In his forthcoming book, photographer Bertil Nilsson documents the work of circus acrobats. It's a beautiful tribute to the human body; the grace and strength of the artists made more apparent by the fact that each performer was photographed naked...

For Undisclosed: Images of the Contemporary Circus Artist, Nilsson visited 17 practice spaces, largely in Canada and Europe, and took photographs of 47 different performers to complete his five year study of the subject.

The series features acrobats, ‘aerialists' and contortionists, many of whom are caught in mid-flight or mid-pose as they rehearse their routines.

Many of the images are more abstract, revealing twisted flesh, straining muscles and even the effects of an acrobats' regime on the body: rope marks appearing like tyre tread on one performer's skin.

The book, made in collaboration with designer Wayne Ford and with an essay by Laura Noble, is published this September by Canalside Books and can be pre-ordered from undisclosedcircus.com. More of Nilsson's work can be seen at bertil.co.uk.

The cover uses GF Smith Colorplan Amethyst with Wire emboss, a tip-on image with matt varnish and transparent foil stamp on the spine. The endpapers are GF Smith Colorplan Pale Gray. The book is set in Lyon and printed in duotone on Hello Fat Matt 1.3 Natural 150gr by Lecturis in Eindhoven, The Netherlands.