Plantar stimulation prevents the decrease in fatigue resistance in rat soleus muscle under one week of hindlimb...

Area of Science:

• Physiology
• Muscle Biology
• Biomedical Engineering

Background:

• Support afferentation is crucial for maintaining postural muscle function, structure, and phenotype.
• Muscle disuse, characterized by a lack of support afferentation, leads to reduced slow-twitch fiber percentage and muscle performance.
• This decline negatively impacts overall quality of life.

Purpose of the Study:

• To investigate the effects of simulated support afferentation on the soleus muscle during hindlimb unloading in rats.
• To determine if mechanical stimulation can counteract the detrimental effects of disuse on muscle properties.

Main Methods:

• Hindlimb unloading model in rats was used to simulate muscle disuse.
• Plantar mechanical stimulation was applied to simulate support afferentation.
• Soleus muscle functional properties, mitochondrial DNA copy number, fiber type percentage, and gene expression signaling were analyzed.

Main Results:

• Mechanical stimulation prevented the increase in muscle fatigue induced by unloading.
• The percentage of slow-type muscle fibers and mitochondrial DNA copy number were maintained.
• CpG methylation in the PGC1α promoter region and myonuclear content of transcriptional activators were partially preserved.

Conclusions:

• Support afferentation, simulated via plantar mechanical stimulation, is effective in maintaining the slow-twitch oxidative and fatigue-resistant phenotype of soleus muscle fibers during hindlimb suspension.
• These findings suggest that mechanical loading is a key factor in preventing muscle atrophy and functional decline during periods of disuse.