Randomized Controlled Study of Factors Influencing Body Composition and Exercise Quality of Male Adolescents Aged 13–15 Years Based on Cross-Lagged Models: Obesity Level, Salivary Testosterone, and Exercise Combined with Caloric Restriction Intervention

Abstract

Background: Obesity is a worldwide health problem with many disadvantages for children and adolescents, especially for the sexual development of boys. Exercise and caloric restriction are effective in improving obesity; however, the factors influencing these improvements should be studied in detail. We conducted a randomized controlled study of factors affecting changes in body composition and physical capacity in males aged 13–15 years. Methods: Subjects were divided into three groups based on body fat percentage (BFP), and randomly divided into control and intervention groups. The experimental conditions of this study were based on an exercise camp with a 12-week closed training period. The intervention group received a combination of aerobic exercise, resistance exercise, and caloric restriction. All subjects were uniformly housed and had a standard time for diet and rest, whereas the control group performed their coursework during the exercise intervention time and had no dietary restrictions. The subjects were tested for body composition and physical capacity before and after the intervention. Results: The effect of exercise training and energy-restricted diets on fat loss and physical capacity was limited to relatively lower extremity explosive strength and cardiorespiratory endurance, with a significant effect on body composition. Fat mass reduction was influenced by obesity with a high level of individual variability, with higher levels of obesity resulting in greater reductions in fat mass. The reduction in BFP was not affected by the level of obesity, and there was a mild causal relationship with salivary testosterone (ST) in the intervention group but not in the control group. ST was predictive of future BFP in exercisers; individuals with high ST had a greater reduction in BFP under conditions of prolonged exercise and caloric restriction. Conclusions: More obese male adolescents can obtain greater fat mass reduction with the intervention, but fat-free mass and exercise quality are minimally affected by the level of obesity. Adolescent males with higher ST ground tend to gain improvements in body composition, and ST can be predictive of future BFP but needs to be in the context of an exercise intervention.

Keywords

• obesity
• exercise
• salivary testosterone
• body composition
• physical capacity
• cross-lagged analysis