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Ask the High Perfomance Lab

May 25, 2008 12:25 PM

PLEASE NOTE: The medical opinions in USTA.com's Ask the High Performance Lab are responses intended for the average player. Please consult with your primary physician before beginning any new exercise program.

Michael F. Bergeron, Ph.D., FACSM is an applied physiologist and Assistant Professor at the Medical College of Georgia in Augusta, GA in addition to serving on the USTA Sport Science Committee.© USTA
The answers to this week’s "Ask the Expert" column come from Michael F. Bergeron, Ph.D., FACSM. Dr. Bergeron is an applied physiologist and Assistant Professor at the Medical College of Georgia in Augusta, GA in addition to serving on the USTA Sport Science Committee.

His research includes studies on exercise and sports performance and nutrition, with an emphasis on the effects of exercise in the heat on fluid and mineral balance, as well as thermal and cardiovascular strain.

Dr. Bergeron has worked with a number of junior, collegiate, and professional tennis players on training and nutrition related to preparation, competition, and recovery in the heat.

From Todd of Pembroke Pines, Florida: I have a tendency to cramp late in my matches. I carbohydrate load and take potassium, as well as amino fuel drinks to help. And yes, I drink a lot of water.

What can help me make it through in hot summer matches?

Dr. Bergeron: Localized cramping (such as in the calf only) is usually related to fatigued or overworked muscles, due to overloading or insufficient conditioning or range of motion. However, the cramping you are probably referring to is prompted by an electrolyte deficit – primarily sodium and chloride (salt). Supplemental carbohydrate (though good for your on-court energy needs), potassium, or amino acids will not help.

You need to replace the salt lost from sweating. In fact, excessive water intake (without the electrolytes) can increase the cramping risk and may lead to hyponatremia (low blood sodium). Day-to-day, your salt intake needs to match your sweat salt losses.

Much of this can be done by eating salty foods; however, it’s often necessary to add a little salt to your on-court drink and recovery fluids. This helps you to retain and distribute the water throughout your body vs. being in the bathroom too often from drinking too much plain water.

From Nadia of Sydney, Australia: I am a junior tennis player. I get at least 8 hours of physical activity a day. I am at a reasonable weight; but I could lose at least 5 kg. I have been on a high-protein, low-carbohydrate diet; but I find I can’t stick to it.

Do you know of any really good diets where I can lose weight ASAP and quickly, but will still give me enough calories to last each day?

Dr. Bergeron: It’s critical for you (especially, as a junior player) to consume enough calories and a balance of nutrients (carbohydrates, protein, fats, vitamins, minerals, etc.) to support normal growth, development, maturation, and your extensive physical activity. You cannot play well or even be well, if you are not getting enough calories and nutrients.

Too much protein is a bad idea, as is too little carbohydrate. It’s difficult to be on a “diet” and train or compete successfully, especially if you are trying to lose weight too quickly.

With the help of your pediatrician and a good sport dietician, take a close look at your current eating habits (including timing of meals) and come up with a suitable diet strategy to help you achieve a more optimal weight and body composition. Importantly, appropriate and healthy weight losses (or gains) should happen slowly, if the change is going to be effective, healthy, and long-lasting.

From Kent of Melbourne, Florida: It is apparent that the professionals on tour do not ingest the typical sports drinks that are used in mainstream America. Their drinks have a different color and there are other visual indicators that indicate they are not Gatorade, etc. (labels are always absent when they are drinking these "mystery" beverages).

Do you have any insight into what kind of mixtures they are using?

Dr. Bergeron: Actually, many of the players (especially on the women’s tour) drink exactly what many Americans drink - Gatorade® and water.

Some of the European sports drinks that are also used are very similar to Gatorade® in nutrient content. One such drink on the men’s side is Lucozade™. Some players are also using Cytomax™; though this is not as popular as it once was.

From Jason of Clearwater, Florida: I am a nationally ranked 30's player and didn't have a great summer season, due to a bout of self-diagnosed heat stress. For some reason, the heat seemed to affect me more than others at the national level and I'm not sure why. I had an EKG and an echo stress test done, the results of which were remarkably good. So, I'm at a loss.

I'm not sure how to better condition my body to cope more effectively with the brutal Florida heat. I found something through a trainer called "Gookinaid" developed by Gookin, one of the creators of Gatorade, but that didn't seem to help much more than staying hydrated. Any suggestions?

Dr. Bergeron: There are a number of contributing factors to excessive heat strain and thermal intolerance. Lack of sleep, excessive fluid-electrolyte deficits, insufficient acclimatization to the heat, poor fitness, excessive body fat, recent illness, certain clothing and colors, and some medications can all make one less tolerant of the heat.

However, some people are simply heat-intolerant, having a physiological disability in metabolic heat dissipation, due to an inherent thermoregulatory dysfunction. A measure of your body and skin temperature, along with heart rate, during an exercise-heat stress would confirm whether or not this is the case.

Before that, make sure none of the above factors are the main reason for your heat intolerance. Often, for example, players are a lot more fluid- and electrolyte (primarily salt)-deficient than they realize.

If you would like to submit a question that may be answered by our Health & Fitness team or want to share an idea for a future column, please click here.

Click here for USTA.com's Health & Fitness Archive.

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