Technical Description Of The Pull In Weightlifting
how the hell gravity actually works)
Coaching techniques in Weightlifting
may vary, but the mechanics which dictate the techniques do not. This is
because the biomechanics of lifting comes from the unchangeable source of
the laws of physics themselves. There is a body of research on
Weightlifting spanning forty years based upon scientific facts and not
nebulous concepts doled out by hobbyists masquerading as coaches.
The information provided below is
the technical description of the Snatch and Clean pull from the start of
the lift through the completion of the 2nd pull or "explosion." It
was taken from the scientific research done on Weightlifting (see
bibliography.) The research some have referred to
as “dogma.” However, it is this same “dogma” which has created decades of
World/Olympic records and champions and continues to do so today.
After reading this article you will
understand the basics of “modern” pulling mechanics and why they are the most
effective and efficient way to pull a barbell.
- the rate at which
something speeds up or slows down
- the measurement
of the rate and direction of change in the position of an object
- the magnitude of an objects rate of change of position
- the tendency of a force to rotate an object
Center of Gravity
- the mean location of the gravitational force acting on a
Common Center of Gravity
- the center of gravity of the lifter and the barbell
calculated as one unit.
“Obviously, the most advantageous
starting position for the levers of the kinematic chain will be such that,
during the loading, the moments will be the smallest for all the levers;
because this will require the smallest muscle moments”
-Ilya Pavlovich Zhekov-
Biomechanics Of The Weightlifting
The lifter must assume a starting
position in which he/she can create maximal vertical acceleration to the
barbell with the least amount of effort. The moment forces acting on the hip,
knee and ankle joint must be minimized in order for the lifter to separate the
barbell from the floor while maintaining an ideal body position for the
subsequent “2nd Pull” or “explosion.” This optimal starting posture can only be
realized through proper manipulation of ankle, knee, and hip angles. Therefore,
the correct starting position will depend on the lifters height, body
proportions, and the grip width. These variables must be manipulated so the
shoulders are over or slightly ahead of the bar at the point of lift off, the
elbow joint is aligned with or in close proximity with the knee joint, and the
bar is over the metatarsal-phalangeal joint (the
2nd joint of the toe) as is the lifters balance of pressure. Upon lift off, the knees should be at an
angle of approximately 80-110°, depending upon body segment ratios. Lifters
with short extremities and long torsos will have a smaller starting knee angle
than lifters with long extremities and a short torso.
As the bar is lifted from the floor
(primarily through leg extension), the muscles which extend the torso work
isometricly. This allows the hips and shoulders to rise at the same rate,
moving the torso upward and slightly forward. During this initial extension of
the legs the bar will shift towards the body approximately 4-12 centimeters
(depending on the height of the lifter) until the knee angle reaches
approximately 135-145°, the torso approximately 30° relative to the platform,
and the hip is at an angle of approximately 85-90°. At this point the shins
will be vertical, the lifters balance of pressure will have shifted slightly
towards the ankle, and the bar will be at the lower third of the thigh in the
Snatch and a little above the knee for the Clean. During this phase of the
pull, speed of the barbell increases due to the large applied vertical force,
which produces acceleration and increased power output by the athlete. Because
the moment forces on all of the largest joints of the body are so great as the
legs straighten, it is imperative the barbell come back towards the lifter
during the first pull. In the book The Snatch The
Clean And Jerk Robert Roman
states “The movement of
the barbell in this manner is more advantageous than a strictly vertical
elevation of the weight”
This action minimizes the horizontal distance
between the bar and the hips, decreasing the moment force, allowing for proper
utilization of the leg extensors. If a straight barbell path is used, the
common center of gravity will be shifted forward towards the toes. This causes
a large increase in the moment forces of all the working joints and a decrease
in the bodies ability to create the acceleration, speed and power necessary for
an efficient lift.
Once the legs have extended to a knee
angle of approximately 135-145°, the bar has reached a maximum speed and
therefore has an acceleration close to zero. The legs are no longer able to
influence the speed and positive acceleration of the bar. Therefore a transitional
period occurs as the muscles which extend the torso become active.
2nd Pull or “Explosion”
There is a transition from the 1st to
the 2nd pull . As the torso begins to extend toward the vertical, the bar
continues to rise while the hips move toward the bar and the knees move back
under the bar. The shins are at an angle of approximately 70° with the torso at
60° relative to the platform. The hip joint is at an angle of 110-115°. During
this transition there is a leveling or small decrease in the speed of the bar
until the “power position” is reached. This is immediately followed by the 2nd
pull or explosive phase of the pull marked by maximal vertical force,
acceleration, and power output
due to ankle, knee and hip extension and elevation of the shoulder girdle
At the point of full extension (end of
the explosion) the athletes heels leave the ground, the lifters body is
extended and inclined backwards. The bar will begin to travel in an arc away
from the lifter. At this point the lifters center of gravity will shift
backward. However, the common center of gravity remains over the foot as a
result of the barbells forward movement.
As the lifter begins the decent, the
barbell will then again come back to towards the lifter due to the strong
force acting on the bar by the action of
A Word On Barbell
The weightlifter and barbell have a
relationship called the “weightlifter-barbell system.” In this system it is the
force of gravity which provides the resistance the lifter must overcome. It is
a self-tuning system which is continuously adjusting and looking for the
correct combinations of muscle contractions and relaxations in order to create
a “best” way to lift the barbell.
While it is true moving an object in a
straight line represents the shortest distance between two points and requires
less work. It is not the “best” way to lift a barbell. In mechanics, work performed against gravity
is measured by the height an object is raised and does not depend upon its
trajectory. Since the
weightlifter-barbell system is self-tuning, it will seek out the “best” most
efficient bar trajectory. Which is one where the forces acting on the ankle,
knee, and hip, are minimized. This can be accomplished in two
ways: reducing acceleration, or reducing the lever arm of the working joints in
order to counteract the force of gravity. Reducing acceleration is inefficient
and will negatively effect the outcome of a lift. Reducing the lever arm of the
working joints is the only effective means to overcome the force of gravity.
This is precisely what occurs when the lifter shifts the barbell toward the
body during the first pull.
Between Mechanics And Technique
Although some top lifters may have
observable differences in “technique”, this is not an indication of new or
better lifting mechanics. The mechanics for lifting a barbell properly are 100%
objective. It’s important to note, mechanics are not the same as one’s technique.
Mechanics of Weightlifting are the forces involved with lifting a barbell and
the causes behind them. Technique is the visual manifestation of these forces.
Causes behind force production such as gravity, mass, and distance can be
measured with precision. Using the aforementioned constants, variables involved
with the mechanics of force production such as joint angles, bar trajectories,
and balance are manipulated in order to establish the most efficient pulling
The observable differences in
“technique” have to do with an individual’s peculiarities such as anthropometry
or leg/torso strength distribution. These peculiarities will dictate actions,
which will suit an individual lifter’s needs. Simply mimicking a particular
athletes pulling technique without possessing their anthropometry or
peculiarities will often lead to poor pulling mechanics.
Learning how to properly execute the
Snatch and Clean and Jerk will be a direct function of the competency of your
coach. Although competent coaches may use differing methods for teaching
technique, we are all teaching the same mechanics.
Until the laws of physics change, the
mechanics of lifting a barbell and the forces involved will remain as described
by scientists and coaches for four decades. Getting an idea from watching a
video then discussing it on a forum is not Scientific Method it is opinion, and
should be stated as such.
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