P3.248: Predictors of Exercise Test Tolerance Among Adolescent Athletes with Concussion

Background: Following concussion, early aerobic exercise is beneficial in promoting recovery, however some athletes exhibit exercise intolerance. The purpose of this study was to evaluate factors associated with post-concussion exercise test cessation among adolescent athletes with concussion.

Methods: We conducted a cross-sectional study of adolescents with concussion assessed within 21 days of injury who were symptomatic at rest. Participants completed clinical assessments and underwent an exercise test on a stationary bike (modified YMCA branching exercise protocol; Figure). Participants were grouped into three groups, according to the reason for stopping the exercise test. These included symptom worsening (Visual Analog Scale Δ ≥3 cm), reaching age-predicted maximum heart rate (HR [220 bpm-age]) or goal maximum exertion (Rating of Perceived Exertion [RPE] ≥17), and completion of the protocol. Those who completed the test or reached maximum HR/RPE were considered exercise tolerant, while those who stopped due to symptom exacerbation were considered exercise intolerant. Participants also answered questions about their injury characteristics and medical history.

Results: We enrolled 105 individuals who underwent the bike test: 24 (23%) who stopped because of symptom exacerbation, 64 (61%) who stopped due to HR or RPE, and 17 (16%) who stopped once they completed the entire test protocol. Overall, the average maximum HR achieved during the bike test in the sample was 170.3±21.0 bpm, which was not significantly different among groups. Those who stopped due to HR/RPE were younger than the “completed test protocol” group (15.5±1.4 vs. 17.0±1.1 years; p< 0.001). In addition, a smaller proportion of those who completed the test protocol were female relative to the other two groups (6% vs. 59% vs. 63%; p< 0.001). Those who were exercise intolerant reported significantly greater pre-test symptom severity, more dizziness, greater neck disability, and worse convergence (Table).

Conclusion: Individual factors such as age and sex were significantly associated with stopping for reasons other than test completion. Exercise-intolerant participants reported a greater symptom burden, dizziness, neck disability, and oculomotor function than those who were exercise tolerant.