Serge Berthoin

Endurance Training and Aerobic Fitness in Young People

Training-induced adaptations in aerobic fitness have been extensively studied in adults, and some exercise scientists have recommended similar training programmes for young people. However, the subject of the response to aerobic training of children and adolescents is controversial. The effects of exercise training on prepubertal children are particularly debatable. The latter may be partly explained by different training designs, which make comparisons between studies very problematic.We have analysed the procedures applied to protocol design and training methods to highlight the real impact of aerobic training on the peak oxygen uptake (V̇O2) of healthy children and adolescents. In accordance with previously published reviews on trainability in youngsters, research papers were rejected from the final analysis according to criteria such as the lack of a control group, an unclear training protocol, inappropriate statistical procedures, small sample size, studies with trained or special populations, or with no peak V̇O2 data. Factors such as maturity, group constitution, consistency between training and testing procedures, drop out rates, or attendance were considered, and possible associations with changes in peak V̇O2 with training are discussed.From 51 studies reviewed, 22 were finally retained. In most of the studies, there was a considerable lack of research regarding circumpubertal individuals in general, and particularly in girls. The results suggest that methodologically listed parameters will exert a potential influence on the magnitude of peak V̇O2 improvement. Even if little difference is reported for each parameter, it is suggested that the sum of errors will result in a significant bias in the assessment of training effects. The characteristics of each training protocol were also analysed to establish their respective potential influence on peak V̇O2 changes. In general, aerobic training leads to a mean improvement of 5–6% in the peak V̇O2 of children or adolescents. When only studies that reported significant training effect were taken into account, the mean improvement in peak V̇O2 rose to 8–10%. Results suggested that intensities higher than 80% of maximal heart rate are necessary to expect a significant improvement in peak V̇O2.There is clearly a need for longitudinal or cross-sectional studies that investigate the relationship between maturity and training with carefully monitored programmes. Further research is also needed to compare interval training and continuous training.

Effect of 2 Soccer Matches in a Week on Physical Performance and Injury Rate

Background: Recovery duration may be too short during the congested fixtures of professional soccer players with regard to maintaining physical performance and a low injury rate. Purpose: To analyze the effects of 2 matches per week on physical performance and injury rate in male elite soccer players. Study Design: Cohort study; Level of evidence, 3. Methods: Match results, match-related physical performance, and injuries were monitored during 2 seasons (2007–2008 and 2008–2009) for 32 professional soccer players in a top-level team participating in the UEFA (Union of European Football Associations) Champions League. Total distance, high-intensity distance, sprint distance, and number of sprints were collected for 52 home matches. Injuries and player participation in matches and training were recorded throughout the full season. Results: Physical performance, as characterized by total distance covered, high-intensity distance, sprint distance, and number of sprints, was not significantly affected by the number of matches per week (1 versus 2), whereas the injury rate was significantly higher when players played 2 matches per week versus 1 match per week (25.6 versus 4.1 injuries per 1000 hours of exposure; P < .001). Conclusion: The recovery time between 2 matches, 72 to 96 hours, appears sufficient to maintain the level of physical performance tested but is not long enough to maintain a low injury rate. The present data highlight the need for player rotation and for improved recovery strategies to maintain a low injury rate among athletes during periods with congested match fixtures.

The effect of in-season, high-intensity interval training in soccer players.

&NA; Dupont, G., K. Akakpo, and S. Berthoin. The effect of in‐season, high‐intensity interval training in soccer players. J. Strength Cond. Res. 18(3):584–589. 2004.—The effects of inseason, high‐intensity interval training on professional male soccer players’ running performances were investigated. Twentytwo subjects participated in 2 consecutive training periods of 10 weeks. The first period was considered a control period and was compared with a period where 2 high‐intensity interval training exercises were included in the usual training program. Intermittent runs consisted of 12–15 runs lasting 15 seconds at 120% of maximal aerobic speed alternated with 15 seconds of rest. Sprint repetitions consisted of 12–15 all‐out 40‐m runs alternated with 30 seconds of rest. Results from the high‐intensity interval training have shown that maximal aerobic speed was improved (+ 8.1 ± 3.1%; p < 0.001) and that the time of the 40‐m sprint was decreased (‐3.5 ± 1.5%; p < 0.001), whereas no change in either parameters were observed during the control period. This study shows that improvements in physical qualities can be made during the in‐season period.

Passive versus Active Recovery during High-intensity Intermittent Exercises

PURPOSE To compare the effects of passive versus active recovery on muscle oxygenation and on the time to exhaustion for high-intensity intermittent exercises. METHODS Twelve male subjects performed a graded test and two intermittent exercises to exhaustion. The intermittent exercises (15 s) were alternated with recovery periods (15 s), which were either passive or active recovery at 40% of .VO2max. Oxyhemoglobin was evaluated by near-infrared spectroscopy during the two intermittent exercises. RESULTS Time to exhaustion for intermittent exercise alternated with passive recovery (962 +/- 314 s) was significantly longer (P < 0.001) than with active recovery (427 +/- 118 s). The mean metabolic power during intermittent exercise alternated with passive recovery (48.9 +/- 4.9 mL.kg-1.min-1) was significantly lower (P < 0.001) than during intermittent exercise alternated with active recovery (52.6 +/- 4.6 mL.kg-1.min-1). The mean rate of decrease in oxyhemoglobin during intermittent exercises alternated with passive recovery (2.9 +/- 2.4%.s-1) was significantly slower (P < 0.001) than during intermittent exercises alternated with active recovery (7.8 +/- 3.4%.s-1), and both were negatively correlated with the times to exhaustion (r = 0.67, P < 0.05 and r = 0.81, P < 0.05, respectively). CONCLUSION The longer time to exhaustion for intermittent exercise alternated with passive recovery could be linked to lower metabolic power. As intermittent exercise alternated with passive recovery is characterized by a slower decline in oxyhemoglobin than during intermittent exercise alternated with active recovery at 40% of .VO2max, it may also allow a higher reoxygenation of myoglobin and a higher phosphorylcreatine resynthesis, and thus contribute to a longer time to exhaustion.

Relationship between oxygen uptake kinetics and performance in repeated running sprints.

The purpose of this study was to test the hypothesis that subjects having a shorter time constant for the fast component of

Recovery in SoccerPart II—Recovery Strategies

\dot{V}{\text{O}}_{2}

Recovery in Soccer

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