Even mild to moderate dehydration can create potentially damaging consequences to your body during exercise. In a study conducted by Loughborough University, low levels of dehydration reduced the mental and physical capabilities of athletes and resulted in poorer performance. Dehydration thickens your blood, reduces heart efficiency, increases body temperature and heart rate. Exercising under these conditions is dangerous and only prolongs the symptoms of dehydration, causing even a mild case to increase in severity.
Exercise
Exercising while dehydrated can produce significant consequences. Vigorous activity in hot or humid conditions above 80 degrees Fahrenheit can result in fluid losses greater than 1 liter per hour. Your body may lose more water than it can absorb, making it more difficult to stay hydrated the longer you exercise. Dehydration is also a cumulative process, according to the Mayo Clinic, making it possible to become dehydrated with even a moderate exercise routine if you do not drink enough fluid to replace what you lose on a daily basis.
Consequences
Dehydration occurs when fluid is lost in significant amounts from the body. As fluid is lost from the bloodstream and body tissues, an electrolyte imbalance occurs. Exercising under these conditions can have consequences ranging from mild heat cramps to potentially life threatening heatstroke. Seizures can occur as a result of the electrolyte imbalance, causing involuntary muscle contractions and a potential loss of consciousness. Low blood volume can also cause hypovolemic shock, which creates a drop in blood pressure and significantly decreases the amount of oxygen available to the body, making exercise dangerous.
Symptoms
If you demonstrate any of the following symptoms, you should avoid working out until you have become properly hydrated. Symptoms of mild dehydration, which should still be monitored carefully, include a dry, sticky mouth, thirst, dry skin, headache, decreased urine, dizziness and constipation. If these symptoms are not properly treated, severe dehydration can occur. These symptoms include extreme thirst, little or no urination, rapid breathing, fever, extreme irritability, unconsciousness and require immediate medical attention.
Prevention
To prevent dehydration, drink an adequate amount of fluid several hours before exercise to allow the fluids to absorb into your tissues. While exercising, stay in cooler, shaded areas if possible and carry fluids with you at all times. Try working out during the early morning and late evening hours when the heat and humidity are at their lowest points. If your workout lasts longer than 45 minutes, consume a sports drink that contains sodium and potassium during the session. After working out, you should consume 24 oz. of water for every pound of body weight lost to properly rehydrate.
References
- Mayo Clinic; Dehydration; Mayo Clinic Staff; 2011
- "Running Well"; Sam Murphy; 2008
- "Anatomy and Physiology: The Unity of Form and Function"; Kenneth Saladin; 2010
