Hydrating your Exercise

Despite the recent warnings in the literature of the possible hazards from drinking too much water, most of us need to drink more. The warnings against excessive drinking were related to research findings on marathon and triathlon participants who suffered water intoxication (hyponatremia) while running in the longer events. Those who suffered from this condition were typically the slower runners who were drinking frequently while at the same time losing exceptionally large amounts of sodium from sweating. Due to the long and strenuous exertion this loss of sodium created a severe imbalance between their hydration level and the electrolyte (sodium) levels causing symptoms such as nausea, fatigue, stupor and even coma and death. In such severe exertion cases, even sports drinks do not supply enough sodium. One possible remedy to this risk is to eat salty snacks during the race.

However, most individuals are not training to such an extent that they should be concerned about drinking too much. On the contrary, most individuals are not drinking enough water which, if gone unchecked during a hot or humid day, could create the same or worse problems as those that are associated with too much water. Additionally, the benefits of exercise can be limited when appropriate hydration levels are not maintained. Fluid losses of just 2% of your body weight (about 1.5 liters in a 150 pound individual) can cause a significant drop in performance.

Typically the daily recommendation is to drink about ½ ounce per pound of body weight or about 10-eight ounce glasses if you weigh 160 lbs. If you are working in a stressful (hard work, hot) environment then 2/3 ounce per pound or 13-14 glasses are recommended a day.

During exercise, studies show that different individuals lose more water faster than others in similar environments (hot, cold, humid, etc.). It is quite individual. So the recommendation for fluid intake during exercise should be determined according to how much water weight you typically lose during your exercise. If you lose 2 pounds of weight during a 1-hour exercise bout then you should be trying to replace a similar amount during your exercise activities. For each pound of body weight you lose you will want to try to replace it with 16 ounces of water. See sweat rate calculator to determine your sweat rate at http://www.fitstop-lab.com/tools/sweatratesheet.xls

Sport drinks are also recommended to help maintain electrolyte (salt) balance and maintain blood glucose levels (for events lasting longer than 1 hour). Typically, a 5 to 8% solution (carbo/fluid) is recommended.
Keep in mind that dehydration due to fluid loss can have a dramatic effect on the body’s performance and could also lead to significant heat illnesses like heat exhaustion or even heat stroke and death. So keep the water coming especially on the hot and humid days. And if you are experiencing the joy of a marathon or similar exerting event then be sure to pack the salty snacks for along the way.