NEW YORK, April 25, 2014 — High-performance multi-layered solid core tennis racquets won “hands-down” over conventional hollow racquets in a recently published scientific study that measured the effectiveness of the two designs in dampening shock and vibration and reducing the harmful energy transmitted on ball contact that can cause wrist, arm, elbow and shoulder injuries.
Three dual-core and two triple core frames that are exclusively designed and manufactured by the Xenecore and Donnay brands were tested against five hollow-core racquets from the leading manufacturers in the study published by Elsevier Ltd., a global academic publisher of medical and scientific literature.
“Overall, the dual and triple core designs demonstrated significantly lower shock forces and vibratory forces and dampened vibration quicker than the hollow designs,” reported the authors from OrthoKinetic Technologies. LLC of Southport NC, which conducted the test using an ISO17025 certified third-party independent test facility and a team of highly qualified mechanical and biomechanical engineers.
The dual and triple core designs successfully dampened the oscillations (the pendulum-like back-and-forth movement of the vibrations after impact) by at least 35% for the dual core and 50% for the triple core compared to the hollow frames, according to the study. The range of vibration dampening time in all models tested was from two-tenths of a second for a triple-core frame to .8 seconds for one of the hollow frames.
Additionally the authors reported that the amplitudes (the greater the amplitude the more energy it transmits) during oscillations following the initial shock impulse force for the core-handle design resulted in a reduction of shock force “by at least 65%” compared to 22% for the hollow frames.
It is well documented that the long-term repetitive impact on the upper extremities in tennis can increase the risk of tissue fatigue and injury, leading to inflammation of the tendons and soft tissue in the wrist, elbows and shoulders and small stress fractures and chronic degeneration of the surrounding soft tissues from small tears that were incompletely healed.
“The solid-core racquets help players avoid arm injuries because the tendons in their elbows, forearms and shoulders are seeing less stress,” said Dr. Joshua Dines, an orthopaedic surgeon specializing in Sports Medicine at New York’s Hospital for Special Surgery and former team doctor for the U.S. Davis Cup team.
“I think in addition to using proper technique and avoiding overuse, solid-core racquets provide a huge potential safety benefit for recreational players.”
The purpose behind the study is that there is little that has been written and documented about the effects of racquet frame design on the extremities compared to volumes on how poor player mechanics and even how tight and harsh string can result in increasing stress transfer and vibration from the racquet to the player.
“Poor stroking technique is frequently accused, conveniently diverting scrutiny from racquet design, but, as the calculations on this site prove, risk factors for tennis elbow include: (1) light racquet weight and (2) head-heavy balance. Stiff frames are also bad,” according to RacquetResearch.com.
The International Tennis Federation (ITF), the global governing body of the sport, reported in the British Journal of Sports Medicine in 2006 that “the combination of the increased stiffness of modern rackets and the tendency for tennis balls to have become harder has led to an increased shock transmission from the racket to the player, which is probably a major contributor to tennis elbow.” The ITF also states that about half of recreational tennis players will suffer at least one bout with tennis elbow during their playing lifetimes.
This epidemic wasn’t the case when all tennis racquets were made from flexible solid-core wood. Vibration on ball contact disappeared quickly because it was dampened by the flexibility of the solid wood. But they weighed as much as 16 ounces, making them difficult to maneuver, especially for smaller and less accomplished recreational players.
However, with the advent of new carbon materials racquet manufacturers were able to reduce weight by making the frames hollow and compensate for the weight loss with much stiffer frames that were much more powerful than the flexible wood frames.
But while the lighter and stiffer racquets have made the game more accessible for recreational players, some critics say it has gone too far. Tennis legend Martina Navratilova, for one, complained that modern composite racquets have “added too much power and have put enormous wear and tear on young bodies” in an article titled “Sidelined in their Prime” that appeared in the Jan. 9, 2009 edition of Newsweek.
“More injuries are likely,” she sternly warned, “unless tennis’s governing bodies modify the [large numbers of tournaments on the] calendar and fight back against the racquet manufacturers that have hijacked the game.”
“The study shows that hollow rackets transmit 45,000 pounds of force per match and kids in intensive training programs hitting 2,000 balls a day means 400,000 pounds of force is transmitted to the arm with hollow racquets,” said Jerry Choe, CEO of Xene Corporation that designs and manufactures the Donnay and Xenecore racquet brands. “After six straight months of 6 hour days, they will need surgery.
The Xenecore material and process results in the manufacture of solid frames that achieve the highest strength-to-weight ratio in the industry,” added Choe.
As a result, the Xenecore and Donnay racquets match hollow racquets’ power potential in a flexible frame like the old wood racquets but without the weight. “It’s what we call ‘arm-safe performance,”’ Choe said, “all the zing but without the sting.”
Other racquet companies fill a few of their models with a solid core substance for their sponsored tour professionals and high-level tournament players but the substance (usually polyurethane) makes the racquet too heavy for recreational players.
“It’s not just a claim or a slogan,” he adds. “We’re so confident that we’re guaranteeing players won’t suffer an upper extremity injury while using a Xenecore or Donnay racquet. If they do – even if it’s a wrist, arm, elbow or shoulder injury from improper stroke mechanics, they can choose to return it for a full refund with a note from the attending physician about the injury.”
(To see the full study entitled “A mechanical study on tennis racquets to investigate design factors that contribute to reduced stress and improved vibrational dampening,” go to http://www.sciencedirect.com/science/article/pii/S1877705813010667 and click on the “download the PDF” in the upper left-hand corner.)
Donnay and Xenecore designs, manufactures, and distributes premium tennis equipment, apparel, and accessories under the Donnay brand. The technologically advanced and innovative new X-P Dual, X-Dual and Formula and Pro One racquets developed using XēneCore™ Technology represent the return of Donnay to the global market. Headquartered in New York City, the company’s products can be found in tennis specialty shops as well as online.