Rest between exercise periods and many of us bang it out on the weekend and you need a rest period in between, where the joints and muscles and rest of your schedule call system can recuperate. gregg: how long do the artificial knees and hips last? i was reading material here and i one study shows they last about 20 years. that is it? the problems, those studies were done in an elderly or older population and now, we are putting them in in younger people, in the 5th decade of life and they are more physically fit an active than the older people and the studies, we can t ex-strap plate that data, we have to do more studies in younger population and they say it is a 20 year knee and put it into someone who is 50, who will keep active, he may wear out the joint before it is warrentied. heather: so, your best advice to weekend warriors, as you keep calling them? rest? i include myself in that category, rest, proper stretching and conditioning, and proper nutrition is key. and, don t focus on one exercise