When you are exercising, sweating is the main way your body
maintains optimal temperature. The more you exercise and the higher the
temperature around you, the more you will sweat.
You will need to drink fluids during and after exercise to
replace fluids lost in sweat and prevent dehydration.
When you are dehydrated, your exercise performance will
suffer, the exercise will feel much harder, and the risk of heat stress
increases. And you cannot rely on thirst when you are exercising, as you have
usually lost significant fluid before you feel thirsty.
The choice of drink options can be confusing.
You cannot go past plain water, which is all you will need
to replace fluid, especially in low intensity and short duration sports. But if
you are involved in high intensity and endurance sports, a sports drink with
added carbohydrate (often in the form of glucose, sucrose or fructose) and
electrolytes will enhance your performance.
The carbohydrate in these drinks provides a muscle energy
source as well as improving flavour.
Electrolytes such as sodium are lost in sweat and must be
replaced during and after prolonged exercise. Sodium in a drink improves your
fluid intake as it stimulates the thirst mechanism, promotes both carbohydrate
and water intake in the intestines, and reduces the volume of urine produced
after exercise.
And a word of warning about alcohol. It is not a good choice
immediately after exercise. It impairs vital recovery processes and may also
reduce your ability to rehydrate effectively.