Tabs or dinner? Sodium works, but only when long, hot and salty sweating come together — and cramps are less often a salt problem than the shelf claims.
Straight talk: for the vast majority of training sessions you do not need electrolyte tabs. Ordinary food covers your needs, and your body is remarkably good at regulating the rest itself. Sodium only becomes interesting when three things come together: long, hot, and a high sweat rate.
What sodium then genuinely does is documented: it supports thirst and fluid retention [1] — you stay more willing to keep drinking, and more of what you drink stays in. That is no performance magic, but on a four-hour session in high summer it is exactly the difference that matters.
And now the part the shop shelf does not tell you: cramps are not automatically an electrolyte problem. The evidence for that is inconclusive — there are good reasons to look at neuromuscular fatigue too, that is, muscles simply asked to work harder or longer than they are used to. Anyone selling you salt as a guaranteed cramp cure is selling you something.
So this guide sorts out three things: who really needs salt, what cramps probably are — and why the other end of the scale, overdrinking, is more dangerous than a little salt shortfall.
Electrolytes are dissolved salts in your body water: sodium, chloride, potassium, magnesium, calcium. They keep nerve signals travelling and keep fluid where it belongs.
For sport, one of them matters above all: sodium — it is the electrolyte you lose in meaningful amounts through sweat, and the only one with a clearly documented role, namely thirst and fluid retention [1]. Everything else has far thinner grounding in a sports context than the labels suggest.
It is not your sport that decides, but the combination of three factors:
Two examples: 90 minutes of running at 12 degrees — no, your dinner handles that. Four hours on the bike at 30 degrees, jersey gone white — yes, here sodium belongs in your drink or your food. And since you are drinking and eating anyway: carbohydrate in the same bottle counts towards your fuelling, where a single type of sugar hits its absorption ceiling at around 60 g per hour [2].
There is an honest answer and a convenient one. The honest one first: this can only be measured properly with a sweat test, and almost nobody needs one.
The convenient version is observation from practice — not a measurement, but usable:
If two or three of those show up regularly, you are probably one of the saltier sweaters — and then sodium pays off on long hot sessions more than it does for your training partner, whose shirt looks the same dry as it did new.
Muscle cramp is the electrolyte industry's best-selling argument — and its worst-supported one. The evidence that cramps in sport come solely from electrolyte losses is inconclusive. There is a second, well-founded explanation: overloaded control between nerve and muscle under fatigue.
What that means for you in practice:
Honesty is the more useful answer here than a promise.
Now the part almost always missing from "drink more, salt more". Exercise-associated hyponatraemia develops when someone takes on more fluid than they lose over several hours. The sodium in their blood becomes too dilute — and that is a medical emergency, not a nutrition detail.
Those typically affected are slower participants in long events who drink at every station "to be on the safe side" even though they sweat little. And one point that is often misunderstood: electrolyte tabs are not a free pass. The decisive lever is not adding more salt, it is not drinking more than you lose.
For everyday life the answer is unspectacular: food. A normal salted meal covers the need after almost any session — broth, cheese, bread, a salty soup, and it is done.
Tabs and capsules are above all one thing: convenient. On the bike, in a race, in a heat camp, wherever eating does not work. They can do what salt can do — no more. And magnesium, the best-selling cramp remedy of all, has the thinnest grounding of the lot in a sports context. We deliberately give you no dose here: if you suspect a deficiency, have your blood values checked medically rather than guessing.
This guide puts training practice in context and does not replace medical or dietetic advice. If you have high blood pressure, a heart, kidney or liver condition, take diuretics or lithium, or are pregnant, do not raise your salt intake on your own initiative — that belongs in a medical conversation.
Exercise-associated hyponatraemia is an emergency. Warning signs are headache, nausea and vomiting, confusion or disorientation, puffy fingers and face, and weight gain during the effort. In that situation: do not drink more, do not carry on, get medical help immediately. Call the emergency number if in doubt.
If you suspect a mineral deficiency, blood values belong in medical hands. We deliberately give no doses — self-supplementation without a proven deficiency can do harm, and a guide cannot make a diagnosis. Cramps that recur without an obvious trigger, hit hard at night, or come with numbness also belong in a consulting room.
Combine the two cheapest tests there are: weigh yourself once before and after a long session to learn your sweat rate — then look at your dry, dark shirt. High sweat rate plus white marks means sodium is worth it for you on hot days. Low rate and no marks means save your money.
And the trick almost nobody thinks of: the salty meal belongs before the long hot session, not in the middle of it. A salted plate of pasta, a broth or a cheese sandwich two hours beforehand is more convenient than any capsule — and you do not head into the heat with empty stores.
Only a sweat test measures it properly. In everyday life, observation helps: white marks on dark clothing once dry, salt crusts on forehead and eyebrows, stinging eyes, a salty taste on your lips. If those show up together regularly, sodium is worth it on long hot sessions — it supports thirst and fluid retention [1].
Less often than the advertising claims. The evidence for electrolyte loss as the sole cause is inconclusive; overloaded control between nerve and muscle under fatigue explains many cases at least as well. Check pace, duration and training status first. Trying sodium is cheap and harmless, but it is no guarantee.
A dangerous dilution of the sodium in your blood, caused by drinking more than you lose over several hours. Warning signs are headache, nausea, confusion, puffy fingers and weight gain during the effort. It is a medical emergency — get help immediately, do not drink even more.
It is the best-selling cramp remedy with the thinnest grounding in a sports context. We deliberately give no dose: if you suspect a deficiency, have your blood values checked medically rather than supplementing on a hunch. With recurring cramps, managing your training load is the more promising lever.
For almost every training session, yes. A salted meal after training covers the loss — broth, cheese, bread, a salty soup. Tabs are the more convenient route for long hot races where eating on the move does not work. They cannot do anything salt cannot.
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