The Oly Encyclopedia 76

When to Terminate the Jerk Drive

There are a number of issues to consider when determining when the active thrusting of the lifter against the bar should be completed and when the movement into the squat under should begin in the jerk. All things (e.g., launching speed) being equal, the higher the bar is when force ceases to be applied to it, the greater height the bar will ultimately achieve. Therefore, if the lifter could achieve an identical launching speed with the legs bent at an angle of 150 or standing on the toes, it would be to the lifter's advantage to release the bar while on the toes. The bar would then travel higher, and the lifter would not have to lower the body as much to catch the bar in the jerk. As a practical matter, this is simply not the case, since the lifter applies maximum force with the thigh extensors and not the gastrocnemius muscle (the muscle that is primarily responsible for extending the foot when the body rises on the toes).
Offsetting the consideration of the height of the bar is the consideration of how quickly the lifter can move from the extended position in the final explosion to the necessary split or squat position. If the position on toes leads to the lifter's taking longer to get into the split, it might offset any advantages that could accrue from a higher absolute drive. A longer time getting into the split leads to a greater bar drop. This means both that some of the added height advantage could be lost because the bar will descend from the highest point it has reached before it can be caught and that the bar will take longer to control because it will have had time to build up a greater downward speed than if its descent had been arrested earlier. Therefore, the decision about where to terminate the drive must be balanced on three considerations: a) the means by which maximum bar speed can be achieved; , b) the height of the bar at release; and c) the time it takes to get into position to catch the bar from the position at which the drive has been completed. Most lifters stay with the drive too long. Significant additional force cannot be applied once the thighs have reached a nearly straightened position. Lifters who extend the body much further than this are wasting valuable time which could be better used to move under the bar. The telltale sign of this is the lifter driving the bar to a relatively high position but then catching the bar on bent arms with the feet positioned in a relatively narrow split. This has occurred because the lifter has wasted valuable time in the drive, time that contributed little to the upward progress of the bar and that could have been used to reposition the feet and body under the bar.