On-field rehabilitation in football: current practice and perceptions. A survey of the English Premier League and Football League.

INTRODUCTION: Return to play related research is increasing rapidly, with two recent competency-based frameworks offering conceptualised support for on-field rehabilitation (OFR) decision-making. It is still unknown, however, who is responsible for OFR and how they typically select, monitor, and progress OFR processes. AIMS: The purpose of this study was to investigate current OFR practice within English professional football to support practitioners with decision-making and highlight opportunities for future research related to the design, monitoring, and progression of OFR. METHODS: Sixty-nine practitioners responsible for the design and implementation of OFR at 69 clubs (75% of the English Premier League and Football League) responded to a survey containing 30 questions (14 open and 16 closed). RESULTS: The main findings were that therapists (physiotherapists/sports therapists) have the largest influence on OFR, followed by physical performance coaches (sports scientists/strength and conditioning coaches), technical coaches and medical doctors. There was more agreement for the ordering of specific OFR drills earlier in the process when activities are easier to control. The most frequently reported objective monitoring tool was global positioning systems (GPS), with functional/clinical experience/expertise remaining subjectively vital. GPS outputs (e.g., sprint metrics and accelerations/decelerations) were most used for between session decision-making, with verbal communication being key for within session decision-making. CONCLUSION: Future research should use evidence of current practice, such as drill design and monitoring techniques, to explore drill-level analysis and give practitioners greater insights into which stage of current OFR frameworks specific drills fall, and how they might be more objectively progressed/regressed.

A preliminary investigation into the evaluation of possession-based small-sided games and the influence of decision-making ability in identifying talented pre-pubertal soccer players

IntroductionThe aims of this study were 1) to assess if talented players can be identified within possession-based small-sided games (SSG), and 2) to determine if, decision making, physical, and time-motion characteristics correlated to success in a possession-based SSG.MethodsEight, highly-trained U10 soccer players (Mean ± SD; age: 10.3 ± 0.2 years; stature: 1.41 ± 0.04 m; body mass: 35.2 ± 3.3 kg) participated in this study. Six 4 vs 4 possession based SSG's were played. Time-motion characteristics were measured using micromechanical devices (MEMS). Countermovement jump, 10m and 30m speed tests were conducted. Participants were presented with 28 video clips of 5 versus 5 match-play sequences to assess decision-making ability.ResultsThe main finding of this study was a large significant relationship between Game Technical Scoring Chart (GTSC) and Total Points (TP) (r = 0.784, P <0.05). There were no significant correlations between the decision-making test and GTSC and TP. A significant and largely inverse correlation between decision-making and countermovement jump (r = -0.737, P <0.05) was observed.ConclusionsOur results demonstrate that the more talented players were also the most successful players in the possession based SSG. The players’ decision-making ability, however, did not influence their success in the SSG. (AU)

Hormonal responses during two different concurrent-training trials in youth elite soccer players: does changing the organization of training impact the hormonal response to concurrent exercise?

BACKGROUND: There are no data describing the acute hormonal responses to concurrent-training programmes in youth elite soccer players. Therefore, the aim of this study was to describe the total testosterone (T), cortisol (C), and growth hormone (hGH) responses during two same-day concurrent-training (CT) trials in elite soccer players. METHODS: Thirteen youth elite players (age: 17.0±0.2 years; height, 1.80±0.07 m; body mass, 73.1±5.7 kg; V̇O2max, 64.4±4.8 mL-1.kg-1.min-1) from an English premier league soccer club completed two CT trials. "Trial 1" (CT1); E (10.30 a.m.) followed by S (02.00 p.m.) and Trial 2 (CT2); strength-training (S) 09.00 a.m. followed by a soccer-specific endurance-training session (E) at 10.30 a.m. Venous blood samples were collected at 5 time-points around training and food intake (T1; 08.00 a.m., T2; 09.45h, T3; 12.30h, T4; 01.45 p.m. and T5; 03.15 p.m.) and analyzed for T (nmol/L) and C (nmol/L) and hGH (ug/L). RESULTS: There was no main effects found between exercise conditions for any hormones (T; P=0.22, C; P=0.07, hGH; P=0.21). Effect size analysis revealed a moderate effect for T at T3 (ES=0.63, CT1; 18.4±3.8, CT2; 15.7±4.7 nmol/L-1). A moderate effect for T Area Under the Curve (AUC) was observed between conditions (CT1; 300±76 versus CT2; 244±81 [AU]; ES=0.71). A moderate effect was apparent for C concentrations T4 in (ES=-0.95, CT1; 230±69, CT2; 314±105 nmol/L-1). Moderate effect sizes were observed at T3 and T4 (ES=0.82, CT1; 1.28±1.17, CT2; 0.47±0.75, ES=0.72, CT1; 0.11±0.05, CT2; 0.07±0.06 ug/L-1 respectively). A moderate effect for hGH AUC was observed between trials (CT1; 14±11 versus CT2; 5±9; [AU], ES=-1.08). CONCLUSIONS: The organisation of the concurrent-training protocols used in this study has a negligible impact upon the acute T, C and hGH in youth elite soccer players.

Assessing Differences in Cardiorespiratory Fitness With Respect to Maturity Status in Highly Trained Youth Soccer Players.

PURPOSE: The purpose of the study was to examine differences in measures of cardiorespiratory fitness and determinants of running economy with respect to maturity status in a group of highly trained youth soccer players. METHODS: A total of 21 highly trained youth soccer players participated in this study. On separate visits, players' peak oxygen uptake (VO2peak), running economy at 3 different speeds [8 km·h-1, 80% gaseous exchange threshold (GET), and 95% GET], and pulmonary oxygen uptake (VO2) kinetics were determined. Players also performed a Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1). Players were categorized as either "pre-PHV" (peak height velocity) or "mid-PHV" group using the measure of maturity offset. Independent t tests and Cohen's d effect sizes were then used to assess differences between groups. RESULTS: The mid-PHV group was significantly taller, heavier, and advanced in maturity status. Absolute measures of VO2peak were greater in the mid-PHV group; however, when expressed relative to body mass, fat-free mass, and theoretically derived exponents, VO2peak values were similar between groups. Pre-PHV group presented a significantly reduced VO2 response, during relative submaximal running speeds, when theoretically derived exponents were used, or expressed as %VO2peak. VO2 kinetics (tau) were faster during a low (standing) to moderate (95% GET) transition in the pre-PHV group. Yo-Yo IR1 performance was similar between groups. CONCLUSION: Although measures of VO2peak and Yo-Yo IR1 performance are shown to be similar between groups, those categorized as pre-PHV group display a superior running economy at relative submaximal running speeds and faster taus during a low to moderate exercise transition than their more mature counterparts.

The impact of joint angle and movement velocity on sex differences in the functional hamstring/quadriceps ratio.

BACKGROUND: Females are two to eight times more likely to suffer a non-contact injury compared with males thus the purpose of this study was to explore the influence of joint angle and movement velocity on sex differences in the functional hamstring to quadriceps ratio (H/QFUNC). METHODS: Isokinetic concentric and eccentric torque were determined in 110 participants (55 males and 55 females) through a 90° range of movement at 60, 120, and 240°/s. Testing was performed with the hip flexed at 10°. The H/QFUNC was determined at three specific joint angles (15, 30 and 45° flexion) and where peak torque occurred for concentric knee extension. RESULTS: A significant interaction effect (P<0.01) for sex and joint angle was observed with women demonstrating a lower H/QFUNC than males, especially at more extended knee positions. A significant sex by velocity interaction (P<0.01) indicated a lower H/QFUNC in women as velocity increased. Significant main effects (P<0.01) indicated that irrespective of sex the H/QFUNC increased as the knee extends and velocity increases. CONCLUSION: Given the reduced H/QFUNC in females compared to males at more extended knee positions and faster velocities, this may contribute to the observed sex bias in reported injury rates.

Influence of oxygen uptake kinetics on physical performance in youth soccer.

PURPOSE: To examine the relationship between oxygen uptake kinetics (VO2 kinetics) and physical measures associated with soccer match play, within a group of highly trained youth soccer players. METHODS: Seventeen highly trained youth soccer players (age: 13.3 ± 0.4 year, self-assessed Tanner stage: 3 ± 1) volunteered for the study. Players initially completed an incremental treadmill protocol to exhaustion, to establish gaseous exchange threshold (GET) and VO2max (59.1 ± 5.4 mL kg(-1) min(-1)). On subsequent visits, players completed a step transition protocol from rest-moderate-intensity exercise, followed by an immediate transition, and from moderate- to severe-intensity exercise (moderate: 95 % GET, severe: 60 %∆), during which VO2 kinetics were determined. Physical soccer-based performance was assessed using a maximal Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) and via GPS-derived measures of physical soccer performance during soccer match play, three 2 × 20 min, 11 v 11 matches, to gain measures of physical performance during soccer match play. RESULTS: Partial correlations revealed significant inverse relationships between the unloaded-to-moderate transition time constant (tau) and: Yo-Yo IR1 performance (r = -0.58, P = 0.02) and GPS variables [total distance (TD): r = -0.64, P = 0.007, high-speed running (HSR): r = -0.64, P = 0.008 and high-speed running efforts (HSReff): r = -0.66, P = 0.005]. CONCLUSION: Measures of VO2 kinetics are related to physical measures associated with soccer match play and could potentially be used to distinguish between those of superior physical performance, within a group of highly trained youth soccer players.

The evaluation of small-sided games as a talent identification tool in highly trained prepubertal soccer players.

The aim of this study was to evaluate physiological and technical attributes of prepubertal soccer players during multiple small-sided games (SSGs), and determine if SSGs can act as a talent identification tool. Sixteen highly trained U10 soccer players participated and separated into two groups of eight. Each group played six small-sided (4 vs. 4) matches of 5-min duration. Each player was awarded total points for the match result and goals scored. A game technical scoring chart was used to rate each player's performance during each game. Time-motion characteristics were measured using micromechanical devices. Total points had a very large significant relationship with game technical scoring chart (r = 0.758, P < 0.001). High-speed running distance had a significantly large correlation with game technical scoring chart (r = 0.547, P < 0.05). Total distance covered had a significant and moderate correlation with game technical scoring chart (r = 0.545, P < 0.05) and total points (r = 0.438, P < 0.05). The results demonstrated a large agreement between the highest-rated players and success in multiple SSGs, possibly due to higher-rated players covering larger distances in total and at high speed. Consequently, multiple SSG could be used to identify the more talented prepubertal soccer players.

Electromechanical delay of the hamstrings during eccentric muscle actions in males and females: Implications for non-contact ACL injuries.

Sex differences in neuromuscular functioning has been proposed as one of the factors behind an increased relative risk of non-contact anterior cruciate ligament (ACL) injury in females. The aim of this study was to explore sex differences in electromechanical delay (EMD) of the hamstring muscles during eccentric muscle actions and during a range of movement velocities. This study recruited 110 participants (55 males, 55 females) and electromyography of the semitendinosus, semimembranosus and biceps femoris was determined during eccentric actions at 60, 120 and 240°/s. No significant sex differences were observed irrespective of muscle examined or movement velocity. Irrespective of sex EMD significantly increased with increasing movement velocity (P < 0.01). There was no significant difference in the EMD of the 3 muscles examined. Our findings suggest that during eccentric actions of the hamstrings that there are no sex differences, irrespective of movement velocity. This would suggest that other factors are probably responsible for the increased relative risk of non-contact ACL injury in females compared to males.

The effect of concurrent training organisation in youth elite soccer players.

PURPOSE: This study compared the adaptive responses to two concurrent training programmes frequently used in professional soccer. METHODS: Fifteen youth soccer players (17.3 ± 1.6 years, 1.82 ± 0.06 m, 77.0 ± 7.3 kg; VO2 peak, 62.0 ± 4.7 ml(-1) kg(-1) min(-1)) who compete in the English Premier League volunteered for this study. In addition to completing their habitual training practices, the participants were asked to alter the organisation concurrent training by performing strength (S) training either prior to (S + E, n = 8) or after (E + S, n = 7) soccer-specific endurance training (E) 2d wk(-1) for 5 wk(-1). RESULTS: With the exception of 30 m sprint, IMVC PF, quadriceps strength (60°/s(CON), 180°/s(CON), 120°/s(ECC)) pooled data revealed training effects across all other performances measures (P < 0.05). Whilst ANCOVA indicated no significant interaction effects for training condition, the difference between the means divided by the pooled standard deviation demonstrated large effect sizes in the E + S condition for in HBS 1-RM [S + E vs E + S; -0.54 (9.6 %) vs -1.79 (19.6 %)], AoP-M [-0.72 (7.9 %) vs -1.76 (14.4 %)], SJ [-0.56, (4.4 %), vs -1.08, (8.1 %)], IMVC-LR; [-0.50, (20.3 %) vs -1.05 (27.3 %)], isokinetic hamstring strength 60°/s (CON) [-0.64, (12.2 %) vs -0.95 (19.2 %)], 120°/s(ECC) [-0.78 (27.9 %) vs -1.55 (23.3 %)] and isokinetic quadriceps strength 180°/s (CON) [-0.23 (2.5 %) vs -1.52 (13.2 %)]. CONCLUSION: Results suggest the organisation of concurrent training, recovery time allocated between training bouts and the availability nutrition may be able to modulate small but clinically significant changes in physical performance parameters associated with match-play. This may have practical implications for practitioners who prescribe same day concurrent training protocols.

Talent identification in youth soccer.

The purpose of this review article was firstly to evaluate the traditional approach to talent identification in youth soccer and secondly present pilot data on a more holistic method for talent identification. Research evidence exists to suggest that talent identification mechanisms that are predicated upon the physical (anthropometric) attributes of the early maturing individual only serve to identify current performance levels. Greater body mass and stature have both been related to faster ball shooting speed and vertical jump capacity respectively in elite youth soccer players. This approach, however, may prematurely exclude those late maturing individuals. Multiple physiological measures have also been used in an effort to determine key predictors of performance; with agility and sprint times, being identified as variables that could discriminate between elite and sub-elite groups of adolescent soccer players. Successful soccer performance is the product of multiple systems interacting with one another. Consequently, a more holistic approach to talent identification should be considered. Recent work, with elite youth soccer players, has considered whether multiple small-sided games could act as a talent identification tool in this population. The results demonstrated that there was a moderate agreement between the more technically gifted soccer player and success during multiple small-sided games.