Cramps: It's Not a Lack of Salt!

By Jake Francis

Cramps have been an issue, ever since I can remember. Professional sport players get it, and us everyday folk get it too. But why do we get it? Well, first we have to go over what cramps are.

Let's clarify at this stage, I am mostly referring to exercise-associated muscle cramps. Muscle cramps are where muscle fibres contract fully and suddenly. It causes pain and loss of function and can last between seconds and minutes (I once had cramps that lasted a good ten minutes). Currently, there are two suggested theories on how this happens. The first is the dehydration or electrolyte depletion mechanism. This is essentially where the loss of electrolytes that occurs during exercise results in a neural imbalance. This causes sudden muscle contraction. The second theory, the altered neuromuscular control theory, is where afferent nerve fibres are being excited, with a lack of excitation of inhibitory nerve fibre. This results in muscle cramps.

Now let's look at the first theory - a loss of electrolytes. This is puzzling to me because it suggests there's a lack of electrolytes in the body. Let's assume this is true for a minute. This means that these electrolytes need replacing to ease cramps - so an electrolyte drink, salt or sodium tablets. My question is, if it isn't replaced, how do cramps ease even without this? I know they can be eased, because I can see players stretch it out on the pitch, or I massage the muscle to loosen it off... The other thing is, we consume salt in almost every food we consume... It's almost impossible to cut salt out of your diet. So, how can we lose that many electrolytes to cause that problem?

You might be able to tell, I think this theory is a load of rubbish. The second theory is more promising and seems to be more accepted in the literature (as this comparative review states). It makes more sense to me, because most cramps occur towards the end of games or in extra time. So, this means fatigue must play a huge role. Those inhibitory nerve fibres help us to control how much force we produce in a muscle and when to stop to contracting. If we are fatiguing, they are losing their ability to do this. Therefore, when we ask our muscle to contract, there is no control there, so it contracts fully and struggles to switch off again, as the inhibitory fibres catch on. Much more logical.

This also follows with why those with weaknesses or imbalances in muscles tend to get cramps quite quickly. For example, if you don't train or use your hamstrings, and I ask you to do a hamstring bridge, I find usually that person's hamstrings start cramping. Obviously, it doesn't fully explain random bouts of cramps at rest or whilst sleeping. However, there is always something in the research to improve.

So, basically, the reason we get cramps during exercise is down to fatigue and/or a lack of neuromuscular endurance. This means we prevent cramps by increasing neuromuscular endurance.


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