On Court Player Towel

Speed Logo Zone Hat


Peace & Love T-shirt

Whit's Tennis Tips: Strings & Tennis Balls

Whitney Kraft, Director of Tennis at the USTA Billie Jean King National Tennis Center, is here to answer your questions on the game of tennis in his column on USTA.com called “Whit’s Tennis Tips". Whether you're looking for that perfect racquet, having a dispute over scoring a match, or just looking to improve your game, all you have to do is Ask Whit.
* Please note, due to the volume of emails Whit receives, he is not able to answer every email.

From: Brad
Subject: Strings for Young Juniors

I have a talented eight year old. He plays in boys 10 and is already having success. He also was invited to participate in a USTA high performance camp 10/11 this June in Boca. I have some questions about strings. He uses a Wilson 6.1 junior 26 inch racquet. He was using Wilson NXT 17 string, but he wears it down pretty quickly. What is your opinion on the polyester strings either alone or as a hybrid for this age player? Also, what is your opinion on stringing below the range recommended by the racquet manufacturer in order to increase power? If you feel that it is OK to string low, is there a number that you would not go below?

Thanks for your advice.

Hi Brad,

At this moment, I don’t think poly strings are a good choice for a number of reasons. First, they attenuate power to allow big hitters more control, and it sounds like you are seeking more power, not less. Second; poly is hard on the arm…my main concern with growing kids is each time they grow, it takes approximately six months for the muscle to catch-up to the added bone length. These growth spurts are a vulnerable period for injuries.

If your son should begin to experience any wrist, elbow or shoulder pains, I think it is wise to re-evaluate equipment, as well as technique and training. The onset of an overuse injury to the arm can happen whenever equipment or technique changes occur, so it is wise to keep tabs on how any changes “feel” to his arm. The reason I point this out now is string breakage problems will likely influence you more as your son gets bigger and stronger, thus breaking strings sooner. Most adjustments in string type to reduce breakage add stress to the arm. You might also look towards frame models that are less prone to breaking strings, as long as the frame itself is not hard on the arm, and has the playing characteristics that suit your son.

Slightly lower tensions are a good choice to add power, and a soft string (poly is very stiff) like NXT plays well at lower tensions. Lowering the tension will extend string life by itself. To further reduce breakage, try moving up to a thicker 16 gauge, or try hybrid NXT gauges…16 on the mains and 17 on the crosses. To find the right tension, I suggest adjusting tension by only a couple lbs at a time, and bear in mind that the thicker 16 gauge will not pull as tight as 17. E.g. the same tension will feel slightly lower on a thicker string of same type. At some point; a poly hybrid will make more sense to add control, but I would caution using poly until it is really needed. It is common that young juniors want to use the equipment of the pros they like; but I always advise to find the equipment that best suits the individual.

Your son will be going through many changes over time….physiologically, technically, and tactically. Equipment, strings and racquets are also ever changing. Having a certified pro and a certified racquet technician to advise will keep your son healthy and hitting well.


From: James
Subject: Strings

Hey Whit!

Thanks for providing this forum.

First question is: On my Head Liquidmetal Radical, I use a hybrid string with my mains strung at 58lbs and my cross strings tensioned to 55lbs; thus, I find I have some awesome control, but I crave more power. My racquet speed is insane, yet, I find that I am not hitting the ball any harder...should I increase the tension on my strings?

Second question is: Is there any legitimacy to training with a string/line 3 feet above the net in order to develop good top spin and deep court placement?

Thanks much. Have a good one.


Hi James,


Power and control are a trade-off in string tensions, and you will get more power with a lower tension. You could also consider thinner gauges, and/or livelier string type to add power. The options you choose will need experimentation, which are compounded when using hybrids due to more interactive variables. Natural gut on the crosses is a common hybrid option for those wanting more power, with minimal control loss.

The string-line trick is an excellent method for depth and margin for error training. We refer to it as “windows” of clearance and often demonstrate by holding our racquets on edge above net to visually show students the various windows they should strive to hit through. I.e. window one for passing shots and first serves in singles and window three when volleying from the service line in an attempt to volley deep down the middle.


From: Zelka
Subject: Numbers on Tennis Balls

Is there a difference between the numbers on the tennis balls? I am getting mixed messages.


Hi Zelka,

Numbers on balls are meant to assist players on side by side courts to keep track of balls designated to a particular match or court so even wear and maintaining original balls becomes easier. Different numbers don’t indicate differences in manufacturing, but different colors of stencils often indicate hard court balls as opposed to clay court, grass, indoor or high altitude balls.

Hope this helps,

Print Article Email Article Newsletter Signup Share

Whit's Tennis Tips doesn't work without your questions, so please send those tennis related questions you've always been trying to get answered to AskWhit.

Knowledge Areas:

Improve Your Game Homepage

USTA Membership
Learn More or Login
Learn More or Login
Newsletter Signup

Copyright 2017 by United States Tennis Association. All Rights Reserved.

Online Advertising | Site Map | About Us | Careers | Internships | Contact Us | Terms of Use | Umpire Policy | Privacy Policy | AdChoices

Connect with us! Facebook-38x39 Twitter-38x39 Youtube-38x39