From this New York Times Article, Whatever Happened to Jane Fonda in Tights? , are quotes from those who did years of aerobics: The above quotes are anecdotal, and the plural of anecdote is not data. There are plenty of people who do aerobic activities with no adverse effects. Heredity plays a factor. The key is to not to overdo it and avoid or minimize those activities that are more likely to lead to injury. As an insurance policy it would help to engage in personal training program that strengthen those joints that are prone to injury. Our personal trainers in Austin and New Orleans have worked with many who can no longer do aerobics, but they have no problem strength training using our equipment and protocol. We use MedX equipment that is more easily tolerated by the joints, we are able to restrict movement to a pain-free range of motion, and we lift the weights in a smooth fashion to avoid the jerking movements that lead to injuries For more information about our personal training program go to http://kellypersonaltraining.com/ (Austin) or http://www.ultimate30.com/ (New Orleans)