Do Preseason Running Mileage and Video Analysis Predict In-season Injury Among High School Cross Country Athletes

Abstract

Cross country is a popular high school sport. Over one third of high school cross country runners sustain a lower extremity injury each season. Despite this high rate of injury, there is little known about risk factors for injury in this population or appropriate preseason running mileage. Identification of risk factors has been limited to static alignment measures which have not been proven to be reliable measures for dynamic movements, such as running. Increased Q-angle (valgus) has been proposed as a possible predictor for injury in high school runners but has not been a reliable measure when utilizing 2D video analysis. Frontal plane projection angle (FPPA) has been found to be a reliable 2D measure of this valgus angle during dynamic running analysis. PURPOSE: To determine if increased FPPA and summer running mileage predict lower extremity injury during one high school cross-country season. To describe gender differences in running gait analysis for teenage runners. METHODS: Demographics, running history, anthropometric measures and running video analysis were collected on 28 (17 males, 11 females) high school cross country runners. Running related injury incidence was recorded during the 2008 cross country season. RESULTS: 10 athletes reported an injury during the cross country season. All injuries occurred to the lower extremity. Mean FPPA for injured was not significantly different than non-injured (p=.73). Mean preseason running mileage per week was less in injured (20.7 miles/week) compared to non-injured (26.6 miles /week) (p=.12). Gender analysis revealed females had significantly higher mean FPPA (9.3° vs 6.4°, p=0.03), lower mean hip external rotation strength (8.6kg vs 12.3kg, p=.0001) and hip drop (82% vs 41%, p=0.03). CONCLUSION: Lower preseason training mileage (inadequate preseason conditioning) may be a risk factor for injury for male and female high school cross country runners. Females demonstrated increased FPPA and hip drop during 2D running video analysis which may predispose them to higher incidence of running related injuries