Running Cramps: What Causes Leg cramps while running?

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Every runner has experienced running cramps at one point or another – whether you’re just starting out and getting the hang of things, or you’re an experienced runner in a big race. 

No matter who you are, those cramps will show up when you’re least expecting them, and can be extremely frustrating in the middle of your run. 

The good news?

Running cramps are not totally random – they can be prevented and can be dealt with when they sneak up on you. 

In this article, we talk to PTs and coaches about how to avoid – and treat – leg cramps when running.

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What Causes Cramps While Running?

The first thing you need to understand about running cramps is what causes them. Whenever you reach the root of the problem, you always get to the solution faster. 

When you get that pain in your calf or leg, here’s what’s really happening: your muscles are spontaneously contracting.

That involuntary contraction causes the muscles to spasm, which then stops the blood from flowing into the muscles. Because of that, the muscles lose important oxygen and vitamins which they need to continue functioning. 

The fact is, muscles do not spontaneously contract because they just feel like changing things up in their regular routine. Muscles contract and spasm for several different reasons. 

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Pete Jacobs, an Ironman triathlete champion and performance and health coach, says, “Cramps exist because of a lack of ATP production, ATP [adenosine triphosphate] is ‘energy’ in our body, and without it, our muscles can’t move and therefore become locked in a cramp.

Lack of ATP production is caused by all the things we associate with fatigue or poor health, such as:

  • Lack of oxygen in the cells (through sharp shallow breathing like hyperventilating)
  • Deficiency in electrolytes (potassium/magnesium/sodium)”

Dr. Michael Bogden, PT, DPT, and co-founder of FWDfuel Sports Nutrition, brings up another cause of leg cramps while running. 

One common but frequently untreated cause of leg and calf tightness is actually sciatic nerve issues.  

Despite many runners not having pain running down the leg, doing a lot of desk work, long commutes, or simply having poor posture can cause a lot of nerve irritation leading to tightness in the leg muscles down to the feet.”

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What happens in the body to cause that nerve irritation?

There is a breakdown in communication between the muscles and tendons and the nervous system. As your muscles get fatigued, the communication becomes confused. That’s why the muscles cramp. As a runner, you can feel this in your upper leg (in the quads and/or hamstrings), in your calves, and even in your feet. 

Here are some other common causes of running cramps, which can accelerate what’s happening between your muscles and nerves. 

You didn’t warm up or stretch before your run: It’s very common for runners who go from zero to intense running to get hit with cramps. The muscles started in a tight state. With all that extra pressure without any warning, it becomes too much for the muscles to bear. 

Your body’s electrolyte balance is off: If you exercise for a long time and do not replenish water in time, the electrolyte will be insufficient, which will cause leg cramps.

You’re exercising excessively: the calf muscles are in a tense, long-term high-load state, so strain can also cause leg cramps.

Lack of sleep: running in a state of fatigue ends up in high mental pressure, leading to muscle tension, and causing leg cramps.

Wearing the wrong running shoes: These can force your foot into unnatural positions, which increases muscle pressure during running and also cause leg cramps. Make sure you get the best running shoes for your feet to prevent cramps. 

Poor breathing while running: this makes your blood flow too slowly, which makes your muscles work harder (without getting enough oxygen) and causes cramps. See How To Breathe While Running.

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How to Avoid Running Cramps

There are many things you can do to prevent cramps from happening in the first place. 

  • Don’t take shortcuts in your training: If you’re not properly strengthened and prepared for your weekly long run or the race itself, you’ll end up with leg cramps. 
  • Pace yourself: Always remember to start up slow, then get faster as you go. Give yourself that chance to warm up before picking up the pace. 
  • Hydrate properly: before, after, and (sometimes) during the run.
  • Drink electrolyte-enhanced water: Especially when you’re running in hot weather, be sure to replenish the electrolytes you lose when you sweat – sometimes you just need more electrolytes than you’ll get from regular water. 
  • Wear compression gear: If you regularly experience calf cramps while running, you can compress your calves with breathable gear that protects your calves from the intense heat and the effects it can have on your body.
  • Keep track of what causes your cramps: When you get consistent leg cramps while running, take notes of what you’re doing before, after, and during your run; try to analyze what could be causing this problem and repair it. 
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What to Do When You Get a Cramp While Running

Even with all of the above preventative methods, cramps can still happen.

If the pain isn’t too bad, you’ll probably try to keep going and ignore it until the pain worsens and you’re forced to stop. 

If you don’t want this to happen, deal with the cramp when you first notice the signs.

Slow down your pace and focus on breathing. The temptation is to change your breathing to try to compensate for the pain, but that will just worsen the cramp. 

You may also need water, so it’s a good idea to stop running and slow down to a walking pace. Take that opportunity to rehydrate and give your muscles the recovery they need. 

If the leg or calf cramps become excruciating, stop the run completely and take a break to do light some light stretches. Massage the cramped area in a circular motion to get the blood flowing normally again. Both of these together should alleviate your pain and get you back on the trail again. 

Related: How To Stop Foot Cramps: Try These 9 Tips

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Here are some stretches that can help you get rid of the pain:

  • Do a lunging calf stretch: lunge forward, keeping your focus on the calf of your back leg. Feel it stretching out and breathe through the stretch. Switch legs and do it with the other one.
  • Stretch against a wall: Face the wall, placing your heel as close to the wall as you can get. Your toes should be up, almost like they’re climbing the wall. Lean into your calf and let the simple motion stretch it out. 
  • Downward dog: To stretch out your upper leg, do the classic yoga pose, downward dog to stretch out your hamstrings and quads. 

If the pain is so bad that it’s causing you to limp, then you may want to finish your run for the day and take care of your body before running again. 

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Exercises to Avoid Running Cramps in the Future

Even though it’s great that you have tactics to solve running cramps from now on, it would be even better if you could prevent them from happening in the first place. 

Dr. Bogden offers this advice:

“The solution is doing press-ups or cobra stretches before running, standing back extensions if feeling symptoms coming on during a run, and adding lumbar support to work chairs and/or getting a sit-stand desk to help improve posture and reduce nerve irritation.”

In addition to your pre and post run stretches, be sure to incorporate flexibility and strength training into your weekly training schedule. These will build up your stamina and endurance much more effectively than running every would do. 

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A great way to prevent cramps while running is to ease yourself into your training. There’s no rush to run fast or run far right away – it’s much better to follow a training plan that takes you gradually through the distance and speed milestones, with a schedule that fits your fitness level.

We offer a large library of free half marathon and marathon training plans, that fit just about every level of runner, from total beginner to advanced ultramarathon runners. 

Download one to add some structure to your weekly runs and get you on track for your next race!  

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Photo of author
Mia Kercher is a hiker, cyclist, and runner. After finishing her first marathon in 2013, she continued the sport but found a new passion in trail running. She now explores the glorious mountains in Portland, Oregon.

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