For fifty years, Professor Hermógenes' centre in downtown Rio has been at the heart of the city's yoga movement. There is barely a teacher in town that hasn't been influenced (or, indeed, taught) by him, and since hanging up his mat in his eighties, his grandson has taken over the centre's running. If it is authenticity you are looking for, then the pioneer's several books and doctorate from the World Development Parliament in India should suffice, and the classes still resonate with his influence, down to the separation of the sexes to ensure maximum concentration. Meditation classes are also held, but all require a medical clearance note, two passport photographs and R$30 registration fee.