Exercise Intensity and Recovery on Circulating Brain-derived Neurotrophic Factor

Introduction Brain-derived neurotrophic factor (BDNF) is an exercise-induced neurotropin mediating neuroprotection and synaptic plasticity. Although exercise intensity is implicated as a potentially important mediator of BNDF release after exercise, the optimal exercise stimulus (interval vs continuous) and intensity (submaximal vs supramaximal) for augmenting circulating BDNF levels remains unknown. Irisin, an exercise-driven myokine, may also contribute to neuroprotection by upregulating BDNF. Purpose To examine the response and recovery of plasma BDNF and irisin after acute exercise of differing intensities. Methods Eight males (23.1 +/- 3.0 yr of age; V & x2d9;O-2max 51.2 +/- 4.4 mL center dot kg(-1)center dot min(-1)) completed four acute exercise sessions: 1) moderate-intensity continuous training (MICT, 65% V & x2d9;O-2max); 2) vigorous-intensity continuous training (VICT, 85% V & x2d9;O-2max); 3) sprint interval training (SIT, "all out"); and 4) no exercise (CTRL). Blood was collected preexercise as well as immediately, 30 min, and 90 min postexercise. Plasma BDNF and irisin were assessed with commercially available enzyme-linked immunosorbent assay kits. Results Plasma BDNF levels increased immediately after exercise in the SIT group (P < 0.0001) with plasma concentrations recovering 30 and 90 min postexercise. The BDNF levels after MICT were reduced 30 min postexercise compared with immediately postexercise (P = 0.0189), with no other changes across time points in MICT and VICT groups. Plasma BDNF area under the curve in SIT was significantly higher compared with CTRL, MICT, and VICT (P = 0.0020). No changes in plasma irisin across exercise groups and time points were found (P > 0.9999). Conclusions Plasma BDNF levels increased in an intensity-dependent manner with SIT eliciting the highest BDNF concentration immediately postexercise. These results identify SIT as a time-efficient exercise modality to promote brain health through BDNF release.