The theories suggesting that exercise-associated muscle cramps are caused by electrolyte-depletion have been overshadowed by 'neuromuscular fatigue' theories in recent years, but a new study has suggested that sodium intake can help reduce cramping.

Sports Scientist and Precision Fuel & Hydration founder Andy Blow discusses the lab-based study and what the findings could mean for the future of cramp research...

Some background

Muscle cramping is a subject of deep interest for me as I suffered with cramps repeatedly when I was training and competing seriously in triathlon.

It’s an insanely frustrating phenomenon for athletes because very few things can derail a performance more instantaneously than a bad cramp.

It’s equally infuriating from a scientific point of view because no-one really seems to be able to pinpoint the singular cause of cramp, or find a way to reliably prevent or treat exercise-associated muscle cramps.

In the past, muscle cramping was almost universally put down to either dehydration, electrolyte depletion, or some other kind of disturbance in body fluid levels.

Whilst there's a huge body of historical and anecdotal evidence in support of these theories, there's been a definite trend in recent years for many ‘experts’ to discredit the role of electrolyte imbalance in cramping, with preference given to the increasingly popular 'neuromuscular fatigue' theories.

These newer theories have a lot of merit, but what we’ve seen is a classic ‘pendulum swing’ from one old idea ("muscle cramps are all down to dehydration/electrolyte depletion") to another newer one ("muscle cramps are all down to fatigue"), without many people stopping to consider that both might actually play a role (independently or together) in the issue.

Image Credit: Johnny Yao via Wikimedia (copyright free).

A new lab-based study to investigate the cause of cramp

Because the study of cramping purely from a neuromuscular standpoint has become more common in recent years, I was interested to see a brand new paper, entitled ‘Electrolyte beverage consumption alters electrically induced cramping threshold’, in the Muscle and Nerve Journal earlier this year.

It gave me reassurance that there's still people in the scientific community who are interested in looking at the issue from an electrolyte perspective.

What the researchers did in this study was take a small group of ‘cramp-prone’ individuals (i.e. people who reported getting exercise-induced calf cramps on at least a monthly basis) and found a way to reliably cause them to cramp (in their feet) by wiring them up to electrodes, which stimulated the muscles to contract until a cramp occurred. Sounds lovely doesn’t it?!

Because the researchers could control the strength of the electrical stimulation causing the contractions in the muscles, they could effectively assess the ‘threshold’ at which cramping occurred by ratcheting up the level of stimulation - they did this on two separate occasions with each athlete:

  1. They increased the level of stimulation 15 minutes after a participant drank a strong electrolyte drink (500ml of fluid with ~840mg sodium, so similar in composition to PH 1500).
  2. They increased the level of stimulation 15 minutes after the participant drank a flavoured ‘placebo’ drink with no sodium in it.

The design of the study meant that the participants didn't know which order they’d do the trials in (i.e. it was ‘blinded’).

What did the results show?

The results showed that the threshold of stimulation required for the onset of cramping was increased and the severity of the cramps experienced (which was measured by reports of pain by the participants) were reduced when they’d taken the sodium rather than the placebo drink.

Whilst the effect was not universal (5 out of 9 participants showed an increase in cramping threshold and 6 out of 9 reported less pain), it was significant enough for the authors to conclude that the consumption of a strong sodium drink did have a measurable effect on cramping in these 'cramp-prone' athletes as a group.

The results showed some striking similarities to a 2005 study in the Journal of Athletic Training that demonstrated onset of cramping could be delayed significantly (if not prevented entirely) in athletes who consumed a carbohydrate/electrolyte drink before exercise when compared with a placebo. 

What do the results mean? 

What I found most interesting in reading all of this was that, in many ways, the results of the study resonate strongly with countless reports we’ve received from athletes who've told us about how pre-loading with PH 1500 (as well as consuming PH 1500 during exercise) has helped them improve their performances.

Not a week goes by when we don’t get a handful of emails or messages into PH HQ from athletes telling us a stories about how taking in a very strong sodium drink has positively impacted their experiences with cramp; by either reducing the severity of it or stopping it from happening altogether.

None of this is to say that taking in sodium is a cure for all cramping though.

If it was then cramping would be far less of an issue than it still is for many, and we’ve seen a few troubling cases where no amount of fiddling with fluid and electrolyte intake seems to make a difference.

But it does seem to work for a large number of people and it's encouraging to see some lab-based evidence emerge that might stop everyone from completely throwing out the dehydration/electrolyte imbalance theory altogether just yet!

If you’re interested in understanding more about this topic, our in-depth blog on cramping is well worth a look and it includes suggested protocols and interventions to try if something is 'cramping' your style... (sorry, terrible pun!).