Here is a summation of the historical section:
Now, we can move on to
"Chinese Weightlifting Philosophy: 3 Principles and 5 Words
3 Gravity Principles
In China, modern weightlifting has 3 movement categories (Li 2000):
1) Extension, such as during the lifting portion of the barbell, driving the jerk after dipping, or standing up after catching the bar,
2) Squatting, such as the squatting during a snatch or clean, and dipping during a jerk or squatting to catch a power or squat jerk,
3) Support, such as catching a clean on the clavicle and shoulders, and supporting a snatch or jerk with straight arms overhead.
The question is, "how does one perform these movements to lift the most amount of weight in the easiest way?"
To answer this question, Gu (1994), presented the following model:
This model shows that lifting an object is a combination of horizontal and vertical forces, depicted by the lower case f's and designated by the arrows.
The combination of horizontal and vertical forces results in a diagonal force, which is represented by the capital F's.
In this model, box M is balanced directily over its center of gravity O and the shortest distance for the box to reach a certain height is in a straight line.
To move the box in this straight line requires the vertical forces f3 and f4 be equal; otherwise, one side of the box would lift higher, which causes it to tilt and swing and requires more energy to stabilize.
The following 3 Gravity Principles must hold to preserve a straight movement:
1) The horizontal forces f1 and f2 must be of the same magnitude,
2) f1 and f2 must be applied simultaneously, and
3) f1 and f2 must pull in opposite directions.
If f1 increases in magnitude after applying f2, or f2 decreases in magnitude after applying f1 then f1 > f2 which violates the "equal magnitude" principle. In this case there will be an imbalance in the resultant forces (F1 > F2) such that box M moves diagonally and leftwaard from the center of gravity O.
While the box will eventually reach the required height, we know from mathematics that a diagonal line is longer than a straight line, so following a diagonal path takes more time, work, and energy than a single straight line.
If f1 were applied first, followed by f2 or vice versa, then the "simultaneous" principle is violated, and the object will oscillate as it moves vertically, which takes more time, work, and energy than a straighter path. And if f1 and f2 are in the same direction, then the "opposite direction" principle is violated, and the box M will also move horizontally in that direction.
The 3 gravity principles ensure that the object travels the minimal distance required to reach the desired point.
Additionally, they maximize vertical force because the horizontal forces balance each other out.
The results above imply that if the human body can preserve its stability, then it can fully utilize its strength to lift a weight effectively. The founders extended the model above to analyze the human body during weightlifting movements. We can see that the ankles, knee, hips, and shoulders are a system of levers that each apply a vertical and horizontal force (lower case f), which results in a resultant force (capital F), as illustrated below:
When the ankles and hips extend, they produce a forward force as well as a vertical force; however, when the knees extend or the shoulders retract, elevate, and externally rotate, they produce a backward force as well as a verticsal force.
If the athlete exerts these forces powerfully, then the movement naturally resembles a vertical jump. In a vertical jump, the athlete is balanced over the ball of the foot (or 60% of one's foot length measured from the heel), and pushes though it to achieve maximum height.
If we draw a vertical line through the balance point in the foot, then we establish line O which is the efficient pth the barbell can follow to preserve the athlete's balance as they produce vertical force.
At heavy weights, the combined center of gravity of the barbell and the athlete is approximately balanced over this line. For the barbell to move closely along this line during the lifting portion of a snatch or clean, it requires the following condition from the body:
f1 + f3 = f2 + f4
This condition means that the magnitude of the backward forces generated by the shoulders and knees (left-hand side) must equal the magnitude of the forces generated by the hips and ankles (right-hand side). Additionally, these forces must be applied simultaneously and in their respective horizontal directions to ensure lifting along a stable center of gravity.
There are many ways to miss a lift, but the reasons can all trace back to violating one or more of the 3 gravity principles. Hence, this analysis forms the foundation for Chinese coaches and researchers to analyze an athlete's force application.
After extending, the athlete must squat under the bar, which requires the body to move downward and inward. The figure below shows these downward forces.
During the squat, the forces of the shoulder, hips, knees, and ankles are opposite from the forces exerted during extension because these joints must now bend the joints and lower the body (Li 2000) Specifically, the hips and ankles must flex to produce a backward force while the knees and shoulders produce a forward force.
While the magnitude of the force depends on the barbell, body weight, and the athlete's musculature, the horizontal forces must be equal in magnitude, applied in opposing directions, and applied simultaneously (f1 + f3 = f2 + f4). The body should be upright and balanced over the midfoot to minimize the horizontal distance for the joints to travel and preserve a stable squat position.
Finally, supporting movements must also implement the 3 principles. These movements are static actions because they do not generate speed nor position changes, but the muscles are tense to generate support strength (Li 2000).
Figure 2-3 (above) illustrates the forces during a squat, which continue until the athlete reaches their bottom position.
Figure 2-4 (below) shows the forces during the split jerk, which requires extension from both legs.
In the split position, the balance point is the center of the surface formed by the feet, and the line of gravity runs directly upward through the athlete's body through the center of the barbell.
Each leg must exert a horizontal force that is of equal magnitude, in the opposite direction, and applied simultaneously (f1 = f2) to maintain balance over this point. This balance allows the athlete to concentrate the vertical forces from both legs to support the barbell and keeps the torso along the center of the support surface.
Next: Analysis of Weightlifting Techniques.
Enjoy Your Lifting!
I look at the game of soccer and the age in the USA that kids begin to play. By the time they are in their senior year of high school alot of them have played 12 years. Twelve years of honing reflexes building speed and understanding tactics on
ReplyDeletethe field. I mention this in relation to the sport of both Weightlifting ,Powerlifting and the field events in Track. None of these sports are introduced to young people in a effective manner in the USA. I think of the mountain of bad advice Football coaches give lifters not to mention totally under educated Gym teachers. The level of strength we could see if young athletes had the proper guidance would crush our competitors given our access to decent food and training .
Our lifters would have a much better shot with funding, but hey, let's be realistic, this ain't a country, it's a business now, bought and sold to the highest bidder, with gov funding going to all manner of "stuff" . . .
Delete