Electrolytes: why water alone doesn't hydrate you
5 min read
Hydration isn't about volume of water — it's about whether that water reaches your cells. That depends on electrolytes: charged minerals that control fluid balance, nerve signalling and muscle contraction. Drink litres of plain water after heavy sweating and you can dilute what's left, which is why you can feel worse rather than better.
ElectrolytesWhat sweat actually costs you
Sweat isn't just water. Sodium is lost in by far the largest quantity, followed by smaller amounts of potassium, magnesium and calcium. Sweat rate and sodium concentration vary enormously between people — the white salt marks on a dark shirt are a genuine signal.
- Sodium — controls fluid retention and plasma volume; the one you lose most of
- Potassium — works opposite sodium to manage fluid inside cells
- Magnesium — involved in muscle contraction and relaxation
- Calcium — required for the muscle contraction signal itself
When you actually need them
For a 30-minute easy session in a cool gym, water is fine. The case for electrolytes gets strong when sweat losses climb.
- Sessions past roughly 60 minutes, or anything intense
- Training in heat or humidity, where sweat rate can double
- Endurance work — running, cycling, long court sports
- Low-carb or fasted training, where the body holds less sodium and water
Reading the label
Most mainstream sports drinks are built around sugar with a token pinch of sodium. If hydration is the goal rather than fuelling, what matters is the sodium content per serving — the number many brands keep quietly low because salt is a hard sell.
Zero-sugar formulas separate the two jobs: take electrolytes for hydration, and carbohydrate separately when the session needs fuel.
How to use them
Sip through the session rather than downing a stick pack at the end. Steady intake keeps blood sodium stable, which is the entire point.
In heat, starting hydrated matters more than catching up later — a serving 30 minutes before you begin is the highest-value one.
Common questions
Isn't sodium supposed to be bad for you?
Context matters. Sedentary over-consumption is the public-health concern; replacing what you demonstrably sweat out during training is a different situation.
Can I just eat a banana?
A banana is a decent potassium source but contributes almost no sodium — and sodium is the one you lose most.
Every day, or only on training days?
Training days and hot days. On a rest day in a cool climate, ordinary food and water usually cover it.
This guide is general information, not medical advice. Food supplements are not a substitute for a varied diet and a healthy lifestyle. If you are pregnant, breastfeeding, taking medication or managing a health condition, speak to a healthcare professional before starting anything new.
Altavora Hydration Multiplier Electrolyte Drink Mix | Zero Sugar | Vitamin & Mineral Electrolytes | Rapid Hydration | 15 Stick Packs
£20.00
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