Double-edged sword: The risk vs. reward proposition of polyester strings 

Over the past few decades, no area of equipment has arguably had a bigger impact on pro tennis than polyester strings. Their unique properties allow users to swing with abandon to hit with shots with huge power and spin that remain under control. The downside is the stiff and unyielding nature of the string can take a toll on the body. While its life span is long, its playability is short-lived.

What that means? Just because the strings suit the pro game doesn’t make it right for mere mortals.

If you’re wondering whether you should be using polyester strings, start by answering these three questions.

Are you a string-breaker?

Polys first earned their stripes because of their resiliency, which is a real asset if you’re the type of player who is constantly texting your stringer.

However, if you rarely break strings, playing with a poly may not be necessary. That’s because you need a fast, vertical swing path to be able to bend and move the string to take advantage of its snapback capabilities. That’s what gives shots that bump in spin. If you don’t have the speed and type of swing that moves the strings—one that would snap a softer multi-filament with high frequency—it will just feel stiff and uncomfortable, and you won’t reap the benefits.

How old is your arm?

If a lot of tennis mileage has resulted in any sort of chronic wrist, elbow or shoulder pain, the stiffer hitting platform of a poly string bed will probably only make it feel worse. Whatever extra spin you can muster isn’t worth the discomfort and potential added damage it will relay to your arm. You’d be better off playing with a string that is more forgiving.

On the flip side, a developing junior with a healthy arm and big strokes may still want to wait until they’re physically able to handle the rigors of a polyester.

“I recommend waiting until their late teens,” Mark Kovacs, a high-performance coach who has worked with top touring pros and the USTA's player development program, says. “Opinions vary, but I would target until after a young player has their big growth spurt before letting them use polyester strings.”

In either of these instances—young or veteran—Kovacs believes it best to always start with a hybrid before ever transitioning to a full bed of polyester string. Swapping in a softer multi-filament in the cross strings will help mitigate the wear and tear. The difference in spin generation is negligible—lots of pros even opt for this setup—and it’s safer for the arm.

Are you willing to string low and often?

The inherent stiffness of polys means you can—and should—string at lower tensions. Once again, if you’re following the lead of the pros, it has become popular on the tours to string quite low. It’s not uncommon to see tensions in the mid 40-pound range. Some players even drop into the 30s. Not only does this take some of the starch out of the string bed, making it more arm-friendly, but promotes a little more string movement for easier pace and spin.

However, for many recreational players, it’s heresy to string at such low tensions. They think they’ll lose too much control. Polyesters lose tension faster than other strings, so it will only get worse. Their racquet will play like a lacrosse stick, and because they can’t break the string, they’ll be stuck with a unpredictable, launchy frame.

That's why it’s recommended to restring polyesters more frequently than other strings. Not only do the strings lose tension quickly, but they degrade fast with play as well. The combination is why they lose playability and become “dead” well before they’re ready to snap. Keep in mind, pros never test a poly’s durability: They switch to a fresh racquet after (at most) a few hours. Often sooner. So if you’re going to regularly use a full bed of polyester strings, you should replace them at least every couple of months to maximize performance and preserve arm health.