Eating for Life

Monitor your fluid needs closely during hot weather exercise

By Philip Green

During exercise, water’s main function is to remove excess heat generated by exercise activity. The body rids itself of excess heat by allowing water to transport heat to the skin through the process of sweating.

Body fluids (water), electrolytes (i.e. sodium and potassium), and heat are continually dispersed through evaporation on the skin surface. This creates an ongoing need to continually replenish our body’s water reserves during exercise, especially now that Houston’s hot and humid summer is almost upon us.

During exercise, drinking cool water every 10 to 15 minutes helps lower the body’s core temperature. The need to build up and replenish our electrolyte reserves with a sport supplement drink such as Gatorade is best accomplished pre-workout (one hour prior) and post-workout. In addition, any athletic event lasting longer than one hour necessitates the need to consume an additional sport supplement drink halfway through the event.

It’s important to remember that all sport supplement drinks contain carbohydrates that delay the uptake of water within our cells for about 15 minutes. However, the liquid carbohydrates contained within such drinks help replenish depleted glycogen reserves within our muscles. Stored glycogen reserves are the primary source of fuel for all anaerobic exercise. Keeping muscles properly hydrated is also an important factor in avoiding cramping.

The body’s metabolic rate can increase 20 to 25 times during intense exercise, and performance can be compromised in as little as 10 minutes if dehydration occurs. Athletes exercising in hot and humid conditions may lose more than two quarts of water per hour. Research shows that football players can lose as much as two percent of their body weight during 30 minutes of practice. A two percent loss of body weight caused by dehydration can impair the body’s ability to dissipate heat, while a four percent loss can cause heat exhaustion.

Un-replaced fluid losses will eventually raise the body’s core temperature to the point of heat exhaustion, or life threatening heat stroke. At rest, the body’s core temperature is 98.6 degrees. During intense exercise, the body’s core temperature can rise to an unsafe 104 degrees without proper hydration.

Water should be consumed before, during and after intense exercise. Ideally, pre- and post- exercise body weight should be equal, meaning that fluid intake should equal fluid loss. Maximum weight loss during one hour of intense exercise or competition should never exceed three percent of total body weight. Every pound lost during exercise necessitates drinking an additional 16 ounces of fluid to hydrate post-exercise.

Use the following formula to estimate the amount of fluid you may need during your workout:

One-Hour Intense Workout

Your weight x 0.03 (3%) = lbs. of lost fluids x 16 = replacement ounces.

Male Example

180 lbs. x 0.03 (3%) = 5.4 lbs. x 16 = 86.4 oz. to replace lost fluids.

Female Example

120 lbs. x 0.03 (3%) = 3.6 lbs. x 16 = 57.6 oz. to replace lost fluids.

The three percent factor used in the example is only a guideline to help estimate your needs. Your specific fluid loss will vary depending upon your body weight, physical condition, how well your body is acclimated to exercising in hot and humid conditions, workout intensity, the duration of your workout, temperature and humidity.

During hot and humid conditions, drink a carbohydrate sport supplement drink at least 60 minutes prior to exercise. Limit your carbohydrate supplement consumption during exercise because most of these drinks contain a large amount of simple sugars that slow down fluid absorption.

Philip Green is a professional trainer and sports nutritionist and co-owner of Lean Meals. He can be reached at 832-594-0434 and prgfitness@yahoo.com.

According to a report by the National Center on Alcohol and Substance Abuse at Columbia University (CASA), prescription pills are increasingly becoming the illicit drug of choice among the nation’s college students.

According to the report, between 1993 and 2005 the proportion of college students abusing Vicodin and other opiods increased 343 percent, about 240,000 individuals. The numbers increased 450 percent, or by 170,000 students, for tranquilizers such as Xanax and Valium, and 93 percent, or 225,000 students, for stimulants, including Adderall.

Substance abuse treatment experts say prescription drug abuse is especially common among upper middle class students.

The report indicates that prescription drugs are exceptionally easy for young people to acquire. They can get them through the Internet, from their parents’ medicine cabinets and from their friends. In many cases, researchers say, the drugs are acquired through friends who are prescribed these drugs legitimately.

Experts say Adderall, prescribed for attention-deficit hyperactivity disorder, is becoming increasingly popular. According to CASA, more than a third of children ages 11 to 18 in Wisconsin and Minnesota who’d been prescribed Adderall and other ADHD medications say they have been propositioned to sell or trade their drugs.

The report suggests that drug makers could formulate the products to make them harder to abuse and that anti-drug campaigns should focus more on prescription drug abuse. Parents should also be more aware of the problem and limit their children’s accessibility to the drugs.