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Monday, July 5, 2010

Coaches Q and A: Should I Try Nadal's String?

Babolat's new string has become a hot topic in tennis, so we asked Andy Brandi of the Harold Solomon Tennis Institute in Fort Lauderdale, Florida for his thoughts are on the trend.

What do Rafa Nadal, Andy Roddick, Jo-Wilfried Tsonga, Sam Stosur, Franchesca Schiavone and Maria Sharapova all have in common? They all use Babolat’s RPM Blast.

Introduced in January at the Australian Open the RPM Blast string is taking the tennis world by storm, with players gravitating to this string in droves. What's behind this trend?

The RPM Blast, which is black in color, is easier on the arm. It increases spin because it grips the ball during contact and it shoots the ball out of the racket faster for more power. It gives unique feel.

Rooney Levine, who is with Match Point in Fort Lauderdale, says that 25% of those brining rackets for stringing are asking for RPM Blast. She mentions that it easier to string and is replacing Babolat’s Pro Hurricane Tour as the string of choice.

After hitting with it, I would recommend that juniors and female college players use it in a hybrid form. It would allow them to take advantage of the characteristics of the string while being easy on their arms. Be sure that you string it a little looser for better response. Older boys and college age male players can venture into stringing the whole racket with RPM Blast. Because of their added physical strength, it will allow them to take advantage of the string without harming their arm.

So my advice, if you have not tried it, get to your stringer. It will give you an added advantage.

Best of luck!

For a further information on this topic, see Doug Robson's recent article for USA Today.

Do you have a question for Andy or Harold? If so, please send it to clewis[at]zootennis[dot]com with the phrase Coaches Q and A in the subject line.


sloanetosaveustennis said...

Congratulations to Sloane for her Junior Wimbledon doubles victory! And for her first round win today over 77th ranked Alberta Brianti 6-2, 6-4!

Pete said...

This post on RPM Blast string is horribly inaccurate.

For one thing, RPM Blast is a stiff polyester string, which is generally not easy on the arm. While it's softer than most other polyesters, it is still very stiff compared to nylon synthetics or natural gut. Additionally, there is no evidence that textured strings like RPM Blast actually "grip" the ball, and "gripping the ball" does not produce spin. The assertion that this string "shoots the ball off the racquet faster for more power" is particularly ridiculous. Only one thing produces increased ball velocity and spin - force, which is a product of racquet head speed and the weight of the racquet.
3) This coach's recommendations as to how certain ages and genders of player should use this type of string is not only sexist, but does not take into account the key component of which racquet the player is using. The job of a good stringer is to achieve the desired stringbed stiffness for the player, taking into account several factors: type of string, gauge of string, racquet head size, pattern density, and of course tension. Putting RPM Blast in Nadal's racquet at 55 pounds is a lot different than putting it in, say, a Head Prestige Mid at 65 pounds. Females and juniors are not more susceptible to tennis elbow or shock-related injuries than big strong men are. Those types of injuries have almost nothing to do with the size of your muscles, and much more to do with poor technique exacerbated by repetition and equipment issues.

To answer the original question, should you use this string...well, here are some of the pros and cons: typically a stiffer string like RPM Blast changes the ball trajectory off the string bed, making it more difficult to miss the ball long. Many advanced players feel that, with a stiff string, they can swing harder and not have to worry about missing long. Increased swing speed = more spin and power. This string will typically last longer than softer nylon strings, although there is a greater chance of having the string break close to the grommets prematurely. Downsides of a stiff polyester string include decreased "feel" and greater tension loss.

So should you use it? Try it and decide for yourself. Just don't assume that just because Nadal uses it (which, of course, is the main reason why it's becoming so popular), it's going to be great for you too. Everyone wants to be like the pros, but they play a very different game and are working with a very different set of physical tools. The reason why Babolat and other companies makes so many different strings and racquets, instead of just producing what Federer and Nadal use, is because each racquet and string is going to suit one of a variety of different player types. RPM Blast isn't necessarily a "better" string than anything else out there, it just happens to work for the #1 player in the world. So base your decision to use it on whether it helps YOU play better. And if your arm starts to hurt, try stringing at a lower tension, crossing it as a hybrid with a softer string, or just going back to your old string.

USRSA Master Racquet Technician

observer said...


actually the product of weight(mass) and speed (velocity) is momentum-Newton's law. This is what determines rebound ball speed and spin. the string's grip does play a roll much like the rubber is important in table tennis. Force has nothing to do with it.

Your critique is otherwise correct. Any one not making a living from the game and especially younger players and all juniors should be wary of poyester strings and the large shockwave they send up the arm with each ball strike. Men should likely be more wary as they send a larger shockwave up the arm than women so the coaches are mistaken as well.

Physics and physiology play a major role in tennis and in staying healthy.

Pete said...

I stand corrected - momentum is the correct term, not force.

As for textured strings, the ball is on the string bed for such a small amount of time that any "bite" from the string would have a negligible effect. There has yet to be any scientific analysis proving that textured strings create more spin. It's just another gimmick.

Here is an excerpt from from Technical Tennis (2005) by Rod Cross & Crawford Lindsey that sums up my point:

From Chapter 4, section on Can Racquets & Strings Increase Spin? (pg 130-132):

"How do you create more friction and make it last as long as possible in order to generate more spin? Common tennis lore says that you can use:

Tighter.../looser strings
Denser.../open string pattern
Thinner strings
Rougher strings
Soft strings like natural gut
Polyurethane coated strings

... Each of the methods above does indeed affect how friction acts, but not the end result of that action. That fact is that all strings achieve about the same results with respect to spin. Some combinations of strings, patterns, and tensions do it by achieving a higher friction force over a smaller time and others by a lower force over a longer time. But laboratory experiments show that the end result is always the same spin.

You can increase spin by changing the racquet path or speed or by tilting your racquet, but not by altering the stringbed...

You don't get more spin from the strings, only from stroke technique. Your equipment may cause you to hit your stroke differently, and that may cause more spin. But the equipment has very little, if any, direct affect on spin."

observer said...


clearly the contact friction between a string bed and the ball can contribute to more spin. It is likely that this string has not yet been developed and may never as the contact time is short. The point is that polyester strings contribute little if any more "grip" on the ball. likely a negligable amount (unable to be measured) and thus the results you quote. clearly the attempts to make the measurement are because the theory is well accepted and pursued.

The point remains the same. These strings likely contribute to injury and wear to muscles, bones tendons and especially cartilage which does not readily heal itself.

Why use them? Why should kids use them? Why do they? Why should only harder hitting players (men) like the coach said, use them? knowledge and understanding of Physics and physiology remain important.

Best way to learn and generate spin, along with power, is to use proper grips and a proper swing path and then generate racket velocity with proper mechanics and don't forget to use the ground.

This is why Nadal is great. It is not the strings.



The Dude said...

Poly strings allow more force to strike the tennis ball. The stiffer poly strings create more force than less stiff strings. Force = mass x acceleration. Momentum = force x time (of force applied). Remember playing the egg toss game? If a thrown egg hits your hand with a momentum of 5 kg m/s, the force it applies to your hand depends on the time it takes for your hand to absorb the momentum. If you hold your hand very stiffly (poly strings) (and try to make the egg stop in a very short period of time) the ball exerts a high force on your hand, e.g. 100 N for 1/20th of a second. However if you let your hand 'give' and extend the amount of time it takes to absorb the momentum, the egg exerts a smaller force on your hand, e.g. 10 N for 1/2 a second.

Spin is generated by stroke production, force and the stiffer poly strings (more force). Nadal has his unique way of hitting the ball generated by stroke production, racquet head acceleration and stiffer poly string.

Yes, it will lead to more injuries, more so with juniors than with bigger stronger pros.

observer said...


Force has nothing to do with it. review basic physics. Strings absorb momentum and energy and then release it back to the ball. Force and time are irrelevant. Energy is 1/2 mv squared and momentum is mv.

strings and elasticity is what makes tennis diffeerent than all other soprts using firm objects in a collision. the strings introduce the trampoline effect which is where tremendous energy is exchanged twice between ball and racket with every ball strike.

Isaac Newton defined momentum as MV, not FT. You are not smarter than him and it has not changed.

observer of a little knowlege in tennis

The Dude said...

Observer, despite your condescending response, you failed to explain the very real and noticeable physical effects on spin/momentum when playing with poly strings that every pro player and hard hitting junior can feel.

BTW, if you understand mathematics, it is all related and the same:

F = d(mv)/d(t) = ma

where F is the net force applied, mv is momentum, m is the mass of the body, and a is the body's acceleration.

Review your physics, your math and Newton.

From Wikipedia: Second Law: A body of mass m subject to a force F undergoes an acceleration a that has the same direction as the force and a magnitude that is directly proportional to the force and inversely proportional to the mass, i.e., F = ma. Alternatively, the total force applied on a body is equal to the time derivative of linear momentum of the body.

I'm done with this, you can now continue your rant.

observer said...


I gueess wikipedia trumps Isaac Newton's precise definitions....you stated momentum equals force times time. Still incorrect, and not the same as accurate laws of motion, applied properly. It's not all the same that is why they are called LAWS

No one can explain why "every pro and hard hitting junior feels anything" since no one has spoken to them all. Another not very scientific statement.

BTW Serena uses natural gut.