Dose-response of eccentric training to prevent hamstring injuries in soccer players: a systematic review with meta-analysis

The high demand in soccer leads to a high prevalence of injuries in the sport, with approximately 8 injuries per 1000 hours of play. Therefore, this systematic review with meta-analysis aimed to determine the effects and dose-response of eccentric training on hamstring injuries in soccer players. We searched various databases between June and October 2023 for this purpose. We selected only randomized controlled clinical trials that included interventions with Nordic or eccentric hamstring exercises performed by soccer players. Ten studies were included for qualitative analysis, and nine for quantitative analysis. The mean age of participants in the included studies was 22.03 +/- 3.1 years, ranging from 14.7 years to 41 years. When calculating the overall Odds ratio, it was observed that performing Nordic exercises as part of the warm-up or after matches significantly decreased the probability of injuries (OR: 0.376; 95% CI: 0.241- 0.586; p < 0.001). This systematic review with meta-analysis suggests that Nordic exercises are effective in reducing the likelihood of injury in soccer players, regardless of sex, level of competition, time of exercise, and dose used. However, better results were observed in male soccer players, especially professionals, when the exercises were performed after training, with low-frequency doses (1 time per week), high volumes of work (>30 repetitions/week), and with an intervention duration longer than 3 months.