A small group of martial arts masters in China’s central province of Henan are the practitioners of a kung fu stunt known as the “iron crotch”. The move involves a log, capped with a steel plate, measuring 2 metres (6ft 7in) in length and weighing 40kg (88lbs) that is swung through the air before it being smashed into the crotch area of the practitioner. The person at the receiving end of the stunt is said to use “qigong” breathing techniques to avoid injury. Wang Liutai, a 65-year-old kung fu…