Sports Nutrition:
Dehydration - A major cause of decreased human sports performance!

DEHYDRATION- A major cause of decreased performance!
By Mark Kovacs, M.Ed, CSCS, USATF II (Sprints)
Editor of High Performance Training
Editor's Note: The importance of proper hydration levels for health and fitness performance cannot be overlooked. Improved hydration habits have been shown to be effective in aiding in weight loss, body fat loss, as well as in your ability to withstand high intensity of aerobic exercise and enhanced sporting performance. Learn proper hydration and track your body water loss.

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, blood flow to the skin increases, and the body attempts to cool itself by sweating. During intense exercise, the body temperature rises as high as 39 degrees Celsius (105 degrees Fahrenheit) and the muscle temperature can rise as high as 40 degrees Celsius (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 reduces the amount of oxygen available for vital organs, which can lead to severe health risks as well as a drop in athletic performance.
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 certainly not an optimum level for athletic performance. Below is a table that summarizes the effects of minimal fluid loss during exercise.

Body Water Lost Symptoms

1 % Few symptoms or signs of any thirst present; however, there is a marked reduction in VO2 max.
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.
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Dehydration can cause any or all of the following:

• Increased heart rate (beats per minute)
• Increased lactate acid in muscles (increased blood acidity)
• Increased body temperature
• Decreased strength
• Any of the following medical conditions: heat cramping, heat exhaustion & heat stroke

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 therefore advisable to consume a supplement, which contains these added minerals, before any strenuous exercise.

One such supplement that contains these electrolytes is a “sports drink.” Although these sports drinks can 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 working muscles.

The carbohydrates that are found in sports drinks are designed, when used as directed, to help in performance, but do not play a direct role in hydration. The added nutrients, potassium, sodium, and calcium, along with the water content of the sports drink, are the determining factors 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 targets fitness enthusiasts that want to protect against dehydration, but who are looking to keep their calorie count and sugar intake to a minimum, which can help with weight loss goals.

Caffeinated drinks should typically be avoided before and during exercise. Caffeinated products increase urine output, which raises the amount of fluid loss. This fluid loss is exactly what we are 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, especially in relation to hydration, is alcohol. Alcohol, like caffeine, increases urine output, which increases 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 negative effect on hydration levels. If you’re planning on exercising the morning after consuming alcohol, drink plenty of fluids, including those necessary electrolytes.

Taking in the required electrolytes, as well as satisfactory levels of fluids, will determine your 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 M.Ed, CSCS, USATF II (Sprints)
Editor of High Performance Training



Dehydration can cause any or all of the following:

• Increased heart rate (beats per minute)

• Increased lactate acid in muscles(increased blood acidity)

• Increased body temperature

• Decreased strength

• Any of the following medical conditions: heat cramping, heat exhaustion & heat stroke


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