Maybe it was something he’d eaten. Perhaps it was nerves. Surely it wasn’t a lack of match fitness?
When Andy Murray started wincing with the severe pain of cramp during his first-round match at the US Open, no one was more surprised than the Scot himself.
“It's not the worst I have ever felt necessarily, but it's the worst I have ever felt after an hour and a half of a tennis match,” he said after struggling through to beat Robin Haase in four sets and performing his very own version of Monty Python’s Ministry of Silly Walks.
It’s unusual – not to mention silly – for a tennis player to start seizing up after just 90 minutes of play. Especially in several regions all around the body at the same time.
As Murray admitted: “For me it was unexpected. Normally it's kind of a gradual thing – after two-and-a-half, three hours, maybe. [But] it came extremely early on.”
The problem is that sports scientists can’t agree on the exact causes of or remedies for cramp. So no one knows for sure how best to prevent it.
Watch highlights of Murray's US Open final win over Novak Djokovic in 2012:
The jury is out. [Presumably, they’re in their deliberation room vigorously rubbing each other’s leg muscles.] Tired muscles certainly don’t help – but a professional athlete like Murray wouldn't have tired muscles after just 90 minutes of play.
A lack of electrolytes is certainly a contributing factor – but Murray insisted he had eaten and drunk correctly before his match. And the fact he urinated straight after his match was proof, he said, that he wasn’t dehydrated.
There are sometimes neurological reasons for cramp. An affliction called paroxysmal exercise-induced dystonia (or PED) causes sudden involuntary movements in all areas of the body. Could Murray really have been suffering from this?
He was as baffled as everyone else. But here was his most sensible explanation:
“The fact that it was the whole body would suggest that maybe it was something to do with my eating or drinking. If it’s through fatigue in one part of your body, then, yeah, that would probably be down to conditioning. But cramping in my left forearm? I mean, I didn't use my left forearm a whole lot today compared with other parts of my body.”
At least Murray was able to close out his match. Spare a thought for poor old Steve Johnson, American No.3. In his first-round match his hand started cramping so severely that he couldn't even hold his racket. Then his leg went. Then his arm, too.
Eventually he had to abandon the match. Officials even brought out a wheelchair because they thought the hapless chap might not be able walk back to the locker-room.
'”It's not the end of the world, but it feels like it right now,” he said.
Murray is 3rd favourite to win the US Open at 11.00