measure of running economy, and for runners an appropriate scaling with body mass is recommended.
Article
The physical requirements for women soccer players appear to be similar to those for men, with high levels of aerobic capacity, sprint speed and recovery being fundamental for success (Krustrup et al. Med Sci Sports Exerc 37: 1242-1248, 2005). Specific interventions designed to improve training status in male soccer players have been assessed in several previous studies (e.g. Hoff et al. Br J Sports Med 36: 218-221, 2001). However, to our knowledge only one study has examined the responses to training interventions in female players (Polman et al. J Sports Sci 22: 191-203, 2004) and the most effective method remains to be determined. PURPOSE: To examine the effects of three training interventions on the aerobic and anaerobic capacity of collegiate level female soccer players. METHODS: The aerobic and anaerobic capacities of 23 members of an NAIA division 1 soccer program were assessed pre- and post-training by a 20m multi-stage fitness test and a 5m multiple shuttle test (Boddington et al. J Sports Sci 19: 223-228, 2001). Participants were matched for aerobic capacity and assigned to one of three training groups, and trained twice per week for 4 weeks. One group participated in a novel high intensity interval training (HIIT) intervention consisting of a series of 30 s shuttle runs at speeds above the velocity at aerobic capacity, interspersed with 30 s periods of rest. The second group completed interval training (IT) consisting of 4 bouts of 4 min running at 90-95% maximum heart rate followed by a 3 min rest period. The final group completed continuous training (CT) involving a continuous 28 min run at 70-80% maximum heart rate. RESULTS: Aerobic capacity increased significantly in both the HIIT and IT groups (mean ± s.d: HIIT: 10.2 ± 4.5%; p < 0.001, IT: 6.1 ± 2.5%; p < 0.01) and increased by a small but non-significant amount in the CT group (3.8 ± 4.6%; p = 0.19) The distance covered during the anaerobic performance test increased in all groups, but only significantly in the HIIT group (HIIT: 31 ± 19 m; p < 0.01, IT: 14 ± 23 m; p = 0.26, CT: 13 ± 23 m; p = 0.34). CONCLUSION: The novel HIIT intervention results in significant increases in both aerobic and anaerobic capacity and therefore appears to be an effective method of fitness training for female soccer players.
Article
The purpose of this study was to compare the effect of two different methods of organizing endurance training in trained cyclists. One group of cyclists performed block periodization, wherein the first week constituted five sessions of high-intensity aerobic training (HIT), followed by 3 weeks of one weekly HIT session and focus on low-intensity training (LIT) (BP; n = 10, VO(2max)  = 62 ± 2 mL/kg/min). Another group of cyclists performed a more traditional organization, with 4 weeks of two weekly HIT sessions interspersed with LIT (TRAD; n = 9, VO(2max)  = 63 ± 2 mL/kg/min). Similar volumes of both HIT and LIT was performed in the two groups. While BP increased VO(2max) , peak power output (W(max) ) and power output at 2 mmol/L [la(-) ] by 4.6 ± 3.7%, 2.1 ± 2.8%, and 10 ± 12%, respectively (P < 0.05), no changes occurred in TRAD. BP showed relative improvements in VO(2max) compared with TRAD (P < 0.05). Mean effect size (ES) of the relative improvement in VO(2max) , W(max) , and power output at 2 mmol/L [la(-) ] revealed large to moderate effects of BP training compared with TRAD training (ES = 1.34, ES = 0.85, and ES = 0.71, respectively). The present study suggests that block periodization of training provides superior adaptations to traditional organization during a 4-week endurance training period, despite similar training volume and intensity.
Article
The present study examined the effect of additional speed endurance training (SET) during the season on muscle adaptations and performance of trained soccer players. Eighteen subelite soccer players performed one session with six to nine 30-s intervals at an intensity of 90%-95% of maximal intensity (SET) a week for 5 wk (SET intervention). Before and after the SET intervention, the players carried out the Yo-Yo intermittent recovery level 2 (Yo-Yo IR2) test, a sprint test (10 and 30 m), and an agility test. In addition, seven of the players had a resting muscle biopsy specimen taken and they carried out a running protocol on a motorized treadmill before and after the SET intervention. After the SET intervention, the Yo-Yo IR2 test (n = 13) performance was 11% better (P < 0.05), whereas sprint (n = 15) and agility (n = 13) performances were unchanged. The expression of the monocarboxylate transporter 1 (n = 6) was 9% higher (P < 0.05). and the expression of the Na/K pump subunit β1 (n = 6) was 13% lower (P < 0.05) after the SET intervention. The Na/K pump subunits α1, α2, as well as the monocarboxylate transporter 4 and the Na/H exchanger 1 (n = 6) were unchanged. After the SET intervention, the relative number of Type IIx fibers and oxygen consumption at 10 km·h were lower (P < 0.05), whereas V˙O2max was unchanged. In conclusion, adding ∼30 min of SET once a week during the season for trained soccer players did lead to an improved ability to perform repeated high-intensity exercise, with a concomitant increase in the expression of monocarboxylate transporter 1 and an improved running economy.
Article
To examine physiological responses to submaximal field running with changes of direction (COD), and to compare two approaches to assess running economy (RE) with COD, ie, during square-wave (SW) and incremental (INC) exercises. Ten male team-sport athletes performed, in straight-line or over 20 m shuttles, one maximal INC and four submaximal SW (45, 60, 75 and 90% of the velocity associated with maximal pulmonary O2 uptake [vVO2pmax]). Pulmonary (VO2p) and gastrocnemius (VO2m) O2 uptake were computed for all tests. For both running mode, RE was estimated as the O2 cost per kilogram of bodyweight, per meter of running during all SW and INC. Compared with straight-line runs, shuttle runs were associated with higher VO2p (eg, 33 ± 6 vs 37 ± 5 mL O2·min-1·kg-1 at 60%, P < .01) and VO2m (eg, 1.1 ± 0.5 vs 1.3 ± 0.8 mL O2·min-1·100 g-1 at 60%, P = .18, Cohen's d = 0.32). With COD, RE was impaired during SW (0.26 ± 0.02 vs 0.24 ± 0.03 mL O2·kg-1·m-1, P < .01) and INC (0.23 ± 0.04 vs 0.16 ± 0.03 mL O2·kg-1·m-1, P < .001). For both SW and INC tests, the changes in RE with COD were related to height (eg, r = .56 [90%CL, 0.01;0.85] for SW) and weekly training/competitive volume (eg, r = -0.58 [-0.86;-0.04] for SW). For both running modes, RE calculated from INC was better than that from SW (both P < .001). Although RE is impaired during field running with COD, team-sport players of shorter stature and/or presenting greater training/competitive volumes may present a lower RE deterioration with COD. Present results do not support the use of INC to assess RE in the field, irrespective of running mode.
Article
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.
Short duration high-intensity interval training improves aerobic conditioning of female college soccer players
  • A E Rowan
Prevention, diagnosis, and treatment of the overtraining syndrome: Joint consensus statement of the European College of Sport Science and the American College of Sports Medicine
  • R Meeusen