This story is a great feature on aging with fitness, from the LA Times. The paper also reports that age can actually be an asset in sports. You can be as fit or fitter than a much younger person.  "I firmly believe that we have underestimated as a culture, and maybe even in the field of exercise science, what older adults are capable of doing. It's really important for people to realize that you should not underestimate what someone can do based on age, gender or chronic disease."