Association of military training with oxidative stress and overreaching

Abstract

We hypothesized that increased oxidative stress and disrupted redox balance may be predisposing factors and markers for overreaching (OR). Purpose: To examine whether oxidative stress markers and antioxidant status and physical fitness are related to overreaching during an 8-week military basic training (BT) period. Methods: Oxidative stress and antioxidant status were evaluated in the beginning, after 4 and 7 weeks of training in 35 males (age 19.7 ± 0.3 yrs) at rest and immediately after a 45-min submaximal exercise. Physical activity (PA) was monitored by accelerometer throughout BT. Indicators of OR were also examined. Results: From baseline to wk4 increased daytime moderate to vigorous PA led to concomitant decreases in the ratio oxidized to total glutathione (GSSG/TGSH) and GSSG. After 4 weeks of BT, GSSG/TGSH and GSSG returned to the baseline values at rest, while PA remained unchanged. At every time point acute exercise decreased TGSH and increased GSSG and GSSG/TGSH, while a decrease was observed in antioxidant capacity after 4 weeks of training. In the beginning of BT, OR subjects (11 of the 35 males) had higher GSSG, GSSG/TGSH and malondialdehyde (a marker of lipid peroxidation) at rest (P<0.01-0.05) and lower response of GSSG and GSSG/TGSH ratio (P<0.01) to exercise than noOR subjects. Moreover, OR subjects had higher PA during BT than noOR (P<0.05). Conclusion: The sustained training load during the last four weeks of BT led to oxidative stress observable both at rest and after submaximal exercise. Increased oxidative stress may be a marker of insufficient recovery leading possibly to OR.