Staying hydrated during the heat wave

Since the hot weather is here, it’s time to pay attention to fluids. Dehydration is a common cause of poor performance in athletics, but more seriously it can lead to life-threatening heat illness. Every year athletes and recreational outdoorsmen suffer from heat illness with a small number going on to die from heat stroke.

Under normal conditions, with little or no physical activity, the average adult loses between 2-3 liters of fluid in a day. Physical activity greatly increases fluid losses—sometimes up to 5 liters per day.

In order to prevent dehydration, adequate fluid intake should occur well in advance of the anticipated activity. We should all be drinking small amounts of liquids throughout the day:

  • It is also recommended to take in about 500ml of fluid about 2 hours before exercise.
  • To top off the tank on hot days, 250 ml should be ingested about 1 hour before the event.

Drinking small amounts of fluids during the activity is critically important to maintaining hydration. Research has revealed that we are more likely to drink chilled, flavored drinks. Sports drinks that contain some sugar and sodium have also been shown to be better absorbed by the stomach than plain water. In many ways, sports drinks were designed specifically for athletes from taste right down to content to match their needs. Drinks to avoid are ones with a sugar load greater than 8%, like fruit juices, and any beverages that contain caffeine or alcohol. Be very cautious with so-called “energy drinks” which often contain high levels of caffeine or other stimulants. Due to their diuretic effects, they will worsen dehydration rather than replenishing your fluid deficit.

Children and older individuals are even more susceptible to dehydration and heat illnesses and require closer monitoring of their fluid status. These athletes also take longer to acclimatize to hot weather, which will then allow them to handle heat shifts in the body much more easily.

There are two common ways to ensure adequate rehydration—weight checks and urine color monitoring. For every pound lost through exercise, replace it with 20 oz of fluid. Normally an athlete will void clear to light colored urine within an hour of exercise, if the urine is dark or small in volume, then rehydration is inadequate—you’re dehydrated, drink up!

Learning to drink small amounts of water or sports drinks while exercising is a valuable skill and one that needs to be practiced just like throwing, kicking, and catching. It is encouraged to include frequent fluid breaks in your exercise routines. This is a skill that will help save lives as well as improve performance—it’s worth the time and effort!  


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