Single-Sport Athletes Exhibit More Lower Extremity Valgus than Multi-Sport Athletes

Abstract

Single-sport athletes have higher rates of lower extremity injuries than athletes that participate in multiple sports. This may be because athletes who specialize in one sport are subjected to a specific set of repetitive movement demands, ultimately resulting in overuse injuries, whereas multi-sport athletes are exposed to a larger variety of movement stimuli. Differences in high-risk biomechanics, such as lower extremity valgus, between single- and multi-sport athletes may provide further insight into the incongruity in injury rates. PURPOSE: To identify differences in lower extremity biomechanics between multi-sport compared to single-sport athletes. METHODS: Ninety-eight adolescent athletes participated in the study and were grouped based on the number of organized sports they participated in during the previous academic year into single-sport (SS) (n=55, age=15.8±1.3 years, height= 1.7±6.2m, mass=59.9±8.9 kg) and multi-sport (MS) (n=43, age=15.1±1.2 years, height=1.7±7.2m, mass=61.1±10.9 kg) groups. Established 3D motion analysis techniques were utilized to collect three trials of a single-leg broad jump with a subsequent maximal vertical jump on the left leg. Independent t-tests were used to identify significant differences in measures of lower extremity biomechanics (hip adduction and internal rotation, knee abduction and external rotation peak angles, excursions and normalized external moments) between groups (p<0.05). RESULTS: Significant differences were identified during the single-leg task, such that SS athletes exhibited greater peak hip adduction (SS: 10.6±5.4°, MS: 8.5±4.5°, p=0.04), and knee external rotation (SS: 1.9±5.7°, MS: −0.6±5.0°, p=0.02) angles, greater frontal plane hip excursion (SS: 12.1±4.1°, MS: 9.8±3.1°, p=0.003) and greater knee abduction moments (SS: −0.085±0.16 Nm/kg*m, MS: −0.035±0.07 Nm/kg*m, p=0.049) than MS athletes. CONCLUSIONS: SS athletes exhibit higher levels of dynamic lower extremity motion and moments during single-leg landing tasks than MS athletes, which have been shown to increase risk of injury. These findings may help explain why higher injury rates have been observed in athletes that specialize in one sport. Further study of the possible deleterious effects of sport specialization is warranted.