Salt tablets for runners make sense for long runs in the heat, not for everyday training. If you are out for under 90 minutes, water and your normal meals cover what you lose. Past two hours, especially in a Queensland summer, replacing some salt matters. This is the guide we give runners at our Samford gym, written by an accredited exercise physiologist, with what a Perth study found about training in the heat.
Do you need salt tablets for runners?
Sweat is mostly water, but it also carries sodium. Most runners lose somewhere between half a litre and one and a half litres of sweat an hour, and each litre takes several hundred milligrams of sodium with it. On a short run that does not matter. On a long one it adds up.
| Your run | What to take |
|---|---|
| Under 90 minutes, any weather | Water if thirsty. Nothing else needed. |
| 90 minutes to 2 hours, warm | Water plus a sports drink or electrolyte drink. |
| Over 2 hours, hot or humid | Fluid plus a salt tablet or capsule roughly every hour. |
| Salty sweater (white marks on your cap or shirt) | Start salt earlier, from about 90 minutes. |
Read the label on any salt tablet: most hold 200 to 400 mg of sodium. More is not better. Practise with them in training, never for the first time on race day.
Electrolytes for runners: tablets, drinks or food?
Salt tablets are just one way to get sodium in. Drinks and food work too, and many runners never need a tablet.
- Electrolyte drinks give you fluid and salt together. Our guide to electrolyte drinks covers what to look for, including sugar-free options.
- Gels and chews often carry some sodium as well as carbohydrate. See our guide to energy gels for running.
- Salt tablets or capsules suit runners who prefer plain water and want to control the salt separately.
The bigger risk on a long, hot run is drinking too much plain water. That dilutes the sodium in your blood. Drink to thirst, and do not force down extra water.
Work out your sweat rate
- Weigh yourself with no clothes on before a one-hour run.
- Run at your normal pace and note how much you drink.
- Towel off and weigh yourself again.
- Weight lost plus fluid drunk is your sweat rate per hour. One kilogram is about one litre.
Do it once in winter and once in summer. The two numbers are often very different.
Is training in the heat worth it?
Many runners and cyclists think a summer session is a wasted one because they cannot hit their numbers. A 2025 study from Edith Cowan University in Perth tested exactly that. Twenty trained cyclists did eight interval sessions over four weeks (5 x 4 minutes hard), half in a 13 degree room and half at 35 degrees. Before and after, everyone rode a 20 km time trial at 22 degrees.
- The cool group trained at a higher share of their peak power and spent about twice as long near their maximum.
- Heart rate during the hard efforts was the same in both groups.
- Both groups got faster: about 3 percent for the cool group and 7 percent for the hot group. The difference between them was not significant.
The takeaway: hard sessions in the heat still count, even when your pace or power drops. Heart rate is a better guide than speed on hot days. You can read the study on PubMed. It was small and done in a lab, so take it as reassurance, not a reason to seek out the hottest part of the day.
What temperature is too hot to run?
Temperature alone does not tell the whole story. Humidity, sun and wind matter just as much. As a rough guide for Brisbane summers:
- Under 25 degrees: train as normal.
- 25 to 30 degrees: slow your pace, shorten the session, carry fluid.
- Over 30 degrees, or high humidity: move hard sessions to early morning, run in the shade, or train indoors.
How long does it take to adapt to the heat?
Most of the change happens in the first week of regular training in warm conditions, and it is close to complete after about two weeks. You start sweating earlier, your heart rate settles lower at the same pace, and runs feel easier. Build up gently: shorter, easier runs in the heat first, then add length.
Signs of heat exhaustion
Stop, get into the shade and cool down if you notice heavy sweating with pale, clammy skin, dizziness, headache, nausea, muscle cramps or a racing pulse. Confusion, slurred speech, hot dry skin or collapse are signs of heat stroke. That is an emergency: call 000.
Fuelling for summer running
Eat a normal, salted meal before long runs and a proper meal afterwards. Some people add beetroot powder to a breakfast smoothie as part of their everyday diet, and there are easy beetroot powder recipes if you want ideas. Our pre workout snack guide covers timing.
Some runners also like mineral drops for water in their bottle. Daily Bio-Minerals is a concentrated liquid trace mineral complex derived from plant-based sources. It is not a salt replacement, so still get your sodium from a drink, tablet or food on long, hot runs.
When to get it checked
If you keep cramping, fading badly or feeling unwell on hot runs despite getting your fluid and salt right, it is worth a closer look. An exercise physiologist can look at your training load, pacing and summer plan, and build your runs around the heat instead of against it. Training for a long event? Our marathon running plan shows where the long runs fall.