PHYS-31 · Principle
Do I cramp because I need more salt?
Probably not, for most. The evidence leans to fatigue upsetting the nerve signals to the muscle; salt or fluid loss may play a part in some cases, and past cramps are the clearest predictor.
How the body works, as far as the reviews below go: they disagree, and the entry gives both readings. A study entry shows what one experiment measured.
Practical Application
Do I cramp because I need more salt? Probably not, for most. The evidence leans to fatigue upsetting the nerve signals to the muscle; salt or fluid loss may play a part in some cases, and past cramps are the clearest predictor.
What it does not mean: that salt never matters (dyshydration may explain some cases, Maughan & Shirreffs 2019), or that magnesium or quinine is a fix (Cochrane reviews cited by REF-233: no meaningful benefit for magnesium, a small one with side effects for quinine).
Mechanism
In a 2009 review the salt and water account rested on 18 case reports and one case-control study of 10, and four prospective cohorts did not support it; human cramp models, epidemiology and animal data point to altered neuromuscular control (REF-232).
The spindle-tendon-organ imbalance is believed to stem from neuromuscular overload and fatigue; stretching is the most successful acute treatment (Nelson & Churilla 2016).
In laboratory models dehydration did not change the stimulation frequency needed to start a cramp, but the models may not reflect exercise cramps; no folk remedy is consistently effective (Maughan & Shirreffs 2019).
Across nine longitudinal studies (11,274 people), prior cramps carried about 4.4-fold odds; higher post-race potassium (moderate evidence) and magnesium (limited) went with cramps; age, size, hydration and training showed no consistent link (Costa et al. 2026).
Common misreading
"Cramps mean low salt, so take tablets"; "drink more water and the cramps stop".
Backs
SYNTH-83 "Cramps come from dehydration or low salt, so salt or more water prevents them" (the claim this answers) · SYNTH-68 "Do not prescribe salt or extra fluid as the fix" · SYNTH-68 "one narrative review names altered neuromuscular control as the principal cramp mechanism while asking for more evidence"