My body loses water rapidly when exercising!

Good day, Dr Gardner,

Recently, I started exercising but realised that my body rapidly loses a lot of water. I try to drink a lot of water to replenish my body but it seems that it is not enough, although I force myself to drink as much as possible. Are there other liquids I can consume to replenish my body's water? Why is my sweat very fresh (I can't taste any salt)?

Best regards,

Gary

Dear Reader,

Congratulations, Gary, you have really been drinking to your health, and hopefully others will follow in your footsteps.

Fluid must be replaced irrespective of thirst sensation. Ideally, fluids should be replaced as they are lost by drinking seven to eight ounces or more of water or beverage every 15 minutes during continuous exercise.

Even though some commercially prepared drinks are satisfactory as replacement fluids, others such as soft drinks contain 10 to 12 per cent sugar (even more) and are not ideal for rehydration when you are exercising, especially in the heat. Fluids that contain six to eight per cent sugar will be tolerated more easily and can be useful in supplementing energy during prolonged exercising. Sugar takes about 30 minutes after consumption to get to your muscles.

Check sugar content

Try a variety of commercially prepared drinks that have six to eight per cent sugar concentration to determine which one you tolerate best. Those that have above eight per cent glucose, fructose, etc. slow down the absorption of water. Drinks that are too high in fructose can irritate your stomach and small intestines and decrease the movement of food through your digestive tract. Your muscles also have difficulty absorbing them and they are not the most effective in increasing blood-sugar concentration.

A low-sugar-concentration drink is recommended for the first 60-90 minutes for fluid-replacement purposes. During the last 30-to-60 minutes of long-term activity, a drink with increased sugar concentration is better.

Mineral-fortified drinks

Ingestion of pure water causes less fluid retention in your body when dehydrated compared to sugar- or mineral-fortified drinks. These drinks maintain a higher level of water in your body than pure water. Higher water retention retains more of the hormone stimuli for water conversion by your kidney so less fluid is lost via urine.

Cool replacement drinks that have a small amount of electrolytes or mineral salts are superior to cool water in maintaining hydration. Beverages that contain alcohol or caffeine can cause dehydration and increased urination. The ingestion of glycerol with added water can increase total body water compared to the ingestion of an equal volume of water. However, glycerol ingestion can cause side effects such as headache, blurred vision, light-headedness and nausea.

Perspiration that is not salty indicates that you are well hydrated or even hyperhydrated. It is also possible to drink too much water and risk becoming intoxicated or drunk.

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

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