Training Enhances the Recovery of Monocyte Subset Response to a Bout of Resistance Exercise

Abstract

Monocytes play a key role in inflammatory processes. Little is known on monocyte response to resistance exercise. The purpose of this study was to examine the acute changes in monocyte subsets following an acute muscle damaging bout of resistance exercise before (PRE) and after (POST) six weeks of resistance training. Fifteen recreationally active men (22.1 ± 2.2 y) completed an acute, muscle damaging protocol PRE and POST that consisted of the squat (6 sets), leg press (4 sets) and leg extension (4 sets) exercises. Ten repetitions at 70% of 1‐RM were completed for each set. Blood was drawn at baseline (BL), immediately (IP), one (1H), five (5H), 24 (24H) and 48 hours (48H) post‐exercise. Flow cytometry was used to identify monocyte subpopulations: classical (CLAS; CD14++/CD16−) and intermediate (INT; CD14++/CD16+). Repeated measures ANOVA was applied. A significant training x time interaction was observed for CLAS (p = 0.008) and INT (p = 0.036). CLAS significantly increased at 1H (BL, 89.3±5.5% vs.1H, 95.10 ± 4.19%; p < 0.001) and 5H (p = 0.012; 91.79 ± 4.14%) in PRE, while at POST, only a trend toward a significant increase was noted at 1H (BL, 90.66 ± 4.62% vs. 1H, 92.50 ± 3.75%, p = 0.067). Additionally, CLAS was significantly higher PRE than POST at 1H (95.10 ± 4.19% vs. 92.50± 3.75%; p = 0.048) and 5H (91.79 ± 4.14% vs. 88.42 ± 5.46%; p = 0.005). During PRE, the proportion of INT appeared to increase (p < 0.001) from BL (4.23 ± 2.19%) at IP (5.62 ± 2.77%), but decreased at both 1H (p < 0.001; 2.01 ± 1.56%) and 5H (p = 0.001; 3.16 ± 1.82%). However, increases from BL were noted at 24H (p = 0.010; 5.83 ± 3.35%) and 48H (p = 0.049; 6.15 ± 3.25%). At POST, changes in INT were similar to PRE, except proportion of INT returned to BL levels at 5H and remained there throughout the 48H recovery period. In conclusion, resistance training appears to enhance the recovery of monocyte subsets to resting proportions following an acute bout of resistance exercise.