Aged cells in human skeletal muscle after resistance exercise

Area of Science:

• Exercise physiology
• Cellular senescence
• Muscle biology

Background:

• Cellular senescence contributes to aging.
• Exercise may mitigate aging through unclear mechanisms.
• Skeletal muscle aging impacts function and regeneration.

Purpose of the Study:

• To investigate the impact of resistance exercise on senescent cells in skeletal muscle.
• To examine the influence of protein availability on exercise-induced changes in senescent cells and muscle regeneration.
• To identify the cell types associated with senescence in skeletal muscle.

Main Methods:

• Longitudinal study involving young men undergoing resistance exercise.
• Muscle biopsies analyzed pre- and post-exercise (0h, 48h).
• Immunohistochemistry used to detect p16Ink4a+ senescent cells (endothelial progenitor cells) and immune cell infiltration (leukocytes, macrophages).
• Two dietary conditions: low protein (14%) and high protein (44%).

Main Results:

• Resistance exercise reduced senescent cells by 48% within 48 hours.
• Low protein intake amplified immune cell infiltration and led to a greater reduction in senescent cells (-73%).
• High protein intake promoted muscle mass gain after 12 weeks of training and accelerated inflammation resolution.

Conclusions:

• Rapid clearance of senescent cells in skeletal muscle post-exercise is linked to enhanced phagocytosis.
• Adequate protein intake is crucial for muscle repair and growth following exercise.
• Dietary protein influences the inflammatory response and regenerative capacity of skeletal muscle.