Understanding Hydration and Exercise

Understanding Hydration and Exercise

Here are some general guidelines before you venture outside:
- Drink at least 17-20 oz. 2-3 hours before exercise
- Drink 7-10 oz. every 10-20 minutes during exercise
- After exercise drink enough water to replace any weight lost during exercise.

First, let’s look into how water plays a role in your body. For your body to properly metabolize calories, one needs to be properly hydrated. If you are even 1% dehydrated, this can slow down your metabolic efficiency to 5%. For example, if you have solid calories in your belly any water ingested will go straight to the belly to help with digestion instead of hydrating working muscles. During activity this leads to muscle cramping and in cases of high impact activity, undigested foods and fluid will be bouncing around in your belly which can cause side aches, diarrhea and even nausea.

If you grab a sports drink make sure the carbohydrate content is less than 6-8 percent of the calories. Anything more can cause intestinal distress during exercise due to slow gastric emptying and can increase the chance of dehydration.

As I mentioned above, dehydration leads to muscle cramping but can also contribute to achiness of muscles, pain in your joints and headaches. So stay hydrated and keep your muscles and joints lubricated.

Another aspect to look at is heat exhaustion or heat stroke. Our bodies perspire in order to decrease our internal temperature; as blood moves toward the skin, the heat generated evaporates through sweat. With the rapid increase in temperature the body has not had time to acclimate to the heat and you can be more susceptible to heat related illnesses. Even by losing 1-2% in body weight through dehydration it can affect your performance. Be on the lookout for heat cramps, heat syncope (dizzyness) and heat exhaustion. Some signs and symptoms could be cramping, nausea, incoherence, fatigue, vomiting, etc. As an athlete, you may notice your skin blotchy and flushed. If dehydration becomes severe, an athlete may get the goose bumps and the chills because the heat generated is not being evaporated effectively. This is serious and can be life threatening.

Keep in mind, for every 1% decrease in hydration you will experience a 3-5% decrease in performance. As a runner, that can be an additional 3 added minutes to your running time. Avoid letting your thirst be indicative of whether you are hydrated or not. Your thirst mechanism isn’t triggered until you are about 3% dehydrated, which right there is well into 10% decrease metabolic efficiency, cooling, muscle function and performance.

How do you know what your sweat rate is?
As an athlete this is very important when preparing for peak performance.
First weigh yourself both pre and post workout. Take note of whether you were inside or outside, specific weather conditions and intensity of the workout. For every 1lb of weight lost during activity, this would equate to 16oz of water. So for an hour of activity, you are looking at replenishing your body with 32oz of water. For activity over an hour, especially in heat, adding sodium to water helps against electrolyte imbalances. In general, .5 to 1liter of water per hour with .5 to 1 gram of sodium during longer more endurance type of activity will be beneficial.

With the warm weather approaching us, take caution and make sure you are adequately hydrated. To optimize performance and be at the top of your fluid game as an athlete, it is important to understand what is really going on in the body.

Written by Crystal Kennedy
Wellness Director/Personal Trainer, Seattle Athletic Club Northgate