Exercising in the heat? Drink something cold to aid endurance.
I practice Bikram Yoga. Our teachers recommend that we do not bring in super cold water to sip on (or in my case chug) during class. They posit that digesting a very cold drink requires body energy -- energy that would better be used for the poses. According to a 2008 study, they are wrong.
Studies show that drinking a cold beverage before AND during exercise helps endurance in the heat! A study by Medicine & Science in Sports & Exercise found that:
"Compared with a drink at 37°C, the ingestion of a cold drink before and during exercise in
the heat reduced physiological strain (reduced heat accumulation) during exercise, leading to an improved endurance capacity (23 ± 6%)."
1. Cold was defined as 4 degrees Celsius (39.2F) and "Warm" as 39C (98.6 F)
2. This was a super small study! Only 8 male cyclists. The study authors did conduct two trials though.
3. Other evidence suggests that contrary to popular belief cold drinks are absorbed more quickly than warm/hot drinks.
4. WebMD has a helpful article on hydration and fluid replenishment. Various sports drinks are compared too.
So I'm not sure where that leaves me. I lug a refrigerator-chilled gallon of water to class each day along with a Nissan travel thermos of hot tea (with about 1/4 milk)!! Maybe one cancels out the other? Well there is significant evidence regarding milk's benefits as a post-exercise hydration tool:
As part of the study's conclusions, replacing electrolyte loss was highlighted an essential factor in restoring water balance in the human body, to which it was claimed that milk is well suited.
-- The Study appeared in the European Journal of Applied Physiology.