Urinary BDNF-to-creatinine ratio is associated with aerobic fitness.

Circulating levels of brain-derived neurotrophic factor (BDNF) are known to be affected by aerobic exercise. As the previous research focus in humans has been to examine peripheral BDNF levels through blood, serum, and platelet assay, the present study investigated the association between basal urinary BDNF concentration and indices of aerobic fitness in a sample of young adults (n=52). Aerobic fitness was evaluated with self-report of exercise habits and heart rate (HR) assessment during a sub-maximal Step Test. BDNF concentration was determined by enzyme-linked immunosorbent assay and adjusted for creatinine. Results indicated that the basal BDNFlog/creatinine ratio was positively associated with greater frequency of exercise and, during aerobic challenge, a quicker rise in HR upon exercise, lower peak HR during exercise, and lower HR during the recovery period, each indicative of enhanced fitness. These results highlight the utility of urine capture as a non-invasive technique to assess for exercise-mediated changes in peripheral BDNF.