Environmental factors also play their part in the hydration story and can affect your exercise performance.

In Hot Weather

Sweat rates can reach 2.5 litres per hour in hot and humid weather.1 That’s a lot of sweat, and if you don’t replace the fluids and sodium you lose, such a high rate of sweat loss can affect your performance.

If you’re training or competing in hot weather, it’s essential to gain heat experience. This will help you learn how to adapt your training and competition strategies, as well as how much you need to drink, rather than suddenly exposing yourself to hot weather.

In Cold Weather

If you’re exercising in cooler conditions (less than 10°C), your need for fluids is often just as high as it is in hot conditions4.

So the important message for exercising in cool environments is to pay attention to fluid intake. Be aware of your sweat loss when exercising in the cold, and drink according to your sweat rates.

Many winter sports are undertaken also at higher altitudes - such as mountain climbing, and aerial sports. Athletes can also take advantage of training at higher altitudes to help boost their performance in critical events. At altitude, the air is thinner in terms of oxygen supply, but is also drier, resulting in more fluid being evaporated from the body passively (from the airways and the skin). This is the reason why people get dry throats and cracked lips in the first few days of being at altitude. There is evidence that fluid shifts around the body contribute to acute mountain sickness (altitude sickness) 5.

In addition to drier air, higher altitudes tend to be cooler, which as discussed earlier, reduces the drive to drink. Therefore, increasing the volume of fluid consumed to counteract the increased fluid needs occuring during altitude is important. The focus should be on maintaining urine output (pale in colour), as well as ensuring fluid lost during exercise is adequately compensated.

  • 1Rehrer NJ, Burke LM: Sweat losses during various sports. Aust J Nutr Diet 53:S13–S16, 1996.

This information is not medical advice and should not replace consultation with your health care provider or nutritionist before starting a new exercise program or eating plan.