When performing an exercise such as walking or running, you may sometimes notice that your fingers and hands become swollen. Although this fluid retention may be bothersome and uncomfortable, under almost all circumstances it is a normal physiological response to exertion and is not cause for alarm. Some individuals are more susceptible than others to exercise-induced swelling of the hands.
Increased Blood Flow
When you exercise, you are placing an increased demand on your circulatory and respiratory systems. As blood flow increases to your heart, lungs and muscles, it decreases in extremities like your fingers. As a result, your fingers and hands cool, causing their blood vessels to open wider, which results in edema, or swelling. Vasodilation -- the dilation of the blood vessels -- near the skin occurs with exertion and is one of the body's ways to release heat from the blood as exercise warms your system.
Another reason you may notice swelling during exercise is that fluid can become trapped in your hands. Exertion increases the amount of blood pumping through your body. The large muscles of your legs move vigorously in most forms of exercise, but the muscles of your arms are smaller and may not be working as hard. When your upper extremities are below the level of your heart, as they are when you are walking or running, gravity makes it more difficult for fluid to leave your hands, causing them to become puffy.
Although rare, a more severe form of swelling of the body's cells can sometimes occur in athletes participating in demanding sporting events such as marathons. Called hyponatremia, this dangerous condition is brought on by a lack of sufficient sodium in the body. Drinking excessive amounts of water during extreme exertion can trigger an acute disruption of normal sodium levels. Other symptoms, including confusion, fatigue and vomiting, are evident besides swelling in the hands and fingers. Anyone suspected of suffering from hyponatremia will require immediate medical care.
Although there is no way to prevent edema from forming in your hands upon exertion, you can avoid discomfort by removing rings, watches or shirts with tight cuffs before exercising. Once you stop exercising, your circulation and the volume of fluid in your hands should soon return to normal.