In discussing the technical aspects of the classical lifts, attention is often solely focused on the actual pulling or pushing motion (initial pull-
knee bend-final pull, or the thrusting action). A quite important component is often overlooked: the non-support phase of the squat-under
portion of the snatch, the clean, and the jerk. Even a perfectly performed pulling or pushing motion will not, in and of itself, guarantee a
successful lift. Optimal execution of the non-support phase of the squat under can make all the difference in achieving a smooth successful
attempt. The purpose of this article is to provide some insight into why this phase is so critical.
A speedier lifter is able to convey more of his strength to a moving bar. All other conditions being equal, the speedier lifter not only develops
greater force but is able to apply that force to a moving bar with a more protracted effect.
In addition to possessing speed in individual movement, a lifter must possess good speed in individual parts of his body. For instance, in the
initial phase of the pull the knee joints are extended, and as the knees are brought under the bar they are flexed; in the final pull they are
again extended, followed by a final flexion in the drop under phase. And all of this takes place in less than one second!
The greater the athlete's ability to switch rapidly from one movement to another, the greater his ability to transmit power in each individual
movement.
Force is generated as a result of the interaction of the athlete with the barbell, especially during the transition from the final acceleration to
the drop under the barbell in the snatch and the clean and during the transition from the thrust to the drop under the barbell in the jerk.
A moving body possesses kinetic energy (KE) which is proportional to the mass of the object and the square of its velocity. The constant of
proportionality is .5 (one half). So, KE=[(mass)(velocity squared) / 2] [formula (1)].
Kinetic energy is capable of performing work. When movement comes to a stop (i.e. when velocity=0), the kinetic energy has been 100%
expended on the work performed. This concept can be quantitatively expressed as follows:
KE = (mass)(velocity squared) / 2] = FS [formula (2)] where F= average value of force developed by moving body and S= the path through
which the reserve of KE was expended.
At the end of the final acceleration (or thrust in the jerk) the athlete is moving upward with great speed. Instantly, he must then reverse
direction. During this transition, which is produced primarily as a result of the dynamic work of the arms, the kinetic energy in the lifters body
is transferred to the barbell through the arms and continues to produce energy in the direction of the barbell.
From formula (2) it can be seen that the force arising during the dying out of the body's velocity depends on the length of the path through
which the dying out of the body's velocity takes place (i.e. the two variables are negatively correlated). The shorter the path (i.e. the faster
the transition from the final pull to the drop under), the greater the force available.
Studies have shown that elite middleweight lifters can develop more than 200kg of force in the snatch during the switch-over from the final
pull to the squat under.
The importance of this phase can be summarized as follows: anytime the force generated exceeds the weight of the bar it creates
acceleration. If the force is equal to the weight of the bar, then the bar only maintains the speed acquired at the end of the final pull. Finally, if
the force is less than the weight of the bar it still has a positive effect on the upward movement of the bar as it decreases the "braking" action
of the force of gravity, even though the bars speed is decreasing.
Attention to these important facts will go a long way to making you a better lifter.
by Jim O’Malley
