Strictly speaking hilchos tznius for a man

Question

Strictly speaking when going to play basketball, what must a man wear in regards to covering his body, I am asking because as I had learned a man has to cover from his breastbone to and including his upper thigh I remember rabbi showing this to me inside and I want to to find the source or find out if I am mistaken, this would mean that a man can wear a muscle T and shorts to basketball if this is correct or not correct please let me know