Sex Differences in Response to Low- Versus High-Volume Aerobic Exercise for Sport-Related Concussion: A Pilot Randomized Controlled Trial

Objective: To assess sex differences in behavior and motivation of adolescent athletes with sport-related concussion (SRC) versus controls during a 2-week individualized aerobic exercise intervention. Setting: Academic center research laboratory. Participants: Participants were enrolled within 10 days of SRC (n = 32; 15.6 ± 1.4 years, 33% female, 6.18 ± 2.21 days from injury). Twenty-eight control participants (16.0 ± 1.6 years, 33% female) were recruited. Design: Randomized control trial with a 1:1 block randomization scheme stratified by participant sex. Main Measures: Clinical recovery time as determined by the study physician, heart rate threshold (HRt) on the Buffalo Concussion Treadmill Test, adherence rates (calculated as exercise volume completed/exercise volume prescribed), and behavioral assessments including the perceived competence scale (PCS) and the treatment self-regulation questionnaire (TSRQ). Results: Females achieved higher initial HRts ( P = .007), ie, the maximum HR during exercise testing. Males and females with a concussion showed minimal differences in motivation and perceived competence. Although it did not reach statistical significance ( P = .058), females in the low-volume group appeared to recover faster than the high-volume group. This trend was not seen in males. Seven (88%) of exercise-intolerant females had to stop an exercise bout early on 1 or more days due to more-than-mild symptom exacerbation versus 3 (17%) of exercise-intolerant males ( P = .002). Conclusion: Females with a concussion prescribed a high volume of aerobic exercise treatment appeared to take longer to recover than females with a concussion who were prescribed a lower volume, which was not seen in males. Increased training heart rate prescriptions due to higher initial HRts and symptom exacerbation during at-home exercise may have affected female exercise behavior. Although aerobic exercise benefits SRC recovery, this study highlights the need for future research to optimize exercise treatment prescriptions for females after SRC.