Hydration is something many of us take for granted, but it is even more important the more active we are. Water is one nutrient we cannot, nor should not forgo. While we can go for weeks without food, water is a whole different scenario. Without water, death can occur within days.
So why is hydration so important when it comes to running?
Water acts as a coolant when you are exercising. Think of the water within your body as the anti-freeze you put in your car. Sweating is the involuntary response that keeps your body from overheating. When you begin exercising your body's temperature begins to rise, this in turn triggers your brain to signal your sweat glands to increase sweat production to speed up the cooling off process.
Because our bodies are comprised of 40-70% water, just a slight shift in the body's fluid balance can lead to drastic changes in our running performance. Sweating accounts for well over 90% loss in water during a run--add warm temperatures and humidity into the mix and this rate can go even higher. The remaining fluid loss comes from our breathing as well as urine and feces production.
Keeping tabs on your hydration is essential to getting you through your run. Click here for hydration guidelines while you are working out.
Dehydration is defined as losing more fluid than you have taken in which then can affect normal body functions. It can lead to many changes in the body including the following:
It has been reported that for every 1% drop in body weight from fluid loss, there is a 2% drop in your running performance. This may not sound like a lot of weight, but for a 120-pound runner a weight loss of 3 1/2 pounds can lead to a 6% drop in running performance.
- Dry mouth
- A decrease in sweat rate
- An increase in heart rate
- An increase in body temperature
- A drop in blood volume which can lead to a drop in glucose being transported to the muscles to use for energy
- Drop in urine output
Factors that can determine our sweat rate include:
It has been reported that most runners have no clue as to how much water they lose during a run. This is where determining your sweat rate is essential as to how much you need to drink following a run.
- Ambient or air temperature. The higher the temperature there is an increase in sweat production. But note that even in colder temperatures, the body will sweat, but at a much slower rate.
- Humidity levels-The higher the humidity, regardless of the ambient temperature, the more difficult it is for the sweat to evaporate off the skin making it harder for the cooling off process to take place. If you notice sweat rolling off your skin, this is an indication that you need to stay on top of your hydration.
- Wind speed-The higher the wind speed the greater cooling-off effect so that sweat production may be lessened. Calm days may lead to an increase in your sweat rate.
- Body conditioning-The better conditioned you are to a particular activity, the greater the sweat volume, so you will usually begin to sweat sooner into your run.
- Gender- Men tend to sweat more than women, not only due to their bigger size, but also due to their increase in muscle mass.
- Genetics- We are all the product of our ancestral genes, therefore, some individuals sweat more profusely than others, even when not exercising.
- Wearing inadequate clothing-It is important to dress as though it is 20 degrees warmer than the actual ambient temperature. In other words, if the ambient temperature is 55 degrees, you will want to dress as though it is 75 degrees-- usually this means shorts and a short sleeve wicking shirt. You may be a little chilled in the beginning of your run, but within a few minutes, as your body's core temperature begins to rise, so will your sweat rate.
Determining Your Sweat Rate
For example if you lose 3 pounds during your run, you will need to rehydrate with 48 ounces of water, slowly over the course of the day. This is in addition to what you would normally drink.
- Determine a baseline weight by taking your average weight over the course a normal week
- Weigh yourself without clothes and shoes before your run
- After your run, remove all clothing, dry off well including your hair if you are a heavy sweater, and weigh yourself again
- For every pound you lose, you will want to slowly re-hydrate with 16 ounces of water
In rare cases, if you find yourself at a weight greater than you were before your long run be aware that you may have over-hydrated. Drinking too much can be just as serious as not drinking enough. Too much fluid can lead to a condition known as hyponatremia. This condition generally occurs on training runs well exceeding two hours in duration where a runner is drinking more than they need.
According to data reviewed from various marathons from around the world, women are more susceptible to this condition because of our slower marathon times, lower sweat rates and our tendency to stop more frequently at the water stations.
For many runners, hydration is the difference between a great run and a not so great run. Educating yourself is what will allow you to find the proper hydration balance for you. Some runners find that drinking a sports drink with electrolytes added can help keep the body's hydration in check.
Have you ever determined your sweat rate to help with rehydration later in the day? Have you ever experienced symptoms of dehydration and/or overhydration?
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