Hydration and Exercise – When and how much?
Most avid exercisers know that if you weigh yourself before exercise and then replace lost fluids during and just after exercise, you should weigh very close to the same weight post exercise. If you don’t, you may not have met your hydration needs. Serious exercisers also know that pre-loading with water before vigorous exercise can help to reduce the risk of dehydration, especially if you don’t drink during the exercise effort.
When you see marathon runners or long distance cycling enthusiasts in training or a race, they are typically grabbing water and electrolyte replacement drinks from stands along the competition route. The question is – should they drink according to thirst or is there a benefit to just grabbing drinks whenever they see the opportunity and in whatever amount available? A new study suggests that there does not appear to be a difference. The study compared two cycling groups. One group drank “only when thirsty,” while the other group consumed fluids whenever and in whatever amount they desired as they trained. All subjects were similar in height and weight, all had similar training programs, and all were exposed to the same heat conditions.
Researchers measured BMI, specific urine parameters, food and liquid consumption and found little difference in the measurements between individuals who drank specifically for thirst, and those who just drank “as needed.” This study suggests that it may not be necessary to follow strict protocols for fluid replacement, as long as reasonable hydration needs are being met.
Always remember to factor in weather conditions – the more humidity, the more fluids needed.