Exercise Intolerance Among Active-duty Service Members with Persistent Symptoms Related to Mild Traumatic Brain Injury

Research Objectives: Exercise intolerance (EI) following a mild traumatic brain injury (mTBI) has been explored in the acute phase of injury but little is known about this disorder in the chronic phase of injury. The objective of this study was to describe EI in a sample of military service members (SMs) who are reporting persistent post concussive symptoms.

Design: Cross sectional.

Setting: Intrepid Spirit Center at Naval Hospital Camp Pendleton (ISC NHCP).

Participants: Participants (n=28) were recruited primarily from the ISC NHCP and include SMs with a history of mTBI and persistent post-concussive symptoms.

Interventions: Not applicable.

Main Outcome Measures: As part of a larger randomized controlled trial, participants completed a Buffalo Concussion Treadmill Test (BCTT) to determine EI. The BCTT is a validated test of EI, which is diagnosed if concussion-specific symptoms are exacerbated with increased physical activity. This test identifies a heart rate threshold that is used to establish a safe level of exercise for treatment of concussion. Participants post-concussive symptoms were measured with the Neurobehavioral Symptom Inventory (NSI), a non-exertional resting state symptom inventory.

Results: Of the total sample, 29% (n=8) participants had EI. Of those with EI, headache was the most frequent complaint (75%; n=6), followed by dizziness (25%; n=2). There was no statistical difference in self-reported symptom burden between EI and non-EI participants based on NSI Total scores and four sub-scale scores (all p’s > .05).

Conclusions: Recognition and management of EI is critical for both warfighter health and military readiness. Our findings suggest approximately one third of SMs with mTBI and persistent related symptoms may be intolerant to exercise, which non-exertional symptom testing may fail to detect.

Author(s) Disclosures: The authors have nothing to disclose.