Less than almost everyone thinks. When researchers have compared athletes who cramped mid-race against athletes who did not, they generally find no difference in how dehydrated they were or in their blood electrolyte levels. What predicts cramping is racing harder than you trained for, and having cramped before.
We sell an electrolyte drink, so that result is not convenient for us. It is also not the end of it — a narrower version of the electrolyte case does survive the evidence, and it is worth knowing which part.
What the research actually found
The study to know is Schwellnus, Drew & Collins in the British Journal of Sports Medicine — 210 Ironman triathletes followed prospectively, 43 of whom cramped. The finding: no significant differences between crampers and non-crampers in any pre-race to post-race serum electrolyte concentrations, or in body weight change.
The independent predictors of cramping were faster race pace and a previous history of cramping. Not fluid loss. Not sodium.
The same group found the same thing in distance runners: no difference in plasma volume, body mass lost, or plasma electrolytes. And in the lab, deliberately dehydrating people by 3% did not make their muscles easier to cramp.
Exercise-associated muscle cramp (EAMC) is the sudden, painful, involuntary contraction that happens during or just after exercise. It is not the same as a night cramp, and not the same as cramping caused by a medical condition or a medication.
So what does cause them?
The leading explanation is neuromuscular, and it makes intuitive sense once you hear it.
Your muscles have two opposing reflex systems: muscle spindles that drive contraction, and Golgi tendon organs that inhibit it. Fatigue tips that balance — spindle drive goes up, tendon-organ inhibition goes down — and the motor neurons feeding the muscle keep firing when they should stop. The muscle locks.
The 2022 evidence-based review in the Journal of Athletic Training, co-authored by Schwellnus himself, states that the strongest and most recent evidence points to changes in the neuromuscular system. It fits what cramping actually looks like: it happens in the muscles doing the work, in their shortened position, late in an event when fatigue is greatest, and disproportionately to people going harder than their training supports.
Cramp is mostly a fatigue problem, not a fluid problem.
The part that does survive — and we are not going to skip it
Here is where an honest version differs from a contrarian one. Electrolytes are not nothing.
There is a salt-responsive subgroup. American football players with the heaviest sweat sodium losses were roughly nine times more likely to be cramp-prone. That finding did not replicate across ten other sports, so it is not a universal law — but "heavy, salty sweater going long in the heat" is a real profile, and if that is you, the picture changes.
And when you are replacing large sweat losses, what you replace them with matters. In lab work published in the Journal of the International Society of Sports Nutrition, drinking plain water after dehydrating exercise increased cramp susceptibility, while an oral rehydration solution reversed it. Sodium-containing fluid beat plain water.
The 2022 review's own conclusion is multifactorial: cramps arise from "a confluence of unique intrinsic and extrinsic factors rather than a singular cause." Fatigue is the main driver for most people. Salt matters for some people, in some conditions.
What actually stops a cramp
Gently stretch the cramping muscle. This is the best-supported acute treatment in the review — fastest, safest, most effective — and it works by recruiting exactly the tendon-organ inhibition that fatigue suppressed.
Note the asymmetry, because it surprises people: stretching to stop a cramp works; stretching beforehand to prevent one does not.
What actually prevents them
- Train for the effort you are going to make. Cramping tracks racing beyond your conditioning better than it tracks anything you drink.
- Manage your pace, especially early. Faster-than-trained pace is the single most consistent predictor in the literature.
- Replace heavy sweat losses with sodium-containing fluid, not plain water — a narrower and better-supported claim than "electrolytes prevent cramps."
- Stay fuelled. Fatigue is the mechanism, and running out of fuel accelerates fatigue.
And the pickle juice thing, since everyone asks
Pickle juice does shorten cramps — Miller et al. in Medicine & Science in Sports & Exercise found roughly 74ml cut induced cramp duration by about 37% versus water.
But look at the timing: relief arrived in about 85 seconds, and the same study found blood composition essentially unchanged five minutes after drinking it. Nothing was absorbed and redistributed that fast. The leading explanation is a reflex triggered by the strong taste in the mouth and throat, inhibiting the motor nerve output driving the cramp.
Which is a genuinely interesting result, and it means the mechanism is not electrolyte replacement. If pickle juice works for you, it is not working the way the label of any electrolyte product implies.
Worth noting what that reflex does not transfer to: it acts on motor neuron excitability during an active cramp, which is why pickle juice for a hangover is a separate and much weaker question.
When cramping is worth taking seriously
Stop and get medical help if cramping comes with dizziness, collapse, nausea or vomiting, dark urine, or confusion. Those can signal heat illness, dangerously low blood sodium, or muscle breakdown — none of which a drink addresses, and the first response to some of them is emphatically not "drink more water."
Separately, see a doctor about cramps that are frequent or severe, that come with swelling, redness or muscle weakness, or that happen when you are not exercising at all. Those can have causes worth finding — circulation, nerve compression, or a medication you are taking.
Frequently asked questions
Does dehydration cause muscle cramps? Not as the main cause. Studies comparing crampers with non-crampers in the same event generally find no difference in hydration or blood electrolytes; fatigue and going harder than you trained for predict it better.
Do electrolytes prevent muscle cramps? No trial has shown that any electrolyte drink prevents them. What is supported is narrower: when replacing heavy sweat losses, sodium-containing fluid beats plain water.
Why do I cramp and my training partner doesn't? Prior cramping history is one of the strongest predictors, and a subset of people are genuinely heavy, salty sweaters. Relative intensity matters too — the same pace is a different effort for each of you.
What is the fastest way to stop a cramp? Stop, and gently stretch the muscle that is cramping. It is the best-evidenced treatment there is.
Does magnesium help with cramps? The evidence for magnesium supplementation in exercise-associated cramp is weak. It is a popular recommendation with less behind it than its popularity suggests.
Where Snake Oil fits — and where it does not
We are not going to tell you this drink stops cramps. No good trial has shown that any electrolyte drink does, and a company selling one saying otherwise is exactly what this article is about.
What the evidence supports is narrower: 370mg of sodium with 5g of carbohydrate per stick is the pairing that helps fluid actually be retained over long, hot efforts, and staying hydrated and fuelled helps you resist the fatigue that causes most cramps in the first place.† That is a real benefit and a real mechanism. It is one step removed from the cramp, and we would rather say so.
The best cramp prevention is still training for the effort you are about to make.
†These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Related reading: Best electrolyte powder: how to actually choose one · Electrolytes before or after a workout? · The long-day playbook: hiking, running and anything past three hours