Cao Chenrui (2nd R) teaches Zhang Zihao (1st R) Shisuo skills at Qingshuiting Primary School in Nanjing, east China's Jiangsu Province, June 5, 2019. The school has a Shisuo club with 12 students ranging from the third to the sixth grade. Shisuo (stone lock), a stone dumbbell in the form of ancient padlock, is usually seen in the traditional Chinese workout routine. With hundreds of workout moves, Shisuo exercise can not only enhance strength, but also help people to coordinate hands, eyes and the body. Shisuo dates back to the Tang Dynasty in which soldiers first used it to build their bodies. The Shisuo exercise has a long history in Nanjing, east China's Jiangsu Province. Endearing itself to the public in recent years, Shisuo becomes a national fitness activity. Nearly 20 Shisuo teams are formed for regular activities and competitions. (Xinhua/Ma Zhihong)