50 Danish male professional and amateur soccer teams (n=942) were cluster randomized to receive either eccentric strengthening of the hamstring muscle using the Nordic hamstring muscle exercise (intervention) or the usual training program (control). The results after the 10-week program concluded that the control groups had significantly higher rates of acute hamstring injury in comparison to intervention. In addition, the control group had a significantly higher proportion of recurrent injury rates in comparison to intervention.

The Fragility Index is a tool that aids in the interpretation of significant findings, providing a measure of strength for a result. The Fragility Index represents the number of consecutive events that need to be added to a dichotomous outcome to make the finding no longer significant. A small number represents a weaker finding and a large number represents a stronger finding.

The Reporting Criteria Assessment evaluates the transparency with which authors report the methodological and trial characteristics of the trial within the publication. The assessment is divided into five categories which are presented below.

Why was this study needed now?

Hamstring injury accounts for 12% to 16% of all soccer related injuries, making it the most prevalent injury. Eccentric hamstring strength training exercises have undergone a series of developments with an advantage of capability to be done in the field without the use of any equipment. The effect of eccentric hamstring strength training on hamstring injuries have been incongruous in the literature, and this study explores it further.