Click Pics to ENLARGE
A full extension in necessary not only for working muscles in their inner range, etc., but also to make full use of IMPULSE. The speed of the bar does not depend only on the amount of force applied but also upon the time for which it operates (its IMPULSE).
This is another reason why caution must be observed when comparing times of various performers during the pull. One lifter may be faster than another in the second stage of the lift only because he has not extended as fully as he ought to. This is a fault which at first sight would not be apparent and actually the relative time would look good on paper.
Click Pics to ENLARGE
The average speed of those timed in this phase (see Table 11) was just over 1/4 second. Garcy and Tamraz were fastest and Palinski slowest but without the reader knowing all the facts regarding time and distance it would be wrong to draw conclusions. For example, Tamraz did not do a complete extension and therefore did not move as far as the others.
It is suggested that in a good lift, the pull of the bar from the knees to the top of the pull MAXIMUM force should be applied for MAXIMUM distance and time. This last factor (maximum time) is apt to be misleading.The movement should be as fast as possible but force applied for as long as possible.
Sometimes hip thrust and body extension is completed after the feet have left the floor - THIS IS WASTEFUL AND INEFFECTIVE. Power comes from the ground, and when the feet leave the floor, the flight path of your combined center of gravity is already determined and whatever movements you make while in mid-air will not affect it.
The Third Key Position
Around 40 lifters were examined and, being top men in world competitions, most of them were squat stylists.
The position traced was the position of full extension before either foot broke contact with the ground. If the feet remained in contact during a squat, then the maximum extension position was used. Two lines were then drawn:
Line 1: From the center of the base to the hip joint (approx.).
Line 2: From the center of the base to the curve at the back of the neck.
Where the lifter had a good extension Line 1 was ahead of Line 2. Generally speaking the greater the distance in advance the greater the hyperextension.
The lifters were divided into three groups. Group I (13 lifters) where Line 1 was ahead of Line 2. Group II (12 lifters) where the two lines were virtually together. Finally Group III (11 lifters) with Line 2 ahead of Line 1, indicating an incomplete extension. Table 5 shows the positions of the lifters concerned.
In order to get a rough estimate of the position of the center of gravity and for other comparisons, the AVERAGE ANGLE of Line 1 and Line 2 was calculated. Obviously with Group II this was not necessary. The resulting figures are shown in Table 6.
The position of the combined center of gravity will be somewhere between a line from center of bar to floor (90 degree angle) and the lifter's personal center of gravity, but for the purpose of discussion it is thought that the figures in the average column will give a near enough position.
The weight of the bar in relation to the lifter's bodyweight must be kept in mind, e.g. Miyake lifts almost double bodyweight so that the combined center of gravity will be approximately one-third distance between bar and personal center of gravity whereas the club lifter snatching his own bodyweight will have the combined center of gravity of approximately halfway between the other tow centers of gravity.
THIS POSITION OF MAXIMUM EXTENSION IS ALL IMPORTANT.
The flight path of the combined center of gravity is determined by the instant the body breaks contact with the ground and nothing the lifter does after this time will alter this flight path until the body once again makes contact with the ground.
The action of the head should not be overlooked although only about one-thirteenth of the total bodyweight, its position at the end of the spine can have a considerable effect on the body. The head is truly the rudder of the body.
Although the combined center of gravity is over the base, the line of action can be changed by the line of thrust. This is diagonally indicated by a line from hip joint to heel or hip joint to ball of foot as the fulcrum. Whether to ball of foot or to heel seems to be a debatable point. In any case the direction of travel can be judged by plotting the downward pull of gravity, combined with the eccentric thrust, giving the reaction. See illustrations.
The amount of travel will largely depend on the amount of hip thrust employed.
Next: Parallelograms of Force and Transference.