Exercise increases the loss of body water and electrolytes, this loss can impair exercise performance and ability to perform work. Dehydration, which occurs when there is a decrease in total body water, accelerates fatigue and degrades performance. Hypohydration can also negatively affect athletes, eventually leading to substantial losses of body water. During exercise, hyponatremia occurs when excess water is consumed and sodium intake is low (or sodium losses are high). It is important to understand how to maintain water and electrolyte balance during exercise.
For years, recommendations have been made for athletes to drink based on pre-determined hydration schedules: Suggesting when to drink and how much. (There are Position Stands, Consensus Statements, etc.) These include more general recommendations; and more individual recommendations based on monitoring of hydration status, and fluid losses/sweat rates. More recently, although not incredibly new, the “drink to thirst” concept has gained more attention and traction.
The article “Athletes Should Drink Only When Thirsty, According to New Guidelines” expressed that athletes often are mistakenly advised to “push fluids” or drink more than their thirst dictates by, for example, drinking until their urine is clear or drinking to a prescribed schedule. But excessive fluid intake does not prevent fatigue, muscle cramps or heat stroke. In order to solve this problem the article states that using the “thirst mechanism” to guide fluid consumption is a strategy that should limit drinking in excess and developing hyponatremia while providing sufficient fluid to prevent excessive dehydration. I don’t really find this mechanism convincing.
I found the additional article “The Latest Science of Rehydration” to lean more toward fluid scheduling for hydrating. In summary this new science found that in spite of the best prepared schedules, endurance athletes in the heat of competition often forget to drink on schedule. To compensate, they drink larger amounts in single gulps, which can lead to stomach discomfort – that feeling of sloshiness or fullness. And the large gulp strategy also leads to less effective re-hydration. Researchers have shown that ingesting fluids in a metered way produces more effective re-hydration and less GI upset than drinking large volumes. Drinking large volumes of fluid rapidly dilutes the blood leading to increased urine output. The key is to take your hourly fluid needs and break it into six segments and drink one segment of fluid every 10 minutes.
Personally, after my readings I think I am more of a fan of scheduled hydration strategies. I am very hesitant when it comes to the “drink whenever your thirsty” way. Cold weather is a big antagonist in this topic. My additional article made it clear that in the summer, we feel the heat and sweat production is obvious and thirst mechanisms as activated. In the cold, however, our thirst mechanism is suppressed. A case in point is a recent study showing downhill skiers experienced significant dehydration during a morning of skiing, and yet were unable to re-hydrate back to a normal range during a long lunch break even when given free access to fluids. Not only are the thirst mechanisms altered in cold, but we also experience greater water loss through breathing. This is due to breathing cold dry air, which forces our body to work harder to humidify and warm the cold air. Although most of the studies have been conducted in warm weather, cold weather dehydration can negatively impact performance.
When it comes to nutrition and physical activity, listening to your body should always be a priority. Developing an instinct of your own limits and what your body needs is a skill that is developed only from practice. If you feel thirsty, you should by all means always drink. Can the feeling of thirst be relied upon solely as a way to properly hydrate? No. You must monitor your body in several ways, with thirst definitely being one of those ways. Monitoring the color of your urine is also an easy, fool proof way to tell if you have enough fluids in your body. I agree with the recommendation that making sure that you are well hydrated before an event is also important. The recommendation being, 17 to 20 fl oz of water or a sports drink 2 to 3 hours before exercise and 7 to 10 fl oz of water or a sports drink 10 to 20 mins before exercise. This should be part of an athlete’s hydration protocol.
When drinking water I have always heard that you take half your body weight and drink that in ounces. I am a big fan of the gallon of water per day and have tried to get many of my family and friends to do it. I notice that I tend to drink it to fast some days though so I have seen some people write on their jugs. They draw a sort of timeline to follow per hour I believe. I have found that drinking 3/4 of my gallon works for me!