Physiological effects of the stress induced by a high-intensity exercise protocol in rats

The objective of this study was to examine the possible stress physiological effects of a high-intensity training (HIT) in rats. Forty Wistar rats were randomly divided into 2 experimental groups (n=20): EAI or control (sedentary) groups for 12 weeks. Biological, muscle, urinary, plasma, hepatic and renal markers were measured. Food intake (P<0.05), final body weight and carcass weight (both, P<0.001) were significantly lower in the HIT group. Hormonal markers reflected increased levels of corticosterone (P<0.05) and decreased levels of testosterone (P<0.05) in the HIT group. Consequently, the ratio corticosterone/testosterone was higher and the testosterone/corticosterone lower in the HIT group (both, P<0.01). Regarding hepatic lipid profile, the HIT group showed higher liver fat (P<0.01) but lower hepatic triglycerides (P<0.05). Regarding plasma lipid profile, the HIT group showed lower triglycerides concentration (P<0.01) but also higher LDL cholesterol concentrations (P<0.01). Finally, the renal morphology study showed increased kidney connective interstitial tissue (P<0.05). The stress induced by the HIT protocol promoted a catabolism status that could lead to a lower muscular development, a worse hepatic and plasma lipid profile and a renal profile with increased susceptibility to future pathologies. The present study aimed to develop a stress/overtraining protocol that might be carried out in athletes with the purpose to deepen study the effects that this adverse status might induce in the long-term health of the athlete.