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Abstract

International Journal of Exercise Science 12(3): 919-931, 2019. A mild traumatic brain injury (mTBI) is a common injury that happens to people across a range of lifestyles. Rest has been regarded as the most effective remedy to restore impaired physiological functions in those who have experienced this kind of injury. However, recent data suggests that a gradual increase in physical activity post-injury can lead to quicker recovery from negative symptoms. The impact of physical activity on physiologic recovery is not completely understood and the purpose of this study was to better understand how physical activity and sleep influence physiological outcomes following a mTBI. The data collected in this study came from two groups of young adults: a healthy control (n=5) and those that had a mTBI (n = 5). The daily activity was measured using an activity monitor for a week immediately after injury. Physiological measurements of excitability and inhibition within the motor cortex and neurotransmitter concentrations were collected within 72 hours of injury and again at two months to determine if physical activity or sleep within one week after injury had an influence on physiologic recovery. Control participants had higher levels of total (d = 1.2), light (d = 1.3) and moderate physical activity (d = 0.7), and lower total sleep time (d = -1.9), compared with the mTBI group. Across the two months, relative to the control group the mTBI group showed similar changes in excitability (d = 0.13), but greater changes in inhibition (d = -0.66). Changes in the excitatory (d = 0.06) and inhibitory (d = -0.16) neurotransmitters were similar between groups. Neither physical activity, nor sleep quality were significantly associated with the change in motor cortex excitability (R2 ≤ 0.18, p ≥ 0.22), inhibition (R2 ≤ 0.3, p ≥ 0.08) or neurotransmitter concentrations (R2 ≤ 0.15, p ≥ 0.20) between 72 hours and two months post-injury. These preliminary results suggest there is no direct effect of physical activity on physiological outcomes.

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