determination of the swing technique characteristics and performance outcome relationship in golf...

This article was downloaded by: [Northeastern University]On: 12 November 2014, At: 16:56Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK

Journal of Sports SciencesPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/rjsp20

Determination of the swing technique characteristicsand performance outcome relationship in golf drivingfor low handicap female golfersSusan J. Brown a , Alan M. Nevill b , Stuart A. Monk c , Steve R. Otto c , W. Scott Selbie d &Eric S. Wallace ea School of Life, Sport and Social Sciences , Edinburgh Napier University , Edinburgh, UKb Research Institute of Healthcare Sciences , University of Wolverhampton , Walsall, UKc Research & Testing , R&A Rules Ltd , St. Andrews, UKd C-Motion Inc , Germantown, Maryland, USAe Sport and Exercise Sciences Research Institute , University of Ulster , Newtownabbey, UKPublished online: 11 Oct 2011.

To cite this article: Susan J. Brown , Alan M. Nevill , Stuart A. Monk , Steve R. Otto , W. Scott Selbie & Eric S. Wallace (2011)Determination of the swing technique characteristics and performance outcome relationship in golf driving for low handicapfemale golfers, Journal of Sports Sciences, 29:14, 1483-1491, DOI: 10.1080/02640414.2011.605161

To link to this article: http://dx.doi.org/10.1080/02640414.2011.605161

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) containedin the publications on our platform. However, Taylor & Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of theContent. Any opinions and views expressed in this publication are the opinions and views of the authors, andare not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon andshould be independently verified with primary sources of information. Taylor and Francis shall not be liable forany losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoeveror howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use ofthe Content.

This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

http://www.tandfonline.com/loi/rjsp20

http://www.tandfonline.com/action/showCitFormats?doi=10.1080/02640414.2011.605161

http://dx.doi.org/10.1080/02640414.2011.605161

http://www.tandfonline.com/page/terms-and-conditions

http://www.tandfonline.com/page/terms-and-conditions

Determination of the swing technique characteristics and performanceoutcome relationship in golf driving for low handicap female golfers

SUSAN J. BROWN1, ALAN M. NEVILL2, STUART A. MONK3, STEVE R. OTTO3,

W. SCOTT SELBIE4, & ERIC S. WALLACE5

1School of Life, Sport and Social Sciences, Edinburgh Napier University, Edinburgh, UK, 2Research Institute of Healthcare

Sciences, University of Wolverhampton, Walsall, UK, 3Research & Testing, R&A Rules Ltd., St. Andrews, UK,4C-Motion Inc., Germantown, Maryland, USA and 5Sport and Exercise Sciences Research Institute, University of Ulster,

Newtownabbey, UK

(Accepted 11 July 2011)

AbstractPrevious studies on the kinematics of the golf swing have mainly focused on group analysis of male golfers of a wide abilityrange. In the present study, we investigated gross body kinematics using a novel method of analysis for golf research for agroup of low handicap female golfers to provide an understanding of their swing mechanics in relation to performance. Datawere collected for the drive swings of 16 golfers using a 12-camera three-dimensional motion capture system and astereoscopic launch monitor. Analysis of covariance identified three covariates (increased pelvis–thorax differential at the topof the backswing, increased pelvis translation during the backswing, and a decrease in absolute backswing time) asdeterminants of the variance in clubhead speed (adjusted r2¼ 0.965, P5 0.05). A significant correlation was found betweenleft-hand grip strength and clubhead speed (r¼ 0.54, P5 0.05) and between handicap and clubhead speed (r¼70.612,P5 0.05). Flexibility measures showed some correlation with clubhead speed; both sitting flexibility tests gave positivecorrelations (clockwise: r¼ 0.522, P5 0.05; counterclockwise: r¼ 0.711, P5 0.01). The results suggest that there is nocommon driver swing technique for optimal performance in low handicap female golfers, and therefore consideration shouldbe given to individual swing characteristics in future studies.

Keywords: Golf, female players, pelvis, thorax, clubhead speed

Introduction

The importance of golf driving performance is widely

recognised. Many studies have investigated the key

elements of driving performance (Chu, Sell, &

Lephart, 2010), including the application of mathe-

matical models and in vivo measurements. Whilst the

majority of previous work has focused on male

golfers, more recent research has included female

golfers (see, for example, Chu et al., 2010; Egret,

Nicolle, Dujardin, Weber, & Chollet, 2006; Horan,

Evans, Morris, & Kavanagh, 2010; Zheng, Barren-

tine, Fleisig, & Andrews, 2008). All of these studies,

however, chose statistical analysis methods that

group data using the homogeneity principle of

participant selection and so there is an underlying

assumption that the group mean for each variable is a

representation of the homogeneous group. There-

fore, attention should be paid to the swing

kinematics of highly-skilled female golfers which

allows for individual technique variation in order to

establish the existence of common elements of the

swing associated with optimal performance, and

therefore to inform specific coaching.

Egret et al. (2006) studied swing kinematics of

male and female golfers and found significant

differences between groups for shoulder and hip

angles and knee flexion at the top of the backswing.

Their findings suggest that greater magnitude of

rotation is seen in female golfers, but they found no

significant differences in clubhead speed between

males and females, possibly as a consequence of the

range of abilities and subsequent use of group mean

data to conduct the analysis. Zheng et al. (2008)

studied group data from male and female profes-

sional golfers and also found significant differences

in shoulder and pelvis orientation at the top of the

backswing, as well as differences in pelvis orientation

Correspondence: S. J. Brown, School of Life, Sport and Social Sciences, Edinburgh Napier University, Edinburgh EH11 4BN, UK.

E-mail: [email protected]

Journal of Sports Sciences, November 2011; 29(14): 1483–1491

ISSN 0264-0414 print/ISSN 1466-447X online � 2011 Taylor & Francis

http://dx.doi.org/10.1080/02640414.2011.605161

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

16:

56 1

2 N

ovem

ber

2014

at ball impact. They concluded that the LPGA

(Ladies Professional Golf Association) players pro-

duced greater changes in pelvic and shoulder

orientations from the top of the backswing to ball

impact, but had less of an uncoiling effect at ball

impact than their male counterparts.

Horan et al. (2010) conducted the only study to

date using the Cardan thorax alignment rotation

method during the golf swing of males and females,

but found no significant differences between the

sexes in their calculation of pelvis–thorax separation.

There was, however, a difference between the sexes

in the overall position of the upper body at the top of

the backswing due to an increase in thorax and pelvis

sway in males, but no difference for axial rotation of

either segment. Furthermore, the magnitudes of

thorax and pelvis axial rotation were significantly

different at ball contact, with females generating

higher values. Peak clubhead speeds were also

significantly different between the sexes. The analysis

method used here was also based around group data

for the male and female golfers. Although it would

appear that no difference exists in the way that male

and female golfers separate their pelvis and thorax,

this may be the result of taking mean data from each

sex, which masks the individual variation in both

sexes.

Furthermore, even in published golf studies of only

male participants, there appears to be some dispute

regarding the impact of this hip/pelvis–thorax inter-

segment interaction and its effect on clubhead speed,

but the use of pelvis and thorax segments to identify

differences between golfers of varying ability as well as

differences between the sexes remains popular

(Cheetham, Martin, Mottram, & St. Laurent, 2001;

Cole & Grimshaw, 2009; Egret et al., 2006; Horan

et al., 2010; Myers et al., 2008; Zheng et al., 2008).

Methodological issues may have contributed to this

ambiguity between studies (Wheat, Vernon, &

Milner, 2007) and the group profiling of golfers for

analysis by means of either ability or gender is also

common, but variations exist in how this profiling is

achieved. However, the pelvis–thorax separation

previously reported in male golfers as playing an

important role in accelerating the clubhead towards

the ball may apply to some although not necessarily

all golfers. A greater change in length of muscle and

tendon tissues (elastic deformation) would result in

greater strain energy being available, but the premise

that all golfers could utilise this principle is based on

the assumption that they are all equally capable of

either achieving an appropriate level of deformation,

or that their tissues possess the same elastic proper-

ties. Crucially, however, there is evidence of in-

creased musculotendinous stiffness in males

compared with females (Blackburn, Padua, Wein-

hold, & Guskiewicz, 2006; Blackburn, Riemann,

Padua, & Guskiewicz, 2004; Gajdosik, Giuliani, &

Bohannon, 1990), resulting in an increased avail-

ability of strain energy in males compared with

females. Anatomical differences in structure between

the sexes and indeed between players of either

sex may therefore account for different swing

characteristics, particularly in terms of elastic energy

utilisation.

While no golf-specific studies have considered the

selection of movement recruitment strategies be-

tween the sexes, individual athletes may find unique

solutions to a given motor task, suggesting there may

not be a common optimal technique for everyone

(Bartlett, Wheat, & Robins, 2007). The theoretical

control mechanisms behind any differences in

technique within the golf swing are beyond the scope

of this paper, but it is important in the evolution of

the field to establish whether there is a common

technique for optimal performance of female golfers.

The main aims of the present study were: (1) to

establish the key parameters associated with the drive

golf swings of a group of low handicap female golfers

with a particular focus on the axial rotation move-

ment patterns of the pelvis and thorax, as well as

temporal characteristics of the swing; and (2) to

determine if there is an common optimal swing

based on these parameters for this group of highly

skilled female golfers using a method of analysis

(ANCOVA) that accounts for individual differences

in technique. It was hoped that the study would

determine whether the current coaching methods for

female golfers that are based on key features of the

male swing require modification.

Methods

Participants

Sixteen right-hand dominant Category One

(handicap� 5) female golfers (Table I) gave

informed consent to participate in the study as

approved by the university ethics review committee

and in accordance with the university policy for

human experimentation.

Procedures

The height, mass, grip strength, upper body flex-

ibility, and self-reported handicap of each participant

were determined prior to motion capture. Grip

strength dynamometry was selected because it

was deemed the single strength measure most likely

to be associated with the golf swing. Handgrip was

determined by selecting the maximum value from

three attempts with each hand using a Takei

Analogue Handgrip dynamometer (TKK-5001,

Cranlea, Birmingham, UK). Upper body flexibility

1484 S. J. Brown et al.

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

16:

56 1

2 N

ovem

ber

2014

was measured using an Acuflex1 II Trunk Rotation

Test (Novel Products, Inc., USA). Participants were

asked to perform three rotations in each direction

with the highest value selected for analysis using two

different methods in random order:

. Method 1 – according to the manufacturer’s

guidelines, with feet shoulder width apart and

knees slightly bent, participants were asked to

stand at 908 and centrally to the device, arms

length away, and then to rotate backwards

keeping the arm horizontal, reaching with their

outside fist for the sliding scale, with the final

position required to be held for 2 s. This was

repeated for the opposite arm.

. Method 2 – modified from the manufacturer’s

guidelines, the participants were asked to sit on

their heels with their back to the device, again

arms’ length away and to rotate clockwise and

counter-clockwise keeping their pelvis facing

forwards to isolate the rotation of the thorax. As

in Method 1, participants were required to keep

the extending arm horizontal and hold the final

position 2 s.

During both tasks, participants were asked to

maintain an upright body position. Both methods

were used to establish the rotation capability of each

participant in a standing position similar to that used

in the golf swing, and then the adapted method used

to determine the ability of each participant to

separate their pelvis and thorax, given that the pelvis

remained ‘fixed’ during Method 2. This would help

to determine whether the use of such a separation is

related to the maximum voluntary range of trunk

motion or technique selection. Each golfer then

performed 10 drives into a golf net situated 2.5 m

from the tee and ball position while standing on a

golf mat (Figure 1). Participants used their own

driver and wore appropriate golf shoes and minimal

fitted clothing to avoid extraneous marker move-

ment. Kinematic data were collected using 12 infra-

red cameras (ProReflexTM, Qualisys Medical Ltd.,

Sweden) operating at 240 Hz. The equipment was

calibrated according to the manufacturers’ instruc-

tions, with the camera system showing a maximum

calibration residual of 1.5 mm for each camera.

Qualisys Track ManagerTM (QTM, Version

1.8.224, Qualisys Medical Ltd., Sweden) was used

to reconstruct the three-dimensional coordinates of

each of ten 19-mm spherical reflective markers

placed on the following sites: left and right shoulder

acromion processes, left and right anterio-superior

iliac spine (ASIS), left and right posterior-superior

iliac spine (PSIS), thorax tracking markers placed on

C7, T10, L4, and suprasternal notch. Reflective tape

was also placed 0.6 m downwards from the butt of

the shaft of the club and on the toe of the clubhead.

Markers were also placed on the following sites to

allow events within the golf swing to be identified:

left and right lateral shoulders, two upper arm

tracking markers on each arm, left and right, medial

and lateral epicondyles of each elbow, left and right

medial wrist markers placed on the superior aspect of

the styloid process, left and right lateral wrist markers

Table I. Participant information and variable data.

Variable mean+ s

Correlation with

clubhead speed

Age (years) 24.8+ 7.3 N.A.

Height (m) 1.68+ 0.06 N.A.

Mass (kg) 65.94+ 6.23 N.A.

Club shaft length (m) 1.11+ 0.03 N.A.

Handicap (strokes) 1.75+ 2.35 r¼70.612,

P50.05

Grip strength, left hand

(kg � f71)

32.94+ 5.26 r¼ 0.54,

P50.05

Grip strength, right

hand (kg � f71)

35.25+ 5.93 Not significant,

P40.05

Standing flexibility,

clockwise (m)


P40.05

Standing flexibility,

counter-clockwise

(m)


P40.05

Sitting flexibility,

clockwise (m)

0.62+ 0.15 r¼ 0.522,

P50.05

Sitting flexibility,

counter-clockwise

(m)

0.58+ 0.13 r¼ 0.711,

P50.01

Clubhead speed

(m � s71)

39.48+ 2.48 N.A.

Ball speed (m � s71) 55.7+ 3.93 N.A.

Backswing time (s) 1.00+ 0.17* N.A.

Downswing time (s) 0.32+ 0.05 N.A.

*P50.05 within the ANCOVA model.

Figure 1. Plan of capture area with reference to the global

coordinate system (XG, YG, ZG).

Swing kinematics and performance of female golfers 1485

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

16:

56 1

2 N

ovem

ber

2014

placed on a 7.5 cm wand extending out laterally

from the ulnar styloid process, and one lower arm

tracking marker placed on the forearm of each arm.

Thigh and shank markers were also used to stabilise

the optimisation used to calculate model pose and

were located at the following sites: left and right,

medial and lateral condyles of each knee, two upper

leg tracking markers placed non-linearly on the thigh

of each leg, left and right, medial and lateral malleoli,

two lower leg tracking markers placed non-linearly

on the shank of each leg, left and right calcaneus.

A proprietary stereoscopic launch monitor, posi-

tioned to capture images of the clubhead, was

used to measure clubhead speed at impact. The

launch monitor was also used to measure ball speed,

launch angle, and backspin rate within 0.03 s post-

impact. The accuracy in each parameter (clubhead

speed+0.5 m � s71; ball speed+0.05 m � s71;

launch angle+0.18; spin rate+50 rpm) was deter-

mined via comparison with other proprietary equip-

ment (N. F. Betzler, S. A. Monk, E. S. Wallace, & S.

R. Otto, unpublished).

The participants were asked to warm up and

familiarise themselves with the experimental set-up

before motion capture by hitting balls, with their own

drivers, into the net along a target line taped to

the floor parallel to the laboratory ‘‘XG’’ axis. All

participants used a premium three-piece construc-

tion ball commonly used by male/female professional

and low handicap golfers in competitive play. The

participants placed the ball on a wooden tee set at

their preferred height. Once a participant stated that

she was comfortable within the testing environment,

data capture began with a static calibration file of the

participant standing in the anatomical position for

use in generating the subject model using Vi-

sual3DTM software (C-Motion Inc., USA). This

allowed a transformation of the position vectors

between the segment and laboratory coordinate

systems (Cappozzo, Della Croce, Leardini, & Chiari,

2005).

Data processing

The 10 drives plus the static calibration file for each

participant were processed by identifying the location

of each marker using QTMTM software after setting

the tracking maximum residual error to 3 mm. Data

from all files were then exported into Visual3DTM for

further processing and analysis. A model was

generated for each participant using medial and

lateral markers at the proximal and distal ends of

each segment to establish a local right-handed

orthogonal coordinate system originating at the

proximal end of the segment, and oriented with the

z-axis aligned with the proximal and distal axis, and

the y-axis directed anteriorly. The thorax segment

was derived from the location of the ASIS markers

and left and right acromion markers in the anatomi-

cal position, and the pelvis derived from ASIS and

PSIS markers. The position and orientation (pose) of

the thorax segment during the hitting trials was

estimated using tracking markers placed on C7, T10,

and L4. To compensate for soft tissue artefact-

related movement, the pose was estimated using a

global optimisation algorithm (Lu & O’Connor,

1999), which considered measurement error distri-

butions and was solved using a Quasi-Newton

optimisation algorithm. The following constraints

were imposed at the joints:

. pelvis segment – 6 degrees of freedom (relative

to laboratory)

. thorax and thigh segments – 3 degrees of

freedom (no translation relative to pelvis)

. shank segments – 3 degrees of freedom (no

translation relative to thighs).

Kinematic data were analysed for thorax and pelvis

rotations during the drive by considering four phases

of movement based on the following events [adapted

from Neal, Abernethy, Moran, & Parker (1990) and

Robinson (1994)]:

. Event 1: address (AD) – associated with the

frame before motion of the club began, estab-

lished from clubhead markers

. Event 2: top of the backswing (TB) – associated

with the frame before the club began moving

back towards the target, established from club-

head markers

. Event 3: left wrist un-cocking (WU) – time at

which the resultant angle from the lateral elbow

and wrist markers relative to the club shaft

began to increase

. Event 4: left-arm horizontal (LAH) – associated

with the frame at which the left forearm segment

was horizontal (relative to the ground)

. Event 5: impact (IM) – determined by the

position of the clubhead marker relative to the

ball.

The specific events were located at the frame

coinciding with these descriptions, and respective

swing phases were between these frames.

A virtual laboratory (XG, YG, ZG) was created in

Visual3DTM aligned with the tee and a target line

along a line parallel to the XG axis, the global

coordinate system (GCS) determined by the YG axis

representing the anterior-posterior direction, the XG

axis the medial-lateral direction, and the ZG axis the

vertical direction. The segment coordinate system

(SCS) was determined for each segment so as to

simulate the different axes of rotation for each


Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

16:

56 1

2 N

ovem

ber

2014

segment, the origin of which was placed at the

proximal end of each segment using the same

reference direction as the GCS (e.g. ZT-vertical

and YT-anterior) computing the longitudinal axis

first (see Figure 2 for orientation of the SCS). Pelvis

angular position and then displacements were

derived from pelvis orientation relative to the global

coordinate system of the virtual laboratory using

Cardan sequence XYZ, the ZP value providing

segment axial rotation at and between events (Lees,

Barton, & Robinson, 2010). A zero ZP value signifies

that the segment and the target line were parallel,

with a negative value (commonly referred to as a

closed position) indicating a clockwise rotation of the

segment relative to the target line and a positive value

(open) a counter-clockwise rotation relative to this

line. Pelvis translation along the target line was also

calculated based on the pelvis origin position at and

between events. The pelvis–thorax differential was

calculated as the joint angle created by the thorax

relative to the pelvis (about the thorax ZT axis) and

extracting the Z values using Euler angles and

Cardan sequence XYZ, and finally the angular

velocity of this variable was calculated as the thorax

relative to the pelvis resolved into the thorax SCS.

Data analysis

The golf swing data were analysed using the best

three of the 10 trials (Bates, Dufek, & Davis, 1992).

Since the analysis was intended to focus on

participant maximum potential, the best three shots

rather than all 10 were selected. These three shots

were determined by consideration of the launch

characteristics, specifically ranking each shot by

clubhead speed, efficiency (ratio of ball speed to

clubhead speed), launch angle, and backspin rates.

The interdependency of these characteristics is

crucial to achieving greater driving distance; in

particular, optimum launch angle is heavily depen-

dent on backspin rates and ball speed. The highest

clubhead speed, efficiency, and launch angle were

given the highest rankings (Cochran & Stobbs, 1968)

and the backspin values closest to 2500 rpm were

ranked highest. A figure of 2500 rpm was selected as

it is close to the spin magnitude used by golf’s

governing bodies for conformance testing of golf

balls (The R&A, 2011). The sum of the rankings was

calculated and the three best trials selected. Mean

data were derived and are presented from the three

selected shots based on the events and phases

described above, but all three selected shots and

the associated kinematic variables were used in the

statistical analysis.

Analysis of covariance (ANCOVA) using backward

elimination was used (PASW Statistics v.18.0, SPSS

Inc., Chicago, IL) to investigate which variables or

covariates were likely to explain the differences in

clubhead speeds for all 48 trials (16 participants6 3

selected shots), with clubhead speed as the dependent

variable and the kinematic and temporal variables as

covariates. ANCOVA was selected because it has the

capacity to fit a fixed between-participant indicator

variable (n¼ 16) and enables the estimation of a

within-participant source of variation (3 trials) as part

of the error structure. This means that the ANCOVA

partitions two sources of variation: one between

participants and one within participants. Participant

number was therefore used as a fixed factor so that the

analysis allowed for individual differences in club-

head speeds. Clubhead speed data were assessed for

normality by plotting the calculated residuals against

the predicted values, and tests of normality were

carried out to ensure data were normally distributed.

Figure 2. Segment coordinate systems: thorax (XT, YT, ZT) and

pelvis (XP, YP, ZP). The SCS origin was placed at the proximal

end of each segment for analysis but located at the centre of mass

for clarity in the figure above.


Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

16:

56 1

2 N

ovem

ber

2014

Pelvis displacement, translation, and pelvis–thorax

differential data were placed along with temporal data

into the analysis. Pearson product–moment correla-

tions were carried out separately for clubhead speed

relative to flexibility and grip strength since these

measures were not directly associated with any given

golf shot, unlike all other data. In all cases, statistical

significance was set at P5 0.05.

Results

Participant data are presented in Table I and include

both anthropometric and performance measures.

Clubhead speed was chosen as the performance

measure for analysis since all participants used their

own club, inferring a possible ball/club influence that

could affect analysis using ball speed data. A

significant correlation was found (r¼ 0.54,

P5 0.05) between left-hand grip strength and club-

head speed, but not between right-hand grip strength

and clubhead speed. A significant negative correla-

tion was found between handicap and clubhead

speed (r¼70.612, P5 0.05).

Flexibility measures provided in Table 1 showed

some significant correlation with clubhead speed;

both sitting flexibility tests gave significant positive

correlations (clockwise: r¼ 0.522, P5 0.05; coun-

ter-clockwise: r¼ 0.711, P5 0.01) but neither of the

standing tests was significant.

With reference to the data presented in Table II

and Figures 3 and 4, the ANCOVA identified three

covariates (increased pelvis–thorax differential at

the top of the backswing, increased pelvis translation

during the backswing, and one temporal value –

a decrease in absolute backswing time) as determi-

nants of the variance in clubhead speed (dependent

variable) between the participants (adjusted r2¼0.965, P5 0.05). Participants was used as a fixed

factor within the ANCOVA using three shots per

participant, but when this was removed and the

ANCOVA re-run, the model was less useful in

explaining the variance in performance (adjusted

r2¼ 0.734, P5 0.05), indicating a strong reliability

on participants’ own swing technique to produce

faster clubhead speeds.

Data for pelvis–thorax axial (Z) angular velocity at

wrist un-cocking was only slightly above the alpha

threshold (P¼ 0.062) in the final elimination.

Further analysis of these data using a scatter plot

and Pearson product–moment correlation confirmed

that there was a positive correlation between this

variable and clubhead speed (r¼ 0.489, P¼ 0.00);

participant 11 appeared as an outlier. This golfer

began wrist un-cocking very early and proceeded to

un-cock throughout the downswing, so the timing of

this event and therefore the negative values present in

the angular velocity data may have influenced the

results within the ANCOVA.

Figure 3 shows data presented in ascending

clubhead speed order for the timing of specific

events expressed as a percentage of downswing time.

The relative percentage times for wrist un-cocking

Table II. Displacement data for pelvis axial rotation and translation, and pelvis–thorax data for specific events and phases throughout the

swing (mean+ s).

Segment

Displacement between events

BS to TB TB to WU WU to LAH LAH TO IM

Pelvis angular displacement (ZP axis) (8) 751.49+9.56 30.46+19.56 25.17+ 18.03 43.24+ 8.47

Pelvis linear displacement (XG axis) (m) 70.05+0.06* 0.07+0.04 0.05+ 0.05 0.03+ 0.02

Differential at events (8)

TB WU LAH IM

Pelvis–thorax differential (8) 718.33+ 10.36* 724.69+12.86 723.37+11.75 711.38+ 9.91

Pelvis-thorax angular velocity (8 � s71) 741.28+ 50.42 40.44+95.40 96.96+101.94 134.12+ 79.4

Abbreviations: BS¼ start of backswing, TB¼ top of backswing, WU¼wrist un-cocking, LAH¼ left-arm horizontal, IM¼ impact.

*P5 0.05 within the ANCOVA model.

Figure 3. Time at which wrist un-cocking began (¤) and when the

left arm was horizontal (') expressed as a percentage of normalised

total downswing time on the primary y axis, and club head speed

data (~) presented on the secondary y axis. Data are presented in

ascending clubhead speed order.


Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

16:

56 1

2 N

ovem

ber

2014

and left-arm horizontal events would suggest varia-

tion across participants, in that some initiate an early

un-cocking relative to the top of the backswing (0%)

and others delay this action until closer to the event

coinciding with their left arm being horizontal.

Figure 4 represents pelvis–thorax differential data

at events within the swing plotted against clubhead

speed for all participants. Again, the dispersion of

these data points would suggest variation across

participants, with only values at the top of the

backswing showing significance within the ANCO-

VA model.

Discussion

The main aim of the study was to establish the key

parameters associated with the drive golf swings of a

group of low handicap female golfers with a

particular focus on the axial rotation movement

patterns of the pelvis and thorax, as well as temporal

characteristics of the swing. In addition, the study

aimed to determine if there is a common optimal

swing based on these parameters for this group of

highly skilled female golfers using an ANCOVA to

consider between-participant and within-participant

variation in relation to performance. Mean clubhead

speed (39.48+ 2.48 m � s71) and mean ball speed

(55.7+ 3.93 m � s71) were both consistent with a

recent similar study of female golfers (Horan et al.,

2010). The results suggest that greater clubhead

speed was obtained by increasing the pelvis–thorax

differential at the top of the backswing in agreement

with several previous studies (Egret et al., 2006;

Myers et al., 2008; Zheng et al., 2008), and at the

same time increasing the linear displacement (trans-

lation) of the pelvis away from the target along the

laboratory XG axis (Figure 1) during the backswing

in agreement with Horan et al. (2010). It also

appears that faster clubhead speeds require a quicker

backswing, in agreement with Zheng et al. (2008).

The significant correlation found between the

sitting flexibility test and clubhead speed further

supports these findings, since increasing thorax

rotation relative to the pelvis, as seen at the top of

the backswing, would seem to give optimal set-up

position for the initiation of the downswing. In

addition, this relationship between clubhead speed

and flexibility appears to validate the idea that the

pelvis–thorax separation at the top of the backswing

is not simply a secondary phenomenon but is

influential in the generation of clubhead speed.

These variables therefore seem to indicate that the

backswing unsurprisingly plays an important role in

determining the outcome of the swing, but that the

group of golfers used here have established their own

technique during the downswing to generate the

clubhead speeds shown; there are no common

characteristics during the downswing that can

account for the differences in clubhead speeds within

the group. The results provide further evidence of

the nature of elite amateur female golfers’ swing

patterns, as well as adding weight to the limitations of

assuming that a common technique should be

adopted by all golfers for optimal performance.

The conclusions of previous studies on pelvis–

thorax separation have been based on the suggested

utilisation of greater elastic energy produced as a

result of increased pelvis–thorax separation particu-

larly at the top of the backswing. Okuda and

colleagues (Okuda, Armstrong, Tsunezumi, &

Yoshiike, 2002) describe the coiling of the trunk in

terms of generating a stretch in the muscles of the

trunk as a consequence of rotating away from the

address position, and the lower body moving in

the opposite direction to the upper body at the start

of the downswing creating the proximal-to-distal

sequence commonly associated with golf swings. In

agreement with the present study, this separation

certainly appears to be important at the top of the

backswing, but in agreement with Zheng et al.

(2008) who report that females produce less of an

uncoiling effect than males between the top of the

backswing and impact, the present study does not

support the idea that the stretch–shortening cycle is a

determinant of clubhead speed during the down-

swing phase or at ball impact in female golfers. Myers

et al. (2008) found a moderate correlation between

torso–pelvis separation rotational velocity (akin to

the present study’s consideration of pelvis–thorax

angular velocity) and ball velocity at lead-arm

parallel (equivalent to left-arm horizontal in the

present study) and 40 ms before impact in a group of

male golfers, which supports the idea of the utilisa-

tion of the stretch–shortening cycle during the

downswing. However, the lack of support for this

in the present study and evidence of decreases in

musculotendinous stiffness in females compared

with males (Blackburn et al., 2004, 2006; Gajdosik

et al., 1990) may account for the differences in

Figure 4. Mean pelvis–thorax differential and clubhead speed

values for all participants at the top of the backswing (¤, TB), left-

arm horizontal (', LAH), and impact (~, IM)


Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

16:

56 1

2 N

ovem

ber

2014

techniques used and reported clubhead speeds, since

the strain energy derived and available from the

pelvis–horax separation may be reduced in females.

Certainly, the present findings did not suggest that

any of these variables associated with the stretch–

shortening cycle during the downswing consistently

played a role in explaining the variance in clubhead

speed. Further consideration of the data might

suggest that some golfers create more separation,

and some larger angular velocities, but that these

alone cannot explain the variance in clubhead speeds

in all golfers, since other equally long hitters showed

an alternative swing pattern.

The group of golfers who participated in the

present study all used their own driver, and in all

cases this was a club designed for use by male golfers,

which tend to have a greater overall mass than those

designed specifically for females. However, given the

moderate relationship of left-hand grip strength to

clubhead speed found in this study and that there

appears to be no relationship between the players’

height and shaft length selected, it is perhaps not

surprising that the inertial effects of a heavier

clubhead and longer shaft may influence the dy-

namics of the swing, particularly during the transi-

tion phase at the top of the backswing. Indeed,

Kaneko and Sato (2000) found that when the total

club mass was increased, the joint torques of the

shoulders and torso in the latter half of the down-

swing were increased, encouraging an early wrist

release. This may impact on the technique used by

the female golfers in terms of compensating for the

increase in proportional effort needed to compensate

for the inertial effects of the golf club compared with

their male counterparts while using the same

equipment. Given that left-hand grip strength was

only moderately correlated with clubhead speed

(r¼ 0.54, P5 0.05) in this group, these golfers

appear to be selecting their own strategies during

the transition and downswing phases to optimise

clubhead speeds. Consideration of the temporal

characteristics shown in Figure 3 would suggest that

the timing of the action of wrist un-cocking differs

between players, some initiating this motion at the

top of the backswing, others delaying until left-arm

horizontal. There is also evidence (Table I) that a

shorter backswing could assist in generating faster

clubhead speeds but equally this could, if it is also

faster, result in a greater inertial effect at the

transition between backswing and downswing. This

action could well be affected by the inertial para-

meters of the club during the transition phase and

would require greater strength to generate the force

required to change direction. This club–player

interaction therefore warrants further study and

may indicate some of the variation between golfers,

but also the difference in technique adopted by male

and female golfers.

Comparing groups of athletes in an attempt to

define common key variables present in elite

performers is prevalent in the biomechanical litera-

ture. While the ANCOVA provided some indication

of the determinants of clubhead speed in the group

of female golfers tested, it is evident that each golfer

may find her own solution to the problem of

optimising clubhead speeds given the influence of

the participant fixed factor in the analysis and the

variables that did not appear to be significant within

the model. Horan et al. (2010) also suggest that

swing kinematics previously reported as optimal for

male golfers may not be appropriate for females, and

Bartlett et al. (2007) support the notion of athletes

not relying on a common technique for optimal

performance even among elite performers.

In conclusion, aspects of the backswing phase of

the golf swing do appear to be critical in determining

faster clubhead speeds in this group of female golfers.

However, no characteristics were found to establish a

common optimal technique used by these golfers

during the downswing, contrary to previous studies;

some participants showed similarities to previously

presented data but others did not, regardless of

clubhead speed. Critically, it would appear that

individual techniques, whether related to movement

frequency preferences, equipment selection, anthro-

pometric characteristics, or more likely a combina-

tion of these, are prevalent within this group of low

handicap female golfers and contribute in different

ways to each player’s swing pattern. In exploring the

swing characteristics of this group of female golfers, a

valuable story is emerging: assuming that there is a

common technique that produces optimal perfor-

mance appears to be invalid for low handicap female

golfers, and therefore studies that aim to assess the

impact of such characteristics on clubhead speed

may benefit from considering the individual rather

than group data. Nonetheless, we acknowledge that

limiting the analysis to the gross movement patterns

of the pelvis and thorax may not allow consideration

of the complete energy flow through the swing, and

therefore a more detailed analysis of additional inter-

segment interactions is required. In doing so, golf

coaching strategies can be better informed resulting

in improved performance and reduced potential for

injury.

References

Bartlett, R., Wheat, J., & Robins, M. (2007). Is movement

variability important for sports biomechanists? Sports Biome-

chanics, 6, 224–243.


Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

16:

56 1

2 N

ovem

ber

2014

Bates, B. T., Dufek, J. S., & Davis, H. P. (1992). The effect of trial

size on statistical power. Medicine and Science in Sports and

Exercise, 24, 1059–1068.

Blackburn, J. T., Padua, D. A., Weinhold, P. S., & Guskiewicz, K.

M. (2006). Comparison of triceps surae structural stiffness and

material modulus across sex. Clinical Biomechanics, 21, 159–167.

Blackburn, J. T., Riemann, B. L., Padua, D. A., & Guskiewicz,

K. M. (2004). Sex comparison of active extensibility, passive

and active stiffness of the knee flexors. Clinical Biomechanics,

19, 36–43.

Cappozzo, A., Della Croce, U., Leardini, A., & Chiari, L. (2005).

Human movement analysis using stereophotogrammetry.

Part 1: Theoretical background. Gait and Posture, 21, 186–196.

Cheetham, P. J., Martin, P. E., Mottram, R. E., & St. Laurent, B.

F. (2001). The importance of stretching the ‘‘X-Factor’’ in the

downswing of golf: ‘‘The X-Factor stretch’’. In P. R. Thomas

(Ed.), Optimising performance in golf (pp. 192–199). Brisbane,

QLD: Australian Academic Press.

Chu, Y., Sell, T. C., & Lephart, S. M. (2010). The relationship

between biomechanical variables and driving performance

during the golf swing. Journal of Sports Sciences, 28, 1251–1259.

Cochran, A., & Stobbs, J. (1968). The search for the perfect swing.

London: Heinemann.

Cole, M. H., & Grimshaw, P. N. (2009). The X-Factor and its

relationship to golfing performance. Journal of Quantitative

Analysis in Sports, 5 (1), 9.

Egret, C. I., Nicolle, B., Dujardin, F. H., Weber, J., & Chollet, D.

(2006). Kinematic analysis of the golf swing in men and women

experienced golfers. International Journal of Sports Medicine, 27,

463–467.

Gajdosik, R. L., Giuliani, C. A., & Bohannon, R.W. 1990. Passive

compliance and length of the hamstring muscles of healthy men

and women. Clinical Biomechanics, 5, 23–29.

Horan, S. A., Evans, K., Morris, N. R., & Kavanagh, J. J. (2010).

Thorax and pelvis kinematics during the downswing of

male and female skilled golfers. Journal of Biomechanics, 43,

1456–1462.

Kaneko, Y., & Sato, F. (2000). The adaptation of golf swing to inertia

property of golf club. London: Blackwell.

Lees, A., Barton, G., & Robinson, M. (2010). The influence of

Cardan rotation sequence on angular orientation data for

the lower limb in the soccer kick. Journal of Sports Sciences, 28,

445–450.

Lu, T. W., & O’Connor, J. J. (1999). Bone position estimation

from skin marker coordinates using global optimisation with

joint constraints. Journal of Biomechanics, 32, 129–134.

Myers, J., Lephart, S., Tsai, Y. S., Sell, T., Smoliga, J., & Jolly, J.

(2008). The role of upper torso and pelvis rotation in driving

performance during the golf swing. Journal of Sports Sciences, 26,

181–188.

Neal, R., Abernethy, B., Moran, M., & Parker, A. (1990). The

influence of club length and shot distances on the temporal

characteristics of the swings of expert and novice golfers. In A.

Cochran (Ed.), Science and golf: Proceedings of the First World

Scientific Congress of Golf (pp. 36–42). London: E & FN Spon.

Okuda, I., Armstrong, C. W., Tsunezumi, H., & Yoshiike, H.

(2002). Biomechanical analysis of professional golfers’ swing.

In E. Thain (Ed.), Science and golf IV: Proceedings of the World

Scientific Congress of Golf (pp. 18–27). London: Routledge.

Robinson, R. (1994). A study of the correlation between swing

characteristics and club head velocity. In A. J. Cochran & M. R.

Farrally (Eds.), Science and golf II: Proceedings of the World

Scientific Congress of Golf (Vol. II, pp. 84–90). London: E &

FN Spon.

The R&A (2011). Actual launch conditions, symmetry and test

procedure. Available at: http://www.randa.org.

Wheat, J. S., Vernon, T., & Milner, C. E. (2007). The

measurement of upper body alignment in the golf drive. Journal

of Sports Sciences, 25, 749–755.

Zheng, N., Barrentine, S. W., Fleisig, G. S., & Andrews, J. R.

(2008). Swing kinematics for male and female pro golfers.

International Journal of Sports Medicine, 29, 965–970.


Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

16:

56 1

2 N

ovem

ber

2014

http://www.randa.org

determination of the swing technique characteristics and performance outcome relationship in golf...

Documents