Statistical analyses
contusions, groin injury
An a priori sample size calculation showed that for hypothesis 1, 252 players would be needed based on the assumption that 80% of players would report at least one injury during the season according to the study by Thorborg For hypothesis 2, 301 players would be needed based on the assumption that 67% of players would report a groin injury during the season according to the study by Harøy Baseline data are presented descriptively. IR and weekly PR are presented with 95% CI, and incidence and prevalence rate ratios (IRR, PRR) were calculated and compared between all three groups (according to intention-to-treat) using generalised linear models with Poisson distribution, log link and the natural logarithm of total exposure hours or total eligible weeks as offset denominator variables. All data collected from teams and players who dropped out were included in the analyses. Due to uneven sex distribution between groups, all analyses were sex-adjusted. In these calculations, contusions were excluded in line with Waldén 