Despite the cold and many other potential hazards, naked from the ankle down is the way Anna Toombs likes it, and she gets plenty of catcalls in the street as a result.

The 35-year-old co-founder of the personal training company Barefoot Running UK says she’s lost count of the times people yell “where are your shoes?” as she and partner David Robinson negotiate London’s parks and pavements to indulge their passion and train their clients.

“People give you a lot of weird looks,” says Robinson.

They are also getting a lot of inquiries.

A surge of interest in “natural,” or barefoot, training has seen runners around the world kick off their arch-supporting, motion-controlling, heel-cushioning shoes and try to feel the ground beneath their feet.

Top scientists — from sports physicians to podiatrists to evolutionary biologists — are jumping in too.

At a recent sports science conference in London, hundreds of participants, many of them shod but a few daringly barefooted, flocked to a two-hour long discussion about the merits or otherwise of running without shoes.