Robotics and electromyographic kinesiology analyses of in front

Japanese Journal of Biomechanics in Sports & Exercise Vo.7 170-178 (2003)
Original
Robotics and electromyographic kinesiology analyses of in
front handsprings in tumbling
OKA Hideo1）, ICHITANI Koichiro2）, KUMAMOTO Minayori3）
Abstract
most important activities which determine the skill-
In this study, the electrical activity patterns of the antagonistic biarticular and mono-articular muscles of upper extremity, during in the
hand contact period of in front handsprings in tumbling, were analyzed in
terms of electromyographic（EMG）kinesiology and robotics. The mechanical two-joint link models equipped with a pair of the antagonistic biarticular muscles in addition to two pairs of the antagonistic monoarticular muscles were used for robotics analyses. Reversal of triceps
brachii long head（Tlo）and biceps brachii long head（Blo）activities
was responsible for changes in the output force direction during the hand
contact period. It was confirmed that the coordinating activity pattern of
three pairs of the antagonistic muscles contributed to the output force
control and the output force direction control. The results obtained here
suggest the importance and necessity for coordinated muscle activities of
bi-articular and mono-articular antagonistic muscles for analyses of
sports.
fulness of performance including the front hand-
Key words : in front handsprings in tumbling, bi-articular muscles, EMG
kinesiology, robotics
1． Introduction
spring. In the hand contact period of front handsprings of tumbling, the hand contact shock will be
compensated by the stiffness of the upper extremity
induced by the elbow extension force and the shoulder flexion force. The mono-articular elbow extensors and shoulder flexors could directly contribute
to the load compensation during the hand contact
period. However, as to the bi-articular muscles of
the elbow and shoulder joints, the proximal end of
the biceps brachii long head（Blo）acts synergistically on the shoulder joint, but its distal end opposingly acts on the extending elbow joint. On the other
hand, the proximal end of the triceps brachii long
head（Tlo）
, the antagonist of the Blo, acts opposingly on the flexing shoulder joint, but its distal end
Front handsprings in tumbling are rotation move-
synergistically acts on the elbow joint. In front
ments from vertical position to re-vertical position
handsprings in tumbling, a compliant property of
progressing the hand stand position. These per-
upper extremity should be very important to absorb
formances will be completed if the forward kinetic
and control precisely a hand contact force. In the
energy could be converted enough into upward ki-
previous paper（Oka et al. 1992）, in the skilled sub-
netic energy during the hand contact period. As a
jects, the strong discharge was observed only in the
result, the higher the location of the center of grav-
Tlo during the front handsprings in tumbling. In the
ity, the more grand rotatory motion is acquired dur-
unskilled subjects, however, the strong discharge
ing the flight phase after the hand contact period.
was observed in the Blo during the front handspring
Therefore, the hand contact motion is one of the
in the tumbling. They attempted to analyze this dis-
1）
Department of Practical Life Studies, Hyogo University of Teacher Education
2）
Faculty of Engineering, Osaka Electro-Communication
University
3）
Laboratories of Image Information Science and Technology
Submitted for Publication : October 2, 2002
Accepted for Publication : May 21, 2003
170
charge pattern in terms of functional anatomy and
neuromuscular physiology.
More recently. Kumamoto et al. （1994 a, b）,
Oshima and Kumamoto（1995）demonstrated, from
the viewpoint of theoretical and experimental robotics, that the existence of antagonistic bi-articular
muscles contributed to stiffness control and trajec-
Robotics and electromyographic kinesiology analyses of in front handsprings in tumbling
Fig. 1 Schematic diagram of electromyographic kinesiology analyses.
tory control at the end-point of the limb link mecha-
mechanism, using a mechanical two-joint link model
nism, and produced the smooth, quick, and fuzzy
equipped with an antagonistic pair of the bi-
but accurate movements characteristic of animals.
articular muscles, as well as two antagonistic pairs
Also, their group（Fujikawa et al. 1997）found that
of the mono-articular muscles and a robot arm pro-
antagonistic bi-articular muscles showed coordinat-
vided with three pairs of the antagonistic actuators.
ing activities with antagonistic mono-articular muscles in the two relevant joints, and contributed to
2． EMG kinesiology analysis
the output force control and output force direction
Subjects employed in the present experiments
control at the end-point of the limbs. Furthermore,
were 11 Japanese male adults（6 skilled and 5 un-
they showed that the output force distribution at the
skilled）
. All skilled subjects have played the gymnas-
end-point of a limb link mechanism with both an-
tics for more than 10 years, and 3 of them were the
tagonistic mono-articular and bi-articular muscles
top players in Japan including one Los Angeles
was hexagonal, while that of a limb link mechanism
Olympic player. All unskilled subjects were able to
having only antagonistic mono-articular muscles
finish the both front handsprings of tumbling, in the
was square, and that the direction of maximum out-
vertical or a little beyond the vertical position pro-
put force was also different between the two limb
gressing the hand stand position. Referring to our
link mechanisms（Oshima 1999）
. These findings
previous papers（Okamoto et al. 1967, Okamoto and
strongly suggest the importance of determining the
Kumamoto 1973,Yamashita et al. 1983）, following
activity patterns of antagonistic bi-articular muscles
muscles were chosen for EMG analysis : the Blo, the
of the arm and carrying out analysis of their control
triceps brachii lateral head（Tla）
, the Tlo, the ante-
mechanism. Therefore, in this study we performed
rior portion of deltoideus（Da）
, the posterior portion
EMG kinesiology analysis of arm muscles, including
of deltoideus（Dp）, the rectus abdominis（Ra）and
antagonistic bi-articular muscles, during in front
the sacrospinalis（Sac）
. Electromyograms（EMGs）
handsprings in tumbling, and we carried out theo-
were recorded during front handsprings in tum-
retical and experimental analyses of the control
bling. Horizontal and vertical components of floor
171
JJBSE 7（3）2003
Fig. 2 Representative recording of posture, EMGs, reaction forces of subject in front
handspring. Blo, Biceps brachii long head ; Tla, Triceps brachii lateral head ; Tlo, Triceps
brachii long head ; Da, Deltoideus anterior portion ; Dp, Deltoideus posterior portion ;
Ra, Rectus abdominis ; Sac, Sacrospinalis ; FC（z）
, vertical force ; FC（x）
, fore-aft force ;
VS, signal of video frame（A, skilled ; B, unskilled）
.
reaction force during the hand contact phase were
curves of the shoulder joint and the locations of the
measured with high frequency force plate（Hashi-
center of gravity（Fig. 1）
.
moto et al. 1987）.
EMG signals, signals of video frame and force
3． Results
curves were simultaneously recorded with a 14-
There were two patterns in EMG recordings of the
channel electroencephalograph and stored on a
subjects. Pattern 1 was marked discharge of the Tlo
magnetic tape. The magnetic tape was later fed into
in the skilled subjects（G, K, O, H, F, S）
, Pattern 2
a microcomputer programmed to calculate and plot
was marked discharge of the Blo in the unskilled
curves of the center of gravity and floor reaction
subjects（A, U, T, M, Y）.
force vectors through a 16-channel analog-digital
The representative stick pictures with location of
converter. The motion pictures from the video tape
the center of gravity, the EMGs, and the vertical（Z）
were also fed into another microcomputer pro-
and horizontal（X）force curves which were recorded
grammed to calculate and plot angular change
from the skilled and unskilled subjects during the
172
Robotics and electromyographic kinesiology analyses of in front handsprings in tumbling
Fig. 3 Representative recording of EMGs of subject in the hand contact of in front handspring in tumbling
（A, skilled ; B, unskilled）
. All abbreviations and explanations are the same as in Fig. 2.
front handsprings in tumbling are shown in Figs. 2A
and the Dp, small discharge of the Blo was observed
and 2B, respectively. These figures are discharge
but the marked discharge of the Tla and the Tlo
patterns of the Blo, the Tla, the Tlo, the Da, the Dp,
were observed in the skilled（Figs. 2A and 3A）.
the Ra and the Sac. In Figs. 2A and 2B, postures 1,
Marked discharge of the Blo was observed but the
2, 3 and 4 show the points where the front foot con-
small discharge of the Tlo was observed in the un-
tacts the floor, the hand contacts the floor, the hand
skilled（Figs. 2B and 3B）
. Marked discharge of the
leaves the floor, and the rear foot contacts the floor,
Da was observed but the discharge of the Dp was
respectively. In these figures, as shown in the stick
scarcely observed during the hand contact period in
pictures of the unskilled（Fig. 2B）
, even though they
the skilled and the unskilled subjects（Figs. 2 and 3）
.
succeeded in the tumbling, their loci of the center of
As to the trunk muscles of the Ra and the Sac, the
gravity were lower and their rotatory performances
discharge of the Sac and the Ra were scarcely ob-
were smaller than those of the skilled（Fig. 2A）
. It
served during the hand contact period in the skilled
should be noted that peak points of the hand contact
（Fig. 2A）. The small discharge of the Sac was occa-
reaction force curves somewhat delayed from the
sionally observed, the discharge of the Ra was
apparent hand contact points as shown in all the fig-
scarcely observed during the hand contact period in
ures. Figs. 3A and 3B show the EMGs in the hand
the unskilled（Fig. 2B）. Peak values of the hand con-
contact period which were recorded from 2 subjects
tact reaction force of the tumbling in the skilled sub-
in Fig. 2 and 5 of the other subjects（3 skilled and 2
jects were roughly constant. The peak values of the
unskilled）
. These figures show discharge patterns
tumbling was about 2.3 times of BW（body weight）in
of the Blo, the Tla, the Tlo, the Da and the Dp which
the skilled. Even in the unskilled subjects, the peak
play important role on postural control of upper ex-
values of the successful trials did not widely change,
tremity. As to the discharge patterns in the hand
that was about 1.2 times of BW in tumbling.
contact period of the Blo, the Tla, the Tlo, the Da
Fig. 4 shows representative stick pictures, peak
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JJBSE 7（3）2003
Fig. 4 Representative recording of IEMGs of subject in the
hand contact of in front handspring in tumbling. The arrow, force vectors（Newton）; the broken line a, direction
passing hand and shoulder ; the broken line b, direction
passing hand and elbow. All abbreviations and explanations are the same as in Fig. 2.
values of the hand contact reaction force, output
force direction and the integrated EMG（IEMG）
which were recorded from subjects in Fig. 3. In Fig.
4, force directions were divided with two lines at the
wrist joint. Broken line a was direction of passing
through shoulder joint and wrist joint, and broken
line b was direction of pulling down along the forearm, and the arrow is the direction of output force.
In activity levels in antagonistic pairs of bi-articular
muscles, the skilled subjects（G, K, O, H）were
marked activity level of the Tlo, the unskilled subjects（A, U, T）were marked activity level of the Blo.
The output force direction were similar during the
Fig. 5 A, Two-joint link model employed for theoretical
analysis ; B, Calculated activity levels with changes in direction of maximal output force. f1（△：Da）and e1（▲：
Dp）
, Antagonistic pair of mono-articular muscles at shoulder joint（J1）．f2（▽：Br）and e2（▼：Tla）
, Antagonistic pair of mono-articular muscles at elbow joint（J2）
. f3
（□：Blo）and e3（■：Tlo）
, Antagonistic pair of biarticular muscles involved in both joints. E, End-point of
the upper extremity ; a, b, c, d, e and f, output force direction. a―d, direction passing the end-point（E）and shoulder ; b―e, direction passing the end-point（E）and elbow ;
c―f, direction parallel with the humeral region. X, horizontal axis ; Y, vertical axis ; Fmax, maximal output force ;
θ1, shoulder joint angle ; θ2, elbow joint angle ; θf, direction of output force. Ordinate : Activity levels（％）, abscissa : output force direction.
direction a-b in all subjects. The output force direction in the skilled was observed near broken line a,
shoulder joints were well stretched. Fig. 5A shows a
the peak values of output force were 1521N（sub.
two-joint arm link model ; where the model had
G）
, 1586N（sub. K）, 934N（sub. O）and 975N（sub.
three pairs of antagonistic muscles with the same
H）
. The output force direction in the unskilled was
contraction characteristics. The pair of antagonistic
observed near broken line b, the peak values of out-
mono-articular muscles acting on the shoulder joint
put force were 864N（sub. A）
, 695N（sub. U）and
（J1）were designated e1 and f1, the pair of antago-
643N（sub. T）
.
4． Robotics analyses
4. 1
Theoretical analysis using a two-joint link
model
During the hand contact period, the elbow and
174
nistic mono-articular muscles acting on the elbow
joint（J2）were designated e2 and f2, and the pair of
antagonistic bi-articular muscles acting simultaneously on the both joints were designated e3 and f3.
The shoulder and elbow joint angles were expressed
as θ1 and θ2, respectively. E is end-point of the arm
Robotics and electromyographic kinesiology analyses of in front handsprings in tumbling
was in full activity while the other antagonistic muscle showed no activity. The output force direction
during the hand strike period was limited to a range
in and around the a-b interval（between the direction
from the arm end-point to the shoulder, and the direction from the arm end-point to the elbow）. In this
interval, f1（Da）and e2（Tla）
, which are monoarticular muscles around the shoulder and elbow,
respectively, were in full activity, and the pair of antagonistic bi-articular muscles e3（Tlo）and f3（Blo）
at the bottom showed reversal of activity levels.
Changes in the output force direction at the arm
end-point were theoretically confirmed to be responsible for the alternation of the discharge level
between antagonistic bi-articular Tlo and Blo.
4. 2
Experimental analysis using a robot arm
The robot arm was used to ascertain the simulated
Fig. 6 Experimental robot arm provided with pneumatic
controlled artificial rubber actuators. A pair of actuators of
3 & 4 and a pair of 5 & 6 were attached to the shoulder
and the elbow joints, respectively, with chains（7）and
sprockets（7）so that they could act as mono-articular
muscles ; a pair of 1 & 2 was attached to both the shoulder and elbow joints, as bi-articular muscles. 8, rotary encoder ; 9, load cell or position sensors.
results described above. The robot arm used in this
experiment was a system with two degrees of freedom consisting of a elbow and shoulder, each with
one degree of freedom. The robot had six airpressure
controlled
artificial
（RUB-515 S ; Bridgestone,
rubber
Tokyo,
actuators
Japan）with
specifications that simulated the functions of muscles. Fig. 6 shows the experimental robot arm, and
（wrist joint）
, θf is the direction of output force, and
Table 1 shows its specifications. As shown in Fig. 6,
direction a-d is the line passing shoulder through J1
the artificial rubber muscles 3 and 4 act on the
and E. Direction b-e passes the end-point E and J2,
shoulder, muscles 5 and 6 act on the elbow, and
and direction c-f is parallel to line J1-J2. Activated
muscles 1 and 2 act on both joints via a chain and
force level of each muscle to exert the maximum iso-
sprocket. The actions of the artificial rubber mus-
metric output force at the end-point E in all direc-
cles were controlled with a personal computer, via
tions was theoretically calculated using a viscoelas-
an RS-232C interface（PC-9801 DA ; NEC, Tokyo,
tic muscle model. For this reason, in this study, was
Japan）
, using a Servo
selected only EMG which showed the strong dis-
Bridgestone）and Servo Valve unit（SV 0-103 C-06 ;
charge. The analytical procedure was the same as
Bridgestone）
. The direction and strength of the out-
that described by Fujikawa et al.（1997）
. Fig. 5B
put force were detected with a load cell attached to
shows the results of analysis in the two-joint model.
the end-point of the system. Using the above experi-
The results were the same as those reported by Fu-
mental robot arm, we measured the output force of
jikawa et al.（1997）
, regardless of changes in the
the entire system and the activity levels of the three
angles θ1 and θ2. Reversal of the activity level was
pairs of antagonistic muscles to examine whether re-
observed in the antagonistic bi-articular muscle pair
versal of the activity level occurred at elbow and
e3（Tlo）and f3（Blo）between a and b. In the inter-
shoulder angles similar to those at the hand contact.
vals of the output force direction in which reversal
of the activity level was not observed, one muscle
drive
unit（SDU-103 ;
Fig. 7 shows the results at θ1＝85°and θ2＝10°
（Fig. 7 A）；θ1＝80°and θ2＝20°
（Fig. 7B）. In Fig.
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JJBSE 7（3）2003
Table 1 Main specifications of robot arm.
Actuator Bridgestone, RUB-515S
Radius of sprocket
Length of upper and lower arm
Rage of motion
Maximum Contractile force（Umax）
Minimum contractile force（Umin）
Elastic coefficient（k）
（r）
（l）
shoulder（θ1)
Elbow（θ2）
209.60N
ON
33.30m−1
12.25 × 10−3m
30.00 × 10−2m
0―180 degree
0―150 degree
Fig. 7 Output force and muscular activation level patterns in the two-joint link model. Abscissa, Output force direction θf（degrees）; ordinate（left）
, maximal output force in F
（Newton）; ordinate（right）
, activation level（maximal contraction force）in U（％）
. Closed
circles, Output force ; a and b, output force direction. Triangles and squares correspond
to the muscles shown in Fig. 5. The solid lines approximated the open and closed
squares are simulated activation levels of the bi-articular muscles. The broken lines approximated the open and closed triangles are simulated activation levels of the monoarticular muscles of the f1＝Da, and the e2＝Tla. The activation levels of the monoarticular muscles of the e1 and the f2 were zero, and were omitted. The solid lines approximated the closed circles are the simulated maximal output forces. The symbol marks
are the results obtained from the robot arm experiments.
（A, θ1＝85°and θ2＝10°; B, θ1＝80°and θ2＝20°
）
7, the solid curves represent theoretical values, and
curred with a smaller change in the output direction.
the marks indicate experimental results. Solid cir-
Therefore, antagonistic bi-articular muscles were
cles indicate the output force. While the mono-
shown experimentally to make fine adjustments by
articular muscles indicated by open triangles（f1 :
alternating the activity level in response to even a
Da）and inversed closed triangles（e2 : Tla）are in
slight change in the output force direction.
full activity, the antagonistic bi-articular muscles indicated by closed squares（e3 : Tlo）and open
5． Discussion
squares（f3 : Blo）show reversal of activity level with
Electromyography has been employed to analyze
a slight change in the output force direction. Also,
various actions, including sports, and a consider-
as the degree of extension of the elbow and shoulder
able amount of data has been obtained. However,
increased, the output force increased, and reversal
analysis of muscle activities has been mainly con-
of the activity level between the two muscles oc-
fined to individual muscles with respect to functional
176
Robotics and electromyographic kinesiology analyses of in front handsprings in tumbling
anatomy. There have been few attempts to analyze
of the shoulder flexion and the elbow extension.
the coordinated activities of two or more muscles. In
Therefore, the discharge patterns of the Tlo and Blo
this study, activity level of three pair of antagonistic
and alternation of their discharge levels are consid-
muscles was theoretically analyzed to exert the
ered to be sufficient EMG information for evaluation
maximal output force at the end-point E. Therefore,
of the output force direction near the direction a-b
we selected recording of EMG which showed the
on the basis of coordinated activities of the three
strong discharge. Furthermore we picked up only
pairs of antagonistic muscles. The activity pattern of
the hand contact period, the most important activi-
these muscles and the output force direction were in
ties which determine the skillfulness of performance
agreement with the direction of the force vectors su-
in the handspring.
perimposed over the EMGs and action diagrams at
In front handsprings in tumbling that consists of
the shoulder flexion and the elbow extension, when
the hand contact during in front handsprings in
tumbling.
elbow is extending and shoulder is flexing, the
In the skilled subjects as shown in Fig. 4, the bi-
mono-articular shoulder flexor of the Da and the
articular Tlo showed almost full activity, and the Blo
mono-articular elbow extensor of the Tla showed
showed little activity for 20―30 msec prior to the
marked continuous discharges while discharge lev-
peak point of the reaction force of the hand contact,
els of the Tlo and Blo were reversed, in all subjects.
where the discharge of this period will be responsi-
The Tlo and Blo are both bi-articular muscles. While
ble to produce the reaction force, in handsprings of
the Tlo is involved in extension of the elbow and ex-
the tumbling without any exception. Such a dis-
tension of the shoulder, the Blo is involved in flexion
charge pattern strongly indicated that, from the re-
of the elbow and flexion of the shoulder. When el-
sult obtained in the link model analysis, directions
bow is extending and shoulder is flexing, whether
of the output force exerted at the hand will be al-
either muscle acts alone or the two muscles act in
ways controlled to pass through on or very close to
coordination, the two muscles act antagonistically
the shoulder joint, so that almost the maximal stiff-
on one joint, and the activities of the two muscles
ness could be exerted at the hand. In the tumbling of
are paradoxical. This paradox indicates limitations
the unskilled subjects as shown in Fig. 4, the Blo
in the evaluation of functional characteristics of in-
showed marked discharge during the responsible
dividual muscles.
period for the reaction force, while the Tlo showed
In this study, attention was directed to patterns of
little. Their discharge pattern suggested that the
coordinated activities observed between groups of
force direction exerted at the hand will be passing
antagonistic muscles, as well as to the interactions
through the elbow joint, not on the shoulder joint
in a pair of antagonistic bi-articular muscles in the
like the skilled ones. Therefore, the stiffness ex-
humeral region, and pairs of antagonistic mono-
pected at the hand will be only a half of the one of
articular muscles of the shoulder and elbow（f1, e1 :
the skilled as shown in Fig. 7. Indeed, actually
f2, e2 : f3, e3 shown in Fig. 5A）
. However, as the
measured reaction force at the hand contact of the
output force in the stance phase was exclusively in
unskilled were about 1.2 times of BW（body weight）,
or around the interval a-b（shown in Fig. 5B）and as
while the skilled about 2.3 times of BW. A reaction
discharges of the Da, which corresponds to the an-
force of about 1.2 times of BW might be sufficient to
tagonist f1, continued before and after the hand
complete a tumbling, but the larger the reaction
contact, discharges of Dp which corresponds to the
force, the more grand the performance will be ex-
antagonist e1 are considered to have been negligi-
pected to be.
ble. The discharges of the f2 which corresponds to
From the motion analyses data, the skilled sub-
the antagonist Tla during hand contact period was
jects well flexed the shoulder joint, before the hand
considered to have been negligible. It was because
contact in tumbling, whereas the unskilled subjects
of the in front handsprings in tumbling is composed
suddenly extended slightly the shoulder joint just
177
JJBSE 7（3）2003
before the hand contact, resulting in a substatial difference in the stiffness at the hand between the
skilled and the unskilled.
All the muscles in the two-joint link model had the
same contractile characteristics. However, the output forces of muscles in human subjects are different. Therefore, the output force distribution characteristics and the direction of the maximum output
force are expected to be different in a mechanical
model and in a living subject. Particularly, in direction a, the output force and output force direction
are determined by the mono-articular elbow extensors and the mono-articular shoulder flexors and
the bi-articular Tlo（Fig. 5B）. As represented by the
Da, the mono-articular shoulder flexors are much
larger and stronger than the Tlo. Therefore, there is
possibility that the direction of the maximum output
force shifts from the difference of the output forces
of muscles, but it was supposed that such a shift was
little. From the view point of functional anatomical
analysis, the pair of antagonistic bi-articular muscles in the humeral region has been reported to
show unique activities in the hand contact period of
in front handsprings in tumbling. We evaluated this
phenomenon by control engineering analysis, as
well as by EMG kinesiology analysis, and showed
that the output force control and output force direc-
ing. J Jpn Soc Clin Biomechan Rel Res 15 : 293―296
（in Japanese with English abstract）
Oka H, Furuta A, Yoshizawa M, Kumamoto M（1992）
：
Antagonistic bi-articular muscles functioning in front
handsprings in tumbling and vaulting. VII Meeting of
the European Society of Biomechanics, Rome : 253
Okamoto T, Takagi K, Kumamoto M（1967）
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Okamoto T, Kumamoto M（1973）
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Oshima T, Kumamoto M（1995）
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：122―129（in Japanese with English
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Oshima T（l999）
：Introduction of bi-articular muscle coordinate to kinesiology. In : Collection of abstracts
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Yamashita N, Kumamoto M, Tokuhara Y, Hashimoto F
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activities of antagonistic bi-articular muscles, along
with antagonistic mono-articular muscles.
Profile
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Hideo OKA
Professor, Department of Practical LifeStudies,
Hyogo University of Teacher Education.
Sports Biomechanics.
The main focus of my present research is the
importance of coordinated muscle activities of bi-articular and mono-articular antagonistic muscles for analyses of sports.