Introduction

High cumulative workloads and spikes in player workloads have been associated with an increased risk of injury in soccer and other sports. Most studies, however, have been conducted with data from male soccer players or male athletes in other sports, with few studies investigating female athletes. Using metrics collected from GPS units to monitor cumulative load and distance may be valuable for injury prevention. The purpose of this study was to examine the relationship between injury risk and workload as collected from wearable GPS units in NCAA Division I women’s soccer players.

Methods

Lower extremity injury incidence and GPS workload data (player load, total distance, and high-speed distance) of 65 NCAA Division I women’s soccer players were collected over 3 seasons. Accumulated 1-, 2-, 3- and 4-weekly loads and acute:chronic workload ratios (ACWR) were classified into discrete ranges by z-scores. ACWR was calculated using rolling averages and exponentially weighted moving averages (EWMA) models. Binary logistic regression models were used to compare the 7:28 rolling average and EWMA ACWRs between injured and non-injured players for all GPS/accelerometer variables. The prior 1-, 2-, 3-, and 4-weekly accumulated loads for all GPS/accelerometer variables were compared between the injured and uninjured cohorts using two-sample t-tests with an alpha level of 0.05 set as significant.

Results

There were a total of 53 lower extremity injuries that resulted in lost time recorded (5.76/1000 hours ‘on-legs’ exposure time; 34 non-contact and 19 contact injuries). Of the contact injuries, 73.7% occurred in games. The incidence of lower extremity injury during games was over 3.5 times higher than in practice (11.25/1000 hours and 3.07/1000 hours, respectively). The foot/ankle and thigh were the most common sites for injury over the three seasons, with lateral ankle sprains (0.86/1000 hours) and quadriceps strains (0.86/1000 hours) accounting for the highest occurrence during the season. The prior 2-week (7,242 vs 6,613; p=0.02), 3-week (10,533 vs 9,718; p=0.02), and 4-week (13,819 vs 12,892; p=0.04) accumulated player loads and 2-week (62.40 vs 57.25 km; p=0.04), 3-week (90.97 vs 84.10 km; p=0.03), and 4-week (119.31 vs 111.38 km; p=0.05) accumulated total distances were significantly higher for injured players compared to non-injured players during the same timeframes. There were no significant differences in player load, total distance, or high-speed distance ACWR between injured and non-injured players for both the rolling averages and EWMA calculations.

Conclusion

Higher accumulated player load and total distance, but not ACWR, are associated with injury in women’s soccer players.