A multifaceted investigation into the effects of acute exercise on indices of brain function

Participation in regular exercise is important for the maintenance and improvement of brain health across the lifespan. These beneficial effects are realized almost immediately, as a single bout of exercise transiently improves cognitive function after cessation from exercise. This postexercise time period represents an opportunity to strategically prescribe cognitively stimulating activities for enhancing brain plasticity and function. Mechanistically, acute exercise is proposed to upregulate brain-derived neurotrophic factor (BDNF) expression and increase regional activation and arousal of brain areas involved in cognitive control; however, the specific mechanisms underlying this facilitation are poorly understood. The purpose of this study was to (i) investigate BDNF responses to small muscle mass exercise to probe a potential mechanism of BDNF release during exercise; (ii) create and validate an equipment-free exercise protocol for use in a magnetic resonance imaging (MRI) scanner, with the eventual goal of investigating brain responses during exercise that may underlie improved cognition; and (iii) determine the effect of a very brief bout of high-intensity interval exercise (HIIE) on neuroelectric indices of reinforcement learning in young adults. Serum BDNF, platelet, and the amount of BDNF per platelet responses were measured following short-duration, maximal effort and long-duration, submaximal effort forearm handgrip exercise. We assessed the magnitude and reliability of metabolic responses to a novel whole-body isometric contraction (WBI) exercise protocol. We also characterized the amount of head movement created by WBI. The event-related potential component associated with reward-based learning was assessed before and after a bout of HIIE. Forearm handgrip exercise significantly increased serum BDNF, platelets, and BDNF per platelet, suggesting the possibility of splenic and cellular contribution of BDNF in response to handgrip exercise. WBI reliably evokes metabolic responses that are similar in magnitude to previous in-MRI studies, and creates head movement suitable for MRI scanning. HIIE abolishes neuroelectric indices of reward learning, likely owing to incomplete recovery from exercise. These findings advance our understanding of neurochemical and neuroelectric responses to acute exercise and introduce a novel tool that stands to further elucidate the regional brain responses to exercise that may underlie enhanced cognition after exercise.