Rafael Nieto has an impressive role call of pupils hitting the mats in his martial arts classes: he is something of a closely guarded secret among the crew of fitness-obsessed celebrities who train with him. He is rumoured to be the chosen master for Sadie Frost’s inevitable return to body perfection post-birth, and Gemma Redgrave, Martin Shaw and Johnny Lee Miller have all been spotted going in and out of his studio.

So what is the attraction? Zen-Do, which translates as “all paths”, is a new, customised martial art created by Nieto. It is a finely edited mix of moves, drawn from a range of martial arts, including kung fu and kick boxing (punching and kicking), judo (throws), jujitsu (lots of floor work and holds), as well as yoga-style stretching for flexibility and preparation. It’s a fun and fuss-free hybrid, with an easy-going version of the philosophy common to eastern spiritual discipline. “The ultimate goal of Zen-Do, and of all martial arts, is not self defence, but self development, to be a better person”.

Nieto says that the physical benefits are second only to gymnastics. It’s total body fitness. It improves strength and lung capacity, and burns fat, because 40% to 50% of the class is cardio work out. And you know those legs, bums and tums classes? This is perfect for that”.

Queer as folk star Craig Kelly has been practising Zen-Do for three years, and enjoys the unpretentious close-knit atmosphere at Nieto’s classes. “I am not a gym person, but this is a good workout- I am dripping with sweat by the end of class. It’s a sressbuster without a shadow of a doubt. When I go in, I forget about the world outside, as I am so focused on the moves and the sparring, but it’s not full contact, it’s more about technique.

Increasingly, women and casual exercisers are turning to martial arts for self-defence, aerobic and anger-venting potential. This is made easier thanks to people such as Nieto opening sexy exercise studios with high-end facilities. Nieto’s studio Karmaa, opened in Chalk Farm Road, with Japanese sliding doors and airy exposed beams, and offers a wide variety of martial arts, holistic therapies, yoga and pilates.