When I ran the Hamster 24-hour run last year I remember coming through home base, having just completed something like my 7th or 8th 5km loop, and seeing a fellow runner keeled over from terrible leg cramping. She was in obvious agony – her calves and quads had seized so badly she could barely get up from the chair someone had put her in. When she tried, as she was trying to stretch it out, she’d cry out in pain and end up falling back into the chair. I saw someone offer her a ‘magic potion’ that was supposed to stop cramping in it’s tracks. For a moment it appeared she’d pull through. But sadly, she ended up dropping from the race for good not long after that.
I’ve never actually experienced exercise-associated leg cramping, but I know and have worked with plenty of runners who have. It’s an unfortunate reality that exercise-associated muscle cramps (EAMC), a temporarily debilitating condition, affects many athletes – yet according to this recent (2016) review of scientific literature on EAMC, the reason behind why they happen and how to effectively manage them are still not clear.
Over the years there have been many theories as to why leg cramping occurs, including the dehydration theory and electrolyte imbalance theory. However, as stated in this 2009 review as well as the 2016 review referenced above, these two hypotheses do not have scientific evidence from cohort studies to support them (although they do have support from anecdotal reports). For example, this 2004 study of 72 runners concluded there was no substantial difference in hydration levels or electrolyte levels between crampers and non crampers.
I’ve also heard advice to take magnesium to prevent cramps. While this originates from the fact that it’s known that a severe magnesium deficiency can cause cramps (along with numbness, tingling and seizures), this advice is unfortunately completely unfounded particularly when it comes to exercise-induced muscle cramping. This 2012 review noted no specific studies have been done on the effect of magnesium on cramping athletes – and current evidence does not support magnesium use for prevention of any cramping. In fact, this 2004 study demonstrated that magnesium levels were significantly higher in runners who experienced cramping compared to those who were cramp free. No extreme magnesium deficiency going on there. Along the same lines, calcium, while necessary for regulation of muscle contraction, has zero evidence of benefit to those who suffer from EAMC.
It would appear the advice to stay hydrated, or take sodium (salt tabs) or electrolyte drinks (typically containing primarily sodium but also calcium, magnesium and potassium), or utilizing magnesium or calcium (Tums) doesn’t have a strong scientific leg to stand on when it comes to cramp prevention. That said, many runners personally will swear by things such as taking salt – and with no downfall to using salt tabs (other than possible bloating or gastrointestinal distress) I wouldn’t advise against this practice. By all means – if it appears to work for you, keep doing it! But there does appear to be something else going on when it comes to cramping.
Indeed, there is another hypothesis called the “altered neuromuscular control” hypothesis – and this one does have the support of evidence from research studies in human models of muscle cramping, epidemiological studies in cramping athletes, and animal experimental data (although consensus is that further research is required for full understanding of this problem). This 2013 study found that significant and serious dehydration does not affect skeletal muscle cramp threshold frequency (the participants experienced losses of up to 5% of their body weight in sweat). It then summarized that neuromuscular control may be more important in the onset of muscle cramps than dehydration or electrolyte losses. This 2010 study of 49 runners concluded the cause of EAMC may be more due to a faster running pace in the beginning of a race and also possibly pre-race muscle damage (not properly tapered for the race).
In a nutshell, running fast and hard particularly at a rate that may be slightly beyond ones fitness level for extended periods of time (causing neuromuscular overload and fatigue) appear to cause an imbalance between the muscles and the brain (via the Golgi tendon organs and alpha motor neurons), which results in cramping. This is why cramping tends to happen only in races and not training, and in the latter stages or end of the race when the athlete is most fatigued.
Yet the question remains, if not with sodium, magnesium, calcium or hydration, how can we prevent cramping? If altered neuromuscular control is to blame (at least in part if not in full) for exercise-associated leg cramps, what can be done as preventive measures?
In the past, without really knowing why, some athletes have turned to pickle juice, mustard or wasabi to stop cramps. Of these three, you have likely heard of pickle juice – and indeed studies now show us it can stop cramps within about 35 to 85 seconds of ingestion. Originally this was believed to be due to the fact it must provide hydration and salt all in one, until this 2009 study proved that it was neither the water or salt content of the pickle juice that stopped the cramps. Then this 2010 study showed that pickle juice was successful in stopping cramping with researchers concluding it was due to a neural reflex – once the pickle juice hit a nerve centre on the back of the throat, it triggered an oropharyngeal reflex inhibiting the firing of alpha motor neurons in the cramping muscle.
While the ingestion of 2-3 ounces of pickle juice stops cramps, it turns out it’s actually the vinegar in the pickle juice that is responsible for this response. To be specific, it’s the acetic acid in the vinegar that appears to be responsible.
This 2011 study shows that something called TRPA1 currents can be induced by weak organic acids called carboxylic acids including acetic acid (as well as propionic acid and carbonic acid). And wouldn’t you know it, this 2017 study demonstrated how orally ingested TRPV1 and TRPA1 activators help not only alleviate cramping but also prevent it.
If TRPV1 and TRPA1 activators can help alleviate cramping, what substances induce these activations? According to this 2009 pubmed article, this 2008 pubmed article and this 2011 pubmed article, capsaicin (chili peppers), black pepper, eugenol (found in clove oil), ginger and CBD (the non psychoactive cannabinoid) all activate TRPV1. Meanwhile, pungent foods such as horseradish and mustard, as well as cinnamon, garlic and weak carboxylic acids such as vinegar (acetic acid) all activate TRPA1.
Therefore, it makes sense that pickle juice (vinegar), mustard (vinegar and mustard seed) and wasabi (horseradish and mustard) are effective in alleviating cramping. I was even recently asked why coca cola might have helped an athlete get rid of her cramping – which, according to this 2010 pubmed article would have been due to the CO2, reacting with water to form carbonic acid (a carboxylic acid), activating TRPA1.
There’s a company with a product called HotShot led (and invented by) a Nobel-prize winning neuroscientist /endurance athlete and his friend, a neurobiology professor at Harvard. Basically, they put all the above together a few years ago and came up with a product that utilizes cinnamon, ginger and capsaicin all in a 1.7 ounce shot. You could certainly create your own homemade concoction containing TRPV1 and TRPA1 activators – but it’s nice to know there’s a commercial alternative. (I’m in no way affiliated with HotShot – I just like what they’ve done.)
I don’t know what concoction the runner I saw sidelined in last years Hamster 24-hr run was offered. I wonder if she’d had the right mix of vinegar, mustard, wasabi, cinnamon, ginger, hot chili peppers, pepper, garlic and CBD (hey, why not throw them all in?!!) if she’d have pulled through and been able to continue. Of course we’ll never know now – but I can’t be certain it would have allowed her to finish as we still don’t have all the answers.
Clearly proper training (and a proper taper) must be addressed as a strong preventative measure. Certainly stretching is known to alleviate cramping after the fact. It doesn’t hurt to consume adequate electrolytes from a correctly formulated natural sports drink such as Skratch, Tailwind or OSMO (containing at least 300mg sodium per serving). You definitely want to go into exercise well hydrated. And although it doesn’t address the root cause of the misfiring neurons in the first place, reaching for TRPV1 and TRPA1 activators – utilizing them both before exercise in a preventative manner and/or as soon as a cramp hits to stop it as soon as possible – sounds like a pretty good ‘bandaid solution’ to me.
For a multifaceted problem with so many unanswered questions to date, such as cramping presents, addressing it from as many angles as possible is likely the best and most successful solution we have available to us.
To deliciously healthy food and stronger faster running… Cheers,
Sarah J Cuff, RHN