Skeletal Muscle Composition and the Effects of Exercise and/or Prebiotic Fiber in Preventing Diet Related Morbidities
A 12‐week preclinical study in Sprague–Dawley rats investigated the effects of aerobic exercise and prebiotic fiber supplementation on muscle composition and systemic metabolic outcomes in an obesity model induced by a high‐fat/high‐sucrose (HFS) diet. Rats were divided into five groups: a chow-fed Control group, an HFS group, an HFS plus exercise (HFS + E) group, an HFS plus prebiotic fiber supplementation (HFS + F) group, and an HFS group receiving both interventions (HFS + F + E). Researchers measured body composition (using DXA), muscle triglyceride and collagen content, and macrophage density in the vastus lateralis and soleus muscles, along with insulin sensitivity and lipid profiles.
The results revealed that although both exercise and prebiotic fiber supplementation successfully prevented systemic metabolic disturbances—maintaining insulin sensitivity and normalizing serum lipid levels—the HFS diet induced significant alterations in muscle composition. Specifically, all HFS groups showed increased collagen content in both muscles, with the HFS + F group displaying the highest levels, and the vastus lateralis exhibited elevated triglyceride content that was not fully addressed by the interventions. These findings support the conclusion that while aerobic exercise and fiber supplementation can counteract diet-induced metabolic derangements, they do not entirely prevent muscle quality changes, suggesting an adaptive muscular response to metabolic stress.
The study also highlights broader implications regarding the separation between systemic metabolic improvements and persistent alterations in muscle composition, underscoring limitations in current intervention strategies. Future research should focus on investigating the functional consequences of increased muscle collagen and fat infiltration, as well as the underlying mechanisms of muscle metabolic flexibility and inflammation in obesity. Overall, this study reinforces the complex role of skeletal muscle in metabolic health and the need for targeted strategies to preserve muscle quality in the context of diet-induced changes.
