Rory McIlroy’s physical transformation — not to mention an even more important mental change — has been remarkable over the past four years and he was back at it in London yesterday when he made one of his regular trips to GlaxoSmithKlein’s Human Performance Laboratory.

“Back to work today @GSK_HPL #betterneverstops,” the new Open champion informed his 1.97 million Twitter followers, posting several pictures of another exhaustive and exhausting physical check-up.

Back in April, he was pictured looking spent as he had his sweat composition analysed “after an hour on the watt bike in a heat chamber.” It was a similar tale back in February at a previous check-up.

Now working out twice a day, McIlroy’s chiseled physique has made him and even more impressive and longer hitter of the golf ball. But his GSK visits are also about nutrition strategy and planning, which allow him to tailor his fitness regime to suit his current state of well-being and maximise his performance.

“It’s fascinating,” McIlroy said earlier this year. “Coming to the GSK Human Performance Lab gives me detailed insight into the workings of my body and what I can do to improve my performance.

“There’s a growing number of players, both fitter and stronger, competing for majors every season, so it’s really important I look at the physical and cognitive performance aspects of my game to ensure I keep improving.”

Facilities at the centre, located at GSK's global HQ in Brentford, include a swim flume, a 4G artificial turf area and running track for speed and agility testing. 

There is also an environmental chamber capable of producing conditions ranging from -20C to +50C degrees; humidity levels of between 10 and 90 per cent and oxygen levels equal to those at 5,500m altitude.

McIlroy’s training regime, which he intensified when he was dating Caroline Wozniacki, starts early in the day, especially over the winter.

“I’m usually in the gym at seven, and then I'm in there for like an hour and a half, get some breakfast, go to the course,” he said. “I'll probably practise, hit balls and short game and stuff, for maybe ten until one and get some lunch and go out and play some holes, play nine or play 18, and then some days I'll be back at the gym from 5.50 to seven and get some dinner and go to bed.”

There’s no doubt McIlroy’s physical fitness helped him win The Open, where apart from his general play, his mental strength was clearly in evidence. 

“For me to play golf at this level is all mental,” McIlroy said this week. “A lot of guys can go out and shoot 65/66 but it’s being able to do it when you need to.

“If I can be as mentally strong, week in, week out, as I was in The Open, the bad rounds or bad weeks will definitely be avoided.

"It's all a mental thing for me. The physical ability is always there but it's being able to bring that out in myself. If I can get my head right, as I feel I have, then tournaments like The Open last week will happen a lot more regularly.”

His  use of the trigger words “process” and “spot” helped him win his third major and he has no plans to take on a mental coach.

"There are little (mental) exercises you can do,” McIlroy explained. “I have always tried to stay away from psychologists because I feel if you have something that works for you then you have to go with it. 

“It is very individual. It's your own mind, you own thoughts. It's hard for someone to tell you what to think."