Factors Associated with Symptom Resolution after Aerobic Exercise Intervention in Adolescent and Young Adults with Concussion

ABSTRACT Background Aerobic exercise facilitates post-concussion symptom resolution at the group-level, but patient-level characteristics may affect the likelihood of treatment efficacy. Purpose To investigate demographic and clinical characteristics which differentiate post-concussion aerobic exercise treatment efficacy from non-efficacy in the intervention arm of a randomized clinical trial. Methods Adolescent and young-adult participants initiated a standardized aerobic exercise intervention within 14 days of concussion, consisting of self-selected exercise for 100-minutes/week at an individualized heart rate (80% of heart rate induced symptom exacerbation during graded exercise testing). Treatment efficacy was defined as symptom resolution within 28-days post-concussion. Treatment efficacy and non-efficacy groups were compared on demographics, clinical characteristics, intervention adherence, and persistent symptom risk using the Predicting Persistent Post-Concussive Problems in Pediatrics (5P) clinical risk score. Results 27 participants (16.1 ± 2.3 years old, range: 11-21 years; 52% female) began the intervention a mean of 9.5 ± 3.7 days after concussion; half (n = 13; 48%) demonstrated treatment efficacy (symptom resolution within 28 days post-concussion). Those whose symptoms resolved within 28 days had significantly lower pre-intervention Post-Concussion Symptom Inventory scores (21.2 ± 13.2 vs 41.4 ± 22.2; p < .01), greater adherence to the intervention (77% vs 36%; p = .05), and longer average exercise duration (49.7 [36.8, 68.6] vs 30.4 [20.7, 34.7] minutes; p < .01), than those whose symptoms lasted more than 28 days. Groups were similar in age, sex, timing of intervention, and pre-intervention 5P risk score. Conclusions A standardized aerobic exercise intervention initiated within 14 days of concussion demonstrated efficacy for approximately half of participants, according to our definition of treatment efficacy. This multisite aerobic exercise intervention suggests that lower symptom severity, higher intervention adherence, and greater exercise duration are factors which increase the likelihood of symptoms resolving within 28 days of concussion.