Metabolism: Exercise rejuvenates muscle in old mice

Voluntary exercise accelerates muscle repair and restores old muscle stem cells in mice, according to an article published in Nature Metabolism.

With advanced age, muscle mass declines, and the ability to regenerate and repair muscle is impaired. The reason for this decline is likely to involve both a reduced number of muscle stem cells (MuSCs) and a diminishing regenerative capacity with age. Although previous research has studied how to preserve muscle mass with age through exercise, little is known about the benefits of exercise in preserving regenerative capacity.

Thomas Rando and colleagues provided young and old mice 3 weeks’ voluntary access to freely rotating running wheels. The authors found accelerated muscle repair and improved old MuSC function in the older animals. These improvements in MuSC activation were due to the restoration of Cyclin D1 (a protein required for cell-cycle progression) in dormant stem cells back to youthful levels. Cyclin D1 suppresses the pro-ageing TGF-β–Smad3 signalling pathway in the dormant state, ultimately accelerating MuSC regeneration. These changes were less pronounced in young mice.

This research suggests that a short-term, voluntary exercise regimen is a practicable intervention for rejuvenating old MuSCs, although further studied are needed to determine whether these findings translate to humans.