Cardiorespiratory fitness and working memory in persons with traumatic brain injury: a cross-sectional analysis.

Introduction: Cognitive impairment is a highly impactful consequence of traumatic brain injury (TBI) and there are limited evidence-based treatment practices to combat these impairments. Evidence from other populations suggest that aerobic exercise training (AET) is beneficial for a variety of cognitive deficits, but the research in persons with TBI to date is equivocal. One potential reason is the heterogeneity of exercise prescriptions and outcome measures. This stems from the fact that studies have not been designed based on previous data supporting a specific AET prescription to target a cognitive domain. The primary purpose of this cross-sectional analysis was to examine the relationship between cardiorespiratory fitness (CRF), as a cross-sectional surrogate of AET, and cognition in persons with TBI to inform future research.

Methods: Cross-sectional analysis was conducted on baseline data of persons with TBI who completed neuropsychological assessments to evaluate several cognitive domains and a cardiopulmonary exercise test (CPET) to measure CRF. Based on the normal distribution of an outcome, Pearson's r or Spearman's ρ was calculated to measure the relationship between CRF and cognition.

Results: Data were analyzed for all participants who demonstrated valid CPETs ( = 21 of 29). Based on the cycle ergometer-based norms of CRF, males in this sample were in the 69th percentile and females in this sample were in the 56th percentile, with high variability across individuals. Higher CRF, as measured by peak power output (W), was significantly associated with greater working memory ( = 0.465,  = 0.017), even after post-hoc corrections.

Conclusions: These data suggest average and highly variable CRF in persons with TBI of all severity and support cycle ergometry-based CPET testing in this population. Further, these data provide support for future research applying AET to target working memory and possibly other executive functions in persons with TBI. This research is a small step toward large-scale randomized controlled trials that can directly impact clinical care to treat cognitive symptoms post-TBI.