Data System

ISB XXth Congress - ASB **th Annual Meeting

July 31 - August 5, Cleveland, Ohio

ELELECTROMYOGRAPHIC LINEAR ENVELOPE ANALYSIS OF GOLF SWING FOR TRUNK MOTION IN

ASIAN PLAYERS: A CASE STUDY

Chia-Nen Chan1 and Wen-Tzu Tang2

11

Chang-Gang University, Taoyuan, Taiwan, and2National College of Physical Education and Sports, Taoyuan, Taiwan

email: ******@****.*****.***.**

INTRODUCTION

Despite the significant prevalence of back pain among golfers

at all levels of ability, the current literature does not fully

address specific mechanisms responsible for this injury. The

approach of studying trunk motion includes motion analysis

and EMG measurements. Some studies show differences in

trunk motion with kinematic variables for two groups with

non-back pain and back pain, respectively [1]. Most EMG

Figure 1: EMG activity patterns of shoulder and trunk

studies have measured EMG amplitude in each phase to

muscles on left and right sides during five swing phases

understand general on/off activation of trunk muscles in

pass filtered at 8 Hz by DasyLab 6.0 System to derive the

different phases. However, little work evaluates back muscle

EMG linear envelope.

activation patterns with the EMG envelope, which provides

information on the the timing and duration of the burst, and

RESULTS AND DISCUSSION

also detail smuscle activation characteristics integrated with

To analyze the timing and duration of the firing pattern of

kinematics variables. Moreover, most studies have recruited

back and shoulder muscles of the participant, the EMG linear

western players as participants who usually have higher

envelope as shown in Figure 1 was studied for each muscle. In

anthropometric scores. Recently, Asian professional golf

the early phase of the takeaway, all muscles presented

players have successful performances in American and Europe,

extremely low activation. However, the latissimus dorsi on

albeit with lower anthropometric scores. . Investigation of

both sides started to activate during the tak-away. In particular,

trunk muscle activation pattern in an elite Asian player

the latissimus dorsi on the right side continued activation until

without pain history may provide useful information to

the top point of the takeaway phase. This muscle presented a

explore the optimal swing for back loading. Therefore, this

similar pattern in the forward swing phase. Comparing the two

study identifies reproducible patterns of trunk muscle activity sides, the left latissimus dorsi presented less activation, and

through use of the EMG envelope integrated the kinematic the latissimus of both sides were silent until the end portion of

variables. We analyze the swing of a golfer who won a Gold the late follow through. The left and right erect spinae and

Medal in 2002 Busan Asian Games. The participant had a low right obdominal oblique presented significant activation until

anthropometric anthropometry score relative to western the top point of the take away, then decline. Overall, the

players. forward and acceleration phases muscles on the upper torso

did not showed burst activbity except for the left erect spinae

METHODS in acceleration phases. Other studies have demonstrated

One male Gold Medal winner in 2002 Busan Asian game greater activation levels on the forward swing and acceleration

aged 25 yearswith height 160 cm and weight 65 kg, with 15 relative to the upswing and follow through, as characterized

years of training, participated in this study. The subject is a by MVC percentage. The burst peak may be reduced in MVC

typical right-handed player. Surface EMG data at sampling percentage because of the long duration of the upswing and

rate of 1200 Hz were collected by Biovision EMG System follow through phase. Furthermore, not many trunk muscle

(Wehrheim, Germany). The muscles of abdominal oblique, groups in our study exhibited a burst in the forward and

erectus spinae, latissimus dorsi, and upper rectus abdominis in acceleration phases, and it is possible that other deep trunk

both right and left sides were studied. The distance of the muscles not involved in this study may play an important role

interelectrode was 20 mm, and the placement of electrode was for these two phases, which should be further investigated for

as described by Zipp (1982). A JVC 9800 digital camera at a back pain research.

sampling rate of 120 Hz captured the subject s swing with a

#7 iron via markers on club, shoulder, elbow, wrist, ilium, and CONCLUSIONS

knee. EMG and video data were synchronized with a simple From previous studies using EMG amplitude analysis for

circuit that simultaneously lit an LED and sent a voltage signal different swing phases, information is available on the general

to the Biovision input box. Kinematic data were analyzed by roles of each muscle in different phases. However, this work

the Kwon3D Software. The swing was divided into five demonstrates dilution of the burst which may associate with

phases: Phase I, upswing; Phase II, forward swing; Phase III, back pain because of repetitive and cumulative acute motion.

acceleration; Phase IV, early follow through; Phase V, late Also, reduced burst activation in the forward swing and

follow through [2]. The subject was asked to perform 10 acceleration which may imply the relevance of exploring deep

swings after a proper warm-up. The four best and most

muscles during the forward swing and acceleration.

consistent strokes were chosen by the subject for later data

analysis. The EMG signal was band-pass filtered at 4 to 500

REFERENCES

Hz (Butterworth digital fliter), full-wave rectified, and low-

1. Lindsay D et. al., J Sports Sci, 20, 599-605,2002.

2. Pink M et. al., Am J Sports Med, 18, 137-140,1990.

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