Xiuzhen miyao, a gymnastic (daoyin/qigong) text of unknown origin, was rediscovered and published with a preface by Wang Zai in 1513 (8th year of the Zhengde reign period of the Ming dynasty). It records 49 exercises. This illustration depicts Wu long tan zhua (Black Dragon stretches out its claws), a technique used to treat pain in the legs and the small of the back. It is practised as follows: Sitting with legs outstretched, one extends both arms to the front, parallel with the legs. Moving [the arms] backwards and forwards, one circulates Qi/the breath.