Want the latest Scottish sport news sent straight to your inbox? Join thousands of others who have signed up to our Record Sport newsletter. Subscribe Thank you for subscribing We have more newsletters Show me See our privacy notice Invalid Email

I’M in downtown Miami with Andy Murray and I’m going downhill – rapidly.

A dream assignment in the Florida sunshine is turning into a nightmare as I toil desperately to keep pace with the US Open and Olympic champion.

While Scotland freezes, its favourite sporting son in on the gulf coast.

The sun is shining and the scenery’s breathtaking but this is no holiday.

This is pain in paradise and I’ve been invited along as Murray pushes his body to the brink, and beyond, in a determined effort to improve on what has been the best year of his life.

The 25-year-old is in the middle of a punishing winter training camp and to get a sense of the torture he endures for up to six hours on a daily basis he has asked me to join him.

By his own admission it’s purgatory and shortly after sunrise on a sun-kissed Miami beach I realise what he means.

I’m just halfway through the warm-up and it’s starting to feel like hell.

First up is a morning run with Jez Green, Murray’s conditioner and fitness coach, taking us through our paces.

A gentle giant of a man, Green has been by the Scot’s side since the start of his career and is widely regarded as one of the best in the business.

As we jog along the grabbing sand, which coupled with the 80 degree heat quickly saps your strength, he offers a valuable insight into the near superhuman capabilities of the world No.3.

Green said: “Andy is a phenomenal athlete. His time over short distances is the equivalent to 10 metres a second.

“He can move as fast as Usain Bolt over the first two or three seconds when he responds to a short ball on court.”

A 20-minute run complete, it is then down to the joy of 400m repeats.

Speed endurance is a key feature of the Dunblane star’s regime and to watch him churn out endless and agonising repetitions is awe inspiring.

My lungs are screaming and my legs feel like blocks of lead after the first 400 metres when Green informs me there are only another nine to go.

The sprints soon become jogs as the lactic acid almost brings me to a halt.

Murray regularly rattles out these drills at full speed with just a minute’s rest in between – his times not far off the world’s top athletes.

Green said: “The amount of strength Andy has in his legs is incredible. I reckon he is capable of running a sub 50 second 400m on the track.”

As we complete the session with a gentle recovery the topic of conversation moves on to this weekend’s Sports Personality of the Year awards, for which Murray has been short-listed.

The great and the good will gather to celebrate the most amazing 12 months in British sporting history – although for the fifth consecutive year the Scot will not be present.

He’d love to be there but with the Australian Open looming large on the horizon there is no time to bask in the glory of an extraordinary summer.

There is also the fact his one and only appearance at the glittering end of year ceremony featured an embarrassing incident in a toilet cubicle.

On the back of winning the junior US Open title in 2004 he won the Young Personality award but only just made it on stage to collect his gong.

Laughing, he said: “I was almost late for that one because I somehow managed to get myself locked in the toilet before I was due to go on stage.

“Someone had to come in and open the door with a knife! I haven’t been back since.”

A BBC film crew will be on hand to beam back live pictures if Murray does win.

Mercifully, there were no cameras around to capture my attempts at Bikram – another exercise designed to make a Yoga virgin like myself feel even more inadequate.

This is the hardcore version of Yoga where you complete a series of complex stretches in a studio heated to just over 40 degrees.

Preventing myself from passing out was an achievement in itself although I had to admit defeat when it came to standing on one leg with the other wrapped around my head.

The 90-minute classes are excellent for injury prevention, flexibility and concentration.

Murray said: “The training I do isn’t always fun and the last few days have been extremely hard but this is the most important month of the year for me.

“This is the only time when I get to do a proper five-week training block – and you cannot take any shortcuts.”

As I was quickly finding out, there are no half measures where Murray, who will cut his festive celebrations in Dunblane short to fly to Abu Dhabi on Christmas day, is concerned.

But while the morning sessions were tough, he was saving the best for last.

After lunch it was on to the gym at the Four Seasons Hotel and a head-to-head duel with the dreaded ‘VersaClimber’.

It’s a weird-looking climbing contraption designed to test the strength and stamina of even the best sportsmen on the planet.

You pump your arms and legs simultaneously and go flat out for one minute intervals trying to maintain a certain level.

Green reckons it is the most under-used piece of equipment in gyms across the country – but thinks it is arguably the best.

Impressively, I kept pace with Murray for the first minute.

The fact he then completed a mind-boggling 30 intervals at the same intensity while I had to be helped off the machine was neither here nor there.

Murray said: “It is by far the hardest thing I do. A lot of boxers and UFC fighters use it.

“You’re climbing with your arms and legs and we have it hooked up to computers so we can see how hard I’m working. It’s so tough.

“I couldn’t even walk when I came off it earlier in the week. My legs all cramped up when I was walking home and I just couldn’t move.”

A fascinating day was rounded off with several sets of squats, chin-ups and press-ups before Murray headed off to scoff 48 pieces of sushi and I dragged my aching body to the nearest bar for a light refreshment.

Two hours later a text arrived from him expressing his gratitude and thanking me for joining him in Miami.

He finished off by saying: “Just been for deep tissue massage. Very sore but not as sore as you will be in the morning!”