Download Specific Movement Power Related to Athletic Performance in Weight

JOURNAL OF APPLIED BIOMECHANICS, 1996,12,44-57
0 1996 by Human Kinetics Publishers, Inc.
Specific Movement Power Related
to Athletic Performance in Weight Lifting
Kazuo Funato, Akifumi Matsuo, and Tetsuo Fukunaga
In order to evaluate how mechanical power relates to athletic performance in weight
lifting, specific movement power (SMP) was investigated using a newly developed
dynamometer. Four simulated pull movements in weight lifting were measured:
weight lifting pull (WL), second pull, back strength pull, and shoulder shrug pull.
Subjects included 12 elite (EL) and 14 district (DI) level Japanese weight lifters.
Athletic performance was defined as the highest total combined weight (snatch plus
clean and jerk) lifted during competition. The highest SMP was observed in the WL.
Force, velocity, and power relations were derived from the WL, showing higher
velocity and power values in EL than DI at an identical force level. SMP in WL
was found to be significantly correlated to athletic performance. SMP measured as
a simulated pull movement in weight lifting employing the present dynamometer
appears useful in evaluating athletic performance. Furthermore, this dynamometer
provides force-velocity relationships during multiarticular explosive movements.
Many dynamometers have been developed to evaluate mechanical variables such
as force, velocity, and power exerted in various human movements. In these methods,
used to evaluate physiological characteristics of human muscle in vivo, the force exerted
by the muscles is typically measured through a restricted range of motion and at a
controlled velocity of an isolated single-joint movement. The results of these experiments
showing the force, or torque, velocity relationship for groups of muscles in vivo are
then typically compared to the traditional force-velocity relationship obtained for isolated
muscles. However, few studies describe the force-velocity relationship for a total body
movement that involves multiarticular action.
While the force-velocity relationship is well documented for isolated muscles,
performance in sport events cannot be fully explained using data for isolated muscles
or data obtained under constrained, isolated, single-joint muscle action. In athletic movements, factors such as muscle length changes, accelerating multijoint actions, and varying
levels of submaximal activation will be different for each muscle involved. Methodological development is necessary to measure relationships of force, velocity, and power
exerted in a specific movement pattern (i.e., specific movement power; SMP) in order
to describe power during the athletic performance. In weight lifting, for example, power
measured during the simulated athletic movement 'pattern (Figure 1, a and b) might be
important in describing athletic performance.
For isolated, single-joint actions in humans (e.g., elbow flexion), the shape of the
force-velocity relationship is fundamentally similar to that obtained in isolated muscle
The authors are with the Department of Sports Sciences, College of Arts and Sciences,
University of Tokyo, 3-8-1 komaba, Meguro-ku, Tokyo, 153, Japan.
Specific Movement Power
45
preparations in vitro. However, in multiarticular joint actions, many authors show a
more linear force-velocity relationship, for example, in bicycle pedaling (Sargeant,
Hoinville, & Young, 1981; SjQgaard, 1978), vertical jumping (Komi, 1979; Tsarouchas &
Klissouras, 1981), and throwing (Toyoshima & Miyashita, 1973).
Explosive mechanical power output developed during total body movement is the
most important factor in successful weight lifting. Many reports have recognized that
performance in weight lifting is strongly correlated to the acceleration and subsequent
power of the barbell. Mechanical power of the bar is transferred from the body to the
bar through the sequential development of power from individual muscles and muscle
groups in the human muscle-joint system. Consequently, the primary interest in understanding successful weight lifting focuses on where in the lift sequence joint and/or
muscle power is the dominant power generator. Recently, using the combined methods
of ground reaction force and high-speed film analysis, Enoka (1988) has reported joint
or muscle moments during the pull movements in weight lifting. Baumann, Gross,
Quade, Galbierz, and Schwirtz (1988) reported that an increase in weight lifted in the
snatch technique was accompanied by an increase in hip extensor muscle torque but
was not related to muscle torque calculated around the knee.
Baumann et al.'s report (1988) suggested that individual muscle torque might be
significant in successful weight lifting. No further studies were undertaken concerning
mechanical potential and load-velocity characteristics during specific movements. Measuring the SMP in various loaded conditions might provide information for improving
individual athletic performance.
In order to evaluate SMP, a new dynamometer was developed for measuring
force, velocity, work, and power under inertial loading conditions during multijoint
explosive movements involved in a weight lifting pull. The purpose of the present study
was to measure mechanical power output during the different pull movements in weight
lifting and to evaluate athletic performances as a way to develop a useful application
of the dynamometer.
Methods
Subjects
Twenty-six Japanese weight lifters served as subjects. The group consisted of 12 elite
lifters (including 4 1984 Los Angeles Olympic lifters and 8 1988 Seoul Olympic lifters)
and 14 district lifters (highly ranked college freshmen). All lifters, including the Olympic
lifters, maintained active training schedules at the time of these measurements. Body
height, weight, and body composition are presented in Table 1. Body density and residual
volume of their total lung capacity were measured by underwater weighing and 100%
oxygen rebreathing methods. Percent body fat and lean body mass (LBM) were determined from body density using the equation developed by Brozek, Grande, Anderson,
and Keys (1963). Similar values for both percent body fat and LBM were observed in
elite and district groups. Athletic performance expressed as the highest total lifted weight
(snatch plus clean and jerk) during official competition and its ratio to LBM were
significantly higher @ < .001) for elite lifters than for district lifters (Table 1).
Apparatus
The Power Processor (Vine Co. Ltd., Tokyo), designed to measure force, velocity, work,
and power, was employed during this investigation and is presented in Figure 2. The
46
Funato, Matsuo, and Fukunaga
Table 1 Body Height, Body Weight, Body Composition, and Athletic Performance for Elite and District Weight Lifters
Athletic performance
(total weights lifted)b
Body height
(cm)
Elite weight lifters
District weight lifters
Total
Body weight
(kg)
LBM"
(kg)
% Body fata
Absolute
(kg)
Relative
(kglkg LBM)
n
M
SD
M
SD
M
SD
M
SD
M
SD
M
SD
12
14
26
166.1
168.4
167.4
9.4
4.4
7.1
74.32
72.50
73.34
20.53
9.05
15.13
10.0
12.4
11.3
5.4
4.2
4.8
66.07
63.16
64.50
14.65
5.21
10.52
299.2***
232.6***
263.3
58.1
20.6
53.4
4.56***
3.69***
4.09
0.31
0.23
0.52
"% Body fat and LBM were measured by underwater weighing. Total weights represent the sum of the best records in snatch and clean and jerk
established in an official competition during the previous 3 months. ***p < .001. Other values are nonsignificant.
Funato, Matsuo, and Fukunaga
I
I
I
I
d
I
7-t1
- - - - - - - - - --.u
-
Figure 2
(a) Mechanical structure of newly developed Power Processor dynamometer and (b) its diagram. A = rotary encoder; B = wire winder; C =
rewinder motor; D = electrical disk brake; E = strain
gauge; F = inertia load.
main structure of the Power Processor consists of a rotary encoder, electrical winder,
magnetic brake system, load cell, and inertial loading system. The time spent during
11500 rotation (0.72") of the inertia wheel was measured by rotary encoder. Tension in
the wire was recorded by a load cell (type LUB100, Kyouwa-Dengyo, Japan). The
magnetic brake system and electric motor were respectively used to stop the rotation
of the inertia wheel and rewind the wire around the inertia wheel axis. The loading
system was initiated by adding different weight plates to the inertia wheel. Loading
force (F) of this dynamometer was calculated as follows:
Specific Movement Power
49
where I is the moment of inertia, m is mass of the plate, R is radius of the plate, r is
the radius of the inertia wheel, and w is angular velocity. From Equation 2, 119 and
rdwldt indicate the equivalent mass and the acceleration acting perpendicular to the axis,
respectively. Equivalent mass was controlled from 50.7 kg to 312.0 kg by changing the
weights of plates.
Instantaneous velocity and tension in the wire were recorded by the rotary encoder
attached to the axis of inertia wheel and the strain gauge mounted in the Power Processor
(Figure 2). Electrical signals from the rotary encoder and load cell were sampled every
5 ms and stored on an IC memory card for subsequent analysis by a personal computer
(PC9801Vm, NEC Co., Tokyo).
Procedures
Each subject pulled the wire in a maximal effort. The wire wound around the inertia
wheel axis was connected to the subject's hands through the bar and pulley system
(Figure la). As illustrated in Figure 3, four simulated pull movements in the weight
lifting action were selected: weight lifting pull (WL), second pull (SP), back strength
pull (BS), and shoulder shrug pull (SS). The WL movement showed the pull from the
starting position to the final pull (chest level) of the weight lifting action. In an actual
weight lifting pull, SP is described as the acceleration phase immediately after the bar
passes the knee. We defined the SP movement starting with the bar positioned on the
knee, the knee flexed at an angle of 90°, and the trunk and arms kept straight. The
subjects then performed the SP by extending the hip, knee, and ankle joint simultaneously.
The BS began with the hip joint flexed at 45O and the knee joint and arms kept straight.
The pull was performed only by hip extension. In SS, the legs, trunk, and arms were
kept straight and the pull was performed only by shoulder joint elevation, involving
mainly the trapezius and the levator scapulae muscles.
Mechanical Measurements
Linear velocity of the wire was calculated from the rotational velocity of the inertia
wheel recorded by the rotary encoder. An instantaneous power curve was then derived
by multiplying the instantaneous linear velocity and force curves. Work (W), mean force
(MF), mean velocity (MV), and mean power (MP) were determined by time integration
of the respective instantaneous variables:
Statistical differences of mechanical variables between elite and district weight
lifters were studied by Student's unpaired t test. Pearson's product moment correlations
were used to describe the relationship between SMP and athletic performance. Statistical
significance was accepted at an alpha level of .05.
Funato, Matsuo, and Fukunaga
Power
(W)
Force Velocity
MV:1 6 9 d s
) Weightlifting Pull
Power Processor
0-
to
O
tl
Time(ms)
Power
(W)
1000
Force Velocity
(N) (mlsec)
3500
1750 TAI Load: 10 kgw
.spL
l
to
0
Time (ms)
tl
Force Velocity
(N) (mlsec)
(w)
1750 TAI Load: 10 kgw
1
) Back strength Pull
to
0
Time (ms)
Power
(W)
1750 TAI _ Load: 10 kgw
1
'
.
.
14
3500
'
!
0-
0-
1000
Power
-
14
MV:1 A l d s
Second Pull
;2&,
(":4"%)
(N)
-,
3500
1750 TAI Load: 10 kqw
tl
0 310ms
W151?.l
MF 5870N
MV 0 97dS
MP 488 1W
1
6
I000
Force Vel
(N) (m/Gcj
3500
S
T
14
.
.
. .
Figure 3
Measurement posture of four specific movements and typical recordings of
velocity, force, and power curves for each. to = starting time in power curve; t, = ending
time in power curve; D = duration of the power curve (tl-to); W = work; MF = mean force;
MV = mean velocity; MP = mean power; PP = peak power.
Specific Movement Power
51
Results
Typical examples of instantaneous velocity, force, and power curves obtained from four
simulated pull movements in an elite weight lifter are shown in Figure 3. Two peaks
were observed in both force and power curves during the WL and SP movements, while
only single peaks in force and power curves were observed during the BS and SS
movements.
The changes in MP in relation to the equivalent mass for each movement condition
are shown in Figure 4. Maximum MPs were exerted at certain equivalent mass conditions.
Higher values in MP were observed in the WL movements compared to the SP, BS,
and SS movements. Significantly ( p < .05) higher values for MP were observed in elite
lifters compared to district lifters in almost all loading conditions during the WL and
SP movements, while similar values of MP between elite and district lifters were recorded
during the BS and SS movements.
Means and SDs of maximum values of MP, MF, MV, and W, obtained from the
measurements of five different loads for each group, are shown in Table 2. Significantly
( p < .05) higher values for absolute MP and relative MP (MP/kg LBM) were observed
in elite lifters than in district lifters in each movement except for the SS. The highest
MP values were observed in the WL (14.5 Ifr 2.4 W/kg LBM for elite lifters and 10.5
Equivalent mass (kg)
0
100
200
300
400
Equivalent mass (kg)
Equivalent mass (kg)
0
100
200
300
400
Equivalent mass (kg)
Figure 4 - Changes in mean power (W/kg LBM) with equivalent mass for each movement
condition. Elite lifters. e District lifters.
Table 2 Mechanical Variables Obtained From Trial During Which Maximum Mean Power Was Recorded
Mean power
(W)
M
SD
WL
SP
BS
SS
Elite
District
Elite
District
Elite
District
Elite
District
Mean power
(Wkg LBM)
M
SD
Mean force
(N)
M
SD
Mean force
(Nkg LBM)
M
SD
Mean velocity
Work
(mls)
M
(J)
SD
M
SD
Specific Movement Power
53
+ 1.9 W/kg LBM for district lifters). MPs of SP, BS, and SS movements corresponded
to 94%, 72%, and 43% of MP, respectively, in the WL movement. MF and MV values
were similar between elite and district lifters for all movement patterns. Relative values
of the work done during SP, BS, and SS to that of the WL were 79.8%, 53.3%, and
29.0% for elite lifters and 67.2%, 46.9%, and 26.3% for district lifters, respectively.
In the WL movement, force-velocity and force-power relationships from five
different loads were represented for district and elite lifters, respectively (Figure 5).
Subject R.I. (see Figure 5), winner of the bronze medal at the Los Angeles Olympics
in 1984, holds the highest athletic performance total weight record (165 kg in snatch
and 205.5 kg in clean and jerk in the former 82.5 kg body weight category) among the
elite lifting group in this investigation. With increasing MF, MV decreased linearly and
MP tended to peak. Among the elite lifters, higher MV and MP were observed than for
district lifters at an identical MF level.
The relationship between MP and athletic performance in weight lifting is presented
in Table 3. Performances were assessed as the total weights lifted in the snatch and the
clean and jerk trials during the same competition. A statistically significant linear
correlation was observed between MP and performance. The highest correlation (r =
.728, p < .001) was observed in the MP of the WL (compared to the other three
3.5
-z
U,
3.0
,
Subject R. I.
Elite lifters
District lifters
-E-
.
c- - -c- - -
-2-
.
.= 2.0 .
2.5
h
20,
5
:::@
to
Y
%
0
8r
m
0
1.5
1.0
.
.
0
5.
Q
Y
0.5
.
0
;
L
3
6
.
m
9
a
t
1 2 1 5 1 8
Mean Force ( N 1 kgLBM )
0
0
.
.
.
3
6
9
I
.
,
1 2 1 5 1 8
Mean Force ( N / kgLBM )
Figure 5 - Relations between mean force and mean velocity (left) and mean force and
mean power (right). Subject R.I. is national record holder (snatch, 165.5 kg; clean and jerk,
205.5 kg; total 370.0 kg in the previous category of 82.5 kg) who won a bronze medal in the
1984 Olympic Games in Los Angeles.
Table 3 Correlation Coefficients Between Athletic Performance and Mean Power
(P-) for Total Weight Lifters
Athletic performance/LBM
54
Funato, Matsuo, and Fukunaga
Table 4 Correlation Coefficients Between Mean Power in WL Movement (P-WL)
and Mean Power in SB, BS, and SS Movements
Total weight lifters
P-SP/LBM
P-BS/LBM
P-SSLBM
Elite weight lifters
P-SP/LBM
P-BS/LBM
P-SS/LBM
District weight lifters
P-SP/LBM
P-BS/LBM
P-SS/LBM
movements). MP of the WL was linearly correlated to the MPs developed during the
SP, BS, and SS movements in both elite and district lifters except for the SS in the
district lifters (Table 4).
Discussion
A great deal of interest has been devoted to monitoring maximum power output values
of humans during whole-body tasks involving time periods of 1 s or less. Wilkie (1960)
reported maximum power output values in humans in relation to exercise duration. He
estimated that the "theoretical upper limit" of approximately 6 hp (4,476 W) was set
for a single exertion lasting less than 1 s. Actual measurements of short-term power
output are restricted by the patterns of movement and/or the amount of muscle mass
involved. Using a newly developed dynamometer, the Power Processor, we directly
measured both force and velocity in order to calculate work and power under varying
inertial loading conditions during an explosive multiarticular movement. Many ergometers have been developed for measuring selected mechanical variables of human movement during high-intensity, short-duration exercises. Stair climbing (Bosco, Luhtanen, &
Komi, 1983; Margaria, Aghemo, & Rovelli, 1966) and the Wingate test (Bar-Or, 1987;
Patton, Murphy, & Frederick, 1985) are widely accepted methods for evaluating human
anaerobic capacity during repetitive muscle contractions. Mechanical power measured
under such protocols, however, might be different from the power developed during
one contraction of muscle.
Special devices using isometric or isokinetic loading systems (e.g., Alexander,
Nicholas, Sokolow, & Saraniti, 1982; Ivy, Withers, Brose, Maxwell, & Costill, 1981;
Perrine & Edgerton, 1978; Seger, Westing, Hanson, Karlson, & Ekblom, 1988; Thorstensson, Grimby, & Karlsson, 1976; Wickiewicz, Roy, Powell, Perrine, & Edgerton, 1984)
have been widely used for evaluating muscle strength and/or power developed during
Specific Movement Power
55
a single contraction during efforts lasting less than a few seconds. In those cases, to
determine the characteristics of human muscle in vivo, isolated single-joint movements
such as flexion and extension of elbow or knee joints were generally adopted for the
test condition.
On the other hand, the vertical jump test (Bosco et al., 1983; Davies & Rennie,
1968; Davies, Wemyss-Holden, & Young, 1984; Gray, Start, & Glencross, 1962; Sargent,
1921) has been commonly used to evaluate human power output during multiarticular
movements. It is difficult to obtain the characteristics of power in relation to velocity
or force in the vertical jump since the load is restricted to the subject's body mass
against gravity. In other words, power output during the vertical jump does not always
represent the maximum potential of the subject being tested.
Mean power of the WL was higher than that reported during maximum acceleration
pedaling (Bosco et a]., 1983; Patton et al., 1985) but was lower than the instantaneous
power value calculated from high-speed film analysis on barbell elevation speed (ranging
from 1,400 W to about 4,000 W; Garhammer, 1981) and vertical jump (3,0004,000 W; Gregoire, Veeger, Huijing, & van Ingen Schenau, 1984). From a methodological
perspective, load was based on each subject's body weight; that is, the load is merely
body weight in the vertical jump and stair climbing tests and brake resistance (which
is set as 7.5% of body weight during the Wingate test; Bar-Or, 1987) in bicycle pedaling.
In order to detect the maximum potential for human power output, the power measured
in those methods does not necessarily yield the maximum value because the load-velocity
characteristics as observed in prescribed mono-articular movements, even in the vertical
jump, stair climbing, and bicycle pedaling movement, must exist.
The most interesting finding in the present data is the linear force-velocity relationship in a multiarticular movement such as weight lifting. As indicated in Figure 5, with
increasing MF, MV decreased linearly and MP tended to peak. MF-MV relationships
(see Figure 5) did not tend to be hyperbolic as those obtained from mono-articular
movements. To date, there are few studies reporting a force-velocity-power relationship
during human multiarticular movements (Grieve & van der Linden, 1986; Toyoshima &
Miyashita, 1973). Some studies report a similar tendency in linear force-velocity and
parabolic velocity-power relations.
There are few studies concerning the load-velocity relationship for a total body
movement that involves large muscle groups recruited in sequence of a human skeletal
kinetic chain. Reports of a force-velocity relationship for vertical jump movements with
varying loads being heavier or lighter than the subject's body weight have been presented
by Komi (1979). Tsarouchas and Klissouras (198 1) also demonstrated the relatively linear
load-velocity relationship in the vertical jump; they pointed out that power increased with
a higher loaded condition, resulting in maximum power being produced at the heaviest
loaded condition. Force-velocity and force-power relationships were very similar to
those observed in the present study (Figure 5). Similarly, in bicycle pedaling, a linear
relationship in force-velocity and a parabolic relationship in power-velocity were reported by Sargeant et al. (1981). In general, although each muscle or muscle group
possesses a fundamental force-velocity relationship, multiple-joint action involving those
muscles or muscle groups demonstrates a relatively linear force-velociq relationship,
and maximum power might be derived at a heavier loaded condition (not at about 1/3
of the maximum force loaded condition as obtained from mono-articular movements;
Hill, 1922). As suggested by Tsarouchas and Klissouras (1981), the linear force-velocity
relationships in multiarticular movement might result from the disproportionate recruitment of many muscle groups in response to the increased load. It can be said that the
determination of optimum load (optimum matching of force and velocity) to generate
maximum power is specific to various multiarticular movement conditions.
56
Funato, Matsuo, and Fukunaga
Mean power achieved during the simulated pull movement (WL) was strongly
correlated to athletic performance in weight lifting (Table 3). Few studies describe the
relationship between athletic performance and the mechanical measurements obtained
from dynamometer testing. As athletic performance is composed of skill based on certain
physical resources, it is necessary to measure performance using a system where both
ire integrated (i.e., specific movement
This newly developed dynamometer
must be capable of such measurements.
In the biomechanical research on Olympic-style weight lifting, much attention has
been paid to calculating mechanical work, energy, and power (Enoka, 1988; Garhammer,
1989),but there has been little application of these data in athletic performance evaluation
(Baumann et al., 1988). Our results indicate that in evaluating athletic performance, it
is important to select the mechanical power related to the specific athletic movement.
Moreover, protocols must be able to monitor training effects on selected muscle groups
in each lifter.
Values of work done during the SP, BS, and SS movements relative to work done
during the WL movement were 79.8%, 53.3%, and 29.0% in elite weight lifters and
67.2%, 46.9%, and 26.3% in district-level weight lifters, respectively. We defined those
relative values of work as the segmental significance of the work. Lower segmental
significance of the work in SP and BS in district weight lifters might be pointed out
compared to values of elite weight lifters. In the elite weight lifters, the work during
SP movement (Table 2) and its relative value to that of WL movement were significantly
higher than for district weight lifters. SP movement mainly occurs by the simultaneous
extension of hip, knee, and ankle joints. In a series of actual weight lifting pulls, the
bar receives the largest acceleration during this second pull phase (Garhammer, 1989),
and it is accepted that the SP movement is the most important phase in the weight lifting
action (Baumann et al., 1988). For the MP, WL correlated significantly to SP, BS, and
SS in both elite and district groups. District weight lifters demonstrated not only lower
SMP for all movements but also poor segmental significance of the work in SP and BS
compared to the elite weight lifters. Those findings suggest that in district weight lifters,
a lower mean power value in WL movement would be attributed to the relatively less
work done by leg or hip extension.
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