As far as Rafael Nadal is concerned, the more tennis played on grass, the better it is for his health — and the numbers back him up.
The former world No. 1, who has long been troubled by niggling injuries, applauded the ATP’s decision to lengthen the time between this year’s French Open and Wimbledon by one week — opening up slots for a precious few more tournaments on grass.
“I think clay and grass are surfaces that are a bit less aggressive for the body,” the Spaniard, who has spoken in the past about hard courts taking a toll on his body, told CNN’s Open Court.
“To save a little bit more (of) your body, it would be great if we could play more and more on grass and clay.”
Nadal knows exactly what he’s talking about, according to a leading sports physicist in Australia.
“He is correct; injuries on grass are less common,” said Professor Rod Cross of Sydney University, who co-wrote the book “The Physics and Technology of Tennis,” told CNN.
There is strong evidence to back up these claims. Cross has compiled data since the 1970s on the number of incomplete matches in the four grand slam events, and the results are eye-opening.
In 2014, male players withdrew from 10 matches at the Australian Open and a further 10 during the U.S. Open — both played on hard courts. The clay-court French Open had five incomplete matches, while Wimbledon’s grass sustained only one, according to Cross.
Even though hard courts are nowadays by far the most common surface on the men’s and women’s tours and thus more injuries could be expected on them, Cross explained that they are not as forgiving because of their strong grips, which allow less sliding and create more impact on joints.
“(There is) a bit more thumping and jarring, and the large force is transferred to the rest of the body, which causes injuries,” he said. “That’s part of the problem.”
Women, he said, sustained far fewer injuries in the grand slams mainly because they played best-of-three sets, as opposed to five. Females withdrew out of only nine grand slam matches in all of 2014, with Wimbledon again posting just one non-completion.
Less power in the women’s game is also a factor. “Men can do much more damage to themselves,” Cross said.
Cross has also compared withdrawals in grand slams from 1978-1982 (when two of the four majors were played on grass, and players still used wooden rackets) to those from 1995-2004.
In both time periods, Wimbledon had by far the lowest ratio of match withdrawals: 2% in 1995-2004, and only 0.3% from 1978-1982.
On the other hand, Australia’s switch to hard courts in 1988 led to a nearly fourfold increase in the number of injury dropouts. From 1995-2004, 3.1% of matches were withdrawn versus just 0.8% during the earlier, grass-court period in Melbourne.
The U.S. Open — which switched to DecoTurf, a type of hard court, in 1978 — posted by far the highest ratio of incomplete matches, at 4.3% for the 1995-2004 period.
The results were posted in a report by Cross in the Medicine and Science in Tennis journal.
ATP president, Chris Kermode acknowledged that re-introducing grass is a step in the right direction: “(Rewarding) a variety of styles of play is important for the sport overall,” he said in a statement.
‘We look at providing a variety of surfaces throughout the season on the ATP World Tour. With this in mind, the newly strengthened and expanded grass-court season…represents a positive development,” he added.
But surface alone isn’t to blame, according to Cross. He observed that the advent of larger graphite rackets — adding four centimeters in width on average over their wooden counterparts — called for less precision, enabling players to shift their grips to swing as hard as possible.
The increased speed in the game has also resulted in more injuries, he said.
That has also changed the game entirely where matches are increasingly fought out on the baseline, resulting in extended rallies.
“Players don’t rush the net anymore because they will either be passed on the sideline, or they will be lobbed,” said Cross, who still enjoys playing tennis at the age of 72.
One more intangible could be at fault for higher dropouts: hot weather’s impact on hard courts.
“Grass is 10 to 20 degrees cooler than hard courts on a hot day,” said Cross, who has measured the temperature of the surface during Australia’s summer, when its Open is played.
“On a hot day like 40C (104F), the temperature on the court itself can be 60C (140F). If you took your shoes off you’d actually burn the skin off your feet.
“That’s physically exhausting and I think it’s crazy to have courts that are so hot,” he added, noting that heat exhaustion may have added to the number of incomplete matches on hard courts over the years.
Nadal has been dogged by various injuries over the years to his his knees, back, wrist and feet. Last year he had stem-cell treatment on his back after missing playing time with a sore wrist and appendicitis. Ahead of Wimbledon he is ranked 10th, his lowest position in a decade.
After losing in the quarterfinals of the French Open to world No. 1 Novak Djokovic earlier this month, Nadal appeared to be back on track with a win at the Mercedes Cup in Stuttgart — his first grass title since his second Wimbledon success in 2010.
Just two days later, however, the Mallorcan stumbled again, losing in the first round of the Aegon Championships at London’s Queen’s Club to 65th-ranked Alexandr Dolgopolov of Ukraine.
Nadal has won nine of his grand slams on clay, and two on grass; his total of 14 is tied for second all-time among the me with Pete Sampras.
Until 1975, three of the four tennis slams were played on grass. Costly and cumbersome upkeep, however, left only Wimbledon as preservationist of the grass court once Australia switched to a synthetic hard court in 1988.
Today, onlly 10 percent approximately of ATP tournaments are played on grass, with a majority on hard courts (37) and clay (22).
Nadal hopes the extra week on grass will be the start of a new trend, but isn’t holding his breath.
“It’s something that is just a dream,” he said, of expanding the grass season. “It will not happen I think, but having one more week (on grass) is something that means a lot to everybody and the players too, so we hope that it continues for a lot of years.”
Like most Spaniards, Nadal grew up on the clay courts, and his record nine French Opens will always identify him with that surface.
But Nadal has also enjoyed great success at Wimbledon, reaching five finals and winning two — including the epic 2008 duel against longtime foe Roger Federer.
The five-set battle, twice interrupted by rain, was the longest singles final in tournament history, and a match considered by many within the sport as the greatest of all time.
Nadal was not able to defend his Wimbledon title in 2009 due to a knee injury.
“Obviously Wimbledon is very, very important for me personally,” he said. “(It) doesn’t matter what happened in the past.”
Should Nadal stay injury-free over the upcoming fortnight, he could be a dark horse on the rarest of all surfaces.