Energy Substrate Utilization and Body Composition Following Exercise Preconditioning During Alternate-Day Fasting and Concurrent Exercise in Mice
TL;DR
Exercise preconditioning was associated with the maintenance of lower adiposity during short-term ADF combined with concurrent exercise, while differences in substrate utilization were observed under some conditions.
Abstract
Highlights What are the main findings? Exercise preconditioning was associated with lower body fat percentage and fat mass, and these differences were maintained after alternate-day fasting and concurrent exercise. Exercise preconditioning was associated with significantly higher resting oxygen uptake, carbon dioxide production, respiratory exchange ratio, carbohydrate oxidation, and energy expenditure after the intervention. What are the implications of the main findings? Exercise preconditioning may be associated with the maintenance of lower adiposity and distinct substrate-utilization patterns during a subsequent combined intervention. Future studies should conduct longer-term human interventions to evaluate the feasibility, adherence, lean-mass preservation, and metabolic benefits of exercise preconditioning in real-world settings. Abstract Background/Objectives: Alternate-day fasting (ADF) combined with exercise has been suggested as an effective lifestyle strategy for reducing fat mass while preserving lean mass. However, whether exercise preconditioning before ADF plus concurrent exercise affects subsequent body-composition and substrate-utilization responses remains unclear. This study aimed to evaluate the effects of exercise preconditioning during a subsequent ADF plus concurrent exercise intervention. Methods: Seven-week-old male ICR mice were assigned to the non-exercise preconditioning (Non-ExPC) or exercise preconditioning (ExPC) group (n = 8/group). After the 4-week preconditioning period, both groups underwent 7 days of ADF plus concurrent exercise. Resting energy metabolism was measured during the intervention, and body composition, exercise energy metabolism, muscle and motor function, blood biomarker concentrations, and plasma hormone levels were assessed before and after the intervention. Results: Both groups showed significant reductions in body weight, body fat percentage, and fat mass after the intervention. Lean mass decreased in both groups without between-group differences. The ExPC group maintained significantly lower body fat percentage and fat mass than the Non-ExPC group and showed significantly higher resting oxygen uptake, carbon dioxide production, respiratory exchange ratio, carbohydrate oxidation, and energy expenditure during the intervention. During exercise, the respiratory exchange ratio and carbohydrate oxidation significantly increased in both groups, whereas fat oxidation significantly decreased only in the ExPC group. Conclusions: Exercise preconditioning was associated with the maintenance of lower adiposity during short-term ADF combined with concurrent exercise, while differences in substrate utilization were observed under some conditions.