Everything we hear and read about physical exercise is good for various aspects of our physical and mental health. One of those involves reviving aging muscles and bones. New research from South Korea may help explain how and why. Authors of the study in Nature Communications discovered a key protein secreted by muscles during exercise strengthens both muscle and bones and in so doing suppresses musculoskeletal aging. They divided participants into young or elderly. Exercise improved the protein level in blood of both groups, but it took longer in the elderly. The study provides a greater understanding for why exercise becomes less effective with age and points the way to treat age-related bone and muscle loss.