What Causes Cramping After Workouts?

A woman is experiencing a leg cramp.
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Muscle cramps are a common occurrence in both novice and seasoned athletes. The exact mechanism that triggers a cramp is not clear, but several conditions have been pointed out as likely culprits, including dehydration, electrolyte imbalance and muscle fatigue. Working out in a hot environment and not warming up or stretching before exercise can also contribute to post-workout cramping. If cramps persist despite taking precautionary measures, consult a doctor to rule out an underlying medical condition.


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A cramp is the result of your muscle contracting forcibly and involuntarily without relaxing. A mild cramp will usually last for a few seconds, while a more severe cramp can last for minutes or hours and is often painful. Severe cramps can cause the muscle to contract so forcefully it forms a knot or lump under the skin. The upper legs and calves contain the muscles most frequently afflicted with cramps, but you can get a cramp in any muscle in the body.



If you are out of shape or or workout when you are tired, your muscles are likely to fatigue easily. Muscle fatigue alters spinal neural reflex activity, which can lead to cramping. If you overexert yourself, your muscles get depleted of oxygen, which causes a build up of waste. The waste products, primarily lactic acid, can cause your muscle to spasm. As the American Academy of Orthopaedic Surgeons points out, once the contraction begins, your spinal cord puts out signals for your muscle to keep contracting. Additionally, if you don't warm up or stretch your muscles, they can't contract as smoothly and forcibly, which leads to cramps.


Dehydration and Electrolytes

If you work out in a hot environment and sweat a lot, you will lose a lot of fluids. The loss of fluids can contribute to cramping, primarily because you have an imbalance of electrolytes in your body. Electrolytes, particularly potassium, calcium, sodium and magnesium, are minerals that conduct electrical currents and contribute to muscle contraction. If they are out of balance or you are lacking sufficient amounts in your body, cramps can result. Not getting enough electrolytes in your diet can lead to similar results.



To prevent post-workout cramps, drink water during, before and after your workout. Drink plenty of water throughout the day as well. Clear urine is a sign of proper hydration, so if your urine is dark or colored, you need to drink more water. If you are sweating profusely during a workout, hydrate by drinking a beverage enhanced with electrolytes. Get plenty of rest, and avoid pushing beyond your limits. If your muscles get tired during a workout, stop and rest until your muscles recuperate. Avoid working out if hot temperatures, and if you start to overheat during a workout, stop and find a cool place to rest. Drink plenty of water while you're resting, and don't start exercising again until your body cools down. Eat plenty of fruits and vegetables high in mineral content, and take a multi-vitamin to ensure you're getting enough electrolytes in your system. If taking precautionary measures doesn't stop your cramps from occurring, consult a doctor.


When you feel post-workout cramps coming on, stop whatever activity you are engaged in, and stretch the affected muscle. Keeping it stretched, rub and massage the muscle until the cramp goes away. Persistent cramps can be treated with heat if the muscle is tight, and it is best to use cold packs if the muscle is sore or tender. Drink water or a sports drink enhanced with electrolytes for hydration. If the cramps are severe or don't respond to self-treatment, seek medical attention.



Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.