Are Off-Field Activities an Underestimated Risk for Hamstring Injuries in Dutch Male Amateur Soccer Players? An Exploratory Analysis of a Prospective Cohort Study

Purpose: The purpose of this study was to explore what extent male amateur soccer players participate in off-field activities and whether these off-field activities are associated with the development of hamstring injuries. Methods: Amateur soccer players (n = 399) from first-class selection teams (n = 32) filled out a baseline screening questionnaire concerning off-field activities (i.e., work and study type and hours, traveling time, sleep, energy costs, and time spent on other activities) and their history of hamstring injury as a part of a cluster-randomized controlled trial. Throughout one competition, the players reported weekly their hamstring injuries, which were verified by medical/technical staff. Multivariable Firth corrected logistic regression models were used to explore associations between off-field activities and hamstring injuries. Results: Sixty-five hamstring injuries were recorded. Previous injury was significantly associated with hamstring injuries (OR ranging from 1.94 [95% CI 1.45–2.61] to 2.02 [95% CI 1.49–2.73]), but off-field activities were not. Conclusion: Although amateur soccer players spent a relatively large amount of time on off-field activities, we did not find off-field activities measured at baseline to be associated with hamstring injuries in the subsequent competitive soccer season. In contrast, previous hamstring injury was found to be strongly associated with (recurrent) hamstring injuries.