Proper hydration is very important in many ways, specially before and during practice. Health and performance can suffer at any extreme condition, meaning in both ways. Thais is, if the body’s hydration status is too low or too high (dehydration and hyponatremia, respectively).
In general, water performs several important functions in the body:
Dissolves and transports minerals, vitamins, proteins, and other important substances throughout the body.
Speeds up the breakdown of food and absorption of nutrients.
Regulates body temperature.
Helps speed up chemical reactions in the body.
Determining Hydration Needs
If you are not practicing on any particular day, two liters of water plus water from a healthy diet—this includes several servings of fruits and vegetables—is adequate for hydration. This basic formula can be scaled up for larger people and those exercising and sweating a lot, and down for smaller individuals. To be more specific, there is a general guideline for proper hydration (unless if there’s a health condition related to it):
Body weight. A slightly easier way to estimate water needs is by weight. Consume 30 to 40 milliliters of water for every kilogram of weight. If you weight 50 kilograms, for instance, you need at least 1.5 to 2 liters of water per day.
Still talking about a general guideline, it’s also important to consider factors that change basic fluid needs. You need to up these baseline fluid intake amounts in the following situations:
When temperatures are high, you sweat more and need more fluids to replenish lost water.
More intense and longer workouts also increase sweat output.
Exercising during warm weather conditions requires that you increase fluid intake even more.
The first topic (we will talk about dehydration later this week) is hyponatremia. Less people talk about it, even through it is, like dehydration, very dangerous and it can seriously impact performance during training and competition.
Not everyone is aware of, but over hydrating during long events is as dangerous as dehydration. There are many health conditions that can make us more prone to retaining possibly dangerous levels of fluid during long events and workouts (for that reason it’s very important to have regular checkouts with your doctor during your training leading up to a long event and, frequently, weight before and after practice). Up until a recent past, many athletes followed the advice to stay ahead of thirst and drink as much as possible during events. It’s normal during long training sessions and events to dehydrate to a certain extent. The body under certain circumstances tries to adapt producing hormones that, among other things, try to keep the sodium/potassium equilibrium constant.
Does so by controlling the sodium excretion in the sweat and urine (sweat control happens at a slower rate than urine). The body also tries to get sodium from the bones, among other reactions, if necessary. The body, under certain health conditions, may not control the sodium concentration in the blood as efficiently. So, as a result, it may be prone to retain more liquid. That fact, associated with an over consumption of liquids may cause the sodium outside the cells to be less concentrated.
Since most of potassium is localized inside the cells it may cause tissue swelling (water passes freely from less to more concentrated gradients).
That condition is called hyponatremia. If the tissue swelling happens in the brain it can be dangerous. A few of the symptoms of hyponatremia may include;
- Weight gain during training (it’s normal to dehydrate to a certain degree during practice and competition so gaining weight should not be something that’s expected).
- Vomiting (from liquid accumulation in the stomach/intestines).
- Low consciousness level.
- Photophobia (light sensitivity).
- Hands and feet swelling (normally noticed as the event identification bracelet gets tighter).
- Concentrated urine, in extreme cases (as the extra cellular fluid gets lower).
Quick facts; The average weight loss during a marathon, for example, is 2-3 Kg. The mean liquid absorption by the intestines is about 600ml per hour. Due to the great variability of sweat rates between individuals under specific circumstances it’s virtually impossible to come up with a general hydrating guideline that would be fit for everyone. For example, a runner competing under extreme cold/freezing weather may sweat as little as 100ml/hour as it would be an advantage (high sweat volume in this condition may freeze and cause hypothermia).
On the other extreme, a 150Kg football player may sweat as much as 3000ml/hr under extreme hot conditions. There are a few risk factors associated with the hyponatremia (low blood sodium concentration) development; Long events completed at slower paces (combination of low heat generation and high fluid intake), the use of certain medications such as NSAIDS (a class of anti inflammatory drugs that can make the organism more sensible to the anti diuretic hormone), events that last longer than 4 hours.
General guidelines during practice and competition is to drink between 300-500ml every half an hour and also drink on demand, as you feel thirsty.
Liquids should not be too concentrated (liquids that are too concentrated make you more prone to dehydration). To learn more about intra training carbohydrate and liquid/gel consumption click here. Besides having medical support to uncover possible health issues before you prepare for an event, always look up for a nutrition professional so you can get your personalized hydration right during long workouts (in preparation for long events).