Franck Le Gall

Anthropometric and fitness characteristics of international, professional and amateur male graduate soccer players from an elite youth academy

We compared anthropometric and fitness performance data from graduate male youth players from an elite soccer academy who on leaving the institution were either successful or not in progressing to higher standards of play. Altogether, 161 players were grouped according to whether they achieved international or professional status or remained amateur. Measures were taken across three age categories (under 14, 15 and 16 years of age). Players were assessed using standard measures of anthropometric and fitness characteristics. The skeletal age of players was also measured to determine maturity status. Multivariate analysis (MANCOVA) identified a significant (p<0.001) effect for playing status. Univariate analysis revealed a significant difference in maturity status in amateurs and professionals versus internationals (p<0.05), in body mass in professionals versus amateurs (d=0.56, p<0.05), in height (d=0.85, p<0.01) and maximal anaerobic power (d=0.79, p<0.01) in both professionals and internationals versus amateurs. There was also a significant difference in counter-movement jump (d=0.53, p<0.05) and 40-m sprint time (d=0.50, p<0.05) in internationals versus amateurs, as well as a significant main effect for age and playing position (p<0.001). Significant differences were reported for maturity status, body mass, height, peak concentric torque, maximal anaerobic power, and sprint and jump performance with results dependant on age category and playing position. These results suggest that anthropometric and fitness assessments of elite youth soccer players can play a part in determining their chances of proceeding to higher achievement levels.

Incidence of Injuries in Elite French Youth Soccer Players A 10-Season Study

Background Research on age-related injury incidence in elite youth soccer is needed to identify high-risk groups. Purpose To investigate the incidence of soccer-related injuries in elite French youth players based at the Clairefontaine Football Center. Study Design Cohort study (Prevalence); Level of evidence, 1. Methods Injuries sustained by players in the younger than 14-, 15-, and 16-year-old age groups during 10 seasons were diagnosed and documented by a sports physician according to type, location, severity, the date the injury occurred, and playing position. Results Altogether, 1152 injuries were documented across all age groups with 69.1% and 30.9% sustained during training and matches, respectively. A total of 4.8 injuries per 1000 hours’ exposure time were recorded and 11.2 and 3.9 injuries per 1000 hours for matches and training, respectively. There was no significant difference in injury frequency between age groups. The youngest group sustained more training injuries (P < .05) and osteochondroses (P < .05) and fewer match injuries than did the oldest group. Injury incidence varied throughout the season, peaking in September in all groups. The majority of injuries lasted less than 1 week (60.2%), contusions were the predominant injury type (30.6%, P < .05), and the upper leg was the site most often injured (24.5%, P < .05). Conclusion Those players younger than 14 years incurred more injuries in training and sustained more growth-related overuse disorders. Older players were more often injured during matches. Injury incidence and the frequency of overuse disorders were highest early in the season.

Injuries in Young Elite Female Soccer Players An 8-Season Prospective Study

Background Epidemiologic data on injuries in young female soccer players at elite levels are scarce. Purpose The aim of the present study is to investigate the incidence of soccer-related injuries in young elite female French players. Study Design Cohort study; Level of evidence, 2. Methods Injuries sustained by players between 15 and 19 years of age, during 8 seasons, were diagnosed and documented by a sports physician according to type, location, severity, the date the injury occurred, and playing position. Results Altogether 619 injuries were documented for 110 players (92.4%). Of these injuries, 64.6% (4.6/1000 training hours; 95% confidence interval [CI], 4.2–5.0) and 35.4% (22.4/1000 match hours; 95% CI, 19.4–25.4) were sustained during training and matches, respectively. The risk of injury was greater in the youngest (under age 15) group compared with the oldest (under 19) group (relative risk 1.7; 95% CI, 1.3–2.3). Traumatic injuries amounted to 536 (86.4%) and 83 (13.4%) were overuse injuries. There were 51.9% minor injuries, 35.7% moderate injuries, and 12.4% major injuries. Most injuries were located at the lower extremities (83.4%), with the majority affecting the ankle (n = 157). The most commonly diagnosed injury was ankle sprain (16.8%). Twelve anterior cruciate ligament ruptures were sustained, with the majority occurring during matches (n = 10; 1.0/1000 match hours; 95% CI, 0.4–1.6). Reinjuries accounted for 4.4% of total injuries, and September was the predominant month for injury (14.2%). Conclusions The results, when compared with those of other investigations on female soccer players, revealed high rates of both traumatic injury and match injury, whereas recurrence of injury was low. Injuries, notably sprains, to the ankle were common, suggesting a need for the implementation of specific injury prevention strategies for this joint.

Analysis of repeated high-intensity running performance in professional soccer

Abstract The aims of this study were twofold: (1) to characterize repeated high-intensity movement activity profiles of a professional soccer team in official match-play; and (2) to inform and verify the construct validity of tests commonly used to determine repeated-sprint ability in soccer by investigating the relationship between the results from a test of repeated-sprint ability and repeated high-intensity performance in competition. High-intensity running performance (movement at velocities >19.8 km · h−1 for a minimum of 1 s duration) was measured in 20 players using computerized time–motion analysis. Performance in 80 French League 1 matches was analysed. In addition, 12 of the 20 players performed a repeated-sprint test on a non-motorized treadmill consisting of six consecutive 6 s sprints separated by 20 s passive recovery intervals. In all players, most consecutive high-intensity actions in competition were performed after recovery durations ≥61 s, recovery activity separating these efforts was generally active in nature with the major part of this spent walking, and players performed 1.1 ± 1.1 repeated high-intensity bouts (a minimum of three consecutive high-intensity bouts with a mean recovery time ≤20 s separating efforts) per game. Players reporting lowest performance decrements in the repeated-sprint ability test performed more high-intensity actions interspersed by short recovery times (≤20 s, P < 0.01 and ≤30 s, P < 0.05) compared with those with higher decrements. Across positional roles, central-midfielders performed more high-intensity actions separated by short recovery times (≤20 s) and spent a larger proportion of time running at higher intensities during recovery periods, while fullbacks performed the most repeated high-intensity bouts (statistical differences across positional roles from P < 0.05 to P < 0.001). These findings have implications for repeated high-intensity testing and physical conditioning regimens.

Risk factors, testing and preventative strategies for non-contact injuries in professional football: current perceptions and practices of 44 teams from various premier leagues

Purpose Little is known about injury prevention practices in professional football clubs. The purpose of this study was therefore to determine the current perceptions and practices of premier league football clubs internationally concerning risk factors, testing and preventative exercises for non-contact injuries. Methods A survey was administered to 93 premier league football clubs internationally. The survey included four sections: (1) persons involved in the injury prevention programme: position, quantity, role, qualification; (2) perceptions regarding non-contact injury risk factors; (3) tests used to identify non-contact injury risk and (4) non-contact injury prevention exercises used, their perceived effectiveness and implementation strategies. Results 44 surveys were successfully returned (47%). The position of physiotherapist was the most represented position in the injury prevention programme. The top five perceived risk factors in rank order were previous injury, fatigue, muscle imbalance, fitness and movement efficiency. The five most commonly used tests to identify injury risk (in rank order) were functional movement screen, questionnaire, isokinetic dynamometry, physical tests and flexibility. The top five exercises used by clubs were (also in rank order) eccentric exercise, balance/proprioception, hamstring eccentric, core stability and, sharing the fifth position, Nordic hamstring and gluteus activation. Conclusions The survey revealed the most common perceptions and practices of premier league football clubs internationally regarding risk factors, testing and preventative exercises. The findings can enable reduction of the gap between research and practice.

Injury risk factors, screening tests and preventative strategies: a systematic review of the evidence that underpins the perceptions and practices of 44 football (soccer) teams from various premier leagues

Purpose To systematically review the scientific level of evidence for the ‘Top 3’ risk factors, screening tests and preventative exercises identified by a previously published survey of 44 premier league football (soccer) teams. Also, to provide an overall scientific level of evidence and graded recommendation based on the current research literature. Methods A systematic literature search (Pubmed [MEDLINE], SportDiscus, PEDRO and Cochrane databases). The quality of the articles was assessed and a level of evidence (1++ to 4) was assigned. Level 1++ corresponded to the highest level of evidence available and 4, the lowest. A graded recommendation (A: strong, B: moderate, C: weak, D: insufficient evidence to assign a specific recommendation) for use in the practical setting was given. Results Fourteen studies were analysed. The overall level of evidence for the risk factors previous injury, fatigue and muscle imbalance were 2++, 4 and ‘inconclusive’, respectively. The graded recommendation for functional movement screen, psychological questionnaire and isokinetic muscle testing were all ‘D’. Hamstring eccentric had a weak graded ‘C’ recommendation, and eccentric exercise for other body parts was ‘D’. Balance/proprioception exercise to reduce ankle and knee sprain injury was assigned a graded recommendation ‘D’. Conclusions The majority of perceptions and practices of premier league teams have a low level of evidence and low graded recommendation. This does not imply that these perceptions and practices are not important or not valid, as it may simply be that they are yet to be sufficiently validated or refuted by research.

The developmental activities of elite soccer players aged under-16 years from Brazil, England, France, Ghana, Mexico, Portugal and Sweden

Abstract The developmental activities of 328 elite soccer players aged under-16 years from Brazil, England, France, Ghana, Mexico, Portugal and Sweden were examined using retrospective recall in a cross-sectional research design. The activities were compared to the early diversification, early specialisation, and early engagement pathways. Players started their involvement in soccer at approximately 5 years of age. During childhood, they engaged in soccer practice for a mean value of 185.7, s = 124.0 h · year−1, in soccer play for 186.0, s = 125.3 h · year−1, and in soccer competition for 37.1, s = 28.9 h · year−1. A mean value of 2.3, s = 1.6 sports additional to soccer were engaged in by 229 players during childhood. Players started their participation in an elite training academy at 11 to 12 years of age. During adolescence, they engaged in soccer practice for a mean value of 411.9, s = 184.3 h · year−1, in soccer play for 159.7, s = 195.0 h · year−1, and in soccer competition for 66.9, s = 48.8 h · year−1. A mean value of 2.5, s = 1.8 sports other than soccer were engaged in by 132 players during this period. There were some relatively minor differences between countries, but generally the developmental activities of the players followed a mixture of the early engagement and specialisation pathways, rather than early diversification.

Work-rate of substitutes in elite soccer: A preliminary study

The aim of this study was to investigate the work-rate of substitutes in professional soccer. A computerised player tracking system was used to assess the work-rates of second-half substitutes (11 midfielders and 14 forwards) in a French Ligue 1 club. Total distance, distance covered in five categories of movement intensity and recovery time between high-intensity efforts were evaluated. First- and second-half work-rates of the replaced players were compared. The performance of substitutes was compared to that of the players they replaced, to team-mates in the same position who remained on the pitch after the substitution and in relation to their habitual performances when starting games. No differences in work-rate between first- and second-halves were observed in all players who were substituted. In the second-half, a non-significant trend was observed in midfield substitutes who covered greater distances than the player they replaced whereas no differences were observed in forwards. Midfield substitutes covered a greater overall distance and distance at high-intensities (p<0.01) and had a lower recovery time between high-intensity efforts (p<0.01) compared to other midfield team-mates who remained on the pitch. Forwards covered less distance (p<0.01) in their first 10-min as a substitute compared to their habitual work-rate profile in the opening 10-min when starting matches while this finding was not observed in midfielders. These findings suggest that compared to midfield substitutes, forward substitutes did not utilise their full physical potential. Further investigation is warranted into the reasons behind this finding in order to optimise the work-rate contributions of forward substitutes.

Physical performance and subjective ratings after a soccer-specific exercise simulation: Comparison of natural grass versus artificial turf

Abstract This study aimed to compare the recovery kinetics of physical performance and subjective ratings in response to a soccer-specific exercise simulation on natural grass and artificial turf. Physical performance tests and subjective ratings were assessed on 13 professional soccer players before, immediately after, 24 h and 48 h after the test. Physical performance tests included squat jump, countermovement jump, 6-s sprint on a non-motorised treadmill and isokinetic eccentric hamstring assessment (2.09 rad · s−1). Hamstring peak torque decrement was higher (P < 0.05) on natural grass than on artificial turf immediately (-4.0%, CI 95%: -10.0 to 2.0%, Effect Size [ES] = 0.29), 24 h (-3.1%, CI 95%: -9.3 to 3.1%, ES = 0.29) and 48 h (-3.8%, CI 95%: -8.5 to 0.9%, ES = 0.43) after the test. Squat jump performance decrement was significantly lower (P < 0.05) on natural grass than artificial turf 48 h after the test (+3.7%, CI 95%: 1.1 to 6.3%, ES = 0.40). Sprint performance showed no change from baseline performance for both trials throughout the protocol. No significant interaction between surface and time was found for countermovement jump and subjective ratings. These results suggest that a one-off exercise on artificial turf does not induce greater fatigue nor does it delay the recovery process when compared to natural grass among regular artificial turf players.

A four-season prospective study of muscle strain reoccurrences in a professional football club

The aim of this investigation was to characterise muscle strain reinjuries and examine their impact on playing resources in a professional football club. Muscle strains and reoccurrences were prospectively diagnosed over four seasons in first-team players (n = 46). Altogether, 188 muscle strains were diagnosed with 44 (23.4%) of these classed as reinjuries, leading to an incidence of 1.32 strain reoccurrences per 1,000 hours exposure (95% Confidence Interval [CI], 0.93–1.71). The incidence of recurrent strains was higher in match-play compared with training (4.51, 95% CI, 2.30–6.72 vs 0.94, 95% CI, 0.59–1.29). Altogether, 50.0% of players sustained at least 1 reoccurrence of a muscle strain, leading to approximately 3 days lost and 0.4 matches missed per player per season. The incidence of recurrent strains was highest in centre-forwards (2.15, 95% CI, 1.06–3.24), peaked in May (3.78, 95% CI, 0.47–7.09), and mostly affected the hamstrings (38.6% of all reoccurrences). Mean layoff for nonreoccurrences and recurrences was similar: ∼7.5 days. These results provide greater insight into the extent of the problem of recurrent muscle strains in professional football.