THE EFFECT OF BODY MARKERS ON GOLF DRIVING PERFORMANCE
INTRODUCTION: No study to date has reported if and how the use of body markers used in three dimensional optical tracking methods to study swing kinematics in golf affect movement performance. Egret et al. (2004) studied the use of electromyographic equipment during the golf swing and concluded that the equipment significantly influenced the kinematic pattern of the golf swing. Researchers have previously concentrated their methodological analyses on such factors as the type of marker used, either wand or skin marker (Kirtley, 2002) or skin movement artefact during movement (Holden et al., 2007). The golf swing is a movement that is closed-chain, non-impact and does not cause excessive unwanted movement of skin and wand markers. It is therefore concluded that the golf swing lends itself well to kinematic analysis using body markers. The aim of the present study was to evaluate the effect of body markers on golf driving performance for tests carried out in a laboratory setting. METHOD: Seven category 1 (<5 handicap) golfers (22.1 ± 2.3 yrs, 77.4 ± 9.7 kg, 1.80 ± 0.09 m and 0.2 ± 2.4 handicap) took part. All golfers were male and right-handed. Performance for each shot was determined through analysis of club head and ball impact characteristics measured using a commercially available launch monitor (GolfTek TM Pro V). Subjects were positioned on an artificial grass surface wearing golf spikes as they normally would on a golf course and selected their own tee height. Thirty four body markers were attached to the subject: acromion, lateral epicondyle of the elbow, wrist centre, C4, anterior superior iliac spine, sacrum, greater trochanter, lateral epicondyle of the knee, anterior epicondyle of the knee, medial malleolus, lateral malleolus, 2 nd metatarsal head, heel, and the geometric centre of mass (COM) of the upper and lower arms, and upper and lower legs. Humeral and radial markers were positioned on 63.5 mm (2½″) wands and femoral and tibial markers were positioned on 101.6 mm (4″) wands. Additional club markers were placed on the golf club shaft 254 mm (10″) from the club butt and on the toe of the club head. A 240 Hz 5-camera Motion Analysis Corporation™ Falcon Analogue system tracked all body and club markers during the subjects' swings when body markers were attached, and only the club markers for shots performed without body markers. Subjects warmed up as they normally would before playing golf. Using their own driver subjects were instructed to hit the golf ball eight shots for each randomly assigned set-up along a target line marked on the floor into netting 4.5m away.