Athlete burnout, biomarkers, and mental and physical health: A longitudinal examination of physiological mechanisms and processes.

Burnout is becoming increasingly common in athletes. It has also recently been found to increase the risk of further physical and mental health consequences. However, few studies have examined possible explanatory mechanisms of this relationship. Therefore, the present study aimed to test whether changes in key physiological systems may help explain the relationship between athlete burnout and mental and physical health outcomes over time. Following a pre-registered protocol, with open methods, code, and data, we recruited 64 competitive athletes who completed measures of athlete burnout, physical symptoms, depressive symptoms, and insomnia as well as provided saliva samples for the analysis of biomarkers (testosterone, dehydroepiandrosterone-sulphate [DHEA-S], secretory Immunoglobulin A [sIgA]) at three timepoints over six months. In multilevel analyses, at the between level, burnout was associated with all health outcomes, and testosterone was associated with physical symptoms. At the within level, total burnout and a reduced sense of accomplishment predicted increases in depressive symptoms and, in the exhaustion model, decreases in sIgA predicted increases in insomnia. In exploratory Bayesian analyses, at the within level, burnout additionally predicted decreases in testosterone, DHEA-S, and sIgA. However, we found no indirect effects linking burnout to health via changes in biomarkers. Overall, we found further evidence for the links between burnout, biomarkers, and mental and physical health over time, however, it is possible that the mechanisms underpinning these relationships are more complex.