The Effect of Exercise Training on Resting Concentrations of Peripheral Brain-Derived Neurotrophic Factor (BDNF): A Meta-Analysis

<div><p>Background</p><p>The mechanisms through which physical activity supports healthy brain function remain to be elucidated. One hypothesis suggests that increased brain-derived neurotrophic factor (BDNF) mediates some cognitive and mood benefits. This meta-analysis sought to determine the effect of exercise training on resting concentrations of BDNF in peripheral blood.</p><p>Methods</p><p>MEDLINE, Embase, PsycINFO, SPORTDiscus, Rehabilitation & Sports Medicine Source, and CINAHL databases were searched for original, peer-reviewed reports of peripheral blood BDNF concentrations before and after exercise interventions ≥ 2 weeks. Risk of bias was assessed using standardized criteria. Standardized mean differences (SMDs) were generated from random effects models. Risk of publication bias was assessed using funnel plots and Egger’s test. Potential sources of heterogeneity were explored in subgroup analyses.</p><p>Results</p><p>In 29 studies that met inclusion criteria, resting concentrations of peripheral blood BDNF were higher after intervention (SMD = 0.39, 95% CI: 0.17–0.60, p < 0.001). Subgroup analyses suggested a significant effect in aerobic (SMD = 0.66, 95% CI: 0.33–0.99, p < 0.001) but not resistance training (SMD = 0.07, 95% CI: -0.15–0.30, p = 0.52) interventions. No significant difference in effect was observed between males and females, nor in serum vs plasma.</p><p>Conclusion</p><p>Aerobic but not resistance training interventions increased resting BDNF concentrations in peripheral blood.</p></div

Subgroup analysis of difference in effect sizes between males and females.

<p>Diamonds indicate SMD and 95% CI. Test for subgroup differences: P = 0.50.</p

Exercise intervention characteristics of included studies.

<p>Exercise intervention characteristics of included studies.</p

Subgroup analysis of BDNF concentration changes in serum vs plasma.

<p>Diamonds indicate SMD and 95% CI. Test for subgroup differences: P = 0.06.</p

Search and selection of articles.

<p>Search and selection of articles.</p

Subgroup analysis of aerobic exercise interventions vs resistance training interventions.

<p>Diamonds indicate SMD and 95% CI. Test for subgroup differences: P = 0.004.</p

Baseline study population characteristics.

<p>Baseline study population characteristics.</p

Resting peripheral BDNF concentration change pre- to post-intervention.

<p>Diamond indicates SMD and 95% CI. Significance of overall effect: Z = 5.00, P < 0.00</p