Response to reader - Drinking water during exercise

Dear Dr Gardner,

Is it very effective to do abdominals and consume water at the same time? Someone told me it can cause the abs to lose its power in the process. I know that rehydrating the body is commonplace when persons are working out, like me. Is this a myth, or is this a fact?

Dear Reader

When you exercise, your body loses water, especially by sweating to keep you cool. As a result of this, the quality of your exercise routine can be affected adversely if you are even slightly dehydrated. Thus it is recommended that you drink water or some other fluid before, during and after your exercise session.

We also lose some very valuable chemicals, via sweating, that are vital to the metabolic activities that enable our nerves to stimulate the muscles to contract (as in strengthening your abdominal muscles). If you are well hydrated during exercise it facilitates smooth movements, keeps your body temperature stable and prevents overheating.

Dehydration can cause weakness and loss of muscle control. By the time your sense of thirst is activated, you would have already lost some body weight, experienced a decrease in your blood volume, and lost some muscle strength as well as some of your aerobic capabilities. You can't rely on your thirst mechanism to tell you when you need water especially during exercise.

A loss of body fluids during exercise could result in an increase in your blood pressure and compromise your physical performance. Even routine physical activities could feel more challenging to perform, and you could become disoriented.

Heat injury

If you do not rehydrate during exercise and your body becomes overheated, this could culminate in a heat injury. Drinking water during exercise is the best way to replace the water you lose in trying to prevent the heat injury. If you do not rehydrate, this will reduce your blood supply and further increase your body temperature. This can be further complicated by decreasing the blood your heart has to work with, forcing your heart to work harder, even for routine activities.

Fluid replacement during exercise reduces the effects of dehydration that would compromise the continuation of the activity. If you ingest too much water, this could result in water intoxication, which would lead to decreased salts in your blood and you could experience dizziness, nausea, poor coordination and confusion.

Our muscles become stronger and are able to produce more power because our nervous system learns to increase the impulses it sends to the muscles to stimulate their actions. An increase in the size of the muscles because of increased protein intake and strength training will also improve your strength and power. Muscle strength also increases as a result of the muscles' improved ability to produce energy in the shortest time possible because of the strength-training activities that you have practised. All of these increased strength dimensions occur in conjunction with water in the environment, as well as facilitating the chemical activities involved.

Dr Kenneth Gardner is an exercise physiologist at Holiday Hills Research Center; email: yourhealth@gleanerjm.com.