The aim of the study was to investigate seasonal variations in fitness and performance indices of professional male soccer players. Eighteen professional male soccer players (age range 22–32 years) completed three similar sets of tests at three stages of the season: before preseason; after preseason and the middle of the competitive in-season. A significant decrease in body mass and percent fat was found during the preseason. A significant improvement (p < 0.05) was found in the vertical jump (preseason: 37.0 ± 5.3, post-preseason: 39.0 ± 4.8, mid-season: 40.3 ± 5.5 cm), the 4 × 10-m agility test (preseason: 8.1 ± 0.2, post-preseason: 7.9 ± 0.2, mid-season: 8.1 ± 0.3 s), flexibility (preseason: 45.2 ± 8.8, post-preseason: 48.2 ± 7.0, mid-season: 49.9 ± 6.9 cm) and aerobic capacity (preseason: 52.7 ± 6.6, post-preseason: 56.4 ± 6.0, mid-season: 57.4 ± 5.4 mL/kg/min) during preseason, with no further change during mid-season. Repeated sprint test (RST) (6 × 30-m) performance indices showed significant deterioration (p < 0.05) in ideal sprint time (IS; preseason: 21.8 ± 1.0, post-preseason: 23.0 ± 0.8, mid-season: 23.2 ± 0.8 s) and total sprint time (TS; preseason: 22.5 ± 0.7, post-preseason: 23.5 ± 0.6, mid-season: 23.8 ± 0.6 s) during preseason, with no further changes during mid-season. However, performance decrement (PD) significantly decreased during the preseason with no change during mid-season. The findings suggest that while power training was probably responsible for the anaerobic fitness improvement, the high-volume training led to improvement in aerobic fitness during the preseason. However, the low-intensity aerobic-type training, coupled with the high total training load, may have led to fatigue and decreases in IS and TS during the preseason.

BackgroundIn individual sports, the effect that injuries have on an athlete’s performance, success and financial profit is implicit. In contrast, the effect of a single player’s injury or one player’s absence in team sports is much more difficult to quantify, both from the performance perspective and the financial perspective.ObjectivesIn this study, we attempted to estimate the effect of injuries on the performance of football teams from the English Premier League (EPL), and the financial implications derived from this effect.MethodsOur analysis is based on data regarding game results, injuries and estimations of the players’ financial value for the 2012–2013 through the 2016–2017 seasons.ResultsWe found a statistically significant relationship (r=−0.46, 95% CI −0.6 to 0.28, p=0.001) between the number of days out due to injuries suffered by team members during a season and the place difference between their actual and expected finish in the EPL table (according to overall player value). Moreover, we can interpolate that approximately 136 days out due to injury causes a team the loss of one league point, and that approximately 271 days out due to injury costs a team one place in the table. This interpolation formula is used as a heuristic model, and given the relationship specified above accounts for a significant portion of the variance in league placement (21%), the remaining variance is related to other factors. Calculating the costs of wage bills and prize money, we estimate that an EPL team loses an average of £45 million sterling due to injury-related decrement in performance per season.ConclusionProfessional football clubs have a strong economic incentive to invest in injury prevention and rehabilitation programmes.

The aim of the present study was to assess prospectively the effect of pre-season fitness on injury rate during the competitive season among professional soccer players. Thirty-one players participated in the study during two consecutive competitive seasons (2015–16 and 2016–17; a squad of 22 players in each season). During the 6-week pre-season training period (8 training sessions and a friendly match every week, 14–18 training hours/week) there was a significant improvement in VO 2 max, a significant increase in ideal and total sprint time and no change in vertical jump, flexibility and repeated sprint-test performance decrement. During the two consecutive seasons, 28 injuries were recorded. Ten injuries were classified as mild (missing 3–7 days of practice/match), 8 as moderate (missing 8–28 days) and 10 as severe (missing >28 days). The rate of match injuries was higher (9.4 per 1000 match hours) compared to practice injuries (4.7 per 1000 training hours). Most injuries were overuse injuries (72%) of the lower limbs (71%). Most of match injuries occurred during the last 15 min of each half. There were no differences in fitness characteristics in the beginning of pre-season training between injured and non-injured players. However, improvements in VO 2 max during the pre-season training period were significantly lower among injured players (0.9±5.5%) compared to non-injured players (10.4±6.5%, p<0.05). Our results emphasize the importance of pre-season training in professional soccer players not only for improvement in fitness but also for injury prevention during the following competitive season.

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