The Yijin Jing (simplified Chinese: 易筋经; traditional Chinese: 易筋經; pinyin: Yìjīnjīng; Wade–Giles: I Chin Ching; literally: “Muscle/Tendon Change Classic”) is a Qigong manual containing a series of exercises, coordinated with specific breathing and mental concentration, said to enhance physical health dramatically when practiced consistently. In Chinese yi means change, jin means “tendons and sinews”, while jing means “methods”. This is a relatively intense form of exercise that aims at strengthening the muscles and tendons, so promoting strength and flexibility, speed and stamina, balance and coordination of the body.
http://en.wikipedia.org/wiki/Yijin_Jing
Videos
易筋经 （帶口令）
https://www.youtube.com/watch?v=2eLpl-7FznM
with correction
https://www.youtube.com/watch?v=qychE4bLP54
English – Qi Gong des paysans (Yi Jin Jing – 易筋经)
Appelé également “Classique de la transformation des muscles et des tendons”
https://www.youtube.com/watch?v=XJ7r4mDLRmI&feature=youtu.be
Other
http://www.egreenway.com/qigong/yijinjing.htm