Martial Art Institute

(Abstract and Introduction only) Author Wai-Po Tang, Vol.1, n.3, 1999. Webpublish Dec 2001.

A Comparative Kinematics analysis of an expert-novice differences in a Wing Chun Front Kick.

Abstract

This study investigates the kinematics parameters of a martial art (Wing Chun style) front heel kick. The objectives are to establish a profile expert-novice differences during three stages of the whole movement; and to compare past research's findings of the proximal-distal theory at the point of impact. Two dimensional videography (single camcorder) was used to record the movement at a sports hall, and the data was digitised, filtered and smoothed for further analysis. The subjects are one male martial expert of 20 years experience and one male novice with no previous martial art experience. The expert's kicking movement took 0.54s, novice 0.76s, expert peak thigh angular velocity -992.1502°/s vs novice -469.4301°/s, peak knee angular velocity 1476.7608°/s vs 763.4023°/s, peak ankle linear speed 13.4352m/s vs 6.8171m/s. The findings supports previous research's theory of proximal-distal effects on speed. Keywords: Wing Chun, front heel kick, martial arts, kinematics, approach, release and recovery, impact.

Keywords: Wing Chun, front heel kick, martial arts, kinematics, approach, release and recovery, impact.

Introduction

Effective and efficient principles of martial art kicks are often discussed and instructed in clubs and via magazines. There are often debates and claims that training in a particular martial art style will improve kicking performance but mostly unsubstantiated. Recreational practitioners, self-defence artists and sport competitors in martial arts train with a different mentality, but a need in understanding and applying efficient techniques.

There is not much in depth scientific research on martial arts, and most of it has been conducted on Karate (Japanese martial art) and Tae Kwon Do (Korean martial art) but none at all for Wing Chun (Chinese martial art style) techniques. Sorensen et al (1996:483) investigated the dynamics of high front kick by filming 17 skilled subjects (Tae Kwon Do practitioners) with a 50Hz 200 frames/sec high speed camera (Teledyne DBM 45) and a electromyogram (EMG) recorded five major muscle groups of the lower extremity. The subjects performed 3 high kicks aimed at a suspended tennis ball at chin height. The fastest trial was selected for analysis. The inquiry questioned what causes the deceleration of the thigh when kicking, and whether active thigh deceleration enhance the performance of the high front kick.

The findings were conclusive that thigh deceleration was passive and is caused by the lower leg acceleration and by a knee extensor. It is not caused by active deceleration of the glutei or hamstring muscles. Lees and Nolan (1998) reviewed the biomechanics of a soccer kick and stated 'a large angular velocity of the shank (lower leg) results in a high foot speed'. This clearly indicate the proximal end of the leg velocity is paramount to the speed of the distal end of the lower extremity. Wickstrom (1975) also suggested that in a soccer instep kick, thigh angular velocity reduces when the shank angular velocity increases up to impact with the ball; the thigh becomes almost stationary at the point of impact.

Simonian, (1988:185) stated, 'kicking involves the development of angular momentum obtained as the product of a limb's angular velocity and it's moment of inertia. The linear velocity of the kicking foot is the product of the effective radius and the leg's angular velocity at impact'. There does not appear an opposing argument to the proximal-distal kicking theory, however, the previous research concentrated on the relationship of the thigh and shank of a homogeneous group, but no comparative research on the specificity of expert-novice differences.

The examination of differences between two people who are already skilled and those who are minimally skilled represents a relatively new and rapidly growing area of individual-differences research (Ericsson, 1996; Starkes & Allard, 1993). Considering the past research investigated the kick at a certain phase of the movement, there are many variables that would enhance successful in martial arts. Wickstrom's Revised 4 Stage Model 3 Stage Model Backswing Approach Pre-kick Step & backswing 1 1 Forwardswing Release Knee Lift Foot lift & kick 2 2 Release Recovery Leg Rotation Leg Retract 3 3 Follow Through 4 Figure 1.

Comparison of Wickstrom's 4 Stage Model and Revised 3 Stage Model. Kinematic parameters of the Wing Chun's Front Heel Kick (FHK) are divided into three stages so that specific primary variables are selected for further analysis. Wickstrom (1975) stated four stages of a mature kicking motion in football: 1) the withdrawal of the thigh and shank during backswing; 2) the rotation of the thigh and shank forwards, which occur as a result of hip flexion; 3) when the thigh angular velocity reduces, there is a corresponding increase in shank angular velocity up to impact with the ball; and 4) the follow through (Lees and Nolan, 1997). These four 'stages' of the model are specific to a soccer kick but do not consider the approach and recovery as needed for martial art.

A revise stage model needs to be constructed to allow for the specific tactical requirements for martial art kicking technique. This would be a three stage model (see figure 1): i) Approach as from left toe-off to right thigh's backswing and right knee final flexion (important to be discrete); ii) Release initial right knee extension in the backswing phase to impact (important to be fast & powerful); iii) Recovery as from impact to right foot departure from target (important to avoid counter-attack).

The subjects' kicks are recorded by a single video camera along the sagittal plane that provided two dimensional data. The FHK movement is in the sagittal plane about the transverse axis but the is some degree of lateral rotation of the kicking leg in the transverse plane about the vertical axis. However, the rotational magnitude is relatively minimal and this study is focussed on broader variables. Bartlett (1989) stated, 'The advantage of two dimensional cinematography or videography is simplicity, but requires the movement to be in a pre-selected movement plane and introduces perspective error for non-planar movements; however, it yield acceptable results for essentially planar movements'.

This research are concerned with kinematics of the FHK and not kinetics or muscular activation, therefore, single camera can provide acceptable two dimensional data. This study is aimed to establish a kinematic profile of an expert Wing Chun practitioner and a novice kicking characteristics. Comparative analysis will examine three stages of the whole movement; approach (pre contact), flight and impact, and post contact.

The selected kicking technique of this investigation is the Front Heel Kick (Cheen Jet Tek ). It is consider one of most practical kicks in the Wing Chun style of martial art, whereby it is commonly applied in contests. This kick is very similar to a footballer's front instep kick and the Tae Kwon Do high front kick except that the former uses the instep and the latter uses the ball of the foot for initial collision; the type and height of the target is also different. Therefore, the proximal-distal scalars and vectors are comparable to past research on football skills or other similar martial art kicks.

In summary, the objectives are to establish an expert-novice profile and compared the release phase to previous research. The research kinematic parameters of the FHK are: the peak values; Approach- angular velocities and displacement of the right thigh; Release- the relationship of right thigh and right knee's angular velocity against the right ankle's linear speed; Recovery- angular displacement of right thigh and right knee against linear displacement of the right ankle.