All sports have their health benefits, but those benefits come with risks, too. Sports injuries sometimes require surgeries and can lead to lifelong pain for some athletes. Repetitive motion injuries are a serious risk in some sports, and can have life-changing consequences. Scientists in England found that professional soccer players are 10 times more likely to develop arthritis in the hip than the general public. Surprisingly, most of the players who developed arthritis did not realize they were injuring their hips -- the arthritis was caused by repetitive motion. Many professional soccer players require total hip replacements in their 30s or 40s, which is much younger than most hip replacement patients in the general population. Dartmouth-Hitchcock Medical Center in New Hampshire reports that the average age of its hip replacement patients is 64 [sources: Shepard, Banks & Ryan; Dartmouth-Hitchcock Medical Center].
Another significant danger in some sports is traumatic brain injury (TBI). TBI can be disabling or even life-threatening -- actress Natasha Richardson died in 2009 after she hit her head while skiing, and world-class halfpipe snowboarder Kevin Pearce was critically injured during training late that same year. Pearce was rushed to the hospital in critical condition and placed on a respirator after he hit his head on the ice; he spent over three months in the hospital and many more months in rehabilitation. He was wearing a helmet at the time of the accident [source: Branch].
Athletes who suffer brain injuries can continue to get sicker even years after they stop playing their sport. Dementia pugilistica is a degenerative brain disorder caused by repeated blows to the head that was first diagnosed in boxers. This disease causes severe mental and physical disabilities; it can mimic Parkinson's disease or Alzheimer's disease, and it continues to get worse until the patient dies. Heavyweight boxer Jerry Quarry, who fought Muhammad Ali, died in 1999 at age 53 after severe dementia pugilistica left him confused, childlike and unable to care for himself [source: CNN/Sports Illustrated]. The risk of dementia pugilistica makes boxing less than a sure bet for living longer.