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Ask the High Performance 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.

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    Q: I have been on a low carbohydrate diet for an extended period of time and I have been successful with weight loss. I am a 3.5 level singles player. At times I feel that I don't have the proper nutrition before a match. What would be a proper pre-match meal or snack that wouldn't violate my diet, or do I just need to abandon my diet for the day of my match?

    Dr. Riewald: In general, low carbohydrate diets are not recommended for athletes who are looking to optimize their performance in the athletic arena - this includes tennis players.

    The reason is that muscles (and the brain) rely on glucose for fuel, and glucose comes from carbohydrates - in fact, in working with high performance players, we recommended that carbohydrates make up 55-65% of the player's diet.

    So, to eliminate carbohydrates, or significantly reduce them, is depriving your muscles of their primary fuel source. This is something that is not just important on the day of competition.

    Nutrition is a long-term commitment and if you feel your nutrition is poor on the day of competition, it is likely the result of the "accumulated effect" of not having enough energy in your tank on a day-in-day-out basis.

    Q: How much fluid should I drink before training and when? Also how much fluid should I drink while I am training and what should I drink water, powerade etc? And do you know two ways to determine my own hydration level? Will water alone be enough for players to compete at their best and allow full recovery?

    Dr. Riewald: The USTA Sport Science Committee has put together fluid replacement guidelines and this information is available on the High Performance website.

    Click here to download the USA Tennis Hydration Poster.

  • In general, you want to:

    • Top off your fluid stores by drinking 12-16 oz of fluid 1 hour prior to competition.
    • Drink 4-8 swallows of fluid after your warm-up and on EVERY changeover during play.
    • Drink 20-24 oz of fluid for every pound of body weight lost during play to replenish the body's fluid stores.

    Whether to use water or a sports drink is something you have to determine on your own. The three things you should be replacing during or after play are fluids, energy/ carbohydrates, and electrolytes.

    Many sports drinks contain all of these, but you can also obtain these through a combination of drinking water and eating appropriate snacks. Some people have difficulties with sports drinks, so the later suggestion may be for you if drinks like Gatorade or Powerade are hard on your stomach.

    Two simple ways you can determine your hydration status are:

    1. Monitor the color of your urine. In a well-hydrated person, urine will be very light to clear - the color of straw. Darker, more concentrated urine is an indicator that you are dehydrated.

    2. Weigh yourself before and after play. Any weight loss you experience during play is due to fluid loss and that weight should be replaced before the next practice or match. Make sure when weighing yourself, however, that you wear similar DRY clothes, and not the sweaty clothes you came off the court in.

    Q: I have heard the kick serve can be very hard on the shoulder. Two questions: At what age is it safe for a female athlete to begin work on that type serve and what rotator cuff exercises are best to prevent injury for that type serve?

    Dr. Riewald:
    The kick serve is often compared to throwing a curve ball in baseball, in terms of the stress that is placed on the shoulder.

    There is so much concern about protecting the shoulder in little league baseball, in fact, that there are rules in place in many leagues that makes it "illegal" to throw curveballs until the player has reached a certain age - the penalty for throwing a curve ball getting thrown out of the game. In tennis there are no such rules but the general recommendations are not to start hitting the kick serve until the player has reached puberty.

    A player can learn the mechanics of the serve prior to puberty, but should not practice it extensively or use it in competition. Adopting this strategy will help the player develop the technique but will also protect the shoulder from injury and "delay" the stress placed on the shoulder until the player has sufficient strength to handle the loads.

    With that said, there are also strengthening exercises that every player should do to protect the health of the shoulder. These exercises include strengthening of the muscles that externally rotate the shoulder (the motion opposite of what a player does when hitting a serve) and control the shoulder blades in the upper back. Both groups of muscles are important for developing shoulder strength and stability.

    Examples of these exercises are included in the attached exercise sheets. Keep in mind though, that the shoulder acts as one of the final segments in the kinetic chain that transfers power from the ground, up through the body, and eventually to the racket and ball. It is just as important, if not more important, to train the legs and core of the body and not just focus on the shoulder.

    The USTA has also put together the High Performance Profile (HPP) to screen players for strength and flexibility imbalances that could possibly lead to injury. The HPP is presently available for download on the High Performance website.

    We will be posting a list of exercises shortly that show players how to address any strength or flexibility deficiencies that come up in the HPP.

    The answers to this week's "Ask the Expert" column come from Scott Riewald, PhD.

    Dr. Riewald is the USTA Administrator of Sport Science, he reports to Paul Lubbers, Director of Coaching Education. Dr. Riewald and the Sport Science staff work with Coaching Education to provide information to the coaches of top American players through seminars, workshops and newsletters.

    Past Riewald Columns:



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