What’s Causing My Muscle Cramps?

As the weather is warming up, more issues with cramping in the calves are popping up in my conversations with runners, especially as mileage increases and/or people are spending more time on the trails. Muscle cramps occur for many reasons, but the main three I find when dealing with runners are hydration, electrolytes, and mobility deficits.


Hydration is important for all functions in our body, including what happens in the muscles. When the body is dehydrated, muscle cramps can develop. Making sure you are well hydrated before your training or race is important and continuing to hydrate at regular intervals during your training or event is critical as well.

So how much water does your body need? A general rule of thumb is to drink at least half of your body weight in ounces of water a day to support normal daily function.

Adding running to the mix is where things can get a bit tricky; I will keep it as simple as I can for you.

While you are running in the heat and humidity, drink based on thirst rather than attempting to get a certain amount in regularly.  As an endurance athlete, it can be difficult to figure out how much you are drinking at a time and you don’t want to feel water-logged. If you drink when you are thirsty, you should be fine.

Once finished with the run, you can fully replenish. To figure out how much water you need to replenish, the easiest method is to weigh yourself before you go out for your run and then again when you return. The difference in weight is what you lost in sweat and have not yet replaced. For every pound lost, you want to consume 16 ounces of water on top of what your daily minimum is. I don’t expect you to replenish it all immediately, but rather over a period of the several hours, possibly the day.


Without getting too scientific on you, electrolytes are necessary for muscle contraction and relaxation to happen.  Without electrolytes, the muscles cannot function properly. This can result in muscle cramping either during activity or after.

Electrolytes and hydration can go hand in hand. As we sweat, we sweat out electrolytes. If you only replenish water and not electrolytes, it can cause significant electrolyte imbalances, which can contribute to other issues.

When it comes to electrolyte replacements, there are a number of options. An easy, natural option is coconut water. You can also find a number of electrolyte supplements to put into your water if you are carrying water with you.


Something that is often forgotten when it comes to muscle cramps, especially when running hills, is the possibility that it is coming from mobility deficits. When running hills, we require more mobility in our hips and ankles than when running on level ground. Without the proper mobility, the muscles tend to work harder to move the body. Over time, the muscles fatigue and cramping can develop.

So, how do you improve mobility? Here are some of my favorites exercises to address ankle mobility:

And these are great ones to do as warm ups before running.

Once again, I am not saying that one of these three reasons are the cause of your cramps, but they are definitely things to consider if you have been experiencing muscle cramps regularly.

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