1) one common cause would include not drinking enough water. which would cause dehydration which causes injury to your heart because it puts it under allot of pressure
2) lack of rest. if you dont get at least 8-9 hours of rest it would end up making you lack thinking and make you lack being able to control your body properly
3) lack of the right nutrients and carbohydrates in order for your body to act appropriately during physical fitness you have to have the right nutrients and carbohydrates because the right nutrients would help your skeletal system to stay strong and intact.
4) pushing your self to much. some people try to push them selves past what the usually could handle but if you push your self past the limit it would end up in a bad injury cause your bones starten to weaken and it makes you get weaker and end up with a minor or major injury.
5) lack of warm up. before your start doing anything major like running, track , etc... you have to warm up. becuase if you do anything major before warm up you could end up hurting your bones and other things because your body was not ready
