What Causes Leg Cramps, and How Do I Avoid Them?

More than half of adults experience leg cramps at night. Unfortunately, spasms in your foot, thigh, and calf muscles can happen at any time: on a long car ride, at work, or during exercise. Leg cramps occur whenever your muscles suddenly contract, squeezing all the nerve endings inside the muscle fiber. As the hardened muscle applies pressure to the nerves, your brain receives the signal that you’re in pain.  

Humans aren't the only species to experience cramping muscles. The term "Charley horse" is believed to have originated with a cramp-afflicted racehorse. Yet, even as humans (and animals) suffer from cramps at all hours of the day and night, scientists remain unable to provide an overarching theory about why our leg muscles experience these painful spasms. As A. C. Shilton explains in an article on leg cramps for Runner's World, "...Even experts can't say with certainty what causes exercise-induced muscle cramps." Part of the problem is that leg cramps are most likely caused by multiple variables. 

In this article, we'll look at some of the possible risk factors that make you more likely to develop leg cramps. Alongside each possible cause, we'll recommend a few strategies for reducing your risk. These general guidelines may help with mild cramps, but we recommend seeking professional medical advice if you experience any unusual cramping. Leg cramps may be a symptom of a more serious condition. 

Mineral Depletion

Deprived of key minerals, like sodium, magnesium, potassium, and calcium, you're likely to experience severe cramping. A water-electrolyte imbalance negatively affects many bodily systems, including heart function, neurological function, and PH balance. 

Strategies to reduce cramps:

  • Hydrate with a sports drink that contains electrolytes
  • Ask a doctor to test your electrolyte levels
  • Avoid exercising in extreme heat

Dehydration

In order to function properly, your muscles need plenty of water. Without adequate hydration, muscle cells become easily irritated. This causes cramping, especially during exercise. 

Strategies to reduce cramps:

  • Drink fluids during exercise
  • Pay extra attention to hydration in hot or humid weather 
  • Avoid exercising in extreme heat

Muscle Fatigue

Fatigue is one of the most common causes of muscle cramps that develop during or after exercise. With overuse or insufficient conditioning, an affected muscle begins to lose strength and control. Any nerve signals to that muscle can cause involuntary contractions.

Strategies to reduce cramps:

Speed

Studies have shown that running faster actually increases your risk of cramps. In one paper, researchers showed that running the first 28 km of a 56 km race at a faster pace increased a participant's likelihood of developing leg cramps within six hours after the race. (Schwellnus)

Strategies to reduce cramps:

  • Gradually increase running pace to prevent overexertion
  • Wear compression socks to support good circulation
  • Stretch after exercise

Age

Older people are more likely to experience frequent cramps. As we age, our muscle fibers and nerves age with us. Nerves control the movement of your muscles and, with time, they become prone to dysfunction. This causes involuntary muscle contractions. Age also makes you more vulnerable to venous disease, which can worsen leg cramping.

Strategies to reduce cramps:

  • Stretch after exercise
  • Wear compression socks to reduce your risk of venous disease
  • Get plenty of fluids and electrolytes

Pregnancy

Leg cramps are particularly common for women during the second and third trimesters of pregnancy. Pregnant women are also five times more likely to suffer from deep vein blood clots during pregnancy.

Strategies to reduce cramps:

Inadequate Blood Supply 

Claudication is a symptom of peripheral artery disease. When you experience claudication, your arteries narrow so that your muscles don't receive enough blood. In response, you may feel pain or cramping in your legs, especially during exercise. 

Strategies to reduce cramps:

  • See a doctor to treat peripheral artery disease
  • Maintain a healthy weight
  • Maintain normal cholesterol and blood pressure levels

Venous Disease

Conditions like chronic venous insufficiency and deep vein thrombosis may cause blood to pool in the lower legs. When your blood vessels aren't functioning properly, it's common to experience muscle spasms and cramping. 

Strategies to reduce cramps:

  • See a doctor to treat venous disease
  • Wear compression socks to improve circulation
  • Consider surgery, sclerotherapy, or ablation to remove the affected veins

Nerve Compression 

In some cases, a pinched nerve, nerve damage, or peripheral neuropathy from a spinal injury may result in muscle spasms. Many degenerative disorders of the nervous system, such as Parkinson's disease or multiple sclerosis, involve symptoms that include cramps and spasms.

Strategies to reduce cramps:

  • Seek medical advice from a doctor
  • Control pain with physical therapy, medication, or surgery

Medical Conditions 

People with certain medical conditions, such as diabetes, liver problems, or thyroid disorders, may experience leg cramps as one of their symptoms. 

Strategies to reduce cramps:

  • Seek treatment for the underlying condition
  • Stay hydrated

Medications 

Several prescription and over-the-counter medications list muscle cramps as a common side effect. These include birth control pills, diuretics, naproxen (Aleve), albuterol, and statins. 

Strategies to reduce cramps:

  • Talk to your doctor about switching medications or reducing your dosage

With so many possible causes for leg cramps, it's easy to understand why researchers remain puzzled. Dr. Yuen So, director of the neurology clinic at Stanford University, told NPR's Morning Edition about his experience writing a scientific review of treatments for muscle cramps. He explained, "We were surprised to find out how little is documented in the treatment of cramps. A lot we do in medicine is based on anecdotal experience, and in this case, a lot of the treatments we use fall into the unproven category." Until more research is done to evaluate the underlying mechanisms that cause leg cramps, many doctors recommend making overall wellness a priority. As a first step, you should check with your doctor to see if a serious medical condition may be causing your cramps. 

Once you've eliminated medical conditions and medications as potential causes for your cramps, implement solutions for cramping that also benefit your overall health. For example, staying hydrated is an easy decision to make. Hydration is crucial for many bodily functions. Likewise, compression socks don't just help prevent leg cramps, they also reduce your risk of developing varicose veins and deep vein thrombosis. Work with your doctor to develop a cramp-fighting plan that fits into your general healthcare goals. 

Learn more about how compression socks promote cardiovascular health and good circulation. 

Sources: 

Allen, Richard E, and Karl A Kirby. “Nocturnal leg cramps.” American family physician, vol. 86, iss. 4, 2012, pp. 350-355, https://pubmed.ncbi.nlm.nih.gov/22963024/.

Bologna, Caroline. Read This If You've Ever Wondered Why It's Called A 'Charley Horse'. 9 Aug. 2019, www.huffpost.com/entry/charley-horse-origin-name_l_5d4b3e44e4b01e44e4749142

Marnach, Mary. "What causes leg cramps during pregnancy, and can they be prevented?" Mayo Clinic, Mayo Foundation for Medical Education and Research, 2019, https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/leg-cramps-during-pregnancy/faq-20057766.

"Muscle cramp." Mayo Clinic, Mayo Foundation for Medical Education and Research, 2019, https://www.mayoclinic.org/diseases-conditions/muscle-cramp/symptoms-causes/syc-20350820.

Neighmond, Patti. “Warding Off Muscle Cramps As We Age.” Morning Edition, NPR, 22 Mar. 2010, www.npr.org/templates/story/story.php?storyId=124888051

Shilton, A. C. "Oh, Cramp!" Runner's World, Hearst Magazine Media, Inc., 31 Oct. 2014, https://www.runnersworld.com/health-injuries/a20830024/how-to-treat-leg-cramps-while-running/.

Schwellnus, Martin P et al. “Increased running speed and pre-race muscle damage as risk factors for exercise-associated muscle cramps in a 56 km ultra-marathon: a prospective cohort study.” British journal of sports medicine, vol. 45, iss. 14, 2011, pp. 1132-1136, https://pubmed.ncbi.nlm.nih.gov/21402566/.

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