Exercise makes your body feel great, lifts your mood, and sometimes, can make your hands numb. This disconcerting side effect of your favorite calorie-blasting activity can be worrisome, but the actual cause is not a serious problem in most cases. For most people, a minor adjustment to your routine can fix the problem, but others may need to seek medical advice.
Hand numbness is common in fitness walkers who swing their arms next to their thighs for the duration of the session. Keeping your hands low and your arms straight, combined with the centrifugal force of the swinging motion, causes fluid to collect in your hands. You may notice stiff, swollen fingers and numbness when the pressure is great enough to restrict the blood supply. Keep your elbows bent at a 90-degree angle and swing your arms from the shoulder to prevent these symptoms.
If you sweat without drinking water during your workout, you may become dehydrated. Your sweat contains electrolytes that transmit the electrical impulses responsible for many processes within your body, including nerve and muscle function. If you don't replace the lost electrolytes by drinking water or a sports drink, an imbalance results, and your body's ability to transmit muscle and nerve signals to and from your extremities may be impaired. Besides the numbness in your hands, you may experience weakness, fatigue, confusion and muscle spasms, and in advanced cases, seizures and convulsions. Proper hydration helps your body replenish your electrolyte levels, so remember to drink fluid regularly throughout your workout -- if you're thirsty, you're already dehydrated.
Your ulnar nerve runs along the back of your arm, just behind your elbow, through the outside of your wrist and into your hand -- that tingling sensation you get when you hit your "funny bone" is caused by a blow to the ulnar nerve. Pressure on the nerve can create numbness anywhere from your shoulder to your pinky. Common culprits include a tight grip on cardio machine handrails, improper form when lifting weights and insufficient cushioning in gloves. Loosen your grip and purchase weightlifting gloves with extra cushioning in the heel of the hand. Avoid flyes and other exercises that force you to lift your arm with your elbow in a bent position while bearing weight, which can irritate the nerve.
Even though your hand numbness occurs after exercise, it may not be related to the exercise at all. When you exercise, your circulation and nerve signals get switched to "high." If there is a disruption from a damaged nerve or constricted blood vessel, the blood or nerve signals won't reach your hands when it is most needed to feed or stimulate your working muscles. Many illnesses can cause numbness in your hands, so see your doctor if the symptoms persist. Possibilities include diabetes, carpal tunnel syndrome, hypothyroidism and vitamin deficiencies, but only a thorough exam can give you a definite diagnosis. If you also experience weakness, confusion, slurred speech, change in vision or the numbness occurs after a head injury, seek emergency medical attention.