BIOMECHANICAL ANALYSIS ON SOME MARTIAL ART ASPECTS OF TAI CHI CHUAN
T.S-H Wong and A.S-L Fok
School of Mechanical, Aerospace and Civil Engineering
University of Manchester, UK
email: alex.fok@manchester.ac.uk
INTRODUCTION
There is currently a lack of biomechanical studies on Tai Chi
Chuan with the aim of improving the effectiveness of its
movements in a martial arts context. The objective of this
study is therefore to analyze the kinematics and kinetics of
the fundamental defensive and attacking movements of Tai
Chi Chuan by using modern motion analysis techniques.
Power absorption in neutralizing an attack and power
generation in making the counterattack are the two main
topics in this study. These are also the two main elements in
the two-man push-hand exercise of Tai Chi Chuan. The
results gathered from this investigation will help provide
scientifically based guidelines on the correct execution of
Tai Chi movements, thereby increasing their effectiveness
from a martial art's point of view.
METHODS
A male subject was recruited for this experimental study.
Reflective body markers were placed on all his important
joints, as well as the weight and punch bag used in the tests.
Movements of these objects were recorded using a video
camera and the images were then transferred to a computer
for processing using the motion analysis software Peak
Motus 8.3 [1].
The first series of tests focused on the defensive or power
absorption capability of the subject in annihilating a
simulated attack by performing the Tai Chi `sitting-back'
movement. The subject was asked to receive with both
hands an incoming swinging weight released from a distance
and bring it to a stop with the `sitting-back' technique. The
test was repeated by using stances with different longitudinal
and lateral distances between the feet, including a standard
stance recommended by a certain school of Tai Chi Chuan.
In analyzing the movements, the subject was modeled as a
simple damper system which provided a resisting force to
the swinging weight. The time-dependent resisting force was
calculated using the equivalent damping coefficient of the
subject, also time-dependent, derived from the motion
analysis. The stance which produced the lowest resisting
force throughout the whole `sitting-back' movement was
considered to be the most effective. This is because,
according to Newton's 3rd
Law, the force acting on the
subject would also be the lowest.
The second series of tests focused on the attacking aspect of
Tai Chi Chuan by investigating the force generated from the
forward push movement. The subject was asked to start from
the `sitting-back' position, then quickly move forward and
push the punch bag with both hands. This was again
repeated by changing the longitudinal and lateral distances
between the feet. The effectiveness of each stance was
assessed by considering the peak acceleration of the punch
bag, from which the force exerted by the subject could be
calculated.
RESULTS AND DISCUSSION
Fig. 1 presents the resisting force versus displacement
curves for one of the stances used. They show that the
resisting force provided by the subject to the swinging
weight built up rapidly and then fell off just as rapidly as the
weight was being brought to a halt. The maximum resisting
force had a value of approximately 50N, with a
corresponding damping coefficient of about 30 N/m/s. Some
curves have a rather flat profile in the middle together with a
lower maximum resisting force value.
-60
-40
-20
0
0.8 1 1.2 1.4 1.6 1.8 2
Displacement (m)
Resistanceforce(N)
1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th
Figure 1: Resisting force versus displacement curves
By plotting the maximum resisting force against the total
distance covered by the subject for all attempts, a trend of
decreasing maximum resisting force with increasing total
distance was revealed.
In the power generation experiments, forces of around 400N
were reported. Increasing the length of the stance increased
the force generated. This is perhaps not surprising given
that, with a longer stance, the subject was able to extend his
build-up of power over a longer period, thus generating
more power at the end. Changing the width of the stance had
a negligible effect on the results.
CONCLUSIONS
The basic power absorption and power generation
movements of Tai Chi Chuan have been examined using
motion analysis techniques together with a simple
mass-damper model. This study has shown that the standard
stance recommended by a certain school of Tai Chi Chuan
may not be optimum in terms of minimizing the resisting
force in defense and maximizing the force generated in a
counterattack.
REFERENCES
1. www.peakperform.com