Background The FIFA11+ is a dynamic warm-up injury prevention program. Previous studies have examined its efficacy in reducing injuries, however no information is available on whether it changes targeted movement patterns.

Objective The purpose of this study was to examine the changes in peak knee abduction moment (PKAM) over two soccer seasons using the FIFA11+. We hypothesized that athletes will have decreased PKAM over the first season, no changes in the off-season, and further decreases over the second season.

Design Prospective non-randomized intervention study (control team data currently being collected).

Setting Elite collegiate women's soccer.

Patients (or Participants) First season N=83, off-season N=68, second season N=59.

Interventions The FIFA11+ program was initiated during the preseason and completed throughout two consecutive soccer seasons as a warm-up prior to training sessions and games at least 3x/week. Researchers did not influence the training during the off-season.

Main Outcome Measurements PKAM measured during motion analysis of a drop jump at pre- and postseason of two consecutive seasons. Repeated measures ANCOVAs were used to analyse the change over each season and the off-season, with baseline PKAM included in each model as a covariate.

Results There was a significant main effect of time over the first season (preseason 0.24±0.01, postseason 0.23±0.01, p=0.02). PKAM was a significant covariate (p<0.01). There no main effect of time over the off-season (p=0.40), however, PKAM was a significant covariate (p<0.01). There was also no main effect of time over the second season (p=0.29), with PKAM again a significant covariate (p<0.01).

Conclusions The FIFA11+ is effective in preventing injuries, however its mechanism is unknown. The preliminary results of this study indicate this injury reduction may not be occurring as a result of a decrease in PKAM in all athletes.