Electrolytes vs water: when you actually need them

Electrolytes are sold as though every workout needs them and every headache is a deficiency. Most of the time, water is the right answer and it is free. But there is a real line where that stops being true, and in an Australian summer plenty of people cross it without noticing. Here is where it is.

What sweat actually takes with it

Sweat is not water. It is water with salt in it: mostly sodium, some potassium, and small amounts of calcium and magnesium. Sodium concentration varies enormously between people, from roughly 200mg to over 1,500mg per litre of sweat, and it is largely genetic. It is why two people on the same run can have completely different hydration needs.

Drinking plain water replaces the fluid and none of the salt. Below a certain volume that does not matter, because your kidneys handle it. Above it, you are diluting what is left.

When water is genuinely enough

• Sessions under about 60 minutes in mild conditions, at any intensity
• Everyday hydration: office, desk, normal day, normal meals. Your food supplies far more sodium than a tablet does
• Gym sessions where you are not soaked through at the end
• A walk, a swim, a social ride. The marketing says otherwise; the marketing is selling something

There is no benefit to adding electrolytes to a day where you have not lost any. It is not harmful, it is just not doing anything you needed done.

When they start to matter

Two more that people forget: illness, where you lose fluid and salt fast through vomiting or diarrhoea, and long flights and long drives, where you drink less than usual for hours at a time in dry air.

The risk nobody talks about

Over-drinking plain water during long endurance events is a genuine medical problem. Taking in far more fluid than you sweat dilutes blood sodium, and hyponatraemia can be serious. It shows up in marathons more often than dehydration does, usually in slower finishers who drank at every station because they were told to.

The practical guidance is unglamorous: drink to thirst, and when the session is long or hot, put sodium in the fluid rather than drinking more of it.

Electrolyte drink, sports drink, or salt in water?

1. A bottled sports drink is ready to go, which is a real advantage. But a typical 500ml bottle carries around 30 to 35g of sugar, wants a fridge, and is a new plastic bottle every time. If you are not racing, you are mostly buying sugar.
2. Salt in water works and costs nothing. Most people will not drink it twice. Palatability is not a trivial objection. A hydration strategy you avoid is not a strategy.
3. An electrolyte tablet splits the difference: the sodium without the sugar. yohemite Water is 220mg of sodium per tablet with 0g of sugars, four electrolytes, and 11 calories. Ten drinks live in a 36g tube.

The reason tablets pack so well is that they are not a drink yet. A 500ml bottled sports drink is about 480ml of water you are paying to ship and carry around.

How to actually use them

• One tablet in 400 to 600ml of water. 500ml is the sweet spot
• Wait for the fizzing to stop, two to three minutes. Half-dissolved is where the flavour is uneven and people decide they do not like it
• One or two a day is normal, more on a hot day or a long session
• Before, not only after. Starting a hot session already topped up beats catching up afterwards

One caution worth printing: each tablet carries 220mg of sodium. If you are on a sodium-restricted diet, or you are pregnant, check with your GP or a dietitian first. This is a beverage base, not a medicine.

The honest summary

Most of your hydration, most days, should be water. Electrolytes are a tool for a specific job (long, hot, salty or repeated) and they do that job well. Using them every day will not hurt you and will not help much either. Using them on the day you needed them and did not have them is the mistake that actually costs you something.