German photographer Martin Schoeller's new book of portraits aims to highlight the contrast between the extreme physiques of female bodybuilders and the vulnerability expressed through their eyes and nuanced facial expressions. Schoeller is known for treating all subjects the same, whether the New York-based photographer is shooting celebrities for Vogue or unknown members of the Pirahã tribe in Brazil.

You can view a collection of his work at the Smithsonian National Portrait Gallery through 29 September 2009 or grab a copy of the book, "Female Bodybuilders," available through Pond Press or Amazon.