What is dehydration? Dehydration is the excessive loss of water from the body, as from illness or fluid deprivation. Any person who exercises on a regular basis is susceptible to the effects of even mild fluid loss.
The value of the body's most important nutrient, water, cannot be underestimated. Exercise produces body heat, and too much body heat reduces exercise capacity. As the core body temperature rises, the blood flow to the skin increases, and the body attempts to cool itself by sweating.
During exercise the body temperature rises as high as 105 degrees Fahrenheit and the muscle temperature can rise as high as 108 degrees Fahrenheit. These temperatures make exercise difficult because the body and muscles are competing for blood. As the body temperature rises, oxygen becomes more of a commodity due to increased circulatory demands. Oxygen is needed to help with the cooling process, and reduction in the amount of oxygen available for vital organs can lead to severe health risks as well as a drop in athletic performance.
Physical Symptoms and Effects of Dehydration
When you start exercising, as much as two percent of the body water is lost. Although this amount is considered a "normal" range for humans, it is not an optimum level for athletic performance. Below is a table that summarizes the effects of minimal fluid loss during exercise.
Body Water Lost and Symptoms
-- 1% ... Few symptoms or signs of any thirst present; however there is a marked reduction in VO2max [the maximum amount of oxygen used in one minute].
-- 2% ... Beginning to feel thirsty; loss of endurance capacity and appetite.
-- 3% ... Dry mouth; performance impaired.
-- 4% ... Increased effort for exercise, impatience, apathy, vague discomfort, loss of appetite.
-- 5% ... Difficulty concentrating, increased pulse and breathing, slowing of pace.
-- 6-7% ... Further impairment of temperature regulation, higher pulse and breathing, flushed skin, sleepiness, tingling, stumbling, headache.
-- 8-9% ... Dizziness, labored breathing, mental confusion, further weakness.
-- 10% ... Muscle spasms, loss of balance, swelling of tongue.
-- 11% ... Heat exhaustion, delirium, stroke, difficulty swallowing; death can occur.
Dehydration can cause any or all of the following problems:
-- Increased heart rate per minute
-- Increased lactate acid in muscles
-- Increased body temperature
-- Decreased strength
-- Any of the following medical conditions: heat cramping, heat exhaustion and heat stroke.
Staying hydrated properly
The best way to avoid fluid loss is often the simplest. Drink plenty of fluids. Water is sufficient to replenish the fluids that are lost during exercise.
However, water cannot replace the minerals that are lost during exercise-induced sweating. Sweating releases potassium, sodium, and calcium, which are vital for survival. These minerals, also known as electrolytes, are not found in water. It is advisable to consume a supplement containing these added minerals before any strenuous exercise.
One supplement that contains these electrolytes is a "sports drink." Although these sports drinks contain a combination of vitamins and minerals, they also contain simple and complex carbohydrates, predominantly simple sugars, which provide the athlete with an added amount of glucose. This glucose, which is converted by the body into fuel, can later be used to power the working muscles.
The carbohydrates that are found in sports drinks are designed to help in performance, and do not play a direct role in hydration. The added nutrients, potassium, sodium, and calcium, along with the water content, is the determining factor in hydration.
Exercise scientists, along with savvy marketers, have designed the newest product to conquer dehydration -- fitness water. This new product has taken regular water and added minerals and vitamins including those vital electrolytes, potassium, sodium, and calcium. This new product is targeting the fitness enthusiasts who want to protect against dehydration but are looking to keep their calorie count and sugar intake to a minimum.
Caffeinated drinks should be avoided wherever possible. Caffeinated products increase urine output, which raises the amount of fluid loss. This fluid loss is exactly what you're trying to avoid. Many people drink caffeinated drinks before exercise to obtain extra energy. A suggestion to those who need the extra energy: avoid the caffeine and take a vitamin B tablet instead. The vitamin B tablet will give the extra energy desired, without the increased fluid loss.
Another product to avoid in relation to hydration is alcohol. Alcohol, like caffeine, increases urine output and fluid loss. Although most people will not consume alcohol just before exercising, it should be noted that a few drinks the night before a morning workout could have a large effect on hydration levels. If planning on exercising the morning after consuming alcohol, drink a lot of fluids, including the necessary electrolytes. Taking in the required electrolytes, as well as satisfactory levels of fluids, will determine hydration level.
It is vital to monitor the body and to continually take in fluids. By the time thirst sets in, the body has already lost at least two percent of its fluid, and dehydration occurs. At any chance possible before and during exercise consume fluids to avoid the harmful consequences of dehydration.
Mark Kovacs has a degree in Exercise Science from Auburn University and is a certified Health/Fitness Instructor through ACSM (American College of Sports Medicine). Mark also works as a strength and conditioning coach with numerous professional athletes in the NFL, NBA, NHL, ATP/WTA. He can be contacted about fitness related questions or issues at firstname.lastname@example.org.© 2004 Mark Kovacs
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