'Legs Feed The Wolf': An evolutionary perspective on psychosocial stress, physical activity, and their associations with telomere length in NCAA student-athletes and non-athletes

Abstract

Psychosocial stress negatively impacts our mental and physical health, predisposing us to illness, worsened mental health, and accelerated aging. Conversely, regular physical activity, such as exercise and sports training, positively impacts our health. These opposing effects are intriguing because psychosocial stress and physical activity were inextricably linked throughout human evolution. Large populations of humans have only recently begun transitioning into more sedentary lifestyles, uncoupling psychosocial stress from physical activity. Improving our understanding of these two factors and their interactions will, in turn, improve our understanding of the mechanisms through which psychosocial stress impacts health in both modern and ancestral human populations. My dissertation examines whether physical activity moderates the association between psychosocial stress and capillary blood telomere length in NCAA student-athletes and their non- athlete counterparts in the general student population. My first paper develops an in-depth comparison of psychosocial stress in these two groups using a suite of psychosocial stresssurveys and an adapted cognitive interview protocol. Student-athletes (N=65) reported lower levels of current perceived stress and anxiety symptoms (p<0.05) but similar levels of childhood psychosocial stress, recent exposure to external stressors, and depressive symptoms compared to non-athletes (N=57). My second paper utilized self-report and objective measures of physical activity (i.e., accelerometry) to compare physical activity patterns in these groups. Student- athletes (N=60) both self-reported higher levels of physical activity and recorded higher levels of activity via accelerometry (p>0.001) compared to non-athletes (N=50). Interestingly, categorical measures of activity levels (i.e., time spent in moderate-to-vigorous physical activity) identified Rowers as the most active among student-athletes, but continuous measures of activity levels (e.g., total physical activity level) identified Track and Field athletes as the most active (p>0.05 for both comparisons). My third and final paper tested whether higher physical activity weakened the association between childhood psychosocial stress and telomere length estimated from capillary blood collected on Hemaspot HF devices (N=111). Telomeres are DNA sequences that protect the ends of chromosomes. They shorten with cell replication, age, and oxidative stress, leading to functional decline with age and worsened health outcomes. Importantly, psychosocial stress is thought to accelerate TL shortening. My a priori analyses did not support a direct association between psychosocial stress, physical activity, or the interaction of these variables and telomere length. However, a post hoc analysis found that individuals who recorded higher total physical activity demonstrated a positive association between childhood psychosocial stress and telomere length (i.e., higher childhood stress predicted longer telomeres) while individuals who recorded lower total physical activity had a negative association (i.e., higher childhood psychosocial stress predicted shorter telomeres). My results do not offer explicit support for the hypothesis that physical activity moderates the effects of psychosocial stress on telomere length. However, my project adds to the literature in at least several ways. It produced a novel and much-needed comparison of psychosocial stress between NCAA student-athletes and non-athletes. It illustrated and validated several data collection techniques for psychosocial stress and physical activity. Further, my telomere findings offer an exciting direction for the future exploration of psychosocial stress- physical activity interactions. Lastly, this work improves our overall understanding of NCAA student-athletes' mental and physical health and how their unique circumstances intersect with the ongoing effects of the COVID-19 pandemic.