If you exercise intensely and develop a bruise occasionally, it is no cause for concern. However, if you perform light exercise and do not regularly bump into things, an underlying medical problem may cause your bruising. Consult your doctor if this is the case.
Bruising
Bruises occur after vessels under the skin break and leak blood. They primarily occur just beneath the skin, but can happen in the muscles and bones. A bone bruise is the most serious type of bruise -- and often, the most painful. Usually, bruising stems from trauma like being hit or bumping against something, but it also can be the result of problems with your blood or blood vessels. Bruises change color over time because the leaked blood dries up and absorbs back into the skin. Most bruises last approximately two weeks, but can take months to fade entirely.
Exercise and Bruising
Strenuous exercise like marathon running, cycling, skiing or high-contact sports can easily cause bruising, especially on the leg. Placing strain on muscles and bones can take its toll -- particularly if you over-train -- and weakens your entire body including your blood vessels. However, if you participate in light exercise like walking or jogging, and don't experience obvious trauma, an underlying problem likely causes the bruising -- and exercising simply exacerbates the issue.
Underlying Causes of Bruising
Several issues can lead to bruising easily -- some of them are less serious than others are. Certain medications that thin the blood -- including aspirin, corticosteroids, blood thinners and supplements like fish oil and garlic -- can lead to bruising. If you are deficient in vitamins and minerals that affect blood clotting, this can easily lead to bruising without much provocation; deficiencies of vitamin B12 and vitamin K are common culprits. Your blood vessels weaken and your skin gets thinner as you age -- which contributes to easier bruising, according to MayoClinic.com. Women bruise more easily than men do because they have more estrogen, which can weaken blood vessels. Other causes of easy bruising include anemia, hemophilia, leukemia and some forms of cancer.
Recommendations
If you perform strenuous exercise, or if you exercise for long periods, an occasional bruise should not require treatment. However, bruising easily without obvious trauma is always a cause for concern. While you may naturally bruise easily while exercising, consult a doctor to rule out underlying medical disorders. Discuss medications you are taking with your doctor, particularly if you take blood thinners.
