by David Cox Back in 2009, a leading sports scientist in the UK speculated that Rafael Nadal had the knees of a 33 year old. As for the age rating of those knees right now, who knows? Maybe nearer 40. After withdrawing from the Olympics, Toronto and Cincinnati, Nadal's decision to pull out of the US Open came as no surprise.
You have to go back to 2003 to find the last time Nadal entered one of tennis' four majors without competing in a warm-up event. "It's obviously a great shame," Andy Murray said, when informed of Nadal's withdrawal from the final major of the year.
"I like Rafa a lot as a friend. I'm disappointed for him and I think for tennis and also the major competitions, it's a huge benefit when you have the top players playing.
It's obviously tough for him. He's had trouble with his knees in the past.
So, you know, I hope he can rest, doesn't come back too early, and gets them fixed so he can get back to playing his best tennis." However the news which really shocked tennis pundits across the world was the revelation that Nadal was been battling crippling pain in his knees throughout the spring European clay-court stretch.
He may have won Monte Carlo, Rome, Madrid and a seventh French Open title this year but those exertions effectively ended his 2012 season. No player is more accustomed to playing through the pain barrier than Nadal, a man who's been dogged by serious injuries since the age of eighteen and while this news makes his feats on the clay this year appear even more Herculean, maybe it shows that he realises he can no longer play a full season and hope to keep his inflamed knee tendons under control? With a game style which places particularly punishing demands on those joints, one wonders why Nadal has not considered more of a reduced schedule in recent years? His commitment to the Monte Carlo (a tournament both Roger Federer and Novak Djokovic have skipped in recent years) and Barcelona (a non-mandatory ATP 500 event) tournaments may be admirable but his reluctance to cut down on his traditionally intense clay-court campaign may ultimately shorten his career.
Perhaps it is loyalty to the events which have served him so well over the years but on a more sombre note, perhaps Nadal realises that his years on the tour are numbered and he's determined to seal his place as one of the greatest clay-courters in history while he still can? The Spaniard has suffered with tendonitis in both knees since the age of 21 and his hopes of defending his maiden Wimbledon title were ended three years ago when he had to pull out on the eve of the tournament.
Back then Sven Groneveld (the renowned former coach of Michael Stich, Greg Rusedski and Caroline Wozniacki) said that he'd never known a player to be affected with knee problems at such a young age. "When kids play on hard surfaces from a young age, it has something to with their growing, increasing the chance of getting it [tendonitis]," Groenfeld said.
"During growth it is not good to play on hard surfaces." However while hard courts are probably not to blame for Nadal's injury woes (he spent most of his youth training on the clay courts of Mallorca), the Spaniard entered the professional ranks extremely early compared to many of his peers.
He was playing (and winning) futures while the likes of Murray and Djokovic were still find their feet in the juniors, reaching the third round of Wimbledon aged just 16. And while his great rival Federer is a master in economizing movement, gliding across the court, Nadal pounds his cartilage into oblivion with every stride.
Modern sports science has certainly played a huge part in Nadal being able to manage the problem for so long - anti-inflammatory medications, acquatherapy and progressive muscle exercises all playing their part in the Spaniard continuing to compete at the very highest level.
Once tendonitis has taken hold, it is one of the hardest injuries to shake off with tendons taking far longer to recover than more elasticated muscle tissues. Nadal has shown his ability to bounce back in the past. After he was forced to retire in the quarter-finals of the 2010 Australian Open, many doubted his ability to win more majors.
He made a mockery of those predictions by winning the next three slams, including the US Open. However one senses, the problem is far more severe this time round and one wonders if some of the gruelling slugfests he's contested with Novak Djokovic over the past couple of seasons have played their part in his breakdown this summer.
Djokovic's emergence as a real contender in the past eighteen months has seen Nadal push his body to the limit in training in an attempt to keep up and that extra strain may have led to irreversable damage.
"That's what is sort of scary," Federer said during Cincinnati.
"There is obviously the whole debate going on if he is going come back for this year. I hope he will. He's definitely got some more weeks off now. I hope in hindsight this is a very smart decision by him (to skip the US Open). But it's obviously a big blow and disappointing news for the tennis world."