Bruises are a common sports injury. They occur when a blow breaks small blood vessels, which leak out into tissue under your skin, leaving a black and blue mark.
Bruises can be painful and the area may swell. Also, muscles and bones can be bruised.
Typically, bruises look reddish at the start, turn bluish-purple and then, in their final stage, turn greenish-yellow. Most bruising lasts a couple of weeks, but in some cases it can take months for a bruised skin area to return to normal.
The best treatment to minimize bruising and aid in healing is to ice and elevate the area above your heart immediately after receiving a blow.
If you are bruising for no apparent reason or your bruise appears infected, then bring it to the attention of your physician.