What causes cramp during training and racing?

If you have ever experienced cramps you will know how painful and debilitating it can be. It can spell the end of your race and have the even strongest athlete doubled up in pain at the side.

To help us understand what causes cramp and how to avoid cramp in future we turned to sports scientist and founder of Precision Hydration, Andy Blow, for some answers. 



Andy Blow is an expert in hydration, he has co-authored a number of scientific studies and books on the subject. He was once the Team Sports Scientist for the Benetton and Renault Formula 1 teams and remains an adviser to the Porsche Human Performance Centre at Silverstone.

An athlete himself Andy has finished in the top 10 of IRONMAN and IRONMAN 70.3 races, as well as winning an XTERRA Age Group World title. It was his own struggles with cramp that led to him specialising in hydration and founding Precision Hydration.

"I have a strong personal interest in the subject of Exercise Associated Muscle Cramps (EAMC) because I used to be a chronic sufferer back when I was competing. For as long as I can remember I seem to have been especially susceptible to the point where cramps ruined numerous important races for me," Blow begins by telling us. 

What is cramp? 

Cramp is a "painful involuntary contraction of a muscle or muscles". These sudden muscle spasms are often felt in leg muscles and calf muscle, especially for runners, swimmers and cyclists. Some athletes also experience leg cramps at night after training sessions and races. 

What  causes cramp?

What causes cramp is a contentious issue in the scientific community, which may be why you hear so many different explanations from athletes and coaches. 

Essentially there are two theories that stand up to scrutiny. "The Dehydration/Electrolyte Theory is probably the oldest," begins Blow, "it speculates that a significant disturbance in fluid or electrolyte balance, usually due to a reduction in total body exchangeable sodium stores, causes a contraction of the interstitial fluid compartment around muscles and a misfiring of nerve impulses, leading to cramp." And for those of us without a background in Sport Science  " if you lose a lot of sodium and don’t replace it (as is common when you sweat a lot) it can cause fluid shifts in the body that in turn causes cramps."

This theory is based primarily on anecdotal evidence and observation. Many athletes who suffer cramps regularly place the blame at the door of dehydration or lack of electrolytes. However, this theory lacks "concrete proof" from extensive scientific study. 

"There is another more recent theory, " Blow explains, " which lends itself much more to scientific investigation." Neuromuscular theory points the finger at fatigue and muscle overload, "The hypothesis is that fatigue contributes to an imbalance between excitatory impulses from muscle spindles and inhibitory impulses from Golgi tendon organs, and that this results in a localised muscle cramp. In other words, muscles tend to cramp specifically when they are overworked and fatigued due to electrical misfiring."


What to do if you get cramp? 

“One big factor that does appear to support the neuromuscular theory is that stopping and stretching affected muscles is a pretty universally effective method to fix a cramp when it is actually happening,” expounds Blow,  “What stretching does is put the muscle under tension invoking afferent activity from the Golgi Tendon Organs (part of the muscle responsible for telling it to relax) and causing the cramp to dissipate and ease the pain.” 

With no clear cause of cramp, you would imagine that there would be little consensus on treatment either. However, the authors of A 2019 review paper argues while there's no definitive cause of cramp, but rather different causes for different types of cramp, it isn't necessary to know the cause to find a treatment and maybe more time and energy needs to be spent trying to treat / prevent cramp.


Precision Hydration have conducted their own research and surveyed hundreds of athletes who reported suffering from cramp. More than 85% of them had tried more than one method in an attempt to alleviate the issue.


 


How to avoid cramp

Having extensively reviewed the research Blow concludes "there is no ‘magic bullet’ available to kill off muscle cramping at the moment and it doesn’t look like there will be one coming anytime soon." But, based on his own experiences and research at Precision Hydration, he does have some suggestions. "I absolutely think it’s worth looking at your sodium intake in relation to your sweat output. It’s a cheap and simple exercise and has little downside to it. It’s certainly a good idea if your cramps tend to occur during or after periods of heavy sweating, in hot weather, late on during longer activities or if you generally eat a low sodium (or low carb) diet."

If like many athletes you use electrolyte drinks, make sure they are strong enough to make a real difference. Most sports drinks are extremely light on electrolytes (despite the claims they make on their labels), containing only about 300-500mg sodium per litre (32oz).  


Blow explains why higher sodium content is beneficial, "human sweat, on average, comes in at over 900mg of sodium per litre (32oz), and at Precision Hydration we often measure athletes losing over 1500mg per litre (including myself) through our Advanced Sweat Test. It’s therefore a good idea to look for upwards of 1000mg sodium per litre in a drink and over 1500mg per litre if you suspect you are a particularly ‘salty sweater’.” 


To find out more about what type of ‘sweater’ you are take this free online Sweat Test.



Performance insights from INCUS | CLOUD 

Along with addressing your hydration and electrolyte intake you can use the data from INCUS | CLOUD to help identify if there are any patterns or trends in the lead up to an attack of cramp. With the centrally placed INCUS | NOVA able to show left/right differences and pick up changes in technique, impact and body positioning you may be able to identify if fatigue altering your technique is a forerunner of cramp. The unique metrics that the INCUS | NOVA offers, gives fresh insights into how neuromuscular fatigue may play a role in cramp. 



Cyclists, runners and triathletes 

Endurance sports athletes tend to exercise in challenging conditions, often reaching a state of fatigue especially during competition. You can check out some case studies of athletes and how they have found the solutions to their cramp issues HERE.