Why is there bruising on knee's after leg workout?

[Misnwong]

This is for my brother. He had a good leg work out and pushed some good heavy weight. A couple days later he had a big bruise on his knees. After he works out he uses a stick roller to massage out the body parts that he works out that day. Could it possibly be from pushing all the lactic acid towards his knees and not pushing it all the way through where it wouldnt just stop at his knees? or is it something else? Is this normal/common? What are ways to prevent this from happening?

 

[bjg]

it is not normal, but since it is on both knees i would not worry about it, does it hurt? could be some blood from small internal bleeding due to popping of capillary veins etc...
if it is blood it will need some time like a week to go away.

 

[bman64]

What exercises does he do?

 

[fufu]

Was he doing deadlifts, cleans, or RDLs? I get bruised on my knees from those often.

 

[Nokea]

Sounds like he was putting alittle pressure on his knees during power cleans :-/ Hope it isnt to bad dude.