What is the Deal with Mid-Run Muscle Cramps?

This article originally appeared on Trail Runner

The sudden locking and seizing of muscles can bring even the toughest runner to stopping in their tracks. Muscular cramps are a common and painful phenomenon that, while frustrating when experienced, are easy to correct and prevent.

What Causes Cramps

All cramps are caused by a deficit of Adenosine Triphosphate (ATP.) ATP is the molecule found in the cells that is responsible for carrying energy. This involves breaking down food into energy sources and fueling the body. ATP does not store energy, as glycogen (carbohydrates) and fats do, but rather breaks down existing energy stores to transfer to energy immediately.

Several factors come into play while running that can burn through energy systems and the ATP that depends on them.


Stress on the skeletal muscular system can be brought on by running too hard for what the athlete is conditioned for. Katie Carbiener, a doctor of physical therapy and running coach who specializes in gait analysis, says, "It can be overuse or underuse of a muscle. Sometimes, they cramp due to exceeding their strength capacity. For example, a regularly cramping calf or tight calf might be due to using the calf for more of the power in push-off vs using the glute, which should be our primary muscle to create an extension in the hip."

Whether it is an athlete running too fast or farther and with more climbing than prepared for, reaching outside of previously set physical limits often leads to physical pain. Getting to the point where the body is so far outside of its wheelhouse can push the muscles to oxidative stress, where the body creates more reactive oxygen species, or free radicals than it can fight with antioxidants. This causes tissue damage, which, when paired with rest and proper nutrition and hydration, leads to muscle growth.

The tissue damage can also lead to painful cramping as the body requires more energy to continue growing and using muscles.

Nutrition and Hydration

Several nutritional and nutritional imbalances can contribute to cramping in a big training run or race. Jennifer Sommer-Dirks, a registered dietician based out of Eagle, Colorado, who works primarily with endurance athletes, explains that the key to avoiding cramps through nutrition goes back to preventing fatigue. "Adaquiting fueling day to day. Underfueling chronically will always cause issues, whether cramping, energy levels, or injuries." Sommer-Dirks, who, before working with endurance athletes, spent several years as a dietitian in eating disorder treatment, explained that to keep energy reserves high, carbohydrates, fats, and hydration need to be sufficient throughout the day.

While vitamin deficiencies are not helpful in fitness, there is not solid evidence that certain deficits lead directly to cramping. That being said, ensuring that the body is well fed and that diet is balanced is more likely to ensure healthy and running with excess energy to fuel the muscles.


Gait Changes

Overuse of particular muscles, often caused by underutilization or weakness in other muscles, is another cause for cramps occurring while running. Sammie Lewis, a Doctor of Physical Therapy and Running Coach at Golden Endurance, says, " The most common scenario is someone changing their gait mid-run because of pain or a blister. The runner isn't conditioned to run using different muscles and there is premature fatiguing, which leads to cramps." Lewis, who is based in Golden, Colorado and works primarily with trail and ultra runners, goes on to explain that lower-back issues can also lead to imbalances that result in more frequent cramping.


It is common for an athlete to have differences in length, strength, or flexibility from side to side. Carbeiner explaines, "Symmetry is always the first thing I look for. No one is perfect but the more right and left can be similar the less likely for unilateral injuries due to uneven loading and compensation." She goes on to explain that she aims to help all runners find a gait that does not limit range of motion or over utilize one leg over the other. Though it can take time to balance the body, it is often worth it in the long run.

Weather and Altitude

An increase in heat or humidity, especially before the body can acclimate can contribute to unwanted muscle contractions. Heat cramps are often caused by dehydration and a loss of nutrients in the body from excessive sweating. Sommer-Dirks says, "It is always ideal if you can do a sweat rate test. But if not, a good place to start is to aim for 16-20oz per hour with 300-500 mg of sodium." She encourages people to use those numbers as a starting point and make adjustments based on how their body responds.

Similarly, a person's blood volume increases when they go up in altitude, causing hydration and nutrients to be discarded through urination. Increasing hydration and electrolytes while training at higher elevations can help prevent unwanted cramping.


Uneven terrain, especially for someone making the adjustment to running on trails, can also cause cramping. Trail runners, especially, are prone to lower leg cramping as their feet and ankles work to balance. Lewis states, "the most common cramping I see are calves for those running a lot of uphills and quadriceps for those going too hard on downhills." As trail running often involves constantly varying terrain with sustained ascents and descents, the risk of cramping is greatly increased.

What Can be Done in a Run to Work Through a Cramp?

When a cramp hits mid-run or race does not need to be the reason to stop. Taking time to fix the problem and prevent a return visit from the contraction can lead to a less painful finish.

Slow Down and Stretch Out

Often, the best way to deal with a cramp is to relieve the tension in the body. Massaging the affected area or stretching can lessen the rigidity and increase blood flow to the area. If heat is available, a warm compress can help relax the muscles and decrease the pain faster. Lewis encourages, "First thing: slow down, if you are still able to run. If it’s a cramp where you’re unable to run, you can stretch the muscle to help make the contraction stop." She goes on to explain that stopping cramping has different effectiveness for different athletes.

Fuel and Hydration

Beyond ensuring the body is receiving adequate nutrition before and during the run, working to rebalance the body can promote a less painful end to the workout or race. There are also some foods that can jolt the body out of cramping and get the muscles firing appropriately again.


Increasing hydration, electrolytes, and carbohydrates will rebuild energy systems in the body, giving more ATP availability in helping the muscles resume normal function. Sommer-Dirks states, "Adequate carbohydrates, limiting factor in keeping muscles from fatiguing. Anything over 90 minutes should involve consuming carbohydrates."

While every person is different, finding carbohydrate-heavy foods that sit well in the stomach is crucial in preventing fatigue. Overloading the stomach to the point of getting sick will throw off electrolytes even more while overdoing hydration could lead to hyponatremia


If cramps keep occurring and nutrition is adequate, it is possible to shake the body out of the cramping cycle. "Pickle juice or HotShots are two of the most popular ways to jolt the body out of cramping," says Sommer-Dirks. This is because vinegar and cayenne can increase the production of acetylcholine in the body, which is a neurotransmitter that aids in muscle control.


Cooling Down

Taking time to cool down and stretch after a run or workout can prevent future cramps. Fatigued muscles that are not given time to decrease in tightness or soreness which can prevent malfunctions in a standard gait. It is also important to hydrate immediately after a run to help with blood flow to the recovering muscles. Carbiener recommends 500ml of water in the hours following a workout. " Most hydration though is done the day before to hours before to avoid consuming too much and upsetting your stomach" she continues, explaining the importance of staying on top of hydration during a training cycle.


Hillary Osborne, a running coach and personal trainer based in Colorado and specializing in trail and ultra runner strength encourages runners to engage in targeted strength when cramps are prevalent. "An example of a muscle group that can cramp due to weakness are the adductors. A lateral lunge, Copenhagen side plank, or resisted hip adduction will strengthen this muscle." A good use of an off-season is to work on finding and strengthening imbalances in the body to avoid overuse.


Fueling well before and after a run can help with short and long term cramp prevention. Prior to the run, fueling well with carbohydrates and fats can prevent energy systems from dropping too low. "After the run, you will want glycogen to restock your energy and protein to rebuild your muscles," says Sommer-Dirks. It is best to eat within 30 minutes of exercise, with a mix of the three major macronutrients: carbohydrates, fats, and proteins. After a standard workout, aim for 1-1.5g of carbohydrates per kilogram of body weight and around 15-25g of protein.

While there is still growing knowledge of the cause of cramping while running, a nutritional balance and attention to biomechanics can help an athlete move towards pain-free running.

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