Potassium for Muscle Cramp

Finding: No clinically significant alterations in serum electrolyte concentrations and no alteration in hydration status were found in runners with EAMC. Post-race sodium was statistically lower and magnesium higher in the cramp group, but the authors judged these differences clinically insignificant; serum potassium showed no meaningful difference.

Finding: Carbohydrate-electrolyte supplementation did NOT reduce cramp incidence (9/13 crampers with supplementation vs 7/13 with hypohydration). It did roughly double exercise duration before cramp onset (36.8 vs 14.6 min, p<0.01). The beverage was a mixed carbohydrate-electrolyte solution, not isolated potassium; cramps still occurred despite supplementation.

Finding: Studies linking EAMC occurrence to post-event serum electrolyte concentrations were judged unhelpful and inconclusive; the available evidence does not establish that reduced serum potassium increases EAMC prevalence.

Finding: The review challenges the electrolyte-depletion hypothesis, citing evidence that serum electrolyte concentrations and hydration status are not associated with EAMC. It concludes EAMC results from a confluence of intrinsic and extrinsic factors (notably neuromuscular fatigue) rather than a single electrolyte cause, and warns against blanket electrolyte/fluid advice.

Finding: The authors express skepticism about electrolyte depletion as a primary cause, noting that dehydration and electrolyte loss are systemic abnormalities that cannot readily explain localized cramping in specific working muscles. Altered neuromuscular control combined with fatigue is favored over the electrolyte hypothesis.