Stress and Immune Mediators In The Canadian Armed Forces: Association Between Basal Levels and Military Physical Performance

Abstract

Purpose: This study aimed to determine if an association exists between basal levels of stress and immune mediators and military physical performance among Canadian Armed Forces members (CAF). Methods: Blood samples from 219 CAF members (86 women and 133 men), were analysed for levels of cortisol, C-reactive protein (CRP), Adiponectin, INF-γ, TNF-α, IL-1β, IL-2, IL-6, IL-8 and IL-18. Grip strength, aerobic capacity and performance on six military physical performance tests (sandbag fortification, escape to cover, picking and digging, picket and wire carry, stretcher carry and vehicle extrication) were also assessed. A composite score for total performance was computed, based on rank scores from the six tasks. Results: The results from the linear regression analysis showed that higher CRP values were associated with lower total performance scores (slope -23.0,p≤0.05), a slower picking and digging time (slope 45.75,p≤0.05), lower aerobic capacity (slope -71.81,p≤0.05) and shorter plank time (slope -21.82,p≤0.05). A positive association between IL-2 values and grip strength was also observed (slope 20.83,p≤0.05). Adiponectin values were positively associated with plank time (slope 21.42,p≤0.05), but negatively associated with grip strength (slope -8.27,p≤0.05). Conclusion: The results from this study suggest that high levels of immune mediators (like CRP) could be a marker of decreased military physical performance.