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. ABSTRACT: 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.