Effects of a Single Bout of Endurance Exercise on Brain-Derived Neurotrophic Factor in Humans: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Simple Summary The brain-derived neurotrophic factor (BDNF) is important in mediating the brain health, morphology, and function. A single bout of endurance exercise is a critical factor triggering the expression of the BDNF in peripheral blood. Therefore, investigating the concentration of BDNF in peripheral blood can effectively assess the impact of a single bout of endurance exercise on the brain health. We investigate the impact of a single bout of endurance exercise on the BDNF in humans, meanwhile analyzing how a single bout of endurance exercise impacts the peripheral BDNF types by age group. We found that a single bout of endurance exercise has a small to moderate effect on the BDNF expression. The serum BDNF is a sensitive factor reflecting the effects of a single bout of endurance exercise, regardless of age. These results provide significant evidence for the design of sports exercise to maintain brain health in different age groups. We aimed to investigate the impact of a single bout of endurance exercise on the brain-derived neurotrophic factor (BDNF) in humans and analyze how a single bout of endurance exercise impacts the peripheral BDNF types by age group. We performed a systematic literature review by searching PubMed, Elsevier, and Web of Science for studies that included a single bout of endurance exercise in the experimental group and other exercise types in the control group. Eight interventions were included in the study. Overall, a single bout of endurance exercise significantly increased BDNF expression (SMD = 0.30; 95% CI = [0.08, 0.52]; p = 0.001), which was confirmed in the serum BDNF (SMD = 0.30; 95% CI = [0.04, 0.55]; p < 0.001). A non-significant trend was observed in the plasma BDNF (SMD = 0.31; 95% CI = [-0.13, 0.76]; p = 0.017). The serum and plasma BDNF levels significantly increased regardless of age (SMD = 0.35; 95% CI = [0.11, 0.58]; p = 0.004; I-2 = 0%). In conclusion, a single bout of endurance exercise significantly elevates BDNF levels in humans without neurological disorders, regardless of age. The serum BDNF is a more sensitive index than the plasma BDNF in evaluating the impact of a single bout of endurance exercise on the BDNF.