As runners, almost all of us have experienced this situation…

Last week I headed out for a lovely Sunday morning EASY 10km with my trusty pup at hand and a cheerful smile on my face… the sun was shining and I was feeling absolutely fantastic…

That is until… 4km in and all of a sudden I feel intense muscle cramps in my legs.

I stop and try to massage my calves as well as possible… but that doesn’t help, I try to walk it out and that doesn’t help either… 

On my walk home I was thinking to myself all the million-dollar questions…

Will breathing through my mouth as opposed to my nose help prevent cramps?

Should I run slower to prevent muscle cramps?

Will muscle cramp pills help me?

What about using salt to prevent muscle cramps?”

People mean well when giving advice about preventing muscle cramps but the truth is that not even experts can say with certainty what the cause of muscle cramps is.

We do not know EXACTLY what causes cramps… but let’s have a look at what we do know.

Muscle Cramps

Cramps are seldom caused by a lack of electrolytes and in cases where this is the case, it’s generally accompanied by nighttime cramping.

It’s important to note that while a shortage of electrolytes in extreme conditions can contribute to cramping, too high a concentration of electrolytes will have the same impact as too little.

There is only one mechanism for cramps: Cross Bridge fatigue.

Simply put, as we proceed with exercise, there is an association with fatigue, a gradual decay in the signaling that instructs the muscles to contract and relax.

As this process delays we get to a point where your agonist (calf) and antagonist (peroneal and/or anterior tibialis) contract at the same time, this leads to cramping.

The cause of this cross-bridge fatigue is most commonly from muscle fatigue and in less than 30% of cases from nutrition (low magnesium, calcium, and/or potassium).

Strength training is likely contributing to this fatigue in the shorter term but should assist in the longer term.

Let’s have a look at lactic acid and if it’s the reason you are cramping when you run…

Is Lactic Acid The Cause Of Muscle Cramps?

It seems like everyone has their own theories about lactic acid and how they prevent it…

Lactic acid is real, it is measured as blood lactate. Lactic acid is NOT the reason for workouts to end. In fact, blood lactate is cleared very quickly and is used by the body to produce energy.

Everyone needs to understand that lactic acid is an important part of our energy metabolism.

Let’s break down what lactic acid is exactly…

Lactic Acid

Lactic acid is a by-product of the system when your body is breaking down chemical bonds inside the muscle that provides the chemical energy for the body to do mechanical work.

Almost as soon as lactate is produced it is shuttled away by the blood very quickly to the liver where it is processed. 

A lot of people swear that cramping is caused by a build-up of lactic acid…

This is NOT necessarily true… 

It’s more likely that cramps are caused by other by-products of energy metabolism which do cause the acidity or PH of the muscles to drop and for acidosis to take place, which causes interference of muscle function.

The Role Of Lactic Acid

Lactic acid’s role in exercise is still not properly understood.

At least we’ve gotten to the point where we know that it definitely provides some of the chemical energy that we need to produce the mechanical energy of movement. 

What we do know is that massages on the side of the road do absolutely nothing to help you get to the finish line…  so how do we prevent these dreaded cramps??

How to Prevent Cramps

  1. Strength Training

Running is a compounding sport, it places that eccentric strain on your muscles.

Strength training helps build the structures around the joints and helps make the joints stronger, allowing your body to sustain the load from running so much better. 

Making sure you do the correct strength training is important. The good news is we’ve created a free strength training plan for runners that you can download by clicking here.

  1. Pace Yourself Correctly

If you train logging 10-minute miles and you start racing 8:45-minute miles, your muscles won’t be prepared for that effort, and you’ll place yourself at a higher risk of cramping.

  1. Warming Up & Cooling Down Correctly 

Lindsey, Shona, and Devlin walk you through exactly what to do before every run that you do.

It only takes a few minutes but if you start doing this as part of your pre-run routine, you can save yourself a lot of time and heartache down the line because of training missed due to injuries.

Let’s have a look at some common theories when it comes to preventing cramps while running…

Does Salt Prevent Cramps? 

We’ve seen it at races… People taking literal handfuls of salt and shoving it into their mouths… the question is… Does it help?

As we established above, there are a few people who suffer from cramping because of an electrolyte imbalance but that is not the main cause of cramping. Having salt to prevent leg cramps does help those specific people.

If you have very low stores of sodium then it can lead to cramping, although things like magnesium and calcium shortages are probably worse than having sodium shortage.

The reason why people shouldn’t take a blanket approach and just start taking salt tablets is that TOO MUCH SODIUM CAN ALSO LEAD TO CRAMPING.

So, in very long, ultra distances and multi-day races it is important to do some sodium replacement. 

For most people cramping is caused by fatigue, there is a delay in the signaling (due to fatigue) in telling muscles when to relax and contract. 

Eg. Your quads and hamstrings. When your quads are relaxed your hamstrings should contract and vice versa.

Watch this video to see when having salt is handy during race time.

Do Potato Chips Prevent Leg Cramps While Running?

Potato chips can prevent leg cramps because they contain potassium and sodium – two important electrolytes that help your muscles to contract, relax and function smoothly.

However, these nutrients can be found in many different foods, so eating a balanced diet, in general, will also help in preventing muscle cramps.

Potato chips contain potassium and sodium (salt) which are both important electrolytes that help muscles to function properly. 

Potassium aids in electrical impulse generation, so if you’re not getting enough of it, your muscles are more susceptible to cramping.  

It’s important to note that if you suffer from leg cramps, it’s difficult to say which food group you should be eating more of or what supplements you should take if your diet does not allow for all food groups because it’s different for everyone. 

You need to analyze your diet and see which food group you may be neglecting. It’s all about trial and error so find what works for you and stick to it.

When potassium is mentioned the first thing to pop into most people’s minds is BANANAS…

Do Bananas Prevent Leg Cramps While Running?

If you are susceptible to cramping, chances are that you’ve heard the notion that bananas can help to prevent or relieve leg cramps.

Bananas do help prevent leg cramps (to a certain extent). They are rich in several important nutrients including potassium and magnesium. These nutrients play a crucial role in the way our muscles function, so getting enough of them is vital for our muscles to work normally.

That being said, there is no scientific evidence to prove that bananas alone prevent your legs from cramping when you run.

If you’re suffering from tight calves you’ve going to LOVE this guide: Get Rid Of Tight Calves FOREVER – The Ultimate Guide


Devlin Eyden has a passion for seeing his athletes grow and excel. From novice runners or cyclists across all disciplines to elite mountain bikers representing South Africa at World Championships. In addition to helping you ride faster, for longer, Devlin also has the personal touch when it comes to your bike setup, aiming at improving the overall rider experience. With his background as a Sport Scientist as well as a Strength & Conditioning specialist, performance is Devlin’s main priority, be it in the gym, the lab or out on the road or trails. Being a keen runner & cyclist and having completed the Cape Epic among others, Devlin has first hand experience in what it take to reach your goals. If you’re looking for a once-off training program or ongoing, high touch support Devlin has you covered.

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