Would you take on an exercise course so tough they have a paramedic on standby? One plucky writer was up to the challenge... and lived to regret it 

• e-mail

I'll admit, when I was asked to give Gymbox's Flatline challenge a go - I hadn't really looked into it.

'Run around a bit, pick up a few weights, it really can't be that bad', I confidently thought to myself.

How wrong I was. How very, very wrong.

As soon as I nervously strolled through GymBox's arena of physical perfection in Farringdon, central London, I became aware that this was going to be no walk in the park - more a sprint through a park while being chased by a pack of hungry Rottweilers.

Reporter Alex Matthews pushed his fitness to the limit when he tried GymBox's Flatline class

The Flatline was designed by the elite trainers at GymBox and is an extreme test of your fitness, with both strength and stamina pushed to the limit.

Essentially a timed circuit course, the Flatline features different stations involving kettle bells, an atlas stone, burpees, a cycle on an assault bike (which, by the way was true evil), a rope climb and a walk with weights.

I pathetically managed one set of the circuit, you're supposed to complete four and the course record by trainer George Edwards, is six. 

But, as I said, if you think it looks easy - you're just wrong. 

This course, billed as the 'hardest and most dangerous gym class in the world', is designed to break you. And break me it did.

As I got warmed up, I cheerfully spoke to the gym's Master Trainer, Firas Iskandarani, who like most of the staff, resembled more a Greek god than mere mortal.

The course looked standard enough, but before the fun was to begin a form was whipped out. They wanted me to sign a waiver before I took on this circuit of screams.

Essentially a circuit course, Flatline includes different stations featuring atlas stone lifts, weights, burpees, an assault bike, a rope climb and walking weight lift

On the assault bike Gymbox's master trainer Firas instructs you to pedal as fast as you can until a set amount of calories are burnt

I became concerned, but tried to reassure myself it was just part of the gimmick.

Then it was announced that the paramedic that oversees the exercise was stuck in traffic. Paramedic?!

Yes, Gymbox are so concerned about the strain of their endurance obstacle race that they make sure they have a resident medic on-board.

In case, you know... people die and stuff.

But to be honest, the actual moment I realised I was in deep trouble was after Firas took me through the 'warm up'.

Gymbox ask people to complete four laps of the circuit, but Alex could only manage one

 After finishing on the assault bike, people then have to climb up a rope - in a position of their choice - twice, before hitting the next station

I couldn't even get the stretches right for a start. 

But then he ordered me to cycle as hard as I could on the 'assault bike' - an apt description -  and test out the kettle bells, atlas stone and have a go at climbing the rope.

By the end I was knackered and we hadn't even got started.

I tried to jump up and down to get the blood flowing but my legs were like jelly.  

What followed was agony and I only lasted one round. 

The final station is a walking weight lift where people have to march up and down a set distance twice within a time limit

The course record for Flatline is held by Gymbox trainer George Edwards, who managed an incredible six. Alex is pictured recovering after his less than impressive effort

By far the hardest station was the assault bike - after the first three stations your body is close to giving up and with only a few seconds rest after each, it feels impossible to continue.

However, expert trainer Firas urged me on and I pulled through.

By the end of the first round I was broken, I felt ashamed for not giving it another go - but relieved that the pain was over.

The Flatline is an incredible test of your physical and mental strength over a 45 minute-period. It's painful but on reflection a lot of fun. 

Will I go back? Absolutely, but not any time soon.

• For more information on Gymbox's Flatline course visit: gymbox.com/classes/flatline