TNF-α Stress Response Is Reduced Following Load Carriage Training

Abstract

Introduction: Tumor necrosis factor-alpha (TNF-α) is a potent pro-inflammatory cytokine involved in the acute phase stress response. The genetic variant, rs1800629, is located in the promoter region of the TNF-α gene and has been shown to affect the production of TNF-α. The purpose of this study was to determine whether the TNF-α pro-inflammatory response induced by an acute bout of exercise is affected by Marine Corps training and/or the rs1800629 variant and whether the rs1800629 variant is predictive of physical performance in male U.S. Marine Corps infantrymen. Methods Plasma samples were collected before and after a 5 km (Day 12 of training) and 20 km (Day 40 of training) march to measure TNF-α concentration. DNA was extracted from whole blood, and genotyping was performed in 122 Marines. Relationships between physical fitness test measures (run, sit-ups, and pull-ups) and genotype were determined. Results TNF-α concentrations before and after the 5-km march on Day 12 of training were significantly higher than levels observed before and after the 20-km march on day 40 of training (3.4 ± 0.2 vs. 3.0 ± 0.2 pg·mL -1 ; p < 0.05). There was a main effect of time, with lower pre-march TNF-α concentrations than post-march concentrations (2.7 ± 0.2 vs. 3.7 ± 0.2 pg·mL -1 ; p < 0.05). There were no interaction effects between rs1800629 genotypes and march distance (p > 0.05), between genotype and march time point (p > 0.05), or between genotype, march distance, and march time point (p > 0.05). There was no difference for any of the physical fitness test scores between the genotype groups (p > 0.05); nor were there any differences between the absolute runtime, number of pull-ups, or number of sit-ups (p > 0.05). Conclusion U.S. Marine Corps infantry training reduces the TNF-α stress response induced by an acute bout of exercise. The rs1800629 variant does not influence performance or the TNF-α stress response in Marine Corps students undergoing infantry training.