Category FAQs Search : Health

Question: Sweat and dehydration

Answer: When you exercise, your body sweats as it tries to return to its optimal temperature. As sweat evaporates from your skin, it removes heat from the body, but you also lose body fluid.

So, you need to drink fluid during exercise to replace the fluids you lose when you sweat. That way, you’ll reduce the risk of heat stress, maintain normal body function, and maintain performance levels. The general rule is: if you’re sweating, you need to be drinking fluids.

It is possible to drink too much during exercise. Over-hydration, in rare but severe cases, can lead to death. To avoid over- or under-hydration, it can be useful to know your sweat rate. That way, you can work out exactly how much you should be drinking. Or, talk to your GP or an accredited sports dietitian for a fluids plan.

To work out your sweat rate:

- Empty your bladder.
- Weigh yourself in minimal clothing, as close to the start of exercise as possible (this is your initial weight).
- Record the ambient temperature.
- Do your exercise session.
- Record the volume of any fluid you consume during your exercise session (fluid).
- Estimate (or measure!) urine losses during your exercise session (urine).
- Weigh yourself again at the end of your session, in the same clothing as before - be sure to towel off any excess sweat from your body first (this is your final weight).
- Your weight change during exercise, plus any fluids consumed, minus any urine losses, reflects your total fluid loss for that session. To work this out:
* Subtract your final weight from your initial weight.
* Add the weight of fluid (in kg) that you consumed while exercising.
* Subtract the weight of fluid (in kg) you lost through urination.
* To make this into an hourly rate, divide it by the number of hours you spent exercising.

Sweat rate (L/hr) = [initial weight (kg) – final weight (kg) + fluid (kg*) – urine (kg)] / time (hrs)
(*One litre of water or urine is equivalent to one kilogram.)

Remember, this is your sweat rate when exercising at a particular ambient temperature. Your sweat rate will change with the temperature, so it can be useful to measure your sweat rate at different times of the year.

(Source: Victoria State Government, 02 Dec 2020)

Source Link: