Numbness is generally a cause for concern. It is even more ominous when it occurs on the left side because it could be a symptom of a heart attack. This is especially true when the symptom occurs during exertion like running. Wisdom dictates this would be best evaluated by your doctor, but some questions you can answer yourself.
Hand Numbness Due to Cardiac Problem
Although numbness in your hand might be due to several types of problems, the most urgent question to answer regards heart or cardiac issues. The American Heart Association lists chest discomfort such as fullness, squeezing or pressure as the first warning sign. This is followed by discomfort in other parts of your upper body. The third most common symptom is shortness of breath. If you are experiencing these with your hand numbness, the AHA recommends dialing 9-1-1.
Hand Numbness Due to Nerve Problem
Another condition that produces hand numbness is nerve radiculopathy. This means pressure is weighing on the nerve or nerves that go to your hand. This is usually associated with neck pain and, sometimes, weakness. A distinguishing feature of this problem is that each nerve supplies a part of your hand. If you are having numbness in your entire hand, like a glove, you would have to have a radiculopathy that involves pressure on at least three different nerves. Although it sometimes happens, the likelihood of that is fairly remote.
Hand Numbness Due to Circulation
Because the circulation of blood to your hand comes from the brachial artery, any blockage of that artery will cause numbness because of a lack of circulation. This is one way you can get glove-like numbness. Usually, this condition will also be accompanied by a sense of coldness in the affected hand. Blockage is most commonly due to pressure from a muscle that presses down on the artery. This can be due to shortening or tightening in the muscles in the front of your shoulder, where the artery passes through.
Stretches for Hand Numbness
If you have seen your doctor and have ruled out more urgent medical conditions, you can try some treatment on your own. If you are having neck pain with hand numbness, neck stretches and strengthening exercises can help reduce your problem. If you are having coldness in your hand with the numbness, stretching the muscles attaching to your upper arm, like the pectoralis minor can help. Also watch your posture when you run. If you are slumping forward when you run, you might be shortening the muscles with your posture. Keep your posture upright and your chest up when you run.