Women performing the crawling exercises of Prof. Klapp, to strengthen the back. Photographs, 1949.

Rudolf Klapp was a surgeon and orthopaedist at Marburg/Lahn. His crawling exercises were intended to train the muscles of the back without overloading the spine. All the exercises were taken from the walk and movements of four-footed animals, on the ground that mistakes and deformities of the spine were very rarely perceived in four-footed animals. "Deformities are principally caused by the upright walk of men and that is this way the spine is too much loaded" (from accompanying text)