The jerk is broken down into 3 parts each with 2 phases for a total of 6 phases (Grabe & Widule, 1988; Prassas & Fulton, 1994). The 3 parts are the dip, the thrust (which includes the braking portion of the dip) and the movement under either by split or squat along with the stabilization of the barbell overhead (Grabe & Widule, 1988).
Unlocking of knees until bar descends downward
Bar begins to descend downward until maximal downward bar velocity
From maximal downward bar velocity until maximal knee flexion
Maximal knee flexion until maximal knee extension
Movement under and stabilization—Phase 5:
Maximal knee extension until bar reaches maximum height
Movement under and stabilization—Phase 6:
Maximum height of bar until barbell is fixed
The dip should be controlled with very little horizontal movement. Elite lifters reach maximal descending velocity at 62% of the entire dip where as non-elite reached maximal descending velocity at 50% (Grabe & Widule, 1988). Therefore, elite lifters have slower dips and have shorter braking phases as compared to non-elite lifters (Grabe & Widule, 1988). The dip depth should be in the range of 8-13% of lifter height (Lake et al., 2006; Grabe & Widule, 1988). The horizontal movement of the barbell during the dip should be less than 2 cm (Grabe & Widule, 1988). Longer braking phases result in a deeper than optimal half squat (greater than 8-13% of lifter height), and shallower dips result in greater ground reaction forces (Grabe & Widule, 1988). A shorter duration in the braking phase is optimal to impart more stored elastic energy to barbell and for adding to the power of the thrust phase (Ai & Cao, 1995). The direction of the barbell in the split is influenced by the direction of the thrust (Grabe & Widule, 1988). The barbell should travel in a near vertical path with a slight rearward deviation; a horizontal deviation can cause a missed lift (Prassas & Fulton, 1994). The horizontal deviation can result from incomplete hip extension in phase 4 (Prassas & Fulton, 1994). Incomplete hip extension results in a forward inclination of the trunk and a resulting forward drive (Prassas & Fulton, 1994). Also, this results in the bar leaving the shoulders before complete extension of the body, decreasing the possible drive height (Prassas & Fulton, 1994). In fact, hip extension in phase four not only keeps the barbell trajectory vertical but also adds to the drive height (Prassas & Fulton, 1994). Maximal extension of hip, knee, and ankle should be reached at the end of the thrust phase (Prassas & Fulton, 1994). The barbell needs to be driven to 94% of weightlifter’s height for a successful jerk (Ai et al., 2018). This value is for elite weightlifters and non-elites would need to drive the bar to a higher height for a successful lift (Ai et al., 2018). When the front leg knee angle in a split jerk is less than 90 degrees the lifter becomes more unstable, making the recovery more difficult (Prassas & Fulton, 1994).
1. The dip should be controlled with very little horizontal movement
2. The thrust should have a slight rearward direction from the vertical
Ai, K., Bi, Z., & Liu, G. (2018). Bar heights needed for successful lifts in men’s weightlifters. ISBS Proceedings Archive, 36(1), 899.
Ai, K., & Cao, W. (1995). Biomechanical Characteristics of Jerk Technique. In ISBS-Conference Proceedings Archive.
Grabe, S. A., & Widule, C. J. (1988). Comparative biomechanics of the jerk in Olympic weightlifting. Research quarterly for exercise and sport, 59(1), 1-8.
Lake, J., Lauder, M., & Dyson, R. (2006). Exploring the biomechanical characteristics of the weightlifting jerk. In ISBS-Conference Proceedings Archive.
PRASSAS, S. G., & Fulton, K. (1994). A Kinematic analysis of jerk technique in Olympic weightlifting. In ISBS-Conference Proceedings Archive.