lauren hidalgo at san jose state, says she sees problems in former student athletes. >> some general, long-term musculoskeletal problems. so it would be primarily knee and back arthritis that people have as a result. they're very physically disabled often times. >> arthritis is a common side effect. >> i see some people with shoulder injuries from dislocations that weren't addressed when they were an athlete, and now they have looseness in the shoulder, and they also can get osteoarthritis in their shoulder as well. so when you see an athlete, or an ex-athlete in their, you know, 40s and 50s that are having issues, it's almost always from arthritis. >> football is arguably the most dangerous sport in today's day and age. just in the past couple of months in the united states, four high school players have been killed due to football related injuries [inaudible background conversations]. >> football is quite dangerous, because helmets don't really prevent concussions. and so there's a lot of tackling. it's just the nature of the sport predisposes people to head injuries, that they coul