Pre-Season Fitness Level and Injury Rate in Professional Soccer - A Prospective Study

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 six-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 VO₂ 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), eight 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 minutes 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 VO₂ 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%, p0.05). 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.