Lifelong physical activity could protect against age-related loss of muscle mass and function, according to new research. Individuals aged 68 and above who were physically active throughout their life have healthier aging muscle that has superior function and is more resistant to fatigue compared to inactive individuals, both young and old. This is the first study to investigate muscle, stem cell and nerve activity in humans. The researchers from University of Copenhagen, Denmark, found that elderly individuals who keep physically active throughout their adult life, whether by taking part in resistance exercise, ball games, racket sports, swimming, cycling, running and/or rowing had a greater number of muscle stem cells, otherwise known as satellite cells in their muscle. These cells are important for muscle regeneration and long-term growth and protect against nerve decay.