Page 46 of Short List. Read the full article here.

Ben Isaacs grabs a St Bernard (well, his travel card) to take on the latest in time-saving fitness technology

When I was told I had to train at altitude, I was excited. Would it be NFL drills at Mile High Stadium in Denver? Or working out in the Alps?

I needn’t have got my passport out. My trip took me to Bank in London and the nearby Sweatshop flagship store. In the lofty heights of the first floor is the Altitude Centre – a sealed room with air replicating 2,750m above sea level.

That’s more than 1km higher than if you moved the Shard to the peak of Ben Nevis and stood on the top. Before I entered the room I had to get checked out – blood pressure test, health questionnaire, next of kin’s phone number. Exercise at extreme heights is serious business.

My trainer had me do some interval splits on a running machine wearing a heart monitor. He noted my speed and heart rate on one of the displays. The beauty of running at altitude is that the lack of oxygen makes your heart work harder.

This doubles the effect of cardiovascular exercise, thus halving the time needed to become a faster runner, get fitter or lose weight. As I reached the final sprint of my short (15-minute) run, the screens revealed my heart rate had entered the VO2 Max zone. When your heart is beating this fast from exercise, you have surpassed ‘hardcore training’ and entered the highest level your body can endure. The result? Fat-burning faster than a football shirt on a bonfire.

Amazingly, I was no more out of puff than if I’d been running in a gym. It was as though the air itself was doing the hard work for me.

If you normally run for half an hour in the gym you would get double the benefit doing it at altitude – an hour of fitness development and fat-burning for 30 minutes of your time. Here in the heart of Britain’s financial centre, that’s a pretty good return on your investment.

From £28 a session;