Article Title



P. Antonellis, K. R. Campbell, J. L. Wilhelm, N. Pettigrew, J.C. Chesnutt, L..A. King

Oregon Health & Science University, Portland, Oregon, United States

Approximately 2.8 million people sustain a mild traumatic brain injury (mTBI) annually and often report exercise intolerance. While initiating aerobic exercise is safe and may reduce symptoms, not all people have exercise intolerance after mTBI. PURPOSE: To explore patterns of exercise intolerance and symptom resolution before and after physical rehabilitation in people with mTBI. METHODS: Thirty-three people were tested on exercise tolerance with the Buffalo Concussion Treadmill Test (BCTT). Participants passed the BCTT and were considered exercise tolerant if their heart rate reached 85% of age predicted maximum or they achieved a Borg Rating of Perceived Exertion ≥17. Participants were classified as exercise intolerant if they failed the BCTT due to symptom exacerbation (increase of ≥3 symptom points during the BCTT). All participants performed 6 weeks of rehabilitation based on clinical practice guidelines (autonomic, cervical, vestibular/ocular-motor and motor function). General mTBI-related symptoms were assessed using a 22-item questionnaire - the Neurobehavioral Symptom Inventory (NSI; scale: 0-88). RESULTS: Nineteen participants (58%) were classified as exercise intolerant prior to rehabilitation. Of these 19 participants, 12 (63%) passed the BCTT after rehabilitation indicating improvements in exercise intolerance. Regardless of improvements in exercise intolerance, both groups had similar improvement in symptom severity post rehabilitation. Specifically, the group that remained exercise intolerant had a mean reduction of 17±2 points on the NSI and the group that improved their exercise intolerance had a mean reduction of 20±3 points. The group that remained exercise intolerant after rehabilitation had a higher NSI score prior to rehabilitation (46±12) relative to the group that improved exercise intolerance (37±15). CONCLUSION: Our findings suggest that for people with exercise intolerance, rehabilitation appears to be effective in reducing symptoms for people with mTBI, regardless of their improvement in exercise intolerance. However, not all people improved in exercise intolerance after rehabilitation. Further work is needed to elucidate the physiological mechanisms underlying exercise intolerance to better target interventions.

Supported by the US Department of Defense (#W81XWH-17-1-0424).

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