The pull from the knee is a weightlifting movement derivative that can be used in the teaching progression of the clean and snatch exercises. This exercise emphasizes positional strength during the transition phase and the triple extension of the hip, knee, and ankle joints that is characteristic of weightlifting movements.
DeWeese, B.H., Suchomel, T.J., Serrano, A.J., Burton, J.D., Scruggs, S.K., & Taber, C.B. (2016). Pull From the Knee: Proper Technique and Application. Strength and Conditioning Journal 38(1), 79-85. doi: 10.1519/SSC.0000000000000194
Strength and Conditioning Journal
National Strength and Conditioning Association