Sex Differences in Physical Activity and Energy Expenditure after Adolescent Concussion

Purpose: Sex differences may exist in physical activity (PA) behavior among adolescents. PA is recommended soon after concussion to improve recovery outcomes. Our purpose was to examine sex differences in PA engagement after adolescent concussion. Methods: Male and female adolescent athletes within 21 days of concussion wore wrist-worn actigraphy devices for one week to quantify three variables: steps/day, caloric expenditure, and resting heart rate (RHR). We used linear mixed models with random slopes and random intercepts for participants to examine sex differences for each outcome over the monitoring period, adjusting for variables that differed between sexes. Results: We enrolled 122 adolescents with concussion: N=62 female athletes (11.4±4.6 days post-injury, age=15.6±1.4 years) and N=60 male athletes (10.9±4.8 days post-injury, age=15.5±1.9 years). After adjusting for symptom severity, body mass index, and anxiety/depression history, female athletes expended fewer calories (β=-336 calories; 95%Confidence Interval CI: -553, -159; p<0.001) than males, but daily step count (β=-568 steps/day; 95%CI: -2261, 1124; p=0.51) and RHR (β=3.06 beats/min; 95%CI: -1.97, 8.09; p=0.23) were similar between sexes across the week. Both steps/day (β=353 steps/day; 95%CI: 115, 591; p=0.004) and caloric expenditure (β=38.2 calories; 95%CI: 15.4, 61.0; p=0.001) increased each day for the overall sample, though the rate at which they increased did not significantly differ by sex (sex*time interaction: p=0.10, p=0.07 respectively). Conclusions: Compared to males, female athletes recorded lower caloric expenditure but similar steps/day and RHR during a one-week monitoring period after concussion. PA and caloric expenditure increased throughout the monitoring week independent of sex, which may reflect improvement in symptoms or a gradual increase in PA based on guidance from their medical provider.