The average muscle loss in men between the ages of 50 and 70 is 30 percent, Mangan notes, and from ages 70 to 80, another 20 to 30% of muscle is lost:
Add those figures and you’ve got the basis for the fact that most 80-year-old men will have lost 50% of their muscle mass.
It doesn’t have to be that way, if you keep active:
