Even mild concussions can cause memory problems, confusion, depression and personality changes, and medical experts still don't know the long-term effects of repeated mild concussions. College football players with a history of three or more concussions are three times more likely to suffer another concussion than their teammates, so repeated concussions are a concern for football players [source: Guskiewicz].
Besides injuries, some competitive athletes do things to their bodies in their efforts to win that can shorten their lives. Anabolic steroid abuse can cause heart damage and suicidal behavior. Competitive wrestlers have died of dehydration and heatstroke from trying to lose water weight by abusing laxatives or trying to "sweat out" pounds before meets so they can compete in a lower weight category. Football players who play positions in which being heavier is an advantage, such as offensive and defensive linemen, often put themselves at risk for obesity-related disease. In a 1994 study for the National Institute for Occupational Safety and Health, Dr. Sherry Baron found that NFL offensive and defensive linemen had a 52 percent higher chance of dying from heart disease than the general population. Many of those heavy linemen died before age 50 [source: Hargrove].
The bottom line is that while endurance athletes tend to have the greatest longevity -- endurance, team and power sports all have their own benefits and risks. It's important to play safely and weigh a sport's health benefits against its potential dangers. If you're a competitive athlete, do plenty of cross-training and reap the benefits of other sports. If old sports injuries limit your options, take up a no-impact sport like swimming or biking. The key is to make exercise a regular part of your life -- all of it -- for a longer, healthier life.