Electrolytes: When and Why to Take Them
When to take electrolytes for training and hot weather, which minerals matter, and whether you actually need an electrolyte supplement or just water.
Quick answer
Take electrolytes when you sweat heavily — long or intense sessions, hot weather, or if you cramp. They replace sodium, potassium and magnesium lost in sweat, helping hydration and performance. For short, easy workouts in mild conditions, plain water is usually enough.
Water alone isn't always enough when you're sweating buckets. Electrolytes keep your fluid balance and muscle function working properly. Here's when they actually matter.
What electrolytes do
Electrolytes are minerals — mainly sodium, potassium, magnesium and chloride — that carry electrical charge and regulate fluid balance, nerve signals and muscle contractions. You lose them in sweat, and a big deficit can cause cramps, fatigue and poor performance.
When you need them
- Sessions longer than ~60–90 minutes.
- Training in heat or humidity — see hydration in an Australian summer.
- Heavy sweaters, or if you regularly cramp.
- Fasted morning training when you're already low.
When water is enough
For a 45-minute gym session in air conditioning, plain water does the job. You don't need an electrolyte drink for every workout — save them for when sweat loss is genuinely high.
| Mineral | Role |
|---|---|
| Sodium | Main driver of fluid balance; lost most in sweat |
| Potassium | Muscle and nerve function |
| Magnesium | Muscle relaxation and energy |
| Chloride | Works with sodium on hydration |
Timing
Sip electrolytes before and during longer or hotter sessions rather than chugging them after. Many non-stim pre-workouts already include electrolytes for this reason. Magnesium in particular also plays a role in sleep — see magnesium and sleep.
Browse electrolytes and the wider health range.
Supplements support — not replace — a balanced diet and consistent training. Claims are general in nature; always read the label and follow directions for use. If you're pregnant, breastfeeding or managing a medical condition, check with your GP first.