Physiological and Psychological Effects of Treadmill Overtraining Implementation

SIMPLE SUMMARY: Overtraining occurs when an imbalance between training stress and recovery exists, and it is prevalent in athletes, soldiers, physical education, and health education undergraduates as well as a number of female and male adolescents. Despite a broad body of evidence concerning physiological and psychological correlates of this syndrome, the pathomechanisms of overtraining are still poorly understood. This illustrates the need to establish animal models of this disorder. This article outlines and discusses physiological and psychological effects of the current established overtraining model, based on an eight-week exhaustive treadmill exercise that reveals the involvement of imbalanced energy expenditure, exacerbated inflammatory response, increased intestinal permeability, and anxiety status in the development and onset of overtraining. This study highlights the maladaptation of overtraining and provides an animal model to determine the effectiveness of possible strategies, including nutrition and monitoring, for treatment and prevention of overtraining syndromes in future studies. ABSTRACT: Overtraining in athletes usually causes profound and lasting deleterious effects on the maintenance of health and exercise capacity. Here, we established an overtraining animal model to investigate the physiological modulation for future strategic applications in vivo. We subjected C57BL/6 mice to exhaustive treadmill exercises daily for 8 weeks (the exhaustive exercise group). Next, the physiological and psychological outcomes were compared with the regular exercise and sedentary groups. Outcome measures included growth, glucose tolerance, exercise metabolism profiles, cytokine levels, intestinal tight junction gene expression, and psychological behavioral changes. Our results revealed that overtraining negatively affected the physiological and psychological changes in the current model. The exhaustive exercise group exhibited significantly lower endurance performance and imbalanced energy expenditure, causing a decrease in body fat mass and slowing down the growth curve. In addition, the inflammatory cytokines (tumor necrosis factor-alpha, interleukin-6, and interleukin-1β) and immune cells (neutrophils and monocytes) were significantly elevated after successive exhaustive exercise interventions. Furthermore, overtraining-induced stress resulted in increased anxiety status and decreased food intake. Our findings reinforce the idea that an imbalance between exercise and recovery can impair health and performance maintenance after overtraining. This study highlights the maladaptation of overtraining and provides an animal model to determine the effectiveness of possible strategies, including nutrition and monitoring, for treatment and prevention of overtraining syndromes in future studies.