Sodium, Potassium and Muscle Cramps: What Court Sport Athletes Need to Know

Pickleball is stop-start, high-intensity, and often played in Australian summer heat. Just drink water is not adequate advice for that combination — but neither is the assumption that more electrolytes always means better performance.

I play competitively, and sodium-potassium balance is something I think about specifically because of the court sport demand profile — short bursts, rapid direction changes, extended time under heat, and a much higher sweat rate than people register mentally during play. Here's what the actual research says, including where the popular electrolyte narrative overreaches.

What the research actually shows

A 2021 randomized crossover trial by Lau et al. published in the Journal of the International Society of Sports Nutrition directly tested muscle cramp susceptibility during exercise in the heat, comparing plain spring water against an oral rehydration solution containing sodium and other electrolytes. Ten men performed downhill running in 35–36°C heat to induce meaningful fluid loss, and cramp susceptibility was measured objectively using electrical stimulation thresholds, not self-report. The result was clear: cramp threshold frequency decreased, meaning cramp susceptibility increased, with plain water, but increased, meaning cramp resistance improved, with the electrolyte solution. Serum sodium and chloride measurably dropped only in the water-only condition. This is one of the few trials to test the sodium-cramping relationship with an objective physiological measure rather than asking people how their legs felt.

But the picture isn't simply more sodium equals less cramping in every context. A 2019 study by Hoffman and White published in Applied Physiology, Nutrition, and Metabolism surveyed over 1,100 ultramarathon runners and found that two-thirds believed sodium supplementation prevents cramping and hyponatremia, despite accumulating evidence that supplementing beyond what's already in food and drink is often unnecessary during endurance events, and can in some cases increase the risk of overhydration.

A 2023 review by Johnson et al. published in the Scandinavian Journal of Medicine and Science in Sports, analysing over three decades of IRONMAN World Championship medical records (n=3,138), found that exercise-associated hyponatremia, dangerously low blood sodium from a combination of sweat loss and overhydration, presents differently by sex and is a genuine risk in ultra-endurance events. Roughly half of athletes studied were actually dehydrated and had lost weight, meaning both under- and over-hydration are real failure modes, not just one.

What this means for you

The mechanism behind cramping and electrolyte balance centres on the sodium-potassium pump, which maintains the electrical gradient across muscle cell membranes that allows for controlled contraction and relaxation. Sodium loss through sweat, combined with dehydration, disrupts that gradient, which is the physiological basis for why electrolyte replacement, not just water, matters during sustained high-intensity activity in heat.

For a sport like pickleball, played in bursts over an hour-plus, often in direct sun, with genuine but intermittent intensity, the practical takeaway from the Lau trial is that a sodium-containing rehydration approach outperforms water alone for cramp prevention specifically. But the ultramarathon data is an important caution: this isn't a case for maximal sodium intake regardless of context. Match your electrolyte intake to your actual sweat loss and session length, not to marketing claims about how much sodium is required.

For a typical hour of competitive pickleball in Australian heat, a moderate electrolyte drink during play, rather than loading beforehand or over-supplementing just in case, aligns best with what the evidence actually supports.

The biotype angle

Mesomorphs and high-sweat-rate individuals in intense, repeated-effort sports like pickleball, tennis, or basketball get the most direct benefit from the cramp-prevention data — the stop-start intensity profile of these sports closely mirrors the exercise conditions in the Lau trial.

Endomorphs training or competing in heat should pay particular attention to total sweat loss, since higher body mass generally correlates with higher absolute sweat volume and therefore higher absolute electrolyte loss, even if percentage-wise the loss looks similar to a smaller athlete.

Ectomorphs doing longer endurance sessions should take the ultramarathon data seriously — the temptation to over-supplement sodium to be safe during long low-intensity efforts isn't well supported and, per the hyponatremia data, dehydration was actually more common than overhydration in the elite endurance population studied. Match intake to genuine need, not anxiety.

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References:
1. Lau WY et al. Effect of oral rehydration solution versus spring water intake during exercise in the heat on muscle cramp susceptibility of young men. Journal of the International Society of Sports Nutrition, 2021. DOI: 10.1186/s12970-021-00414-8
2. Hoffman MD, White MD. Belief in the need for sodium supplementation during ultramarathons remains strong. Applied Physiology, Nutrition, and Metabolism, 2019. DOI: 10.1139/apnm-2019-0238
3. Johnson KB et al. Clinical presentation of exercise-associated hyponatremia in male and female IRONMAN triathletes over three decades. Scandinavian Journal of Medicine and Science in Sports, 2023. DOI: 10.1111/sms.14401