Of course, a decline of the satellite cells’ ability to divide and repair could also be to blame, but research does not support this idea. In pioneering studies carried out in 1989, biologists Bruce Carlson and John Faulkner at the University of Michigan showed that muscle isolated from a two-year-old rat was repaired faster and better when grafted into two- to three-month-old rats.2 More recently, we isolated these cells from young and old adults and were surprised to find that elderly human satellite cells grew in culture as well as those from young subjects did.3