Acute Aerobic Exercise Alters PBMC microRNA Expression: Insights into Sport- and Sex-Specific Variations
Studying microRNAs in the immune cells of athletes offers a novel perspective on the molecular regulation of immune function and recovery, potentially uncovering strategies to enhance performance and resilience to physical stress. However, PBMC microRNA expression in endurance athletes, such as runners and cyclists, remains underexplored, especially with regard to sex differences. This study aimed to (i) assess sport- and sex-specific differences in PBMC microRNA expression induced by acute aerobic exercise in runners and cyclists, (ii) evaluate the impact of maximal (trial A) and sub-maximal (trial B) exercises, and (iii) examine correlations between PBMC microRNAs and exercise performance. Methods: A total of 58 participants were included: 22 runners (9 females), 18 cyclists (9 females), and 18 active controls (9 females). Participants underwent VO2max and time-to-exhaustion tests, with blood samples collected pre- and post-exercise to analyze PBMC microRNA levels. Results: Runners exhibited a stronger microRNA response than cyclists or controls, with significant sex-based differences. After maximal intensity exercise, 279 microRNAs (255 upregulated) were altered in runners, compared to only 7 microRNAs (none upregulated) in cyclists. Exercise intensity and duration had sport-specific effects on microRNA expression. Time-to-exhaustion in runners and weekly training volume in both groups were significantly associated with changes in PBMC microRNA profiles. Conclusion: This study reveals that PBMC microRNA expression in response to acute aerobic exercise is sport- and sex-specific, providing new insights into the molecular adaptations of endurance athletes and their relationship to athletic performance. Overall design: Small RNA-Seq profiling of Human peripheral blood mononuclear cells (PBMCs) before and immediately after exercise.