Muscle cramp when running

Why do we get muscle cramps? Fitness trainers explain the science and solution

Posted by for Strength

Frustrated by muscle cramps? We asked fitness trainers to explain why we get them and what to do to prevent them.

Whether you’ve had them in the middle of night, waking up to an awful sensation in your calf muscle, or during your workouts, having to drop your barbell as you get shooting sensations in your hand, we’ve all experienced the sheer pain that is muscle cramps

These cramps are caused by a sudden and involuntary contraction of the muscles – and they hurt. There are so many things that can cause these contractions, meaning that avoiding them completely is pretty unlikely. But the good news is that there are simple steps we can take to reduce our likelihood of getting them.

Each week, we ask fitness trainers to answer some of the most googled questions about fitness. This week, personal trainer from Energy House Fitness Zara Ozard and fitness trainer and Strong Women Collective member Emma Obayuvana are explaining everything you need to know about muscle cramps. 



“Muscle cramps and injuries can result from dehydration, overuse of your muscles while you’re exercising, and having my low levels of minerals like sodium, potassium and magnesium. You can also get it from low blood supply to the muscles, either through exercise or a lack of movement.” 


“We can get muscle cramps from holding the same position for a long period of time, which is why some people may get it when they’re asleep because the blood is not moving around the body as it should. Dehydration will also be a big factor because fluids help your muscles contract and relax and keep the muscle cells hydrated. 

When we sweat, we also lose essential electrolytes such as magnesium and potassium. If you’ve got a lack of or an imbalance of electrolytes, it means the signal sent from your brain to contract and relax a muscle can be inhibited, which leads to cramping.

Overworked muscles can also lead to an electrical misfiring of your own body’s nerve impulses, meaning fatigued muscles can cramp more. Carbohydrate intake can also make a difference: if you don’t have enough glycogen stores in the muscles, they’ll get tired more easily and therefore cramp.”

Drinking water during workout
Hydration can help with muscle cramps



“Because the essential minerals that are associated with cramps are lost in sweat, you might find that a sweaty workout can trigger muscle cramps. Generally, overusing muscles or holding muscles in a static position can cause cramps too, which is what we do during exercise. So I wouldn’t say that exercise causes cramps, but I wouldn’t say it helps with it either. I would say it’s more about how you take care of your body in other ways.” 


“The benefits of exercise far outweigh the drawbacks. But if you’re not doing things like stretching, keeping hydrated and recovering enough then exercise can bring on the muscle cramps, particularly if it’s vigorous exercise. It doesn’t help, but it doesn’t hinder. It’s all about the preparation and starving off cramps before, during and after your workout.”



“Immediate relief can come from stopping what you’re doing, stretching and taking a few deep breaths to get oxygen into your body. Afterwards, it might help to add an ice pack or a heat pack to the area. But once you get them it’s too late, so it’s all about prevention. 

Number one is to hydrate well before you exercise. Also try not to exercise straight after eating. Leave it at least an hour, as digestion can trigger cramps. Make sure you’re warm before training too, as warm muscles are less likely to cramp. Make sure that your levels of sodium, potassium and magnesium are up, too. I take magnesium every day and I have noticed that I get less cramps since doing so. Because the mineral helps with muscle recovery it can help to prevent cramps.”


“Stretching, definitely, before and after your training and even during if you feel you need to. Recovery in general will help, whether that’s a massage, foam rolling or jumping in an ice bath. 

Keeping hydrated is also so important, as is keeping electrolytes topped up. An easy way of doing that is with an energy drink, but I don’t particularly like those so I opt for something like a coconut water that is full of minerals.”

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Images: Getty

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Chloe Gray

Chloe Gray is the senior writer for's fitness brand Strong Women. When she's not writing or lifting weights, she's most likely found practicing handstands, sipping a gin and tonic or eating peanut butter straight out of the jar (not all at the same time).