The Del Potro Dilemma

It was a shock to see the great tennis champion Roger Federer blown off the court. It hadn't happened before that I was aware of at the time, and certainly not ever in a major final, but there it was, his racquet rendered useless. His opponent in the US Open that day was simply hitting the ball past him, avoiding Federer's greatness altogether. It was an awesome display and it was clear that the great one had a legitimate challenger in Juan Martin Del Potro of Argentina, US Open Champion 2009. It was such a strong statement from Del Potro, there was no doubt many more titles were in his future. Then he vanished.

Del Potro didn't disappear entirely but his career took a disastrous turn several months later when he sustained a serious wrist injury that sidelined him for many months. It was the beginning of a long series of injuries that kept him from re-gaining full momentum in his career. Though he had leg injuries mixed in along the way, the primary trouble spots have been his wrists, arms and shoulders.

For fans of tennis, it's been a huge disappointment not to see the career of Del Potro blossom entirely. While he isn't the first talented player to have a promising career cut short, Del Potro is unique in that he seemed to symbolize the dawn of a new breed of power player and people could sense he was special after seeing him dominate one of the greatest players of all time. Fans were hungry for more. He was larger than the average tennis player of the day yet moved well, and he was one of the first players to hit forehands consistently above 100 mph. The sound of the ball coming from his racquet was louder and deeper than that of any other player. He was crushing the ball and there wasn't much his opponents could do once he got rolling.

Del Potro was in the first few generations of players that grew up using super-stiff strings with super-stiff racquets. He had likely used super-stiff equipment for over five years and it's safe to say the implications of long-term use were not yet fully understood. Is it possible the career trajectory of this transformational athlete collided with the limitations of his equipment? Considering he never returned to full form, it's an important question for racquet manufacturers to consider.

In fact for BOLT, the story of his rise and fall and his attempts to rise again are a good illustration of the central challenge of modern racquet design: How can the power and spin capacity of new materials and technology, combined with the growing strength, speed and size of modern athletes, be fully optimized for performance while at the same time minimizing the risk of serious injuries?

The "Del Potro dilemma" describes the condition in which an athlete's capabilities begin to exceed the capacity of the equipment to deliver the required performance while preventing an unreasonable risk of serious physical harm. The athlete has maxed out the equipment. As athletes transform through generations, it's crucial that equipment design evolve and keep pace to ensure efficiency and safety. For BOLT and our development of a racquet specifically intended for modern high-impact tennis, the Del Potro story is pivotal.

To be clear, I do not have direct knowledge and details of Del Potro's injuries, his surgeries or any other details of his recovery efforts, or adjustments to his equipment. Undoubtedly every effort was made, medically and within the confines of conventional racquet design, to help him return to the court. Eventually he returned to competitive form on the tour, winning a title in Delray Beach, but he had to adjust his backhand stroke and he certainly hasn't returned to his dominant form.

The Del Potro dilemma highlights the fundamental limitation of conventional racquet design which is unchanged for over 100 years. The conventional design model can't be adapted sufficiently to the increasing strength and size of today's players and the type of tennis required to be competitive, without a significant loss of efficiency and a strong possibility of serious injury. It offers few options to adjust for a player the size and strength of Del Potro, and the fact that he hasn't fully regained his form suggests a sufficient conventional racquet solution hasn't been found.

The dilemma reveals the broken design model like this. Along comes an athlete with extraordinary size and strength, and hitting a tennis ball consistently harder than a ball has been hit before. The chief instrument of his trade is a high-tech racquet made of super-strong, super-lightweight carbon fiber composite material with strings that are barely elastic, which enable him to hit a tennis ball with colossal power and spin. He injures his wrist. It may be that the wrist injury is not directly related to impacting a ball. It could be a stroke deficiency. Either way, stroke deficiency or ball impact issue, the first step in providing a path to recovery and an eventual return to the tour would be to provide relief and protection from ball impact to the wrist.

In a conventional racquet, there are fundamentally two elements that can be adjusted to provide relief and protection for his wrist. Either the string-bed can be softened by changing string and lowering tension, or the racquet frame can be softened by making it more flexible. For an athlete the size and strength of Del Potro this is not a simple matter. If the string-bed is softened with natural gut at a low tension for example, he'll find comfort but he'll also have too much power. Natural gut is springy and doesn't impart spin like his usual string so his shots will tend to fly out. He could use his usual stiff, low power string, but he'd have to drop the tension so significantly in order to achieve sufficient relief from ball impact that he'd experience similar control/power issues as with the gut. The next stringing option would be a hybrid, including some combination of soft and stiff strings. Though the hybrid could provide more possibilities for spin and power, the range is not enough to allow him to play the game as he always did. It's between a rock and a hard place. It requires that Del Potro adapt his game to some degree in order to continue playing. The equipment should be adaptable to him, not the other way around. For his unique situation, a proper string set-up is very difficult to achieve in the context of conventional racquet design.

The second option of softening the frame by making it more flexible presents a similar riddle as the stringing. Impact shock can be reduced and a racquet can certainly be made more comfortable by making it more flexible, but other important aspects of racquet performance are sacrificed in the process. As a racquet becomes more flexible, it becomes less powerful. It becomes less stable too, resulting in a loss of precision and accuracy. These are serious performance limitations, particularly for an athlete like Del Potro. How flexible can a racquet be made for a player that hits a ball as hard as he does? In 2008 his racquet was one of the stiffest available, likely in part to manage the strength of his swing and control his shots. How flexible can his racquet be before he loses control of the ball flight? How flexible can his racquet be before he loses the power that he's accustomed to and the precision he requires?

The Del Potro dilemma marks the end of the current conventional racquet design model. It's the moment when the athlete has outgrown the capacity of the required equipment to fully achieve optimum performance. It's a moment that calls out for the implementation of a better engineering-design model with the capacity to adapt for years into the future, to the ever-improving capacity of athletes.

The design model that applies perfectly to racquets is a common one utilized in a myriad of industries, it has no ceiling on its development into the foreseeable future and it's no secret among the ranks of experienced racquet designers: suspension. The Del Potro dilemma provides a perfect illustration of how suspension can elevate racquet performance to accommodate an athlete of any size or strength or playing level. Del Potro requires a frame that's both flexible and rigid at the same time and he needs stringing that's both soft and stiff at the same time. Unfortunately, these combinations are impossible to achieve with a conventional racquet design. That's where suspension comes in.

The solution afforded by suspension is to add a third element to the racquet equation. The suspension element provides control and comfort, while the frame can be rigid, stable and powerful. For a unique athlete like Del Potro it provides a perfect resolution to his predicament. Instead of frame + strings, the equation becomes, frame + suspension + strings. All of the elements can be controlled independently. The frame can be as stiff and strong as required and the strings can be as stiff as desired too, while the suspension provides feel, forgiveness, comfort and control of ball rebound speed. That is not to say that some degree of flexibility in the frame has no value. Even in the context of suspension design, a flexible frame can have its place. It's when frame flexibility is relied upon as the primary driver of racquet response that it can become a problem.

Of course there's no way to determine if the career of the great Argentinian could have been rescued or lengthened. There is no doubt that string suspension is a perfectly aligned solution to his dilemma, the central dilemma for many more players in the modern high-impact power game of today and even more in the future.

Integrated string suspension on the head frame of a tennis racquet has been a hotly pursued and highly valued design concept for over 100 years. It's been pursued as a commercially viable product over and over for many decades without notable success but now, with the application of high-tech materials and modern production processes, the first commercially viable high-performance racquet with a full load-bearing spring suspension system integrated into the head frame is available. It's called Zipstrip. It's the foundation of the BOLT racquet product line.

Author note: I respect and admire JM Del Potro and I'm sure all tennis fans are saddened by his most recent attempt to return to competition. It's difficult to watch such a talented man unable to practice his craft. I hope all those around him will leave no stone un-turned in helping him get back on the court again in full form, if he so chooses.

BOLT has reached out to Juan Martin Del Potro's representatives a number of times offering to make Zipstrips available for his racquets. His manufacturer can easily adapt his preferred racquet to accommodate Zipstrips for play-testing. Of course we're happy to provide them at any time. We hope to hear from Del Potro's representatives soon.

For further technical info visit: BOLT Racquet Lab