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Application of Biomechanical
Information on Young Weightlifter's Snatch
Performance
Ronald Byrd, PhD and Kyle Pierce, EdD
USA Weightlifting Development Center in Shreveport
Introduction
Weightlifting technique is being subjected to
scrutiny to a greater degree than ever before. Simple
quantitative video analysis, done routinely by many
coaches, is frequently supplemented by analysis that
involves use of various technologically sophisticated
systems. One of these, the V-Scope, was recently used to
examine performance of the athletes in the 2002
Championnat Juvénile du Québec.
This and other such systems are useful tools for
coaches to use during training sessions, but they are
also valuable in assessing performance under the most
demanding of situations, competition.
The object of this paper is to present selected
critical elements of performance of the snatch lift by
Québec’s young weightlifters and to compare their data
with similar information obtained during the 2001 World
Team Trials in the USA in context of comments on key
scientific and coaching elements (Crawley, Smith, &
Cioroslan, 2002).
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Methods
Subjects selected for this study were the winning
male and female weightlifters in each class in the 2002
Championnat Juvénile du Québec (CJQ). Comparison
subjects were 7 male and 7 female U.S. Olympic Training
Center athletes (USOTC).
A V-Scope was used for data capture. This is a
system that tracks one end of the bar during lifting,
providing information on trajectory, velocity, and
acceleration (Hiskia, 1997). There has been some
criticism of tracking only one end of the bar, but
recent research that provides data on both ends of the
bar in a 3-dimensional analysis is supportive of V-Scope
use (Crawley, Smith, & Cioroslan, 2002). For
example, left and right bar velocities for their snatch
lifts were 1.890 and 1.887 for men and 1.940 and 1.917
for women. Vertical bar displacements, left and right,
were 123 and 125 for men and 124 and 123 cm for women.
These are certainly very small and clearly insignificant
differences.
Parameters selected for examination were first pull
velocity pattern, maximum velocity during the first
pull, transition phase velocity pattern, maximum
velocity during the second pull, and crash distance. For
convenience and consistency, comparisons with USOTC data
were made with data related to the left end of the bar
(Crawley, Smith, & Cioroslan, 2002).
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Results and Discussion
Information for each weightlifter is shown in Table
1. It is obvious that some have relatively good
technique and some need much attention to this aspect of
performance. In the discussion that follows, the focus
is on the key scientific and coaching elements presented
by Crawley, Smith, and Cioroslan (2002).
| Lifter |
1st Pull, Constant Inscrease in V?
|
1st Pull, Maximum Velocity
(m/sec) |
1st Pull, % of 2nd Pull Max
Velocity |
2nd Pull, Maximum Velocity
(m/sec) |
Transition, Marked Decreased Velocity? |
Crash Distance (cm) |
Peak >5cm forward |
| J-PG |
Yes |
1.55 |
108 |
1.43 |
Yes |
25 |
No |
| DC |
Yes |
1.31 |
62 |
2.13 |
No |
31 |
No |
| ADA |
Yes |
1.39 |
76 |
1.84 |
No |
29 |
No |
| DV |
Yes |
1.36 |
66 |
2.28 |
No |
1 |
Yes |
| AC |
Yes |
1.30 |
67 |
1.94 |
No |
11 |
No |
| DTF |
No |
1.15 |
65 |
1.78 |
Yes |
- |
No |
| SP |
Yes |
1.46 |
63 |
2.33 |
No |
3 |
Yes |
| PB |
Yes |
0.83 |
40 |
2.06 |
Yes |
0 |
No |
| AG |
Yes |
1.07 |
51 |
2.08 |
No |
0 |
No |
| EP |
Yes |
1.63 |
82 |
2.00 |
No |
9 |
Yes |
| JM |
Yes |
1.20 |
62 |
1.93 |
No |
0 |
Yes |
| MM |
Yes |
1.08 |
47 |
2.29 |
Yes |
27 |
Yes | *The
first 7 are males and the last 5 are females. Items in
red and italics merit attention.
First pull velocity pattern
Crawley, Smith, & Cioroslan (2002) state that
for an efficient lift, the barbell must move with
“constantly increasing speed” during the first pull,
taking the barbell in this way until it passes the knee.
This is certainly in concert with Newtonian physics; any
departure from this constantly increasing velocity would
reduce bar momentum and thus place an extra burden on
the athlete when the second pull occurs. Six of the
seven CJQ male weightlifters and all five of the females
were in concert with this requirement. While this is
clearly a well-based concept, it has been our experience
that it is not a relatively frequent problem. However,
that does not make it any less important and attention
should be given to correcting this error.
Maximum velocity, first pull
The CJQ mean (1.16) for female athletes was similar
to the mean for USOTC women (1.19), but CJQ males’ mean
(1.36) was somewhat higher than that of their USOTC
counterparts (1.16). Crawley, Smith, & Cioroslan
(2002) noted that deviations from the first pull
velocity being about 60% of that for the second pull,
either higher or lower, resulted in lack of success.
Being too slow off the platform would be a challenge
because of the lack of momentum that would assist the
final pull; being too fast might constitute a challenge
to moving quickly and effectively through the transition
so as to obtain maximum benefit from the second pull.
That is, it might cause difficulty in timing and
execution of the skill. Five of the seven males and two
of the five females were reasonably close to this
standard. Athlete C-PJ exhibited an unusual pattern in
which the first pull maximum velocity was actually
higher than that for the second. This individual’s first
pull was excessively fast and was concluded at a
relatively high vertical position, contributing to
inability to explosively execute the second pull. While
this occasionally is seen in good weightlifters, it is
detrimental to performance and is certainly not a
pattern that one should seek to continue.
Transition phase
Crawley, Smith, & Cioroslan (2002) make an
argument against a marked drop in velocity during the
transition between the 1st and 2nd pulls, stating that a
less pronounced reduction would be preferable. This is
certainly consistent with the goal of maintaining
momentum to maximize the effect of the 2nd pull. Only
two athletes of each sex failed to meet this standard,
having sharp reductions in vertical velocity during the
transition. This might be misleading in some cases,
however. At lower level competitions one sees a few
competitors who are so lacking in skill that they
execute a power snatch, failing to catch the bar in the
squat position. Almost without exception, these
individuals do not shift the hips forward in a clear
transition and the velocity curve is almost in
continuous rise. While this might be in tune with
Newton’s laws, failure to execute the skilled transition
and develop the power that would result and then not
being able to catch the weight in the squat position
negates any benefit they might obtain from avoiding any
significant drop in bar velocity during the lift.
Second pull
Crawley, Smith, & Cioroslan (2002) discuss the
need to avoid prematurely moving onto the toes and thus
reducing potential maximum bar velocity and maximum bar
height. Unfortunately, bar velocities alone are not good
predictors of success. Particularly with young
weightlifters who are in the early stages of
development, relatively lighter weights result in
relatively high velocities and relatively high
trajectory peaks. That was the case for these CJQ
athletes. The mean bar velocities were slightly higher
than for the USOTC athletes (198 and 207 cm/sec for CJQ
males and females; 189 and 194 for USOTC males and
females) and ten of the twelve CJQ lifters had higher
peaks than the means of USOTC data. Obviously these
velocities and peaks are such they would not necessarily
reflect a tendency toward moving up to the toes early. A
better indicator of that error might be trajectories
that are forward of the point of liftoff. While this was
not a primary focus in this investigation, 5 of these 12
young weightlifters’ bar peak was >5 cm forward, an
indication that the individual was probably on his/her
toes too early, reducing performance potential.
Crash distance
Crawley, Smith, & Cioroslan (2002) commented
that the vertical distance between the peak and the
catch positions (crash distance) was about 7-8 cm for
good lifts, with unsuccessful attempts showing greater
crash distances. Only two of the CJQ athletes were near
this standard, with four having values around 30 cm.
Five, who executed power snatches, had little or no
crash. Thus two sources of error in this aspect occur.
One, lifting relatively light weights will result in
high bar velocities and much higher peaks than
necessary. In the other case, unskilled athletes will
execute power snatches and thus have little or no crash.
Both cases can serve as “red flags” for coaches,
indicating in one case the potential for handling
heavier weights and in the other a need for serious
attention to technique.
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Summary
Information contained in this report must be
considered in context. These athletes are clearly
capable, each winning his or her weight class in the
2002 Championnat Juvénile du Québec. Obviously any group
of young weightlifters will exhibit less than optimal
skill and performance; this report is not meant to be a
criticism, but rather is an attempt to offer information
that might be useful to coaches. These coaches already
know their athletes in terms of potential and
performance. However, the snatch is a complex and
demanding athletic skill in which performance is so
explosive that the naked eye is often not capable of
perceiving fine departures from optimal. This data is
presented simply to offer coaches additional information
that in many cases will simply reinforce what is already
known and in a few cases reveal details not quite so
obvious.
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References
Crawley, J.D., Smith, S.L., & Cioroslan, D.
(2001) A technical summary of selected snatch lifts at
the 2001 World Team Trials. Weightlifting USA, 19(3),
21-26.
Hiskia, G. (1997). Biomechanical analysis on
performance of world and Olympic champion weightlifters.
In A. Lukacsfalvi (Ed.), Procedings of the Weightlifting
Symposium (pp. 137-158). Budapest: International
Weightlifting Federation. Top
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