Feasibility of a Modified Exertional Bike Test to Threshold Supervised Virtual Aerobic Exercise in Community-Dwelling Individuals with Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) often creates a sequela of symptoms that complicate safely participating in aerobic exercise. Although exertional assessments have been used to evaluate exercise tolerance, data on the feasibility of using test-derived metrics to guide the intensity of aerobic exercise interventions in community-dwelling adults is yet to be presented. This secondary analysis of a wider pilot randomized control trial examined whether a modified exertional bike test (MEBT) could be used to effectively individualize supervised virtual aerobic exercise without exacerbating symptoms in individuals with a mTBI. Adults (18-55 years) diagnosed of mTBI within the previous 12 months completed the MEBT and were randomized to either a 12-week supervised virtual aerobic exercise intervention or active balance control. Those randomized to the aerobic group exercised at 65-80% of HR at MEBT-derived symptom threshold or volitional exhaustion. Descriptive session outcomes, Spearman correlations, and Fisher's z tests assessed (1) the feasibility of symptom-threshold HR intervention metrics, (2) changes in the HR-symptom relationship over time, and (3) the influence of mTBI-related confounders on HR-symptom associations. Participants completed 95.6% of aerobic sessions, with symptom exacerbation (≥3-unit increase) reported in just 3.8% of sessions. Ten of 12 participants displayed a decreased, or negative, HR-symptom severity association over time. In addition, Fisher's z tests revealed confounding variables did not meaningfully modify the HR-symptom association. Sub-symptom-thresholded exercise sessions limited symptom exacerbation, uncoupled the HR-symptom relationship, and improved exercise tolerance over time. These findings highlight the feasibility of exertional symptom-guided virtual aerobic exercise following mTBI and support progression towards larger efficacy trials.