An expert explains why you need to stay adequately hydrated when you work out. By Mavis Teo
Dehydration affects your body’s electrolyte balance and can lead to palpitations and dizzy spells. (Photo: jundpicture / www.pixabay.com)
Why is hydration important?
During a cardio workout, the body produces heat and loses water. When the water deficit is more than two per cent of your body mass, the body suffers from excessive dehydration. This affects the electrolyte balance and affects your performance, explains Dr Lim Baoying, a resident physician at Changi Sports Medicine Centre. It could also lead to palpitations and dizzy spells.
How much should you drink?
Before exercise Start your workout with normal hydration, suggests Dr Lim. You could slowly drink beverages, for example, between 5ml to 7ml for every kilo of your body weight at least four hours before exercise to allow time for your urine output to return to normal before starting. It should be clear and of adequate volume.
After exercise If you have not perspired a lot, there is no rush to replace lost fluids – eating and drinking normally would restore the levels to normal. If you are excessively dehydrated, drink 1.5 litres of fluid for each kilo of body weight to hydrate rapidly. While you need to make up for fluid loss, make sure not to chug down too much water either because it might lead to hyponatraemia instead. To really know how much water you have lost, weigh yourself before and after a workout.
Are isotonic drinks necessary?
For workouts longer than an hour, fluids with added carbohydrates not exceeding six to eight per cent, such as isotonic drinks, help to maintain hydration and performance levels.
For a workout lasting more than a few hours, fluids with added sodium would be optimal for performance and hydration. Added carbohydrates maintain blood glucose level while extra electrolytes replace those lost through sweat.