Biomarker Responses to Acute Exercise and Relationship with Brain Blood Flow

Background: There is evidence that aerobic exercise is beneficial for brain health, but these effects are variable between individuals and the underlying mechanisms that modulate these benefits remain unclear. Objective: We sought to characterize the acute physiological response of bioenergetic and neurotrophic blood biomarkers to exercise in cognitively healthy older adults, as well as relationships with brain blood flow. Methods: We measured exercise-induced changes in lactate, which has been linked to brain blood flow, as well brain-derived neurotrophic factor (BDNF), a neurotrophin related to brain health. We further quantified changes in brain blood flow using arterial spin labeling. Results: As expected, lactate and BDNF both changed with time post exercise. Intriguingly, there was a negative relationship between lactate response (area under the curve) and brain blood flow measured acutely following exercise. Finally, the BDNF response tracked strongly with change in platelet activation, providing evidence that platelet activation is an important mechanism for trophic-related exercise responses. Conclusions: Lactate and BDNF respond acutely to exercise, and the lactate response tracks with changes in brain blood flow. Further investigation into how these factors relate to brain health-related outcomes in exercise trials is warranted.