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The Biomechanical Analysis of the Olympic Snatch Lift
PE 483
JR Jones & John Taylor
3/19/2010
Procedure:
The purpose of this project was to determine the biomechanical advantages
that are taking place during the Olympic snatch lift. Not only are we trying to
determine the correct bar path, amount of time spent in each phase of the
exercise, and/or the specific joint angles during those phases. How does the
increase in weight change the amount of velocity generated throughout the lift?
What is the most efficient method of hoisting that bar overhead in order to
avoid injury and maximize force production? How will the acceleration be
effected during an increase in the weight of the bar in comparison to the lower
weights? What type of variations of this exercise could be used in order to
improve different phases of this lift? These questions were some of the major
reasons JR Jones and I decided to choose this activity. JR had not had much
previous experience with the activity and since he is interested in bodybuilding
and has even competed before, we thought it to be a good idea to divulge into
this topic even further. I am a fan of the snatch exercise as I am also a fan of
plyometric training. I am the type of person that believes that training
explosive type of movements and muscles will improve athletic performance. JR
and I both share the interest of training individuals and would both like to one
day pursue a graduate degree in the field of exercise science, maybe even
biomechanics. We both were interested in the fundamentals of the movement,
especially JR because it was an opportunity to completely absorb the information
since he had no prior bad habits to deal with. I often would worry about not
making mistakes when I would perform the exercise, and therefore, I would assume
that most of my analysis would be spent on fixing the potential mistakes within
each identified phase of my lift and also fix any mechanical flaws. Those types
of flaws have yet to be fully recognized, however, we can assume the having an
arched back is going to inhibit performance and may even result in an injury. We
can assume that if the individual does not have their feet about shoulder width
apart and adjacent with each other, they might also suffer and injury and/or
have trouble completing the lift. The Olympic snatch lift is designed to be
performed with certain movement principles, and through this analysis, we will
attempt to identify each one of those and how that movement principle relates to
the biomechanical conceptual methods such as inertia, impulse, work, and power.
Those principles will be well-known by the end of this analysis, and we as a
group intend on figuring out why and how such events are possible. The velocity
of the bar in motion, the acceleration of the bar, and how the joint actions
begin to change throughout different points in the movement, are all concepts
that were intriguing to both me and JR. Wanting to choose something that would
lead us into brand new territory, unlike a baseball player choosing a baseball
swing or pitch, or field goal kicking using an extra point, I chose not to do
something football related and JR chose something he had never performed prior
to this analysis. I was never a big fan of the Olympic snatch lift growing up
albeit I was a big fan of the power clean, and power clean and jerk. Snatch was
an exercise that you couldn‟t load up the weight as much and required many more
technical aspects than getting underneath a large amount of weight. I saw an
incredible athlete perform the snatch a couple years after that and realized how
great of an athletic tool that it can be. It offers a sound technical learning
experience; the whole body is working in unison, and offers the explosive type
of movement associated with a number of sports. I did a paper in the winter of
2010 about plyometric training (PT) and came to the conclusion that PT helps
athletes in variety of sports, such as volleyball, tennis, and wrestling. I
imagine that after completed a similar study, and/or even completing this
project will lead me to the same conclusion about the Olympic snatch lift.
Mechanical Principles:
The objective of the snatch is to lift the barbell from a resting position
on the ground, to stable a position with overhead with the arms locked out.
Inertia is an object‟s resistance to change. As described by Newton‟s Law of
Inertia, an object in motion will remain in motion unless acted on by and
outside force. Mass is directly related to inertia. The greater mass an object
has, the greater it‟s inertia, or resistance to change. In order for an athlete
to complete a snatch, they have to apply enough force on the bar to overcome its
resting inertia. Once the bar is moving it will not accelerate past its initial
velocity unless the athlete continues to apply a force on the bar great enough
to overcome its moving inertia. An Impulse is the amount of force applied over
time. Inertia of the bar requires a continual force to be applied to it. The
greater the amount of time relative to the absolute time that force can be
applied to the bar, the greater the vertical displacement will be. This is
closely related to work. Mechanical work describes the amount of force applied
over a distance. Similar to an impulse, the greater work, or magnitude of the
force and the distance through which it is applied, the greater the final
vertical displacement of the bar will be. The success of the snatch depends on
the maximum height of the bar to be great enough to allow for the athlete to get
into the catch position under the bar the force of gravity is working on the bar
in the opposite direction of the pull. To overcome the force of gravity and
benefit from inertia to achieve maximal vertical displacement above the point at
which force can effectively be applied the athlete must generate momentum.
Momentum is the quantity of an object‟s movement, and describes the velocity of
the mass of an object. The greater the momentum achieved, the better it will
resist the change of direction imposed by gravity. This is inertia working in
favor of the athlete, resulting in a vertical distance greater than that of the
impulse and work. To generate this momentum the bar must be accelerated to its
maximum velocity.
The total work done on the bar describes the force that is being applied
to the bar, and the distance through which it is applied. To do work no change
acceleration past the initial velocity it is necessary. To successfully perform
the snatch it is necessary to reach maximum velocity. Power is the rate of work
done on the bar. It describes the change in work over time. The greater the
amount of work on the bar over the shortest amount of time, greater the power.
The more power generated means that a greater force is applied to the bar. That
force pulls the bar through a greater distance in a shorter amount of time.
This acceleration results in a greater max velocity of the bar at the end of the
pull. A greater momentum at this point when the athlete can no longer apply
force the bar resists the opposing pull of gravity. The resulting vertical
displacement allows time to achieve optimal position to catch the bar overhead.
The Muscle Snatch
(Dawes, J. 2007)
The snatch exercise is as an exercise that is commonly used to improve
explosiveness and develop overall athleticism (Daws, 2007). The power and full
snatches are a great way to incorporate a dynamic warm-up that will involve
total body movement training. The muscle snatch is an exercise that is performed
much slower than some of its more explosive counterparts such as the clean.
Muscle snatch is a great exercise to incorporate into a training program because
it does provide some explosion and the lift is so technical and dynamic, that
several body parts have to be working in-synch, otherwise there could be a
breakdown that might even result in an injury. Sports that will likely
incorporate snatch into the training regiment include but are by no means
limited to, football players, wrestlers, volleyball players, track and field
sprinters/jumpers, power lifters, and rugby players. The snatch is an exercise
that takes time and effort in order to be performed correctly and efficiently so
the athlete isn‟t at an increased risk of injury. Many athletic events require
the athlete to use one-side of their body at one time, which has led to the
incorporation of more single-arm snatch activities. For example, and NFL
linebacker will benefit from these type of exercises because of situations where
they are asked to shed blocks coming from the opposing team in or to make a
play. Being able to have the hips and single-arm explode in unison during the
single-arm snatch exercise has the ability to translate onto the football field
in that given situation. There are other reasons why the snatch is a great
exercise that becomes incorporated in several strength and conditioning circles,
whether it‟s for a great warm-up or improved performance on the playing field.
Biomechanical comparison of unilateral and bilateral power snatch lifts.
(Lauder & Lake, 2008)
I mentioned before how certain sports might include the unilateral power
snatch because they may encounter situations on the playing surface that would
require a unilateral movement as opposed to a bilateral movement. I saw a
magnificent catch in the 2009 College Bowl series when a North Carolina player
made an acrobatic catch and had to use a couple of one-footed hops to keep in
the end zone. This was a situation where unilateral leg squats might have played
a role in this excellent example of body control. The same situation goes for
this exercise, I used to the example of a linebacker in football benefitting
from unilateral snatch lifts, especially an outside linebacker who encounters
most blocks with one side. Biomechanical characteristics of the one-handed
dumbbell power snatch were examined to determine whether significant differences
existed between unilateral and bilateral weightlifting movements. Kinetic and
kinematic movement data were recorded from 10 power weightlifters during one
handed dumbbell and traditional barbell power snatch performance with loads of
approximately 80% of respective lift one repetition maximums with the use of 2
synchronized Kistler force plates and high-speed 3 dimensional video. The
results highlighted asymmetry in the ground reaction force and kinematic profile
of the one-armed dumbbell power snatch, which was a deviation from the bilateral
movement. In addition, the non-lifting side of the one-armed dumbbell catching
phase was double that of the lifting side loading rate. These results measure
balanced deviations in the movement patterns of the unilateral power snatch
movement both during the concentric muscular tightening of load vertical
displacement, and the loading implications of unilateral landing. That supports
the debate that unilateral variations of weightlifting movements may provide a
different training stimulus. Which would support my theory that certain athletes
will benefit from this unilateral type of training, some more than others.
Triple Extension: The Key to Athletic Power. (Frounfelter, 2009)
This article focuses on the benefits of training triple extension ability
for weightlifters, suggesting that the explosive action of ankle, knee, and hip
during weightlifting is a critical factor in increasing athletic success. It
describes weightlifting movements such as the power clean and power snatch that
can help in improving the triple extension of lifters. Triple extension is a
position of the hips, knees, and ankles that power lifters are trying to achieve
in order to improve performance. I thought this would be a good article to get
off the library reserve system because it has to deal with explosion and since
the abstract isn‟t very long, I am curious to see what the NSCA‟s Performance
Training Journal has to offer. I did find this article in Sport Discus and
therefore it might not be beneficial for me to use once the article arrives and
I have read it over. The topic of triple extension and how the power snatch can
improve that position is why I included this article into my lit review
assignment. This article is only a year old and so that was also another factor
that made me want to get this from the library reserve, new information about
the snatch and how it may improve athletic performance is going to be useful
information. The author has affiliations as a staff physical therapist at the
Baldwin Area Medical Center in Baldwin, Wisconsin. There were enough positives
about this article that allowed me to choose it as one of my 5 sources for this
review, and although I don‟t have too much information on the article, I have
enough reasons for why I should order it off reserve, and for now, that is good
enough for me.
Unsuccessful vs. successful performance in snatch lifts: a kinematic approach.
(Gourgoulis, Aggeloussis, Garas, & Mavromatis, 2009)
The rationale of this study was to determine the kinematic characteristics
of snatch movements that result in an unsuccessful performance, involving the
barbell‟s drop in front of the weightlifter. There were 7 high-level men
weightlifters competing at the international level. The successful and
unsuccessful snatch lifts of each one with the same load were recorded with 2 S-
VHS camcorders, and selected points onto the body and the barbell were digitized
manually using the Ariel Performance Analysis System. The statistical treatment
of the data showed no significant differences between successful and
unsuccessful lifts in the angular displacement and velocity data of the lower
limb joints. No significant differences were also found in the trajectory and
vertical linear velocity of the barbell or the generated work and power output
during the first and second pulls of the lift. However, significant differences
were found in the direction of the barbell‟s resultant acceleration vector,
suggesting that proper force application onto the barbell is a crucial factor
for a successful performance in snatch lifts. Coaches should then pay particular
attention to the applied force onto the barbell from the first pull. The last
two sentences of that abstract were the reasons why I chose this one as one of
my five. It was a good example of how vectors play a crucial role in the snatch
lift, the book shows an example of this, and Dr. Caster used an example from his
Biomechanics course at WOU describing a country where the weightlifters
understood this principle. It‟s not necessarily straight up, but up and
backwards, the difference in your vector may be the difference in successful and
unsuccessful performance.
Coaching of the Snatch/Clean Pulls With the High Pull Variation.
(Waller, Piper, & Miller, 2009)
The information in this article presents the technique of snatch/clean
pulls for strength and conditioning professionals to be used in a strength
program that will enhance an athlete‟s ability to produce speed and power. Pulls
by definition, are explosive lifts of a bar that rests on a platform or pulling
blocks. The focus is given on two pull styles, the clean grip and the snatch
grip, which can reportedly be further broken down into pull and high-pull.
Instructions on the technique of full pull and coaching the pulls are included.
This would be a credible article to get off of the library reserve because it
discusses the differences in techniques between the snatch and the clean and
gives coaching points on both. My topic is the snatch and this could be a good
resource to use in order to emphasize coaching points of the lift and ways those
same coaching points may translate somewhere on the sports playing surface. I do
not have all the information about this article but from what the abstract has
given me and the concept that these are sport science professionals, this seems
like a good article to use. It will be interesting to see if the coaching points
of this article match up and/or relate to the vector concept from article #4.
Technical aspects of this lift should include some understanding of vector
concepts, I hope it doesn‟t just say, „lift the bar straight up and get under
it‟. The language used needs to be critical have some correlation to the other
articles otherwise I might have to throw it out. From what I can tell though, it
seems like a credible article from a well know journal.
Power lifting Versus Weightlifting for Athletic Performance (Chiu, 2007)
It is explained in the article “Power lifting Versus Weightlifting for
Athletic Performance” (Chiu, 2007) that specificity of training is key to
successfully improving performance. If an athlete is required to compete
explosively, then that athlete must train explosively. Explosiveness, or power,
can be defined as Power= force x velocity. To improve power, training should
focus on developing rate of force production, as well as maximal force
production. Maximal strength training improves an athlete‟s ability to produce
force. Standard exercises used in maximal strength training such as the bench
press, dead lift, and squat, improve max force production, but do not elicit max
power outputs. This is due to the speed the exercises are traditionally
performed at. These exercises can be modified to allow for greater power
outputs, but only at the expense of intensity. Performance of these exercises
at lower intensities negates the maximal strength adaptations they are
originally designed to produce.
Weight lifting movements are ground-based exercises that incorporate
multiple joints and muscle groups. The power snatch, and power clean and jerk,
are weight lifting exercises that will improve explosive strength. They require
max, or near maximal power outputs as well as optimal balance and coordination
for successful performance. The characteristics of these exercises are very
similar to the actions executed in most all athletic competition.
Implementation of these into strength and conditioning program will facilitate
the enhancement of such qualities in a safe and controlled environment.
When designing a strength and conditioning program, both max force and
velocity should be considered. To accomplish this, the parameters of the
program should include a variation of loads and subsequent velocities.
Incorporating Weight lifting/explosive power training and maximal strength
training into your program will elicit the best results.
Biomechanical Comparison of Unilateral and Bilateral Power Snatch Exercises
(Lauder & Lake, 2008)
As discussed in the article “Biomechanical Comparison of Unilateral and
Bilateral Power Snatch Exercises” (Lauder & Lake, 2008), the implementation of
unilateral weight lifting exercises into training programs has become
increasingly popular. Using dumbbells in place of barbells allows for a less
technical, yet effective method of implementing variety to strength and
conditioning programs. The rational for the use of unilateral movements stems
from the asymmetry observed in the performance of such an exercise. The idea is
that these may result in beneficial adaptations different from those of
traditional bilateral versions. The power snatch requires a loaded bar to be
lifted overhead in one movement. The performance of this movement is dependent
upon the sequence and the magnitude of the forces applied and the subsequent
lower limb angular displacements. Lauder and Lake conducted a biomechanical
comparison of unilateral and bilateral power snatch lifts. The purpose for this
comparison was to improve upon the current understanding of biomechanical
characteristics involved with these lifts. With this understanding coaches can
better use the snatch exercise and it‟s variations, as a tool to enhance
performance while avoiding injury.
Ten male weight lifters average age (30.2±10.2) years volunteered for the
study. The average height and mass of the subjects was (174±4.4cm) and
(81.5±14.6kg) respectively. Each had at least one year of experience with both
movements having been used consistently as a part of their training programs.
Each individual performed three trials at 80% of both the unilateral dumbbell
snatch and the bilateral barbell snatch. The joint and bar kinematics were
recorded with a 3 dimensional video camera as well as two synchronized force
platforms. This configuration allowed for simultaneous recording of joint
kinematics and vertical ground reaction forces for each leg concurrently. For
better comparison, both the dumbbell and barbell snatch movements were broken
down into comparable phases. These lift-phases were determined by changes in
knee angular displacement and are described in order as: First Pull, Knee
Flexion, Second Pull, unweighting, and catch loading phase.
Analysis of the barbell snatch data supported observations that both sides
work in symmetrical fashion with Joint kinematics and vertical force ground
reaction forces demonstrated negligible dissimilarity. In comparison, the
dumbbell snatch results reflected asymmetry between legs in joint kinematics and
vertical ground reaction forces. The leg same to the arm holding the weight,
though the magnitude was lesser, the vertical ground reaction force patterns
were similar to that seen in the barbell snatch. These patterns present greater
amplitude between the end of the knee flexion phase and the second pull phase.
This, depicting the decrease in ground reaction force just before increased
force production initiating the second pull phase. The non- lifting side leg
pattern shows consistent, and greater vertical ground reaction force being
generated through the pull phase at a significantly faster rate compared to the
lifting side leg. The non-lifting side leg also showed a vertical ground force
generation rate almost twice that of the lifting side leg during the catch
loading phase. This supports the rationale behind the method of incorporating
unilateral exercises into strength and conditioning programs as a way to add
variance.
Patterns illustrating the kinetics of the bar through each snatch variation
were derived from the data as well. The barbell snatch demonstrated greater
horizontal displacement, less vertical displacement, and lower vertical velocity
compared to the dumbbell snatch. These results show the influence the bar has
on the kinematics of the snatch. In the barbell variation the bar must be
pulled up to, and around the knees. As a result, vertical displacement and
velocity are decreased due to the horizontal compensations for the bar necessary
to perform the exercise. The dumbbell starting position between the feet allows
for uninterrupted extension. This encourages vertical displacement.
The results of this study validate the use of unilateral exercises in
strength and conditioning programs. The deviation seen compared to the
traditional barbell snatch supports the use of these exercises as a method for
adding variance to a program. Moreover, the idea that the specificity of such
variations may be especially beneficial athletes competing in unilateral type
events is derived. The placement and the path allowed by using a dumbbell
results in a more direct route overhead and less horizontal displacement. To a
strength and conditioning coach this means that less time can be spent on
technique without increasing the risk of injury. The combination of these
factors have a positive influence on the risk to benefit ratio of a training
program making the single arm dumbbell snatch a great training tool.
Application of the Power Snatch for Athletic Conditioning
(Waller, Piper, & Miller, 2009)
As explained in the article “Application of the Power Snatch for Athletic
Conditioning" (Waller, Townsend, & Gattone, 2007). Power is generated from the
lower extremities‟ rapidly exerting force into the ground. The snatch is a
ground based, full body exercise that emphasizes explosive triple extension.
Triple extension is the act of extending at the hip, knee, and ankle joints.
Triple extension is a fundamental action that most athletic movements are
derived form. When used correctly as a part of a conditioning program, the
snatch can facilitate significant speed and strength adaptations in the legs and
trunk, resulting in improved power production.
Understanding if and when a snatch should be used in a training program
depends on the individual. If the athlete‟s performance is dependent on the
rate of force production then enhancing power output should be the priority of
the training program. This refers to any sport involving jumping, pushing,
lifting, or hitting. Because it shares fundamental mechanics with these
actions, the snatch or a variation of, can be a very affective training tool.
There are many variations of the snatch. Each characterized by its starting
position. The traditional snatch is used in competitive weight lifting and
starts from the ground and finishes in a deep squat position with the bar
overhead. There are four main bordering positions used as a progression for
teaching the snatch. These positions are also the starting positions for common
snatch variations and are listed in order from top to bottom.
1. Power position
2. Bar above the knees
3. Bar below the knees
4. From the floor
The starting position used is dependent on the athlete‟s goals and
capabilities. The power snatch, which begins at the power position at the hips
or mid thigh, is most commonly used. At this position the athlete is at about a
¼ to ½ squat position, most similar to an athletic position. Most variations
starting above the floor end in an extended hip position, adding an overhead
squat component to the movement.
When teaching a snatch the strength and conditioning professional should
use a top to bottom approach. Starting with and overhead squat, progression
takes the athlete down through each position to the floor. It is up to the
strength and conditioning professional to decide when or if progression from the
power position is necessary. Progressing from the overhead squat to the power
position is only appropriate once the exercise is mastered. This meaning that
the athlete can perform the exercise through the full range of motion without
compensation of spinal alignment. Progression from the power position is
dependent upon mastery, as well as need. If a full snatch is not specific to
the movements the athlete performs in competition, then further progression to
that position may not be necessary.
Placement and progression of a snatch exercise variation in an athlete‟s
program can greatly influence its effectiveness. Within the workout session,
the snatch should be the first working exercise. This will insure performance
is not affected by fatigue. Loads should allow for 3-5 repetitions per set
without decline in technique. Sufficient rest periods between reps and sets are
necessary to promote technique as well.
The use of the snatch will vary between training phases related to
competition. In initial preparatory phases the focus is on learning proper
technique.
Any flexibility/stability issues should be addressed at this time to ensure
mastery of initial positions. Assuming the athlete is read, position and load
will be progressed as necessary.
In season training the snatch is still a part of the training program.
During competition the snatch will be used in order to maintain the power
developed from previous training phases. Loads will be high and volume will be
low.
In post season phases when recovery is the priority, snatch variations are
still used, but no progressions in position or intensity are made. Coming full
cycle, back in the preparatory phases, other Olympic type lifts can be taught
because the snatch technique has already been mastered.
The snatch and its variations can significantly improve sports performance
if used correctly. It should be an integral part of the athlete‟s entire
training cycle. The variation should best simulate the actions the athlete
performs in competition. The exercise used should be implemented and progressed
appropriately to the needs and capabilities of the athlete.
Triple Extension: The Key to Athletic Power (Frounfelter, 2009)
Power can be described as the ability to move an object as quickly as
possible over a given distance. This is also a basic description of the
physical aspect of sports. Athletic power can then be thought of as the ability
of an athlete to move them self, or an external object, i.e. ball, bat, bar, or
an opponent. Because power is fundamental to athletic performance, it should be
the basis of program design.
To maximize the results from a strength and conditioning program, it must
be designed to improve the mechanism responsible for power output (Frounfelter,
2009). This mechanism is known as triple extension and describes the explosive
extension of the hip, knee, and ankle joints. Weight lifting exercises such as
the snatch and the clean and jerk are the two lifts performed in competitive
weight lifting. Movements like the snatch, utilize the power generated by
triple extension to move heavy loads from the ground explosively overhead.
These types of lifts are essentially an explosive series of flexion and
extensions that result in maximal power generation. If utilized appropriately,
these exercises are unparalleled in their ability to train and develop athletic
power.
Introduction:
Performance objectives of the first phase begin with the flexion of the
knees, hips, and ankles. The toes are to be pointed slightly outwards, the body
is relaxed at the arms and a lordotic back position is maintained. This is the
starting position of the snatch lift, the butt is down and the head is up, ready
to explode through the movement.
The second phase of the snatch lift is bringing the bar up to about the
chest area and being able to raise the hips and shoulders simultaneously. When
the bar reaches chest-height, the goal is to then drop underneath the bar and
catch it while being in a squat position with the elbows in complete extension.
The third phase of the snatch lift is the “stand-up” phase in which the
individual goes from the squatted position from phase two, into the standing
position. The elbows are still fully extended and from this position, the
athlete is able to move into the final phase, which is the return back to the
first phase.
The final phase of the snatch lift is the “return” phase, where the athlete
is avoiding the act of dropping the bar straight down, and rather returning to
the first phase in control of the bar. Athletes can get lazy when doing these
types of lifts, the clean, is another lift that doesn‟t always produce the type
of results it‟s capable of, because the individual performing the exercise is
not completing the lift by performing the “return” phase.
Key elements of each phase-
1st- Knees, ankles, hips are in flexion. Tight locked back, relaxed shoulders,
feet pointed out wards, bar at the shins, make sure the shoulders are over the
bar and not behind.
2nd- Powerful extension of the hip, knee, and ankle, “pulling under” the bar is a
process of eccentric muscle action and “receiving” the bar requires core and
shoulder stability.
3rd- This action should be performed slowly, with coordination and core stability
so that the athlete doesn‟t loose footing or become injured due to a “jerky”
movement.
4th- Again, it is important the athlete keep this phase as smooth as possible in
order to avoid injury. If the athlete is unable to control the bar on the way
back down, they should consider changing the amount of weight.
The main concept of the snatch lift is the “explosive” aspect of hip, knee,
and ankle extension that takes place, that extension is critical in most sports
movements. The smooth, coordinated approach to the other phases of the lift is
also crucial in core stability and body control. All of these concepts are key
elements to most sporting activities and therefore makes it a popular choice
among strength and conditioning coaches.
The Olympic snatch is a ground based compound movement. The objective of
the snatch is to lift the bar from the ground to a stable position over head.
The successful performance of the snatch is the result of a complex series of
joint actions. These actions can be broken down into phases based on their
contribution to the entire movements. The Olympic snatch is a full-body
movement that can be broken down into 7 separate phases. The analyses of the
phases can help us to gain a better understanding of the motion as a whole.
Preparatory Phase
The preparatory phase is the static starting position for the snatch.
Proper starting position puts the body in a position that will facilitate
optimal force production. Poor starting position will result in minimal force
production. This will have a negative effect performance, and may result in
compensations possibly leading to injury.
First Pull
The first pull starts the movement. It describes the movement of the bar
from the ground to above the knees. This movement should be accomplished
primarily through knee extension.
Scoop
The scoop is a transition phase between the first and second pull. The
objective of the scoop phase is to reposition the body in relation to the bar.
This will relocate the center of gravity to the position necessary to enable the
athlete to utilize the power generated by the hips in the second pull. Failure
to do so will negatively affect performance due to altered range of motion,
particularly at the hips, and increased strain on the back and shoulders as a
compensatory mechanism.
Second Pull
The second pull phase begins with the bar at the mid to top thigh.
Explosive hip extension, accentuated by knee and ankle extension, is the main
source of power for the movement. Athletes using the snatch as a training tool
for other sports often begin their movement from this position (power snatch).
Third Pull
The third pull begins after triple extension reached in the second pull.
Essentially the athlete is pulling himself under the bar as is travels
vertically. Shoulder abduction, external rotation, and simultaneous concentric
hip and knee flexion characterize this phase.
Catch
In the catch phase, the athlete controls and stabilizes the bar overhead.
In the Olympic snatch this is done in the deep squat position. Catching the bar
in the deep squat position facilitates the movement of heavier loads due to the
fact that the athlete does not have to pull the bar as high. This places more
importance on the previous third pull phase. To control and stabilize the bar
in this position requires optimal stabilization strength, especially in the
hips, trunk, and shoulders.
Overhead Squat
The Overhead Squat describes the final phase of the snatch when the athlete
must stand from the deep squat position maintaining control and stabilization of
the bar overhead. Not only is strength of the hip and knee extensors key in
performing this phase, but trunk and shoulder flexibility, and stabilization
strength are crucial.
This analysis is to take two snatch lifts performed by one individual (JR Jones),
and determine the total time that each lift took, as well as the time it took to
perform each phase described in the checklist. The two sets of data will be compared
using a data table and column graph to illustrate relationships between absolute
timing and relative timing. The return phase is expected to take the longest of the
four phases because it is performed with more control in order to avoid injury.
Relative timing will be measured as a percentage, as in the percentage of time it
takes to complete one phase relative to the total time it takes to complete the
entire lift. The purpose of this analysis is to determine areas that could be
improved in order to make the lift more efficient and more successful. There should
be similarities in the amount of time it takes to perform each of the lifts because
they are being performed by the same individual. The objective is to isolate the
movement from beginning to end. An accurate recording can then be used to determine
how much time is spent in for example the return phase, and then how the complete
benefits of this exercise may not be sufficiently attained if the return phase isn‟t
performed by the individual.
The video kinematics measurements were conducted in order to track the
body‟s major joint movements in motion, over the time involved in performing a
standard Olympic snatch lift. From that measurement, the joint angles at the
various phases of movement were calculated for the knee and elbow joints using a
pro-tractor. The knee, ankle, hip, and elbow joints all play a pivotal role in
the snatch lift exercise, and by studying the joints together in relationship to
one another, observations could be completed made regarding the effects of
losing the use of one or more joints or angles. For example, it would be
virtually impossible to do a high amount of weight if the knee joint wasn‟t
allowed to bend because it would cause too much strain on the lower back. The
knowledge of correct joint angles, especially during the transitional phases of
the movement, will help prevent future injury and may offer areas of improvement
that may affect the consistency of the movement and the ability to generate
velocity and conserve energy through the process. The track of the bar was also
recorded to show the path the bar takes while in motion to complete the lift.
Tracking the path of the bar demonstrates the points in which the bar is moving
vertically and horizontally.
This analysis was performed in order to determine the velocity of the bar
as it is moving in the air during the hang-snatch exercise. There will be an
accelerometer attached to the end of the bar that will give a recording through
a computer screen showing the changing points in velocity, acceleration, and
position. The purpose of doing an analysis like this is to compare them to the
other variations of the lift such as adding more weight and/or changing the
style of the lift. Comparing the velocity and acceleration profiles, as well as
how it relates to position would be a good way to observe how the two will
change. I would expect an Olympic style snatch lift to have a higher
acceleration and velocity early on in the lift because of the increased joint
angle. However, there is an increased resistance to gravity the object (bar)
needs to go through so that might also have an effect. The following will be a
description on how exactly the results were obtained. There wasn‟t a lot of
allotted time to use the physics lab on one period of time, and the experiment
that used different weights wasn‟t registering at that day, so there are only
two trial Runs available, acceleration will include the second run, and velocity
and position will include the first trial run.
Methods:
In order to evaluate overall performance of the snatch, each phase will be
analyzed. A checklist outlining the key elements affecting performance in each
phase will be used. The basis for proper technique is taken from the analysis
of technique demonstrated by world class weightlifting competitors. Each phase
can be graded based on comparison to a previous analysis, another athlete, or to
the standards set by world class weightlifting competitors. A high score on a
proceeding phase should facilitate a higher score on the phase of focus. This
analysis will be a beneficial tool to the strength and conditioning coach,
useful for revealing specific weaknesses in technique, allowing for easy
formulation of an effective, individualized plan to improve performance.
Because the snatch is a power movement, video observation will be the most
effective method for analysis.
There is a line of motion so to speak, that looks like a backwards candy
cane. That line is the path the bar travels in order to successfully complete
the lift. When viewing the videos by the Velocity Sports performance institute,
Athletes Performance institute, and others, I was able to compare a variety of
different lifts from both male and female. The grading of their performance will
be constituted solely from the phase checklist above, meaning personal
limitations will only be noted and the individual will not be graded down
because of it. For example, a shorter individual will have an easier time
achieving the portion of the 2nd phase that requires the individual to reach the
position of deep squat. The taller athlete naturally will have a longer set of
arms and although the same visual picture may not exist, it is possible both
athletes are both achieving the necessary postures. I plan to make most of my
future observations form video as opposed to real time, however, I will take
notes during the filming of this exercise and compare what was seen at real time
with what takes place on film.
The experiment was completed using the University of Linfield‟s weight facility, a
ZR 850 Camcorder, JR Jones, a 45 lbs weight bar, two five lbs training plates, and a
tri-pod. The video information was uploading into the imovie application at the ITC
Center at Western Oregon University. The videos were cut-up into individual
repetitions so that each snatch lift could be isolated, broken down, and compared
with other cut-ups. The cut-ups were then transferred into a Quicktime.doc so that
they could be viewed at a framerate of 30 frames per second. Two videos were chosen
from the list and then broken down by each of the four phases determined through the
checklist. A data table was created in order to build a chart that will compare the
two snatch lifts side by side to determine how closely related each phase is to each
other and how the overall timing differs from one lift to the next, keeping in mind
that the weight isn‟t being changed. The weight of the bar and the two training
plates is constant in each of the two lifts performed by JR Jones.
In order to track the movement for the kinematic measurements, a Mac computer was
used in order to convert the iMovie into a quicktime.mov. Once the playback footage
was available, similar to the Phase-Timing analyses, the major joints were pinpointed
using a 17‟‟ Dell Monitor in Western Oregon‟s Hammersly Library. Tracing paper was
attached to the front of the monitor screen and a pencil was utilized to mark the
major joints, (i.e., ankle, knee, hip, and elbow) in a linear pattern at designated
frames. There will be two different videos used for this example to compare the
differences in phases and the degree of angle found in the knee and hip joints. Once
the marks are completed, they are connected to give a two dimensional representation
of body position throughout the action of the snatch. The representation was then
arranged in a sequence from the start of the preparatory phase to the end of the
Third phase of the movement. The return phase of the movement was ignored during this
portion of analyses. As mentioned previously, the end result was measured using a
pro-tractor to record the changes in hip and knee joint action. Ankle or elbow joint
angles can be used as well, however, for this particular analysis, we chose to
measure the hip and knee because of bigger hypothetic changes we expected to observe
in each phase
A 45lbs barbell was taken into the physics lab and set onto the floor in
the middle of the room. An accelerometer was set-up above the bar and a censor
was attached on the end of the bar. The censor was tested several times to
ensure that it was directly, or as close to being under the accelerometer as
possible. Once and accurate reading was determined to be available, JR did a
couple of hang-snatch lifts in order to get a reading on the computer.
Unfortunately, we were only able to get one reading for each variable and ran
out of time because the professor needed his classroom. JR and I came back to
the lab on several occasions to try the test again and it was to no avail, we
did end up getting some results, but they were on Mr. Armstrong‟s personal
computer, which wasn‟t something we had recurrent access too. The results from
the initial experiment ended up giving us our best results and that will be the
data utilized for our results. Keep in mind that using this method, while
changing the style of the lift and/or the weight of the bar will provide
differences in peak velocity and acceleration. Once the data was available, it
was entered into three different spreadsheets and labeled velocity,
acceleration, and position. Getting the information off of the Datastudio.pgf,
and onto the spreadsheet via a notepad application, the 300 plus points in each
needed to be split into intervals for accuracy purposes. I used position as my
starting point and observed that Cell #133 was the point in which there started
to be a change in position. Velocity and acceleration were then broken down into
the same type of intervals. 27 cells were included in each interval, and then
the difference between the cells was determined and then recalculated onto a
data table. That data table was converted into a chart to determine where
velocity and acceleration were in terms of time. The starting points for each
interval were zeroed out in order to get a relative number that would be a
better representation for the chart.
Another approach that we took was graphing all the points in a line chart
using all the number from Cell #133 until Cell 322#, this time just for position
and velocity, since we can determine what acceleration is doing based on the
line of velocity. We chose the Cell #133 again because that was the cell that
began to show a change in position. Before charting the line graph‟s, we decided
to multiply all the Cells (133-322) by -1 in order to flip the chart around and
make it easier to read since the censor for the accelerometer was hanging over
head and not below the bar. Once those numbers were obtained, the line chart was
created for both position and velocity, and is included in the following
results.
Results:
Presented below is a checklist comprised of a workable set of key elements
relative to aforementioned phases. This checklist can be used as a tool to
evaluate the success of subjects in performing Olympic snatch. The checklist
was used to analyze the video footage of two athletes performing the Olympic
snatch.
Athlete #1 is a baseball player who has been involved in strength and conditioning programs for the past 12 years. Despite his
training experience the, has minimal experience with weightlifting exercises. The repetitions performed for this analysis were
his first eve r performed. Detailed explanation and demonstration of the movement were provided before the athlete
performed the recorded repetitions.
Name: Athlete #1 Date: 2010
Starting Position 23 /27
3rd Pull 15 /21
DOB: 1984 1st Pull 23 /27 Catch 25 /28
Experience: 1month Scoop
18 /27 Overhead
Squat 27 /27
Sport: Baseball
2nd Pull 19 /24
Training Phase: Pre-season
Scale: 1-poor 2-fair 3-ideal
Total: 143
79.0 %
Possible: 181
Preparatory Phase: Starting position
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Heels Shoulder width, under knees
Note: Hips up
Note: Hands approx body width outside
shoulders
Note: 3/4 width
Neutral Cervical
Spine
Note: slight Extension at neck
1 2 3 1 2 3 1 2 3 1 2 3
Weight in heels Note:
Back extended Note: posterior
Shoulders over bar Note:
Note:
1 2 3 1 2 3
pelvic tilt, slight rounding of back
1 2 3 1 2 3
Bar under knees Note:
Note: Shoulders
depressed & retracted
Note: shoulder protraction
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___9___/___9___
Total ___5___/___6___
Total ___7___/__9____
Total ___2_/__3_
1st Pull: Ground to knee clearance
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Movement initiated by knee extension
Note: Torso maintains starting angle with
horizontal
Note: Arms extended
Note: Neutral cervical
spine
Note: slight ext.
1 2 3 1 2 3 1 2 3 1 2 3
Weight in heels Note: weight shifts to front half of feet
Back extended Note: posterior pelvic tilt, slight rounding of back
Shoulders depressed &
retracted
Note: slight elevation at end of phase shoulder Protraction
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Bar clears knees close to body
Note: bar never Hips stay flexed
Note:
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___8___/___9_
Total__8__/___9
Total _5__/_6_
Total _2_/_3_
Scoop: Bar moves from just above knee to
upper thigh
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Knees move forward under bar remaining
at shoulder width
Note: knees remain behind bar
Torso angle: + with horizontal unchanged at hip
Note: angle increases at hip
Arms extended
Note: elbow flexion shoulder abduction
Neutral cervical
spine
Note: Extension at neck
1 2 3 1 2 3 1 2 3 1 2 3
Weight in heels Note: mid to front of foot
Back extended Note: Shoulders
depressed & retracted
Note: elevation
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Bar close to body Note:
Hips stay flexed Note:
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___5___/___9___
Total ___7___/___9___
Total ____4__/__6__
Total _2_/_3_
2nd Pull: Triple Ext
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Triple extension Note: Minimal Plantar flexion and hip ext
Aggressive hip extension
Note: does not reach full extension
Arms extended Note: Neutral
cervical spine
Note: Result of change in torso angle
1 2 3 1 2 3 1 2 3 1 2 3
Feet leave the floor
Note:
Back extended
Note: Shoulders depressed and
retracted
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Note: Bar stays close to
body
Note: away early in phase & close in late phase
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ____4__/__6____
Total ____6__/____9__
Total __6___/___6__
Total _3__/_3_
3rd Pull: Downward movement under the bar
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Feet return to ground
Note:
Back extended
Note: Shoulders elevation
Note: shoulders protract
Late phase Neck
extension
Note: retraction
y-1 n-0 1 2 3 1 2 3 1 2 3
Aggressive Knee & hip flexion
Note: Slow flexion= poor ROM
Slight decrease in angle from horizontal
Note: Aggressive high pull and external rotation
Note: Poor speed & ROM in high pull and premature ext rot
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Note:
Note: Bar stays close
to body
Note: Bar travels away from upper body
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___3___/___3__
Total ___6___/___6___
Total ___5___/___9_
Total __1_/_3_
Catch: Downward motion after bar is overhead
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Feet just outside shoulders
Note: Torso parallel to
shins
Note: Arms fully extended over
head
Note: Neutral cervical
spine
Note: protracted & extended
1 2 3 1 2 3 1 2 3 1 2 3
Full squat depth Note: Only half squat
Back extended Note: Shoulders
stable
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Weight in heels Note: weight mid to front foot
Note: Bar over Center
of Mass
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___8___/___9___
Total ___6___/___6___
Total ___9___/___9_
Total _2_/_3_
Overhead Squat: Upward movement from lowest catch position to full
stand
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Full hip and knee extension
Note:
Back extended
Note:
Arms extended
Note: Protracted and
extended
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Feet just outside shoulder width
Note:
Upright
Note: Shoulders stable,
elevated, and retracted
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Weight balanced Note:
Note: Bar over Center
of Mass
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___9___/___9___
Total ____6__/___6___
Total ___9___/___9_
Total __3_/_3_
Athlete #2 is a college football player, who at the time of analysis was entering into spring season. He was successful
competing at the high school level. Though he is no longer weightlifting competitively, variations of these exercises are a
consistent part of his strength and conditioning programs for football.
Name: Athlete #2
Starting 25 /27 3rd Pull 18 /21
Date: 2010 Position
DOB: 1988 1st Pull 25 /27 Catch 23 /28
Experience: 5years competing Scoop
26 /27 Overhead
Squat 27 /27
Sport: Weightlifting/Football
2nd Pull 21 /24
Training Phase: Pre-season
Scale: 1-poor 2- fair 3-ideal
Total: 165
90.7 %
Possible: 182
Preparatory Phase: Starting position
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Heels Shoulder width, under knees
Note:
Hips up
Note: Hands approx body width
outside shoulders
Note: Neutral Cervical
Spine
Note: Extension at neck
1 2 3 1 2 3 1 2 3 1 2 3
Weight in heels Note:
Back extended Note: Shoulders over
bar
Note: Note:
1 2 3 1 2 3 1 2 3 1 2 3
Bar under knees Note:
Note: Shoulders
depressed & retracted
Note: shoulder protraction
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___9___/___9___
Total ___6___/___6___
Total ___8___/__9___
Total ___2___/__3___
1st Pull: Ground to knee clearance
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Movement initiated by knee extension
Note: Torso maintains starting angle with
horizontal
Note: Arms
extended
Note: Neutral
cervical spine
Note: Extension at neck
1 2 3 1 2 3 1 2 3 1 2 3
Weight in heels Note:
Back extended Note: Shoulders
depressed & retracted
Note: shoulder Protraction
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Bar clears knees close to body
Note:
Hips stay flexed
Note:
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___9___/___9_
Total ___9___/___9_
Total __5__/__6__
Total __2_/_3_
Scoop: Bar moves from just above knee to
upper thigh
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Knees move forward under
bar remaining at shoulder width
Note:
Torso angle with horizontal Increases
Note:
Arms extended
Note:
Neutral cervical spine
Note: Extension at neck
1 2 3 1 2 3 1 2 3 1 2 3
Weight in heels Note:
Back extended Note: Shoulders
depressed & retracted
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Bar close to body Note:
Hips stay flexed Note:
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___9___/___9___
Total ___9___/___9___
Total ___6__/__6_
Total __2__/__3_
2nd Pull: Triple Ext
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Triple extension Note: Minimal Plantar flexion
Aggressive hip extension
Note: good ROM motion, speed fair
Arms extended
Note: Neutral cervical spine
Note: Result of change in torso angle
1 2 3 1 2 3 1 2 3 1 2 3
Feet leave the floor
Note:
Back extended
Note: Shoulders depressed
and retracted
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Note: Bar stays close to
body
Note:
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ____5__/__6____
Total ___8__/____9__
Total __6__/__6__
Total __3__/___3__
3rd Pull: Downward movement under the bar
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Feet return to ground
Note: Back extended
Note: Shoulders elevation
Note: Neck extension
Note:
y-1 n-0 1 2 3 1 2 3 1 2 3
Aggressive Knee & hip flexion
Note: Slow flexion= poor ROM
Slight decrease in angle from horizontal
Note: Aggressive high pull and
external rotation
Note: Poor speed & ROM in high pull and premature ext rot
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Note:
Note: Bar stays
close to body
Note: Bar travels away from upper body
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___3___/___4__
Total ___6___/___6_
Total ___6___/_9_
Total ___3___/___3
Catch: Downward motion after bar is overhead
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Feet just outside shoulders
Note: Torso parallel to
shins
Note: approx 15 degrees forward
Arms fully extended over head
Note: Neutral
cervical spine
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Full squat depth Note: Only half squat
Back extended Note: Shoulders
stable
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Weight in heels Note: weight mid to front foot
Note: Bar over
Center of Mass
Note: initial catch bar forward of C.O.M.
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___7___/___9__
Total ___5___/___6___
Total _8__/___9_
Total __3__/__3__
Overhead Squat: Upward movement from lowest catch position to
full stand
Lower Extremity
Trunk
Upper Extremity
Head & Neck
Full hip and knee extension
Note:
Back extended
Note: Arms
extended
Note: Protracted
and extended
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Feet just outside shoulder width
Note:
Upright
Note: Shoulders stable,
elevated, and retracted
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Weight balanced Note:
Note: Bar over
Center of Mass
Note:
Note:
1 2 3 1 2 3 1 2 3 1 2 3
Total ___9___/___9___
Total ____6__/___6___
Total ___9___/__9
Total __3__/__3_
Snatch Anatomical Analysis
Preparatory Phase
The preparatory phase for the snatch is a static starting position. Ankles
are dorsi flexed aligning the toes under the knees and shoulders. The knees and
hips are flexed, and the trunk is hyperextended. The cervical spine is neutral.
The scapula is depressed, retracted, and rotated downward to support shoulder
flexion and horizontal abduction. This shoulder position joined with extended
elbows facilitates a wide grip on the bar. Pronation at the radiolulnar joint
and adduction of the wrist allows for an overhand grip on the bar. Early phase
movement begins when the athlete shifts his weight is back; maintaining a hyper
extended spine and a grip on the bar. The tension force generated through the
arms on the bar acts as a counter balance, allowing the athlete to maintain a
center of gravity as well as increasing tension force (potential energy) in the
athletes posterior side . This potential energy will be converted to kinetic
energy in the form of hip extension after the bar clears the knees.
Pull Phase
The pull phase is a series of full body concentric contractions that result
in the application of maximal vertical force on the bar. The goal of the phase
is maximal vertical displacement of the bar. Early phase movement begins when
the athlete shifts his weight is back; maintaining a hyper extended spine and a
grip on the bar. This is started with knee extension and accompanied with
simultaneous extension at the ankles, shoulders, and hips. Once the bar has
cleared the knees, hip extension becomes the primary joint action. The trunk
remains hyper extended, and the cervical spine neutral. Mid phase, as the hip,
knees, and ankles reach full extension (triple extension), the shoulders abduct,
and the elbows and writs flex. The Scapula elevates and rotates upward
supporting this movement. This adds to the vertical forces on the bar, as well
as decelerates/accelerates the vertical displacement of the athlete. Late phase
the shoulders externally rotate allowing for the passage of the bar overhead.
At this time the hips, knees, and ankle flex concentrically in preparation for
the catch.
Catch Phase
The catch phase describes the athlete accepting, and stabilizing the bar
overhead. The hips, knees, and ankles flex eccentrically slowing decelerating
the athlete as he returns to the ground and into a squat position under the bar.
The trunk remains hyper extended and the cervical spine still neutral. Early
phase concentric muscle contraction causes the elbows to extend, the shoulders
to further abduct and externally rotated concentrically, and then remain in such
position stabilizing the overhead weight via isometric muscle contraction. The
scapula remains retracted, elevated, and upwardly rotated, to support these
positions. The wrist extends from its previous flexion through a neutral
position to an extended position to catch the bar. After catching and
stabilizing under the bar, the athlete stands with the weight overhead. This
late phase of lower extremity joint action involves hip, and knee extension.
The torso, scapula, shoulders, elbows, and wrists continue to be stabilized by
isometric muscle contraction through this portion of the catch phase.
Prepatory Phase
Joint Action Muscles Contractio
n
Ankles Stabilization
Peroneus tertius Extensor
digitorum Extensor hallucis
longus Tibialis anterior
Isometric
Knees Stabilization
Vastus lateralis Vastus
Intermedius Vastus Medialis Gastrocnemius
Isometric
Hips Stabilization
Gluteus maximus Gluteus medius
(post fibers) Adductor magnus
Isometric
Trunk Stabilization Erector spinae
Quadratus lumborum
Isometric
Head/Neck Neutral Stabilization Isometric
Scapula Stablization Trapezius
(mid/lower fibers) Rhomboids
Isometric
Shoulders Stabilization Anterior Deltoid Upper pectoralis
major Isometric
Elbows Stabilization Isometric
Radiolulner Pronation Pronator teres
Pronator quadratus
isometric
Wrist Stabilization
Flexor carpi radialis
Flexor pollicis longus
Extensor carpi radialis brevis Extensor carpi radialis longus
Extensor pollicis longus Extensor
pollicis brevis Abductor pollicis
longus
Isometric
Pull Phase
Joint Action Muscles Contractio
n
Ankles Plantar flexion Pronation
Gastricnemius Soleus Tibialis
Posterior Flexor Digitorum
Longus Flexor hallucis longus
perouneus longus peroneus brevis
Concentric
Knees Extension
Vastus Lataralis Vastus
Intermedius Vastus medialis Rectus femoris
Concentric
Hips
Early Phase: Extension
Gluteus maximus Gluteus medius
(post fibers) Biceps femoris
Semimembrinosus Semitendinosus
Concentric
Late Phase: Flexion
Iliacus Psoas
Rectus femoris Sartorius
Pectineus Gracilis Tensor fascia
latae
Concentric
Trunk Hyperextension Erector spinae
Quadratus lumborum
Isometric
Head/Neck Neutral Stabilization Concentric
Scapulae Early Phase: Downward Rotation Depression Pectoralis minor
rhomboids Lower Trapezius
Concentric
Late Phase: Elevation Upward Rotation
Levator scapulae Rhomboids
Serratus Atnerior Trapezius
Levator scapulae rhomboids
Concentric
Shoulders
Early Phase: Extension
Latissimus dorsi Teres major
subscapularis Infraspinatus
Posterior Deltoid Pectoralis major
(lower fibers)
Concntric
Mid Phase: Abduction
Pectoralis major upper fibers
Deltoid Ant, mid, post, fibers
Supraspinatus
Concentric
Late Phase: External rotaion Infraspinatus Teres minor
Concentric
Elbows
Early Phase: stabilization Triceps brachii
Anconeus
Isometric
concentric
Late Phase: Flexion Biceps brachii
Brachialis Brachioradialis
Concentric
Radiolulnar Pronation Pronator teres
Pronator quadratus
Isometric
Wrist Early Phase: Stabilization
Flexor carpi radialis
Flexor pollicis longus
Extensor carpi radialis brevis Extensor carpi radialis longus
Extensor pollicis longus Extensor
pollicis brevis Abductor pollicis
longus
Isometric
Late Phase: Pamlar flexion Abduction
Flexor Carpi radialis
Palmaris longus Flexor carpi
ulnaris Flexor digitorum sperficialis Flexor
digitorum profundus Flexor pollicisExtensor
carpi radialis brevis Extensor
carpi radialis longus Extensor pollicis longus
Extensor pollicis brevis Abductor pollicis longus
Concentric
Catch Phase
Joint Action Muscles Contractio
n
Ankles
Early Phase: Dorsi flexion Supination
Peroneus tertius Extensor
digitorum Extensor hallucis
longus Tibialis anterior
Concentric
Late Phase: Dorsi flexion supination
Gastricnemius Soleus Tibialis
Posterior Flexor Digitorum
Longus Flexor hallucis longus
perouneus longus peroneus brevis
Eccentric
Knees
Early Phase: flexion Semitendinosus
Semimembrinosus Biceps femoris
Concentric
Late Phase: Flexion
Vastus Lataralis Vastus
Intermedius Vastus medialis Rectus femoris
Eccentric
Hips Early Phase: Flexion
Gluteus maximus Gluteus medius
(post fibers) Biceps femoris
Semimembrinosus Semitendinosus
Eccentric
Late phase: Gluteus maximus Concentric
Gluteus medius
(post fibers) Biceps femoris
Semimembrinosus Semitendinosus
Trunk Stabilization Erector spinae
Quadratus lumborum
Isometric
Head/Neck Neutral Stabilization Eccentric
Scapula
Early Phase: Elevation Retraction Upward Rotation
Levator scapulae Rhomboids
Serratus Atnerior Trapezius
Levator scapulae rhomboids
Concentric
Stabilization
Levator scapulae Rhomboids
Serratus Atnerior Trapezius
Levator scapulae rhomboids
Isometric
Shoulder
Abduction External Rotation
Pectoralis major upper fibers
Deltoid Ant, mid, post, fibers
Supraspinatus Infraspinatus Teres minor
Concentric
Late Phase: Abduction External Rotation
Pectoralis major upper fibers
Deltoid Ant, mid, post, fibers
Supraspinatus Infraspinatus Teres minor
Isometric
Elbows
Early Phase: Pronation Extension Triceps brachii
Anconeus Concentric
Late Phase: Stabilization Triceps brachii
Anconeus Eccentric
Radiolulnar Pronation Pronator teres
Pronator quadratus
Isometric
Wrist
Early Phase: Extension Abduction
Extensor carpi ulnaris Extensor
carpi radialis brevis Extensor
carpi radialis longus Extensor
digitorum Extensor pollicis longus Flexor
carpi radialis
Concentric
Late Phase: Stabilization
Flexor carpi radialis
Flexor pollicis longus
Extensor carpi radialis brevis Extensor carpi radialis longus
Extensor pollicis longus Extensor
pollicis brevis Abductor pollicis
longus
Isometric
The results of each phase will be graded in five categories:
Excellent, Above Average, Average, Below Average, and Needs Significant Improvement (NSI).
Phase Snatch Lift # 1 SL # 2 Comparison
Starting (1st) Above Average Above Average Push (# 2)
2nd Phase Average Excellent #2
3rd Phase Average Above Average #2
Return (4th) Above Average N/A N/A
#1 can be viewed through YouTube.com
http://www.youtube.com/watch?v=yqP8xtlOIXY
# 2 can be also viewed through YouTube.com
http://www.youtube.com/watch?v=9nc4DpIzns8
Snatch
#1
Snatch
#2
Phase Frames
Beginning 17 13
Second 32 28
Stand-up 30 22
Return 108 80
Absolute Timing
Snatch #1 Snatch #2
Time(sec) Time(sec)
0.57 0.43
1.07 0.93
1 0.73
3.6 2.67
Relative Timing
Snatch #1 Snatch #2
100% 100%
9 9
17 19
16 15
58 57
0.57
1.07 1
3.6
0.43
0.930.73
2.67
0
0.5
1
1.5
2
2.5
3
3.5
4
Beginning Second Stand-up Return
T
i
m
e
(
s
e
c)Phase
Absolute Timing
Snatch #1
Snatch #2
Snatch Lift #1 (Training Plates): Phase Preparatory Pull Transition Catch
Hip Joint In Degrees 52° 111° 150° 85°
Knee Joint In Degrees
80° 34° 133° 72°
Inclination 27° 82° 80° 77°
9
17 16
58
9
1915
57
0
10
20
30
40
50
60
70
80
90
100
Beginning Second Stand-up Return
%
t
o
t
a
l
m
o
v
e
m
e
n
t
t
i
m
e
Phase
Relative Timing
Snatch #1
Snatch #2
Preparatory Pull Transition Catch
-1
-0.9
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
1 7
13
19
25
31
37
43
49
55
61
67
73
79
85
91
97
10
3
10
9
11
5
12
1
12
7
13
3
13
9
14
5
15
1
15
7
16
3
16
9
17
5
18
1
18
7
19
3
Series1
Position:
Notice the change in position, how the bar is going up and then leveling
off at a certain point. Note: there are „fuzzy‟ areas of this chart that need to
be filtered, we assume there was some „noise‟ going on that caused the position
points to move up and down so frequently.
Velocity:
The velocity is going up at a rapid rate signifying the bar reaching the
top of the snatch lift and then returning to normal as the performer comes to a
pause at the top of the lift. We also assume an unknown amount of „noise‟
taking place in this activity, and when the individual gets to the third phase
-0.2
0
0.2
0.4
0.6
0.8
1
1 8 15 22 29 36 43 50 57 64 71 78 85 92 99106113120127134141148155162169176183190
S…
of this lift, there is a rolling of the wrist joint action taking place, that
might have affected this chart as well.
Acceleration:
The acceleration numbers that we obtained through this activity were not as
accurate and clean as the position and velocity charts were, so we decided to
explain them using the velocity chart as well. The acceleration is the
∆velocity/∆time, so when we view the velocity curve, we notice an increase in
acceleration, then a point of no acceleration, followed by a period of negative
acceleration or deceleration. The velocity chart then shows a somewhat flat line
which would also represent a point of no acceleration.
Discussion:
A checklist is a valuable tool that can be used to accurately evaluate the
performance of any movement. Such tools are especially useful when analyzing
complex, explosive, movements such as the Olympic snatch. Using the information
gathered from video analysis, each phase is evaluated based on a qualitative
rating of its key elements. From this, a comprehensive grade is derived,
representative of the subject‟s overall strength of performance.
Comparing the video footage in real time, no major differences stand out.
Understanding the complexity of the snatch, this does not make sense giving the
fact that athlete #1 was performing the snatch for the first time, and athlete
#2 had at over six years of experience performing the lift.
Slowing the movement down using computer software, differences in technique
become evident. The results from checklist analysis provide a detailed
evaluation of their strengths and weaknesses. Athlete#2 had an overall strength
of performance score approximately 10% higher than Athlete #1. This is score is
valuable when comparing overall performance between athletes, as well as for
tracking progress. Comparing performance at each stage we begin to see the
individual strengths and weaknesses that set the athletes apart. On average,
Athlete #2 scored 2% higher on a given phase compared to Athlete#1. This
average does not have much value because the maximum point value of each phase
is not equal. When analyzing the scores of each phase, the outliers will be the
best indicators of strengths and weaknesses. Doing so, we see that Athlete#2
scored 8 points higher than Athlete#1 in the scoop phase. This suggests that
the scoop phase is the origin of Athlete #1‟s weakness and may be the
predominant factor affecting his overall strength of performance.
Say these same two athletes plan to reassess and compare their performance
using this checklist again the following month. Each athlete can use the
information on their checklist to design an effective strength and conditioning
program tailored to meet their specific needs. Looking at Athlete #1‟s
evaluation we see that he has a room for improvement in all phases. Noticing
that deviations seem to be greater in the phases following the scoop compared to
the phases leading it, we can deduce that the scoop phase is his greatest area
of weakness and may be the cause of deviation in the later phases. Improvement
in the key elements involved in the scoop phase should be the priority of the
next month‟s strength and conditioning program.
This checklist is a valuable tool, but, each phase describes one, in a
sequence of 7 interconnected movements that combine to produce one fluid
movement.
What may seem like insignificant deviations in technique can alter the next
in sequence, compounding with each subsequent phase. Looking at the scores
following the scoop phase, the difference between scores increases compared to
the phase scores proceeding the scoop phase. These findings agree with our
understanding that each phase is interconnected, and is essentially a
description of one fluid movement.
Evaluated two separate videos, the first one was a video that looked like
it was a “user” uploaded video, and the second video was a training film on the
snatch lift from Velocity Sports Performance institute in Redondo Beach,
California. For the analysis of the first lift, I gave the athlete an above
average starting position because he demonstrated proper foot and bar placement.
During the latter stages of the lift, i.e. after a couple of reps, the athlete
looks to become off balanced in their foot position, a coach should keep an eye
on that. The second phase was given an average grade. It was borderline below
average too because it looks like the bar is unbalanced when the athletes elbows
reach full extension. I would like to see more body control and coordination
during this part of the movement. The third phase is the also considered average
and could also be considered below average depending on the repetition being
observed at the time. There are points when the athlete loses balance on the way
back to standing position, those sliding feet are a sign of improper balance and
body control. The fourth phase is viewable in the first lift and I gave the
grade of above average based on the fact the athlete finished this portion of
the lift. The athlete was only using the bar, which could be part of the
equation as to why the athlete is doing the “return” phase of the lift. This
portion of the lift should be an important coaching point for this athlete
because he has a lot of room to improve performance and it‟s easier to develop
this habit during the beginning stages of this lift.
I viewed the second lift from the side angle and therefore I didn‟t give it
an automatic excellent grade. I assumed, because of the results of the other
phases of this lift, that the female athlete was going to be spot-on during the
starting phase of the snatch lift. The second portion of this lift got the
highest rating possible because of the coordination, explosion, and body control
that is on display during this phase. There is a build up, where the athlete is
beginning to rise up, the build up is slower than the explosive movement that
takes place once the bar reaches about hip level. When the bar reaches hip
level, the athlete “pops” their hips, receives the bar and hits a perfect deep
squat position. When I watch this portion of the snatch lift performed by this
athlete, I feel this would be a perfect example to demonstrate pace, explosion,
and body position. The athlete has a minor amount of trouble around the knee
region when trying to stand back up to the standing position of the lift. This
aspect is still considered to be above average by my standards, the fluidity of
the motion is not perfect and so I didn‟t give it an excellent grade. Not that
the movement or lift in general will ever be exactly perfect, but I can‟t
consider it to be close to it when there are noticeable flaws to be corrected. I
would like to see the same athlete from a front camera perspective in order to
view the athlete‟s knee movement and facial expression during the third phase of
the lift. The “return” phase was Not Applicable for this observation, however, I
do believe that the athlete performs this portion of the lift and it isn‟t
included based on video editing. The person who edited this video is more than
likely trying to show the significance in the 2nd and 3
rd phases of the lift.
Those two phases do represent the most action and the 2nd phase is the phase
considered most important to the athletic applications this lift is said to
provide.
I was really surprised with the similarities that exist between the two lifts,
especially how the percentages remain closely related even though both activities
weren‟t performed in the same amount of total time. The starting phase had a nine
percent relative timing rate in each of the two lifts even though one took about six
seconds and the other about four. In order to get better results and have a greater
understanding of the relationships between the phases and relative and absolute
timing. Having more than just two examples to observe and collect data from will be
able to help distinguish whether or not the percentages were as close as they were
when two were put side by side. By increasing the weight and examining how the total
time of the lift changes as a result would also be an interesting concept to look at
in future experiments. The methods for this experiment were solid, having used a 60
frame per second framerate would have been more ideal, being that the numbers would
have been more accurate. The best thing to do in order to improve the results of this
analysis is to increase the amount of snatch lifts being analyzed and compared. There
were more than two videos to choose from and more than one angle to look at as well.
Being able to use the imovie software in order to cut-up the video into individual
clips and convert them to quicktime was extremely helpful. It was easier to determine
when the starting phase was beginning because it was already cut in such a way that
only a few frames needed to be forwarded before movement was seen. Determing when the
movement changed from one phase to the next was difficult, which is why each phase
was looked at more than once. When a consensus was reached on the amount of frames it
took to go from one phase to the next, the data was recorded. This experiment was
trying to avoid recording numbers based on the first trial of information, after all,
there is usually something portrayed in a video that may not have been identified
before. Comparing the phase timing between a taller person, a shorter person, and
with different weight amounts would be idyllic ways to branch away from this
experiment and use it to develop further results.
After examining the results of the video kinematic analysis, it appeared
that one of the major differences between the joint angles in the each of the
phases; was the degree of knee flexion that occurred. There is an 80°
preparatory knee joint angle followed by a 34° during the pull phase, followed
by a 133° knee joint angle in the transition phase, and finally back down to a
72° angle during the catch phase. We are interested in the amount of knee joint
angle change that might occur when the amount of weight is increased. The hip
joint didn‟t waver as much as the preparatory phase joint angle was 52°; the
pull phase included a hip joint angle of 111°, the transition phase had a joint
angle of 150°, and finally the catch phase included an 85° joint angle. We
assume that increasing the amount of weight will produce and increase in hip
joint angles at the pull and transition phases of the lift due to the individual
attempting to generate more force. The path of the bar was tracked and we
observed that the bar does not go in a straight path vertically, but rather,
moves in a path similar to a backward candy cane. There is a little hitch in the
movement, albeit not a major one in this illustration, but it is observed in
highly mechanical snatch lifts, and that hitch shows the point at which the
individual is starting the pull phase of the lift. During the pull phase, the
bar moves outward and vertically, until the transition phase, when the bar moves
above and behind the head of the individual. The lifter does not want that bar
directly over their head, but rather behind their head with their arms fully
extended and the hips at a joint angle of a little less than 90°. Tracking the
path of the bar an examining it can help the lifter identify whether or not they
are having a mechanical advantage or disadvantage based on their path of the
bar. If the path of the bar is too far out in front, or they don‟t get the bar
back behind their head, their safety and performance could suffer as a result.
The snatch exercise is a lift that can generate power, but if the hip joint
angles and bar path aren‟t efficient, it is harder for the individual to ever
reach that point. Our recommendation for any athlete or individual preparing to
learn the Olympic snatch lift is they should learn each fundamental aspect of
the movement and have an understanding of bar path in order to be more efficient
at the start or learning, that way less biomechanical corrections need to be
made down the road.
We would have liked to compare these results with the results of another
velocity/acceleration profile in which the information is taken using a scale
and a video analysis. As mentioned before, these results need to be compared to
another experiment that includes a different weight or technique such as the
regular snatch. It would have been nice to have the access to a digital laptop
computer that included the datastudio.pgf so that the accelerometer could
actually be set up in a weight facility or even another facility that offered
more space to work with. Access to training plates would also make this an
easier activity as well as a cordless accelerometer. That equipment is very
expensive, but it should be included in the discussion because of its potential
value, if/when it becomes available. As far as the experiment goes, the
individual in the experiment showed an increased velocity and acceleration as
there was also an increase in position. When position leveled off, there was a
decrease in velocity and therefore a decrease in acceleration. The main
differences that would have been seen between the Olympic style snatch and the
hang-snatch would have been there would have been a longer change in position
and therefore a longer change in velocity, meaning it would take longer to reach
peak velocity due to the increase in drag and increase in gravity. There is the
same acceleration rate from zero to ten mph as there is with ten to twenty mph
as long as they are completed in the same amount of time. The acceleration rate
from zero to twenty mph should be different than the acceleration from zero to
forty mph but they might actually be identical depending on the amount of time
it takes to get there. For example, the acceleration from zero to forty mph
happening over eight seconds is actually the same as the acceleration from zero
to twenty mph happening over four seconds. A car going from zero to forty mph in
6 seconds would have a different acceleration than a car going from zero to
twenty mph in 5 seconds. However, the more ticker marks available to measure the
change in distance over the change in time can demonstrate the changes in
velocity. It could be possible that the acceleration points are identical for a
certain period of time, but the change or increase in velocity by one party
would cause the car to accelerate to their location at a faster rate. A real-
life example of this would be observing a 40 yard dash in which one party runs a
6 second forty and the other runs a 4.5 forty yard dash time. If the individual
is given a five yard head start, how long would it take the other individual to
pass him up? If you had the calculations available using the accelerometer,
which offers a lot of position ticker points, you would be able to calculate
this. That information could also be calculated using the velocity equation
after doing phase-timing analyses since there is distance marks available on the
field. We still feel that the accelerometer is actually the better way to
measure this accurately since there are more distance marks available for
position. As to how this information pertains to the snatch lift, the change in
speed in the bar showed a rapid acceleration to its peak, or maximum height.
Force generated by the hips, knee, ankle, and elbow joints all propelled the bar
towards its neutral state of inertia. At that point, the bar had reached the
maximum potential energy capacity and after the period where no acceleration was
present, there was a decelerating point where the individual was coming to a
stagnant position as the movement was completed. Our recommendation is to do
exercises such as high pulls to increase the amount of force generated by the
hip, shoulder, elbow, ankle, and knee joints, so that the bar has an increased
velocity and acceleration.
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