October 2, 2014 - Do you ever leave the gym or a group fitness class feeling a wonderful rush of endorphins one day - but the same workout the next day leaves you feeling foggy with a headache? Of course, there could be many possible explanations. First and foremost, consider a common cause: dehydration. Even though your body is about 60% water, dehydration occurs when any more than 2% of body fluids are lost. To prevent dehydration from overriding your workout's natural mood-boosting effects, here's a research-based strategy to ensure an aqequate H2O intake on your exercise days.
Pre-workout: Consume water more than 4 hours before you exercise. Taking in fluids or foods more than 4 hours prior to exercise allows your body ample amount of time to digest and absorb all substances and to excrete unwanted ones. How much water? The recommendation is to consume 2-3 mL/lb. of your body weight. Try not to “over hydrate” as it can cause more harm than good. An example would be that a 150 lb. person would want to consume approximately 300-450 mL, which is equivalent to about half (1/2) of a 20 fl. oz. bottle.
During workout: Consume fluids throughout your exercise session. It’s ideal to consume 4-16 oz. every 15-20 minutes during exercise. The amount and frequency is based upon an individual’s tolerance. If exercising in extreme heat or at high intensity levels it’s also good to consume 500-700 mg of sodium/L of fluid or at least 1 g/hr.
Post workout: Drink 50% more fluids than you lost in sweat. One way to measure how much water to consume would be to weigh naked (if circumstances allow) both prior to and following exercising. For every pound lost, consume 24 oz. For example, if a 150 lb. person lost 2 lbs. after exercising then they would want to consume approximately 48 oz. of fluids. It’s also suggested to consume sodium chloride (i.e. salty foods, sports drinks) which aid in rehydration with high intensity exercise or exercise in extreme heat.
In addition to feeling foggy, or cognitively impaired, there are several symptoms that you can watch out for to help you realize when you may be dehydrated. Fatigue, decreased urine output, dark urine, lightheadedness, dizziness, dry skin, constipation, headache and dry mouth are several common signs.
In addition to the ways you may notice you are dehydrated, it is important to note losing too much H2O (without replenishing) causes a shortage of fluids necessary for your body to carry out it's normal functions. For example, water helps to remove metabolic waste products through urine; the darker the urine, the more concentrated the waste. Water also aids in the proper digestion of food. Probably the most important function, in regards to fitness, is that water helps to dissipate heat through the skin. With exercise, water absorbs heat from the muscles and cools down the body's temperature through sweating.
Even if you are not able to follow the exact number of recommended ounces based on your body weight, the important thing to remember is that fluid intake is vital! Don’t neglect your body of what it truly needs the most.
Jon Nichols, CPT, Graduate Assistant, UK Health and Wellness
This article was published in Fit News, the monthly online newsletter from UK Health & Wellness' Body Shop Fitness.