Acute neurotrophic responses to a single bout of blood flow restriction and eccentric overload exercise in healthy older men.

Abstract

Blood flow restriction training (BFRT) combines substantial metabolic stress with low mechanical loading, but its neurotrophic effects remain unclear. This study investigated the acute effects of BFRT and eccentric overload exercise (EOE) on neurotrophic biomarkers in healthy older men. Sixty-three healthy older men (60-78 years) were randomized to BFRT, EOE, or a non-exercising control group. Neurotrophic, metabolic, endothelial, and muscle damage biomarkers were measured before and after exercise. Responses were analyzed using repeated-measures ANOVA, Bonferroni-adjusted post hoc comparisons, and correlations. Significant time × group interactions were observed for plasma BDNF (p = 0.017, ηp² = 0.151) and IL-6 (p = 0.001, ηp² = 0.22), while a marginal time × group interaction was observed for serum IGF-1 (p = 0.050, ηp² = 0.096). BFRT induced a significant increase in BDNF (mean change = 226.5 pg/mL, p = 0.006), with a greater change compared to CON (p = 0.014). IGF-1 increased significantly from baseline to 1 h post-exercise within the BFRT group (mean change = 29.2 ng/mL, p = 0.005); however, changes did not differ significantly between groups. IL-6 increased significantly following both BFRT (mean change = 8.26 pg/mL, p < 0.001) and EOE (mean change = 3.56 pg/mL, p = 0.013); however, the increase was greater only following BFRT compared to CON (p = 0.001), with no significant difference between BFRT and EOE (p = 0.123). BFRT elicited greater lactate accumulation than EOE and CON, and changes in BDNF correlated with changes in lactate (r = 0.367, p = 0.007). EOE elicited a greater CK increase than CON 48 h post-exercise, whereas syndecan-1 concentrations remained unchanged. Acute BFRT increased circulating BDNF and IGF-1 in healthy older men, and was accompanied by greater lactate accumulation, modest CK elevations, and no detectable increase in syndecan-1. The association between lactate and BDNF suggests that metabolic stress may contribute to the acute peripheral biomarker response; however, the neurological and clinical significance of these transient circulating changes remains to be established.