omg i just read somewhere that if you exercise too hard on the first day , a bacteria living inseide your muscles becomes acitve ,, causing a degenerative process to start , which could kill you.
the cure is to close your eyes , and spin a 100 times ,, this will makes the bacteria disorientated and the bacteria will go to your kidneys and eventually pass out in your urine.
keep repeating this untill you feel like you will puke or vomit , this is a good sign , cuz majority of the bacteria will be evacuated with it.
hope that helps your friendly PG doctor(actually im in 5th year ,, but dat doesnt matter il be a doctor soon enf)