Statistical analyses
re-injuries, training/match, injuries
REGRESSIONS
All analyses were conducted for male and female players separately. Descriptive statistics are presented with sum, mean ± standard deviation, and Weekly injury prevalence (moving average for 2 weeks*) for Descriptive statistics of weekly reports during seasonSD, standard deviation*Sum of all players during season; Injury incidence rates were calculated as total number of injuries divided by total exposure hours. Both new injuries and re-injuries were included, but injuries that were persistent from baseline were excluded. Seasonal injury incidence rates and time-loss incidence rates are presented as injuries per 1000 h exposure with 95% CI (Table Potential baseline risk factors (age, strength- and/or conditioning training beside regular football training, participation in other sports during football season, perceived importance of sporting success, self-rated training and match load, balance between training/match load and recovery, previous/present injury at start of the season, injury beliefs) for injury were analysed with Poisson regressions. The basic model included the number of new injuries during the season as the target variable, the natural logarithm of total exposure hours during the season as the offset variable, team as a random factor using variance component as covariance structure, and intervention group (extended IBM SPSS Statistics for Windows (V28.0. Armont, New York) was used for all analyses. An experienced statistician was responsible for preparing the database and data analyses.An a priori sample size calculation was made for the randomised trial [