Thermoregulation and How it Affects Your Cycling

Okay, you have heard this before but it is worth stating again—drinking cool water will help keep you riding strong during the hot summer months.

A few years ago I sat through a seminar with Dr. Stacy Sims, who's specialty is thermoregulation. Here is what I learned about the subject and how it can affect cycling performance.

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Thermoregulation is the process our body uses to keep our core temperature around 98.6 degrees Fahrenheit. When our bodies are over heating because of exercise, being outside in the hot temperatures, humid conditions or simply a result of nerves, our core temperature rises and we sweat. Sweating is our body's way of cooling us off. Sweat is made up of 99 percent water and mineral salts (sodium chloride), along with a few other small amounts of our bodies ingredients.

According to Dr. Sims:

• Approximately 63 percent of our entire body mass is water.
• Greater than 50 percent of blood plasma is water.
• Water is the medium for biochemical and metabolic reactions.
• Thermoregulation of the body is regulated by the consumption of water.
• The body is highly sensitive to dehydration.

So, if we are outside training or riding our bikes in extreme conditions, what happens to our bodies if we are not replenishing the water we lose through sweat? As little as 0.5 percent water loss can put a strain on our heart muscle and decrease our cycling performance.

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Dr. John Ivy, in his book The Performance Zone, states the following facts:

• 0.5 percent loss of water can increase strain on the heart
• 1 percent loss of water can reduce aerobic endurance
• 3 percent loss of water can reduce muscular endurance
• 4 percent loss of water can reduce muscle strength, decrease fine motor skills and cause heat cramps.
• 5 percent loss of water can result in heat exhaustion, cramping, fatigue, or a reduction in mental capacity
• 6 percent loss of water can cause physical exhaustion, heat stroke or coma

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If you do become dehydrated the Mayo clinic suggests:

Treating Dehydration in Athletes of All Ages

"For exercise-related dehydration, cool water is your best bet. Sports drinks containing electrolytes and a carbohydrate solution also may be helpful. There's no need for salt tablets—too much salt can lead to hypernatremia dehydration, a condition in which your body not only is short of water but also carries an excess of sodium."

Treating Severe Dehydration

"Children and adults who are severely dehydrated should be treated by emergency personnel arriving in an ambulance or in a hospital emergency room, where they can receive salts and fluids through a vein (intravenously) rather than by mouth. Intravenous hydration provides the body with water and essential nutrients much more quickly than oral solutions do—something that's essential in life-threatening situations."

More: 15 Hydration Facts for Athletes

Remember that if you become thirsty during or after a ride, you are already dehydrated. If you feel signs of dehydration, do not put ice on your body. Ice, or even ice water, is too cold. According to Dr. Sims, the ice will constrict vessels and send the hot blood back to the core rather than cooling the core down. Drink cool water and dip or pour cool water on your bare feet, hands or head to help the body cool down.

How much water you should drink during your ride will depend on how hydrated your body is prior to your ride. Always drink before, during and after your ride, and remember what you eat and drink today will affect how you ride tomorrow.

More: Stay Hydrated During Anaerobic Performance

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