Snatch Analysis Isaka Et Al 1996

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JOURNAL OF APPLIED BtOMECHANtCS, 19^(1, 12,

® 1996 by Humnti Kinelics Publishers, Inc,

Kinematic Analysis of the Barbell Duringthe Snatch Movement of Elite Asian

Weight Lifters

Tadao Isaka, Junichi Okada, and Kazuo Funato

The purpose of this study was to describe the kinematic characteristics of the snatch

techniq ue from the view point of barbell trajectory. Subject.̂ included 6 elite male Asian

weight lifters w ho participated in the first Japan In ternational Friendship To urnam ent

in 1993, Trajecto ries of the barbe ll du ring snatch lifts in the com petitio n w ere video -

taped. Three vertical acceleration peak s of the barbell du ring ihe pull mo vem ent were

observed and corresponded to the first pull, transition, and second pull pha.ses. The

ang le of the resultant accele ration (AR A) of the barbell ave rage d US" in the first pull

and transition pull phases. Lithe second pull ph;ise. the ARA was almost 140°. indicat-

ing that the barbell was accelerated anterioriy. away from the lifter. The results of thisstudy suggest that during the firsi pull and transition pull phases, elite lifters pulled the

barbell toward themselves to produce the needed vertical acceleration and that the

resulting posterior movement of the barbell was controlled by the forward accelera-

tion produced in the second pull phase.

Oly mp ic-style weight lifting co nsists of two different lifts, the snatch and the clean -

and-jerk. Weight lifting contests are judged on the total of the best weight lifted in each of

the two lifts. These lifts are done very rapidly, with propulsion of the barbell again.st

gravity o ccup ying less than 1 s. Weight lifters arc required to gene rate a great deal of

mu scular pow er during each lift (Ga rham me r, 1985. 1993) and to effectively transfer thispower to the barbell. Analysis of top performances during competition produces scientific

knowledge about successful lifting techniques and yields information u.seful for coaching.

The purpose of this study was to describe the kinematic characteristics of the snatch lift

techn ique u sed by elite male Asian w eight lifters from the view point of barbell trajectory.

Methods

Top-level male Asian weight lifters were videotaped during the first Japan International

Friendship Tournament in 1993 in Minakami, Japan. There were national team members

from Ch ina, Korea, and Japan. Th e best weight lifter in each of six weight ca tegorie s from76 kg to +108 kg was chosen for analysis. The weight category, body mass, height, and



Kinematic Analysis of Barbell 509

Table 1 Weight Category and Best Weight Lifted in Com petition Tor Each Subject

Class

7683

91

99

108

+ 108

Subject

U

NK

KB

NY

CD

PH

Mass (kg)

74.05

79.25

90.10

97.85

104.80

122.95

Height (cm)

I6I.5

161.1

174.5

178.5

182.9

181.5

Snatch (kg)

142.5

137.5

155.0

160.0

160.0

160.0

Jerk (kg)

180.0

175.0

195.0

207.5

210.5

200.0

Total (kg)

322.5

312.5

350.0

367.5

370.0

360.0

heaviest successful snatch lift of each subject, which occurred on the third attempt for all

subjects except LJ (76-kg class) and KB (91 -kg cla.ss). who lifted Iheir heaviest weights

on their first lift.

The apparatus used for data collection in this experiment was a Video-Tracker Sy.s-

tem (OK K Inc., Tokyo ) capa ble of autom atically m easuring the trajectories of the illum i-

nated points through a charge coupled device (CCD) camera. The information obtained

with the video-tracker system was subsequently sent to a host computer through a

gene ra I-purpose interface bus for calculation of displacem ent, velocity, and acceleration

in the horizontal (X) and vertical (Y) directions. Raw data were transformed to real distance

units using the calibration scale placed in the field of view. A calibration scale was taken

during an intermission in the competition.

Barbell trajectories during snatch trials in the competition were videotaped at right

angles to the sagittal plane of the lifters. The distance between the CCD camera and the

lifter was 10 m. with the camera h eight adjusted to the middle level of the m ove m ent.

Barbell trajectories of these weight lifters were sampled at 60 fields per second,

A second-order Butterworth filter was utilized with a cutoff frequency of 3,6 Hz to

smooth the position-time data for the barbell. The filtered displacement-time data were

differentiated by the finite difference method (Winter, 1990) to determine the velocity-

time curve. Barbell acceleration information was obtained by taking a derivative of the

velocity-time data. The angle between the direction of the resultant acceleration vector of

barbell and horizontal line was defined as the angle of the resultant acceleration (ARA).

ARA was calculated from the horizontal and vertical acceleration of the barbell.

Correlation analysis among the obtained data was used, and p < .05 was taken to

indicate statistical significance.

Results



510

Vertical

76kg

tsaka,

r1

Okada, and Funato

«

1^

8 I ?4^

50aii

Horizontal

S O c m

Figure 1 — The harh ell trajectories of suhjects durin g th eir heaviest successful snatc h. Verticalreference liucs were drawn through the barhell just prior to lift-olT.

pha ses; start position jus t prior to lift-off, first pull, transition, second pull, catch position,

and finish. The b arbell trajectories shown in Figure 1 were all similar in one respect: At

the beginning of the first pull phase, the barbell moved toward the lifter, followed by

movement away from the lifter, and finally toward the lifter again as the bar descended

with the lifter mo ving under the bar into catch position. In every cas e, except for the 76-kg

class, ihe path of the barbell re m aine d to the right ol' the vertical refe rence line p rojecte d

upw ard from the start position nf Ihe barbell. In the case of the 76-kg cl ass , the bar trajec-

tory remained to the lett after the first pull.

Barbell Displacem ent and Velocity

Vertical displacements from the start position to the highest pull position ranged from

1.52 to 1.63 ni in this study, and vertical displacements from start to catch were 0.96 to

1.15 m. When the vertical displacement to catch was calculated as a percentage of

displacement to highest pull position. LJ (76-kg class) had the lowest value. 6 2 . 1 % , and

CD (108-kg class) had the highest value, 70 .8%.

Lifting the resting barbell effectively requires minimizing each of the horizontaland vertical displacements, the maximum height during Ihe second pull to the catch phase



Kinematic Analysis of Ba rbell

40

E

511

0£flC Q

H

20

10

t

—

11I

i

111•

D

hoHzontal

vertical

total

76 83 91 99 108 +108

200

100

0 so

X-displacement (cm)

horizontal

0 50

X-displacemcnt (cm)

vertical

Figure 2 — TVavel range of harbell calculated from the harbell trajectory.

The time-velocity relationship of the barbell, particularly the maximum vertical



512 Isaka, Okada, and Funat

\ -

2 00

E 100o

.•t: 50

o

^ 0

to

-1000.0 0.5 1.0

time (sec)

1.5

horizontal

vertical

Figurt' 3 — Ueprescntative barheil vclocit.v-tinie curve Kf

catch position (Subject NK).

from the start p4>sition to the

In this study, the maximum vertical velocity appeared during the second pull phase

and averaged 186 cm /s. The highest value (195 cni/s) was observed in NY in the 99-kg

class. There was a significant relationship between the horizontal travel distance and the

ma xim um vertical velocity (/• = .916 . p < .05).

Angle of Resultant Acceleration of the Barbell

The barbell, from a resting position on the platform, was lifted against gravity with thevertical acceleration provided by the lifter. During the pull movement (Figure 4). there




Icm/sec+957.7

2

I

1105.0

Ap11V

Ap3

A / r A

time

200 r

100



514 Isaka, O kada, and Funato

•

n

Apl

ApJ

76 83 91 99 108 +108

Figure 5 — The angles of resultant acceleration at peak vertical accelerations 1, 2, and 3.

pull phase. ARA averaged about 1.37° (±16) with a range of 110 to 158", indicating that

the barbell In all cases was accelerated atiteriorly away from the lifters.

Discussion

The medal awards in weight-lifting contests depend on how much total weight is lifted

with two lifting styles. Movement ofthe barbell is determined by the forces applied by the

weight lifter. The relationships between displacement and time, or velocity and time, are

often used at a practical level as the most important indices for as.sessing lifting technique

(Baumann, Gross. Quade. Galbierz. & Schwirtz. 1988).In this study, barbell trajectories, except for one subject, did not cross the vertical

reference line projected upward from the start position. Rather, the barbell was pulled

toward the lifter during the snatch movement, especially from the first pull to transition

pha se. Th is technique u sed during the first pull and transititm phase most likely requ ires

the body to be inclined away from vertical, and the resulting barbell trajectory follows the

inclination ofthe body. Garhammer (1983) reported a similar pattern of barbell trajectory,

but his data showed the trajectory to cross the vertical reference line. He suggested that

the obtained trajectory may be considered optimal by some experts. The obtained pattems

of barbell trajectory in this study are similar to those of world-class weight lifters at the1985 World Weight Lifting Championship, as analyzed by Baumann et al. (1988), who




between the horizontal travel range of the barbell in the various lifters, with a range of

appro xim ately 10 cm . On the other hand, the vertical travel range of barbell of the lifters

varied w idely from K) to 24 cm .

Two typical barbell veloeily curves have been reported (Baumann et ai., 1988;Garhammer, 1985). One type of velocity curve has two velocity peaks, and another one

steadily increases to a single maximum velocity. Top elite lifters have been characterized

lo have the latter type of velocity pattern and seldom show any notable dip in vertical

veloeity. This meatis that skillful lifters could pull the barbell more smoothly during the

transition pha.se without a marked deceleratioti of the barbell.

M aximum vertical velocities during the snatch movem ent were approximately 1.8

m/s, similar to those of top w orld-class lifters (Ba um ann et al.. 1988). Interestingly, in this

study there was a significant relationship between the horizontal travel range of the bar-

bell and maximum vertical velocity.Linear movement, regardless of direction, results from a combination of several

joint rotations. In lifting, the extensor mu scles about the ank le, knee, and hip join ts co n-

tribute to the control of antago nistic m uscles in a seque nce progres sing from the hip to the

ankle. This sequence is related to the sequence of the three pha.ses of the pull during this

lifting task. When these extensor muscles are maximally activated for a brief period of

time, the lifter's body is pulled backward close to full extension because of the larger

contribution of hip extensors. These muscle activities induce not only greater vertical

velocity but also a small amount of horizontal travel of the barbell. The horizontal move-

ment of the barbell during the pull phase should be considered an effective application ofmu scle pow er and a reaso nable es tima te of moveme tit iti elite lifters wh o utilize hip exten-

sor resources to contribute to the movement. Therefore, a small amount of horizontal

mo vem ent is necessary for good lifting tech nique prov ided the proximal to distal s equen ce

of joint action is followed (Isaka, M itsushim a, & Funato , 1995).

During the pull phase , the elite lifter utilizes the double knee-ben d tec hniqu e, w hich

requires cons iderable practice and dem ands substantial control of knee joint motion

(Burdett. 1982; Enoka. 1979, 1988: Kauh anen, H akkinen. & Kom i. 1984). The d ouble

knee-bend technique involves a rebending of the knee during the transition phase after the

barbell has been lifted to jus t above knee level (Garham me r, 1989). This techniq ue, w hichis unique to weight lifting and which has similar effects as observed iti the countermove-

ment in vertical jum pin g (Garham me r, 1992), perm its reem ploym ent of powerful kn ee

exten,wr muscles through their strongest range of motion and may utilize stored elastic

energy and stretch-reflex facilitation of final knee extensio n to dev elop the exp losive mu scle

power required during the lift (Boseo, Tarkka, & Komi, 1982: Etioka, 1979; Komi &

Bosco, 1978),

Acceleration of the barbell can provide interesting information for evaluation, such

as the timing and direction of the applied force. However, information concerning barbell

acceleration has not been published and utilized to the fullest extent. There were obvi-

ously three peaks in the venicai acceleration that corresponded to the three phases of the

pull movement. Such a pattern is unlikely in a novice lifter, especially the seeotid peak in



51 (i Isaka, Okada. and Funato

otid pull phase, the angle of the resultant acceleration averaged about 140°, with a range of

110 lo 160'̂ , indicating that in all ca.scs the barbell was accelerated anteriorly, away from

the lifters. The results of this s(udy suggest that during the first pull and transition phases,

elite lifters pull the barbell toward themselves to produce effective vertical acceleration.

On the other hand, this posterior movement of the barbell is controlled by the anterior

acceleration produced in the second pull phase.

References

Baum ann, W., Gro ss, V., Qu ade, K., Gaibierz. P., & Schwirtz, A. (1988), The snatch technique of

world class weightlifters at ihe 1985 world championships. International Joumal of Sport

Biomechanics, 4. 68-89.

B os co , C T a r k k a , !.,& Kom i. P.V. (1982 ). Effectof elastic energy and m yoeleclrical polenliation oftriceps surae d uring si retch-shorten ing cycle exerc ise, huemational Journal of Sports M edi-

cine, X 137-140,

Burdett, R.G. (1982). Biom echanics of the snatch technique of highly skilled and skilled weightlifters

Research Quarterly, 5i. 193-197.

Enoka, R.M. (1979). The pull in Olympic weightlifting. Medicine and Science in Sports. II. 131

137.

Enoka. R.M. (1988). Load- and skill-relaled changes in segmental conlributions to a weightlifling

movement . Medicine und Science in Sports and Exercise, 20. 178-187.

Garhammer, J. (1985). Biomechanical proiDes of Olympic weightlifters. Intemational Joumal of

Sport Biomechanics, I, 122-130.

Garhammer, J. (1989). Weightliliing and training. In C.L.Vaughn (Ed.), Biomechanics of sport {pp

169-211). Boca Raton. FL: CRC Press.

Garhammer, J. (1992). A comparison of propulsive forces for weightlifting and vertical jumping

Journal of Applied Sport Science Research. 6, 129-134.

Garhammer. J. (1993). A review of power output studies of Olympic and poweriift ing: Methodol-

ogy, performance prediction, andevaluation tests. Journal of Strength and Conditioning Re-

.wm-h. 7. 76-89.

Isaka, T., M itsushim a. R., & Funato, K. (1995). Kinematic analysis on the snatch technique of world

records in elite female weightlifters (Abstract). \nXVtli Congress ctf ihe Intemational Society

of Biomechanics (pp. 422-4 23). Jyvaskyla. Finland: Gumm eru.s Priming.

Kauhanen. H., Hakkinen. K.. & Ko mi. P.V. (198 4). A biomec hanical analysis of the snatch and clean

and jerk techniques of Finnish elite and di.*itrict level weightlifters. Scandinavian Joumal o

Sports Science, 6. 47-56 .

Ko m i. P.V., & Bosco, C. (1978). Utilizationof stored elastic energy in leg extensor m uscles by m en

and women. Medicine and Science in Sports, 10. 261-265.

Winter, D.A. (1990). Biomechunics and motor control of human movement (2nd ed.). NewYork

Wiley.

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