After ACLR (mean time postoperatively: 24+/-1 months), single-leg hop for distance score was normal, when compared with the contralateral limb. Our results indicate that 2 years after surgery, single-limb postural stability in the ACLR group differed significantly from that in the control group. The persistence of poor stability control may be correlated to an impairment in proprioception.

The purpose of this study was to examine the effect of strength training on physical fitness parameters and injuries occurrence in young elite soccer players. Fifty-two elite young soccer players (13-14 years) were divided on a randomized order into experimental group (EG, n = 26) and control group (CG, n = 26). For EG, 2 to 3 sessions of strength training (90 minutes) were introduced weekly in their training program for 12 weeks (4 × 3 weeks separated by 1-week recovery). Sprint tests (10-20-30 m), T-test time, and jumping tests were measured at the start (T0), at the middle (T1), and at the end of the experiment period (T2). The injury rate was recorded by the medical and fitness training staff throughout the soccer season. Compared to CG, EG performed significantly better in sprint running and T-test time at T2 (p < 0.01). Similarly, the improvement amount for jumping tests was significantly greater (p ≤ 0.05) in EG than in CG. A total of 17 injuries were recorded over the soccer season. The rate was higher in CG (13 injuries) than in training group (4 injuries). This study showed that strength training accurately and efficiently scheduled in youth soccer players, induced performance improvement, and reduced the rate of injuries.

Introduction There is controversy in the literature in regards of the link between training load and injury rate. Thus, the aims of this non-interventional study were to evaluate relationships between pre-season training load with biochemical markers, injury incidence and performance during the first month of the competitive period in professional soccer players. Materials and Methods Healthy professional soccer players were enrolled in this study over two pre-season periods. Data sets were available from 26 players during the first season (2014–2015) and 24 players during the second season (2015–2016) who completed two pre-season periods (6 weeks each). External training load was assessed from all athletes during training using Global Positioning System (GPS). Internal training load was monitored after each training session using rate of perceived exertion (RPE). Before and after each pre-season, blood samples were taken to determine plasma lactate dehydrogenase (LDH), creatine kinase (CK) and C-reactive protein (CRP). Injury incidence and overall performance (ranking of the team after the first five official games of the championship) were recorded for both seasons separately. Results There was no statistically significant difference in mean RPE values of the two-preparation periods (2737 ± 452 and 2629 ± 786 AU, p = 0.492). The correlational analysis did not reveal significant associations between internal and external training load (RPE and GPS data) and biological markers. There was a significant positive correlation between RPE and LDH during the 2015/2016 season ( r = 0.974, p = 0.001). In addition, a significant negative correlation was found between total distance >20 km/h and CRP during the 2015–2016 season ( r = -0.863, p = 0.027). The injury rates for the two seasons were 1.76 and 1.06 per 1000 h exposure for the 2014–2015 and 2015–2016 seasons, respectively ( p = 0.127). Conclusion Our study showed that pre-season training load is not associated with overall team performance. This association is most likely multifactorial and other factors (e.g., technical and tactical level of the team, opponents, environment) may play an important role for the collective team performance. Our findings may help coaches to better prepare their athletes during pre-season.

Background: Small-sided soccer games (SSSG) are a specific exercise regime with two small teams playing against each other on a relatively small pitch. There is evidence from original research that SSSG exposure provides performance and health benefits for untrained adults. Objectives: The aim of this systematic review was to summarize recent evidence on the acute and long-term effects of SSSG on physical fitness, physiological responses, and health indices in healthy untrained individuals and clinical populations. Materials and Methods: This systematic literature search was conducted in four electronic databases (PubMed, Web of Science, SPORTDiscus) from inception until June 2019. The following key terms (and synonyms searched for by the MeSH database) were included and combined using the operators "AND", "OR", "NOT": ((soccer OR football) AND ("soccer training" OR "football training" OR "soccer game*" OR "small-sided soccer game*") AND ("physical fitness" OR "physiological adaptation*" OR "physiological response*" OR health OR "body weight" OR "body mass" OR "body fat" OR "bone composition" OR "blood pressure")). The search syntax initially identified 1,145 records. After screening for titles, abstracts, and full-texts, 41 studies remained that examined the acute (7 studies) and long-term effects (34 studies) of SSSG-based training on physical fitness, physiological responses, and selected health indices in healthy untrained individuals and clinical populations. Results: No training-related injuries were reported in the 41 acute and long-term SSSG studies. Typically, a single session of SSSG lasted 12 to 20 minutes (e.g. 3x4 min with 3 min rest or 5x4 min with 4 min rest) involving 4 to 12 players (2 vs. 2 to 6 vs. 6) at an intensity ≥80% of HR max. Following single SSSG sessions, high cardiovascular and metabolic demands were observed. Specifically, based on the outcomes, the 7 acute studies reported average heart rates (HR) ≥80% of HR max (165-175 bpm) and mean blood lactate concentrations exceeding 5 mmol/l (4.5-5.9 mmol/l) after single SSSG sessions.

Background Agility in general and change-of-direction speed (CoD) in particular represent important performance determinants in elite soccer. Objectives The objectives of this study were to determine the effects of a 6-week neuromuscular training program on agility performance, and to determine differences in movement times between the slower and faster turning directions in elite soccer players. Materials and Methods Twenty male elite soccer players from the Stade Rennais Football Club (Ligue 1, France) participated in this study. The players were randomly assigned to a neuromuscular training group (NTG, n = 10) or an active control (CG, n = 10) according to their playing position. NTG participated in a 6-week, twice per week neuromuscular training program that included CoD, plyometric and dynamic stability exercises. Neuromuscular training replaced the regular warm-up program. Each training session lasted 30 min. CG continued their regular training program. Training volume was similar between groups. Before and after the intervention, the two groups performed a reactive agility test that included 180° left and right body rotations followed by a 5-m linear sprint. The weak side was defined as the left/right turning direction that produced slower overall movement times (MT). Reaction time (RT) was assessed and defined as the time from the first appearance of a visual stimulus until the athlete’s first movement. MT corresponded to the time from the first movement until the athlete reached the arrival gate (5 m distance). Results No significant between-group baseline differences were observed for RT or MT. Significant group x time interactions were found for MT ( p = 0.012, effect size = 0.332, small) for the slower and faster directions ( p = 0.011, effect size = 0.627, moderate). Significant pre-to post improvements in MT were observed for NTG but not CG ( p = 0.011, effect size = 0.877, moderate). For NTG, post hoc analyses revealed significant MT improvements for the slower ( p = 0.012, effect size = 0.897, moderate) and faster directions ( p = 0.017, effect size = 0.968, moderate). Conclusion Our results illustrate that 6 weeks of neuromuscular training with two sessions per week included in the warm-up program, significantly enhanced agility performance in elite soccer players. Moreover, improvements were found on both sides during body rotations. Thus, practitioners are advised to focus their training programs on both turning directions.