Adaptability to eccentric exercise training is diminished with age in female mice

Area of Science:

• Skeletal Muscle Physiology
• Aging Research
• Exercise Science

Background:

• Eccentric contractions can improve muscle function, but age-related declines may impair this adaptation.
• Understanding age impacts on muscle plasticity is crucial for designing effective exercise interventions for older adults.
• Preclinical studies are needed to elucidate molecular mechanisms behind age-related deficits in muscle adaptation.

Purpose of the Study:

• To quantify age-related differences in functional adaptations of skeletal muscle to eccentric contractions.
• To identify age-dependent genetic signatures associated with impaired muscle adaptation.
• To investigate the molecular basis for reduced exercise responsiveness in older muscle.

Main Methods:

• Repeated in vivo eccentric contraction protocols in young (4 mo) and old (28 mo) female mice.
• Measurement of isometric torque before and after training to assess functional adaptation.
• RNA sequencing to identify differentially expressed genes in young versus old muscle post-training.

Main Results:

• Young mouse muscle significantly increased isometric torque (20-36%) after eccentric training.
• Older mouse muscle showed a decrease in isometric torque (up to 18%) following the same training regimen.
• Differential gene expression analysis revealed both shared and age-dependent transcriptional changes in response to training.

Conclusions:

• Skeletal muscle's ability to adapt functionally and molecularly to eccentric exercise declines significantly with age.
• Age-dependent gene expression patterns may explain the reduced adaptive capacity of older muscle.
• These findings underscore that molecular plasticity is not immutable with age and exercise coping mechanisms may be impaired.