Cramping at Kona: Why Fluids and Salt Rarely Fix It

Patrick Lange's 2026 IRONMAN World Championship ended on the bike. He stopped with cramp, and Jan Frodeno relayed during the race coverage that "however much water he took on board, he was still cramping."

That line captures the most common belief about cramp: that it's caused by running out of fluid or salt, and that drinking more or taking salt tablets will fix it. It's also one of the most persistent myths in endurance sport. The best evidence from Ironman racing points somewhere else.

This article explains what the research shows about cramp during long races, why fluids and salt rarely fix it, and what's more likely to help.

What exercise-associated cramp is

Exercise-associated muscle cramp is a sudden, painful, involuntary contraction of a muscle during or soon after exercise. In triathlon, the calves, hamstrings and quads are most often affected, typically late in the bike or on the run. It's different from the general ache of fatigue: a cramping muscle locks and won't release voluntarily.

Cramps are hard to study. They're unpredictable, can't easily be triggered on demand, and often settle within minutes. That's one reason myths about them have lasted so long.

The 210-triathlete Ironman study

The most important study for triathletes was published in the British Journal of Sports Medicine by Schwellnus, Drew and Collins in 2011. They recruited 210 athletes entering an Ironman triathlon. Before the race, each completed a questionnaire about their training and cramping history, was weighed and gave a blood sample for electrolytes, including sodium. Straight after the race, they were weighed again and gave another blood sample, and anyone who'd cramped during or immediately after the race was recorded.

Forty-three triathletes cramped. They were compared with 166 who didn't. The findings:

• No difference in dehydration. Changes in body weight from before to after the race were similar in both groups.
• No difference in blood electrolytes. Changes in serum sodium and other electrolytes were similar in both groups.
• Crampers were faster. They predicted faster finish times before the race and actually finished faster, despite similar training preparation and race history.
• Two independent risk factors. In a statistical model, only a faster overall race time (and faster cycling time) and a history of cramping in the previous 10 races predicted cramping.

The authors concluded that dehydration and altered serum electrolytes don't cause cramp in this setting, and that racing at a high intensity relative to your training is the bigger risk.

One limitation: blood sodium measures what's in your bloodstream, not what's happening inside the cramping muscle. But if salt loss were the main cause, you'd expect at least some difference in blood levels between the groups, and there wasn't.

The same pattern in the marathon

Martínez-Navarro and colleagues tested the same question in 98 marathon runners (83 men and 15 women), published in the Journal of Strength and Conditioning Research in 2022. Each runner had a lab fitness test before the race, and blood, urine and body mass were measured before and after.

Twenty of the 88 finishers (24%) cramped. Again:

• Body mass loss, urine concentration and serum sodium and potassium didn't differ between crampers and non-crampers.
• Crampers had higher markers of muscle damage (creatine kinase and lactate dehydrogenase) after the race and 24 hours later.
• Crampers slowed, relative to their own fitness, from about 25 km.
• Fewer crampers had included strength training in their preparation (25% vs 48%), but this difference didn't reach statistical significance.

Inference: two field studies in two different sports, with no link between cramping and fluid or sodium status, make dehydration and sodium loss unlikely explanations for most race cramps.

The leading explanation: fatigue and nerve control

If not fluid and salt, then what? The leading theory is altered neuromuscular control.

In a 2009 review in the British Journal of Sports Medicine, Schwellnus argued that the evidence for the electrolyte and dehydration theories came mostly from anecdotal observations and small case series, and that four prospective cohort studies didn't support them. The neuromuscular theory, by contrast, has growing support from human and animal research.

The idea is that a fatiguing muscle gets mixed signals. Sensors that excite the muscle become more active, while those that normally inhibit it become less active. The result is a muscle that fires when it shouldn't and won't relax. This would explain why cramps tend to appear when you're working hard relative to your training, in muscles that are fatigued, and often in a shortened position, such as a calf pointing the toes as you push off.

It also fits the Ironman findings. Athletes who raced faster than usual were pushing their muscles beyond what they'd been trained to do at that intensity and duration.

Where fluids and salt might still matter

The science isn't completely settled. In a 2019 review in Sports Medicine, Maughan and Shirreffs pointed out that some cramps may be linked to water and salt imbalances, with evidence mainly from industrial workers in hot conditions, one large intervention trial and small field studies of athletes. Other cramps seem to involve abnormal spinal reflexes linked to fatigue. They suggested there may be several types of cramp with different causes, and that searching for one solution is unlikely to succeed.

A 2022 evidence review in the Journal of Athletic Training, by Miller, McDermott, Yeargin, Fiol and Schwellnus, reached a similar conclusion: cramps probably result from a mix of individual and environmental factors rather than one cause. They argued that individualised prevention is likely to work better than generic advice such as drinking more fluids.

Inference: an athlete who loses large amounts of salt in sweat, in a long hot race, might have a different kind of cramp, and might benefit from paying more attention to sodium. But that's the exception, not the norm, and there's no strong evidence that it describes most triathletes who cramp.

Why "just drink more" can be harmful

The belief that cramp means dehydration can push athletes to drink more than they need. In a long race, that carries a real risk: exercise-associated hyponatraemia, where blood sodium falls dangerously low because of excess fluid. It can cause confusion, seizures and, rarely, death.

Salt tablets don't reliably protect against this either. TriForward's "Salt Tablets Won't Save You" covers the evidence on fluid, sodium and hyponatraemia. The safe default for most athletes is to drink to thirst, and to have a hydration plan based on your own sweat losses rather than on cramp fears.

Pickle juice and spicy drinks: a reflex, not a refill

If cramps aren't caused by low sodium, why do so many athletes swear by pickle juice?

Miller and colleagues tested it in 2010. Ten college-aged men were dehydrated by about 3% of body weight, and cramps were triggered in a small foot muscle with electrical stimulation. Drinking about 75 mL of pickle juice shortened the cramp from around 134 to 85 seconds. Drinking water didn't. Pickle juice had little effect on blood composition five minutes later, far too soon for salt to be absorbed. The authors suggested a reflex: something in the mouth and throat triggers nerve signals that calm the overactive muscle.

Building on this, Craighead and colleagues tested a drink containing compounds that stimulate TRP channels, the receptors that sense spicy and sour tastes. In 39 participants, the drink increased the force needed to trigger a calf cramp and reduced soreness afterwards, without affecting motor function in a second test.

These studies support the nerve-control theory: a cramp responded to something that changes nerve signalling, not to rehydration. But both tested cramps induced in a lab, not cramps late in an Ironman, and neither shows prevention during a race.

Why long-course triathlon is a cramp magnet

Several features of an Ironman line up with the risk factors in these studies.

First, the race is long. Even well-paced athletes spend many hours working their legs, and the neuromuscular theory predicts that cramp risk rises as fatigue accumulates.

Second, the demands shift between disciplines. Cycling loads the quads and hip flexors in a fairly fixed range of movement, often in an aero position that keeps some muscles shortened for hours. Running then asks the calves and hamstrings to absorb impact on legs that are already tired. Inference: the switch from bike to run may be one reason so many triathletes cramp in the first kilometres of the run, but no study has tested this directly.

Third, race day brings adrenaline, competition and a taper that leaves you feeling fresh. All three make it easy to ride or run harder than your training supports, which is exactly the risk factor the Ironman study identified.

A race-day scenario

Here's how this might play out, as an illustration rather than a case from any study. An age-grouper has trained to ride an Ironman at around 180 W. On race day, they feel great and the course is fast, so they average 195 W for the first 100 km. At 140 km, their quads start to twitch on a climb. Assuming dehydration, they drink two extra bottles and take several salt tablets. The cramp gets worse on the run, and they're now carrying extra fluid in their stomach.

The evidence suggests a different response. The twitching was most likely a sign of muscles working beyond their trained intensity. Easing back to the planned power, spinning a slightly higher cadence on climbs and stretching at an aid station if a cramp takes hold would address the likely cause. Drinking to thirst, rather than forcing fluid, would avoid adding a hyponatraemia risk to the problem.

What to do on race day

Based on the evidence, these steps are more likely to help than extra water or salt:

1. Pace to your training. The Ironman crampers raced faster than their preparation supported. A pacing plan based on your recent training, not on a hoped-for time, reduces the risk. TriForward's "Smooth Beats Surgy" and "Your Hour-Four FTP Isn't Your FTP" look at bike pacing.
2. Ease off at the first twinge. A muscle that's starting to twitch or tighten is a warning. Dropping intensity, changing cadence or getting out of the saddle may stop a full cramp.
3. Stretch gently. If a cramp takes hold, a gentle static stretch of the affected muscle is the best-supported treatment. For a calf, that means pulling the toes towards your shin.
4. Restart at a lower effort. Cramps often return if you go straight back to the same intensity.
5. Keep fuelling. Carbohydrate supports performance in long races. The fuelling articles, including "90–120g of Carbs an Hour", cover this.

Preventing cramp in training

The risk factors point to training as the main prevention:

• Train at race intensity for race duration. Cramps happen when muscles do more than they're used to. Long rides with sections at Ironman effort, and long bricks, prepare the specific muscles.
• Consider strength training. The marathon study found a trend towards fewer crampers among runners who did strength work. It's not proof, but it fits the idea that more robust muscles cramp less. TriForward's "Two Sessions a Week" covers strength training for durability.
• Take your cramp history seriously. If you've cramped in recent races, you're at higher risk. Look at what was common to those races: pace, heat, terrain or a lack of specific preparation.
• Practise your race plan. Test fuel, fluids, cadence and position in training so there are no new demands on race day.

Common mistakes

• Drinking extra water to prevent cramp. It doesn't address the likely cause and raises hyponatraemia risk.
• Taking large amounts of salt as a cure. The evidence doesn't support it for most athletes.
• Racing faster than training supports. Faster-than-planned pacing was a key risk factor in the Ironman data.
• Ignoring early warning signs. A twitching muscle is a signal to back off, not to push through.
• Assuming one cramp means one cause. Cramps may have several mechanisms, and what works for one athlete may not work for another.

What we don't know

• Whether "salty sweaters" have a different kind of cramp. The idea is plausible, but it isn't backed by strong trials.
• Whether any drink or supplement prevents race cramps. The pickle juice and TRP studies treated cramps induced in a lab, in small samples.
• How much women differ. The Ironman study abstract didn't report its sex split, and the marathon study was mostly men.
• Whether strength training reduces cramp. The marathon finding was a non-significant trend, not a trial result.

References

• Schwellnus MP, Drew N, Collins M. Increased running speed and previous cramps rather than dehydration or serum sodium changes predict exercise-associated muscle cramping: a prospective cohort study in 210 Ironman triathletes. British Journal of Sports Medicine, 2011;45(8):650–656. doi:10.1136/bjsm.2010.078535
• Martínez-Navarro I, Montoya-Vieco A, Collado E, Hernando B, Panizo N, Hernando C. Muscle cramping in the marathon: dehydration and electrolyte depletion vs. muscle damage. Journal of Strength and Conditioning Research, 2022;36(6):1629–1635. doi:10.1519/JSC.0000000000003713
• Schwellnus MP. Cause of exercise associated muscle cramps (EAMC) — altered neuromuscular control, dehydration or electrolyte depletion? British Journal of Sports Medicine, 2009;43(6):401–408. doi:10.1136/bjsm.2008.050401
• Maughan RJ, Shirreffs SM. Muscle cramping during exercise: causes, solutions, and questions remaining. Sports Medicine, 2019;49(Suppl 2):115–124. doi:10.1007/s40279-019-01162-1
• Miller KC, McDermott BP, Yeargin SW, Fiol A, Schwellnus MP. An evidence-based review of the pathophysiology, treatment, and prevention of exercise-associated muscle cramps. Journal of Athletic Training, 2022;57(1):5–15. doi:10.4085/1062-6050-0696.20
• Miller KC, Mack GW, Knight KL, Hopkins JT, Draper DO, Fields PJ, Hunter I. Reflex inhibition of electrically induced muscle cramps in hypohydrated humans. Medicine & Science in Sports & Exercise, 2010;42(5):953–961. doi:10.1249/MSS.0b013e3181c0647e
• Craighead DH, Shank S, Gottschall JS, Passe DH, Murray B, Alexander LM, Kenney WL. Ingestion of transient receptor potential channel agonists attenuates exercise-induced muscle cramps. Muscle & Nerve, 2017;56(3):379–385. doi:10.1002/mus.25611
• TRI247. IRONMAN Kona 2026 as it happened as Knibb and Luis crowned champions (live race report), 10 October 2026. tri247.com