Temporal Effects Of Acute Cycling On Brain-Derived Neurotrophic Factor And Cathepsin B

PURPOSE: Acute bouts of exercise have previously been reported to modulate circulating concentrations of brain-derived neurotrophic factor (BDNF) and cathepsin B (CTSB). While this evidence has been used to propose BDNF and CTSB as potential molecular mechanisms responsible for acute exercise-induced cognitive enhancements, previous research have yielded inconsistent findings for changes in BDNF or CTSB following an acute bouts of exercise. METHODS: Healthy adults (n = 20; 18-35 y) participated in a randomized cross-over design study to assess changes in BDNF and CTSB during and after an acute bout of cycling compared to a sedentary control. Participants completed a 36-min resting control or cycling at 10% above their ventilatory threshold in a randomized order. Serum and plasma samples were assessed prior to the exercise and resting control (T1), 18 minutes (T2), 33 minutes (T3), 36 minutes (T4), and 94 minutes (T5) following T1. Temporal differences in circulating BDNF and CTSB were assessed using linear mixed effects models with condition (2 levels; exercise and rest) and time (5 levels) as fixed factors and participant intercept as a random factor. RESULTS: A significant condition*time interaction was observed for both BDNF (F = 9.10; p < 0.001) and CTSB (F = 3.33; p = 0.022) wherein both BDNF (Mean Difference [μd] = 282.33 pg/mL; p = 0.004) and log-transformed CTSB (μd = 0.19 pg/mL; p = 0.006) concentrations were elevated at T2 during exercise compared to rest. However, BDNF and CTSB did not remain elevated at exercise cessation (T4) for either BDNF (μd = -73.84 pg/mL; p = 0.238) or CTSB (μd = -0.03 pg/mL; p = 0.093). CONCLUSION: These findings suggest that acute bouts of exercise indeed increase BDNF and CTSB. However, these increases may not be sustained for an extended duration which must be considered in future research designs. Future research is needed to elucidate the implications of these transient changes in BDNF and CTSB concentrations on cognitive function. University of Illinois Urbana-Champaign Campus Research Board