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Journal of Sports Sciences
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Electromyographic analysis of lower limb muscles
during the golf swing performed with three different
clubs
Sérgio Martaa, Luís Silvaa, João Rocha Vaza, Maria António Castrob, Gustavo Reinaldoc &
Pedro Pezarat-Correiaa
a CIPER, Faculdade de Motricidade Humana, Universidade de Lisboa, Lisboa, Portugalade de
Lisboa
b Health College of Coimbra, Polytechnic Institute of Coimbra, Research Centre of
Mechanics Engineering (CEMUC), University of Coimbra, Coimbra, Portugal
c Centro Universitário Metodista, Instituto Porto Alegre, Porto Alegre, Brazil
Published online: 22 Jul 2015.
To cite this article: Sérgio Marta, Luís Silva, João Rocha Vaz, Maria António Castro, Gustavo Reinaldo & Pedro Pezarat-Correia
(2015): Electromyographic analysis of lower limb muscles during the golf swing performed with three different clubs, Journal
of Sports Sciences, DOI: 10.1080/02640414.2015.1069376
To link to this article: http://dx.doi.org/10.1080/02640414.2015.1069376
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Electromyographic analysis of lower limb muscles during the golf swing performed
with three different clubs
Sérgio Marta
1
, Luís Silva
1
, João Rocha Vaz
1
, Maria António Castro
2
, Gustavo Reinaldo
3
and Pedro Pezarat-Correia
1
1
CIPER, Faculdade de Motricidade Humana, Universidade de Lisboa, Lisboa, Portugalade de Lisboa;
2
Health College of Coimbra, Polytechnic
Institute of Coimbra, Research Centre of Mechanics Engineering (CEMUC), University of Coimbra, Coimbra, Portugal;
3
Centro Universitário
Metodista, Instituto Porto Alegre, Porto Alegre, Brazil
ABSTRACT
The aim of this study was to describe and compare the EMG patterns of select lower limb muscles
throughout the golf swing, performed with three different clubs, in non-elite middle-aged players.
Fourteen golfers performed eight swings each using, in random order, a pitching wedge, 7-iron and
4-iron. Surface electromyography (EMG) was recorded bilaterally from lower limb muscles: tibialis
anterior, peroneus longus, gastrocnemius medialis, gastrocnemius lateralis, biceps femoris, semiten-
dinosus, gluteus maximus, vastus medialis, rectus femoris and vastus lateralis. Three-dimensional
high-speed video analysis was used to determine the golf swing phases. Results showed that, in
average handicap golfers, the highest muscle activation levels occurred during the Forward Swing
Phase, with the right semitendinosus and the right biceps femoris muscles producing the highest
mean activation levels relative to maximal electromyography (70–76% and 68–73% EMG
MAX
,respec-
tively). Significant differences between the pitching wedge and the 4-iron club were found in the
activation level of the left semitendinosus, right tibialis anterior, right peroneus longus, right vastus
medialis, right rectus femuris and right gastrocnemius muscles. The lower limb muscles showed, in
mostcasesandphases,highermeanvaluesofactivationonelectromyographywhengolfersper-
formed shots with a 4-iron club.
ARTICLE HISTORY
Accepted 30 June 2015
KEYWORDS
Golf; swing; EMG; lower
limb; club; neuromuscular
patterns
Introduction
The golf swing and its effects are controlled by muscle recruit-
ment patterns (Hume, Keogh, & Reid, 2005). During the golf
swing, the entire body must move in a coordinated manner to
transfer energy to the ball (McHardy & Pollard, 2005). In each
shot, the golfer should choose the club that will facilitate
approaching the hole in as few shots as possible (Hume
et al., 2005).
For a better understanding of how the golf swing is per-
formed, the following kinesiological methods have been used
to characterise neuromuscular patterns: force platforms to
measure ground reaction forces (Barrentine, Fleisig, Johnson,
& Woolley, 1994); 3D kinematic and kinetic analysis (Egret,
Vincent, Weber, Dujardin, & Chollet, 2003; Gatt, Pavol, Parker,
& Grabiner, 1998) and electromyography (EMG) (Marta, Silva,
Castro, Pezarat-Correia, & Cabri, 2012). Most golf swing EMG
studies have focused on trunk movement (Bulbulian, Ball, &
Seaman, 2001; Cole & Grimshaw, 2008; Horton, Lindsay, &
Macintosh, 2001; Marta, Silva, Vaz, Bruno, & Pezarat-Correia,
2013; Pink, Perry, & Jobe, 1993; Silva et al., 2013; Watkins,
Uppal, Perry, Pink, & Dinsay, 1996). There is also published
EMG research on upper limb muscle performance, mainly on
the proximal muscles acting on the scapula (Kao, Pink, Jobe, &
Perry, 1995) and glenohumeral joint (Jobe, Moynes, &
Antonelli, 1986; Jobe, Perry, & Pink, 1989; Pink, Jobe, & Perry,
1990).
According to McHardy, Pollard, and Luo (2006), lower limbs,
especially the knee, experience high forces, but there is a lack
of EMG studies on lower limb muscles (Cabri, Sousa, Kots, &
Barreiros, 2009; Marta et al., 2012). Bechler, Jobe, Pink, Perry,
and Ruwe (1995) have published the only known study speci-
fically on lower limb muscle activity. However, this study
monitored only the proximal muscles acting on the hip and
knee joints, and the authors recorded EMGs using the single-
needle method. Bechler et al. (1995) reported that the gluteus
maximus was the most active muscle of the lower limbs and
that there was higher activity in the trail leg during the take-
away and forward swing and in the lead leg during the accel-
eration and follow-through.
The studies performed by Bechler et al. (1995) and Watkins
et al. (1996) focused on the professional and lower handicap
(<5) participants. However, it is important to notice that
recreational golfers are the majority of the golf population.
Other researchers have emphasised the need for further stu-
dies on golfers of different skill levels and swing types to
determine whether there are any substantial differences
between these subgroups (Egret et al., 2003; McHardy &
Pollard, 2005).
According to Cheetman, Martin, Mottram, and St Laurent
(2001), the legs and hips initiate the development of the club
head speed, with rapid rotation of the pelvis during the for-
ward swing and acceleration phases, especially when maximis-
ing the distance of the golf ball using long iron clubs (Hume
CONTACT Sérgio Marta smamarta@gmail.com Rua Orlando Ribeiro, 2955-211 Pinhal Novo, Portugal.
JOURNAL OF SPORTS SCIENCES, 2015
http://dx.doi.org/10.1080/02640414.2015.1069376
© 2015 Taylor & Francis
Downloaded by [Sérgio Marta] at 10:18 11 August 2015
et al., 2005). Additionally, Egret et al. (2003) reported biome-
chanical and club head speed differences using different clubs,
which would suggest that the muscular demands of the lower
limbs might be affected by the use of different club types. To
the best of our knowledge, only Marta et al. (2013) compared
the EMG amplitude of the trunk muscles when the swing was
performed with two different clubs (pitching wedge and 4-
iron), but no significant differences were found.
The objective of the present work was to compare the EMG
patterns of lower limb muscles during the different phases of
the golf swing performed by middle-aged recreational golfers
with the following clubs: a long iron (4-iron), an intermediate
iron (7-iron) and a short iron (pitching wedge).
Methods
Participants and task
Fourteen volunteer right-handed male golfers participated in
this study. The sample consisted of recreational golfers with a
mean age of 51.1 ± 9.1 years (range 39–64) and a mean
handicap of 14.5 ± 1.5 (range 11.9–17) (Table I). The partici-
pants were instructed to perform 24 shots, eight with each
club type (in blocks of four swings): an accuracy shot with the
pitching wedge (<100 m), an intermediate shot (100–150 m)
with a 7-iron and a long distance shot with the 4-iron
(>150 m). Each block of four swings for each of the three
different conditions was performed in a random sequence.
The participants hit a regular golf ball off an artificial turf
golf mat, with high shock absorption characteristics, towards
a target placed 6 m away using their own clubs (which all had
graphite shafts that were standard length), gloves and shoes.
The participants showed no limitations in golf practice (i.e.,
injuries) at the time they agreed to complete the investigation
protocol. All procedures and objectives of the study were
explained to the participants, all of whom signed a written
informed consent. The Research Ethics Committee of the
Faculdade de Motricidade Humana, Universidade de Lisboa
approved the study, which was in conformity with the princi-
ples of the Declaration of Helsinki of 1975 and 2008.
General procedures
After the explanation of study purposes and collection steps,
the participants answered a brief questionnaire about their
characteristics (age, handicap, experience). The skin was pre-
pared and electrodes were placed as described in Table II. This
was followed by a 5-min warm-up period consisting of golf
swings. After the warm-up, the Maximum Voluntary Isometric
Contraction EMG data (EMG
MAX
) were collected from each
participant. Following the EMG
MAX
data acquisition, reflective
marks were placed for video analysis and, then, synchronisa-
tion procedures were performed. Before the experimental
procedures, all participants were allowed to perform some
swing trials for better adaptation to the task and they started
when they were ready.
Video data recording, processing and analysis
Video analysis was used to identify the golf swing phases.
Video data were synchronised with EMG using the same A/D
converter. For kinematic analysis, a three-dimensional SIMI
Motion 3D system (SIMI Reality Motion Systems GmbH,
Unterschleissheim, Germany) was used. The golf swing was
recorded with five high-speed Basler A602fc (Basler Vision
Technologies, Ahrensburg, Germany) cameras at 100 Hz. The
cameras were placed at the anterior, posterior and superior
oblique and were adjusted for the best 3D reconstruction.
According to Horton et al. (2001), two markers were placed
on the extremities of the individuals’club shaft to divide the
golf swing into the following five phases: (1) the Backswing –
from the address to top of the swing; (2) the Forward Swing –
from the top of the swing to the horizontal club (early part of
Downswing); (3) the Acceleration –from the horizontal club to
impact (late part of the Downswing); (4) the Early Follow-
Through –from the impact to horizontal club and (5) the
Late Follow-Through –from the horizontal club to the com-
pletion of the swing.
EMG data recording, processing and analysis
Bilateral EMG signals were collected from the 10 studied mus-
cles with active surface electrodes (Al/AgCl, rectangular shape
30 × 22 mm) using the AMBU
®
BlueSensor N (AMBU, Ballerup,
Denmark) and telemetric equipment bioPLUX
®
research 2010
(PLUX, Lisbon, Portugal) with Bluetooth connectivity. Sensors
amplified the EMG signals with a bandpass (10–500 Hz), com-
mon-mode rejection ratio (CMRR) of 110 dB and input impe-
dance greater than 100 MΩ. All EMG data were sampled at
1000 Hz, digitally filtered (10–490 Hz), full wave rectified,
smoothed through a low-pass filter (12 Hz, fourth-order
Butterworth digital filter) and amplitude normalised with the
peak 100-ms EMG signal during EMG
MAX
for reference. The
average value of the EMG signal was calculated during each
phase of the golf swing for each repetition, condition and
participants. EMG processing was performed using a routine
by MATLAB
®
software V.R2013a (The Mathworks Inc., Natick,
Massachusetts, USA). To guarantee the quality of the signals,
experienced researchers performed visual inspection before
EMG processing.
The electrodes were aligned with the muscle fibre orientation,
with a centre-to-centre distance of 22 mmat the most prominent
part of the muscle bellies, taking into account the references
described in Table II (Hermens etal., 1999). The ground electrode
was placed over the manubrium sterni (Horton et al., 2001). To
decrease the impedance of the interface between the skin and
electrode, the skin was prepared by removing hair through skin
abrasion and, then, cleaning with alcohol.
EMG signals during maximal voluntary contractions (MVC)
were collected as reference for the amplitude normalisation
Table I. Participant characteristics (n= 14).
Characteristics Mean ± SD Range
Handicap 14.5 ± 1.5 (11.9–17.0)
Age (years) 51.1 ± 9.1 (39.0–64.0)
Height (m) 1.76 ± 0.1 (1.65–1.82)
Body mass (kg) 80.9 ± 8.8 (68.0–90.5)
Experience (years) 9.9 ± 4.9 (5.0–25.0)
2S. MARTA ET AL.
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procedure. Therefore, two isometric repetitions of 3–4 s were
performed to determine the EMG
MAX
for each muscle with the
protocols described in Table II. Participants were verbally
encouraged during the maximal isometric efforts and, to
avoid fatigue, a 2-min rest period was allowed between repe-
titions. The EMG normalising procedure was consistent with
the procedures described by Konrad (2005) and Hermens et al.
(1999) to evaluate the MVC.
Statistical analysis
Data were processed in IBM SPSS Statistics 21.0 (IBM
Corporation, New York, USA) software. Descriptive statistics
were reported as the mean ± SD of the % EMG
MAX
.
Normality was assessed by the Shapiro–Wilk test. A two-way
repeated measures ANOVA was conducted to explore the
impact of the three clubs and phases on each muscle on
both sides, and the univariate analysis was extended to each
phase. In addition to the Central Limit Theorem, data normal-
ity distribution was guaranteed by root square transformation
(Ahrens, Cox, & Budhwar, 1990). Statistical significance
between measures was assessed by the Greenhouse–Geisser
when the sphericity was violated. Alpha level was set at 5%
and, then, adjusted by Bonferroni correction according to the
number of statistical comparisons. Pairwise comparisons were
performed with the Bonferroni test.
Results
Club × Swing Phase interaction
There was a significant Club × Swing Phase interaction in the
right gastrocnemius lateralis (F(4.943, 494.337) = 3.157,
P= .008) due to the club differences and activation levels
during the Forward Swing, Acceleration and Early Follow-
Through phases between the pitching wedge and 4-iron.
Another significant interaction was found in the left semi-
tendinosus (F(6.277, 646.517) = 3.122, P= .004) due to the
club differences and activation levels in the Acceleration
Phase between the pitching wedge and 4-iron. There were
no club interaction differences in the other swing phases
(Table III).
Comparison between the clubs (pitching wedge, 7-iron
and 4-iron)
The intensity of the activation patterns between the three
clubs was similar for the left-side muscles, with the excep-
tion of the semitendinosus (F(2, 206) = 9.458, P< .001)
which showed significant statistical differences between
the pitching wedge and the other two clubs (Figures 1,2
and 3). There were significant statistical differences between
the clubs, especially between the pitching wedge and the
4-iron club, in the right-side muscles. The right vastus med-
ialis (F(1.786, 173.280) = 8.473, P= .001), the right rectus
femoris (F(1.619, 166,719) = 9.220, P< .001), right tibialis
anterior (F(1.726, 165.695) = 7.101, P=.002),rightperoneus
longus (F(2, 194) = 8.093, P< .001), right gastrocnemius
medialis (F(2, 202) = 8.444, P< .001) and right gastrocne-
mius lateralis (F(2, 200) = 9.349, P< .001) showed signifi-
cantly higher values of activation when the swing was
performed with a 4-iron in comparison with the pitching
wedge. These differences were observed mainly during the
Forward Swing and Acceleration phases. Additionally, the
right rectus femoris also showed significant statistical differ-
ences between the pitching wedge and the 7-iron club,
with a lower activation when the pitching wedge was used.
Table II. EMG placement and EMG
MAX
protocols.
Muscle Placement EMG
MAX
protocols
Tibialis Anterior (TA) At 1/3 on the line between the tip of the fibula and the tip of
the medial malleolus
With the ankle joint in dorsiflexion and the foot in inversion
(without extension of the great toe) support the leg just above
the ankle joint. Apply pressure against the medial side, dorsal
surface of the foot in the direction of plantar flexion of the
ankle joint and eversion of the foot
Peroneus Longus (PL) At 25% on the line between the tip of the head of the fibula to
the tip of the lateral malleolus
Support the leg just above the ankle joint and everse the foot
with plantar flexion of the ankle joint while applying pressure
against the lateral border and sole of the foot, in the direction
of inversion of the foot and dorsiflexion of the ankle joint
Gastrocnemius Medialis (GeM) In the most prominent bulge of the muscle In single-limb stance, plantar flexion of the foot with emphasis
on pulling the heel upward more than pushing the forefoot
downward; for maximal pressure in this position, it is necessary
to apply pressure against the forefoot as well as against the
calcaneus
Gastrocnemius Lateralis (GeL) At 1/3 of the line between the head of the fibula and the heel
Gluteus Maximus (GM) At the midpoint of the line between the sacral vertebrae and the
greater trochanter just in the middle of the buttocks well above
the visible bulge of the greater trochanter
In prone position, lift the complete leg (laterally rotated)
against manual resistance
Vastus Medialis (VM) At 80% on the line between the anterior spina iliaca superior
and the joint space in front of the anterior border of the medial
ligament Extended knee without rotating the thigh while applying
pressure against the leg above the ankle towards flexion
Rectus Femoris (RF) At the midpoint of the line from the anterior spina iliaca
superior to the superior part of the patella
Vastus Lateralis (VL) At 2/3 on the line from the anterior spina iliaca superior to the
lateral side of the patella
Semitendinosus (ST) At the midpoint of the line between the ischial tuberosity and
the medial epicondyle of the tíbia
Press against the leg proximal to the ankle towards knee
extension
Biceps Femoris (BF) At the midpoint of the line between the ischial tuberosity and
the lateral epicondyle of the tibia
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Comparison between the phases
All muscles showed low or medium levels of activity (7–31%
EMG
MAX
) during the Backswing phases for each of the three
clubs. The gastrocnemius from both sides, right peroneus
longus, right biceps femoris, right semitendinosus, right glu-
teus maximus, left vastus medialis, left rectus femoris and left
vastus lateralis muscles reached their maximal activity in the
Forward Swing (28–76% EMG
MAX
), whereas, in the right tibialis
anterior, left tibialis anterior, left peroneus longus, left biceps
femoris, left semitendinosus, left gluteus maximus, right vastus
medialis, right rectus femoris and right vastus lateralis, the
maximum amount of activity occurred in the Acceleration
(15–57% EMG
MAX
). In the Early Follow-Through and Late
Follow-Through, all muscles decreased their activity (6–38%
EMG
MAX
). All muscles showed significant statistical differences
between phases, especially between the top activity phase
and other phases (P< .001).
Discussion and implications
This study compared the EMG patterns of lower limb muscles
in middle-aged recreational golfers, during the different
phases of the golf swing, using three different clubs: a short
iron (pitching wedge), an intermediate iron (7-iron) and a long
iron (4-iron). In order to compare the activity patterns
between clubs, we divided the swing into five phases, as
previously performed in other studies (Bechler et al., 1995;
Jobe et al., 1989; Marta et al., 2012,2013; Pink et al., 1990).
Contrary to the findings of Marta et al. (2013) that did not
find differences in the EMG amplitude of trunk muscles, the
results of this study showed statistical differences in muscle
activation patterns of the lower limbs between the swings
performed with different clubs at the different phases of the
golf swing, especially on the right side. In general, differences
in muscle activity levels were observed for the Forward Swing,
Acceleration and Early Follow-Through phases but not during
the Backswing and Late Follow-Through. We observed that,
except for the left semitendinosus, it was mainly the right
lower limb muscles that showed an increased activation inten-
sity when the longer clubs were used (tibialis anterior, pero-
neus longus, gastrocnemius lateralis, gastrocnemius medialis,
vastus medialis and rectus femoris), which likely relates to the
higher club-head speed typically achieved with these longer
clubs (Egret et al., 2003). The use of long and intermediate
clubs appears to be associated with a significantly increased
activity in the hip extensor muscles. Related to the association
between lower limb muscle activity and club head speed, it
has been previously shown that the club head speed is sig-
nificantly correlated with maximal lower-body strength (Keogh
et al., 2009).
Differences occurred in the right tibialis anterior during the
Backswing and Acceleration phases, and in the right peroneus
longus during the Forward Swing Phase, showing lower levels
of activity when the pitching wedge was used. The two por-
tions of the right triceps surae (gastrocnemius medialis and
gastrocnemius lateralis) had significantly higher levels of activ-
ity in the 4-iron club during the Forward Swing, Acceleration
and Early Follow-Through phases. The right vastus medialis
had significantly higher levels of activity in the 4-iron during
the Acceleration Phase, which can be associated to the inter-
nal hip rotation to the final position, as the weight shifts to the
lead lower limb. The right rectus femoris had also significantly
higher levels of activity in the 4-iron during the Acceleration
and Early Follow-Through phase, which can be linked to
dynamic stabilisation of the trail hip during the reduction of
pelvis rotation velocity. The left semitendinosus was the only
muscle on the left side that was significantly influenced by
the club type, presenting lower levels of activity between the
pitching wedge and the other clubs and only in the
Acceleration Phase. The use of long and intermediate clubs
appears to be associated with a significantly increased activity
in the hip muscles extensors and, as stated by Bechler et al.
(1995) is related with the pelvic rotation towards the target.
Table III. Results of the two-way repeated measures ANOVA (Club × Swing Phase interaction, club and Swing Phase) by muscle laterality.
Muscle Side
Club Swing Phase Club x Swing phase interaction
m n F P op m n F P op m n F P op
TA Left 2 202 .808 .447 .187 2.786 281.395 33.776 .000 1.000 6.583 664.857 2.053 .051 .776
Right 1.726 165.695 7.101 .002 .897 2.839 272.582 47.419 .000 1.000 4.616 443.096 2.282 .051 .712
PL Left 2 200 1.220 .297 .264 3.166 316.638 115.585 .000 1.000 6.161 616.113 1.251 .278 .503
Right 2 194 8.093 .000 .956 2.528 245.248 29.164 .000 1.000 5.643 547.365 .968 .443 .372
GeM Left 2 186 .803 .449 .186 2.110 196.244 101.569 .000 1.000 6.776 630.181 .839 .552 .359
Right 2 202 8.444 .000 .963 3.100 313.135 48.983 .000 1.000 5.088 513.881 2.729 .018 .828
GeL Left 2 190 .888 .413 .202 2.838 269.581 188.968 .000 1.000 6.614 628.310 1.247 .277 .522
Right 2 200 9.349 .000 .977 2.938 293.845 37.181 .000 1.000 4.943 494.337 3.157 .008 .879
BF Left 1.771 182.463 2.696 .077 .497 2.612 269.084 122.889 .000 1.000 6.133 631.729 1.584 .147 .620
Right 2 172 .534 .587 .137 1.872 161.011 130.418 .000 1.000 5.558 477.984 1.077 .374 .409
ST Left 2 206 9.458 .000 .979 2.251 231.889 138.924 .000 1.000 6.277 646.517 3.122 .004 .929
Right 2 178 3.755 .025 .680 1.548 137.814 178.783 .000 1.000 5.837 519.523 1.904 .080 .698
GM Left 2 206 2.934 .055 .567 2.034 209.477 164.198 .000 1.000 5.139 529.330 1.375 .231 .495
Right 2 210 1.191 .306 .259 2.307 242.228 118.327 .000 1.000 5.992 629.146 .534 .783 .216
VM Left 2 176 .842 .433 .193 2.486 218.736 138.967 .000 1.000 6.327 556.764 2.148 .043 .785
Right 1.786 173.280 8.473 .001 .949 2.335 226.515 46.264 .000 1.000 4.747 460.434 2.574 .028 .780
RF Left 2 164 .114 .892 .067 2.150 176.275 115.892 .000 1.000 3.996 327.631 .599 .663 .197
Right 1.619 166.719 9.220 .000 .951 2.001 206.143 106.016 .000 1.000 4.247 437.407 2.656 .030 .759
VL Left 2 188 .141 .869 .071 2.352 221.131 142.007 .000 1.000 6.292 591.431 1.578 .147 .625
Right 1.619 168.348 5.090 .012 .754 2.354 244.812 28.467 .000 1.000 4.478 465.705 1.950 .093 .623
Note: TA, Tibialis Anterior; PL, Peroneus Longus; GeM, Gastrocnemius Medialis; GeL, Gastrocnemius Lateralis; BF, Biceps Femoris; ST, Semitendinosus; GM, Gluteus
Maximus; VM, Vastus Medialis; RF, Rectus Femoris; VL, Vastus Lateralis; m, degrees of freedom for the numerator (effect); n, degrees of freedom for the
denominator (error); F, value of the F-ratio; P,P-value; op, observer power. Bold values indicate that the differences are statistically significant.
4S. MARTA ET AL.
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During the Backswing, the lower limb muscles presented
low to medium levels of activity in the studied muscles
(7–31% EMG
MAX
). The Forward Swing and the Acceleration
were the phases when all the lower limb muscles presented
higher activation. In the Forward Swing, when the pelvis starts
rotating to the target-side (Burden, Grimshaw, & Wallace,
1998), the right hip extensors (biceps femoris, semitendinosus
and gluteus maximus) showed high levels of activity (53–76%
EMG
MAX
) to help extend the right hip, while the left quadri-
ceps (vastus medialis, rectus femoris and vastus lateralis) helps
knee extension also with high levels of activity (43–58%
EMG
MAX
). This conjoined activation pattern of extensors of
the trail hip and lead knee was also found in low handicap
(<5) golfers (Bechler et al., 1995) and gives an important
contribution to the pelvic rotation during the Forward
Swing. However, contrary to the findings of Bechler et al.
(1995) that observed near-maximal activation levels for the
right gluteus maximus (100% of Manual Muscle Test) during
the Forward Swing, our recreational golfers showed consider-
ably lower values for the gluteus maximus during this phase
(53–55% EMG
MAX
). Considering the important role of this core
muscle during the Forward Swing (Loock, Grace, & Semple,
2013), this lack of activation of the trail gluteus maximus
probably means this muscle is less active (Marta et al., 2012,
2013) and it could be an important limitation of high-handicap
golfers that should be corrected through proper training. The
portions of the triceps surae (gastrocnemius medialis and
gastrocnemius lateralis) from both sides also reached their
maximum activity (28–45% EMG
MAX
) during this phase. As
the swing enters the Acceleration phase, greater activation is
found in the muscles of the lead lower limb and a decrease of
EMG amplitude takes place in the trail leg muscles. The left
Figure 1. Average percentage value of the normalised EMG (EMG
MAX
) from the leg by muscle laterality on each phase by the club.
Note: TA, tibialis anterior; PL, peroneus longus; GeM, gastrocnemius medialis; GeL, gastrocnemius lateralis; BS, Backswing; FS, Forward Swing; ACC, Acceleration; EFT,
Early Follow-Through; LFT, Late Follow-Through; P, pitching wedge; 7i, 7-iron; 4i, 4-iron; +, significant differences between the pitching wedge and the 4-iron; #,
significant differences between the pitching wedge and the 7-iron; a) –Club × Swing Phase interaction.
JOURNAL OF SPORTS SCIENCES 5
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core hip extensors (gluteus maximus, biceps femoris and semi-
tendinosus) become more active (33–57% EMG
MAX
), especially
with longer clubs. This muscle activity helps stabilise the lead
leg, creating high vertical force as the golfer transfers weight
onto the lead side, thus, facilitating the rotation of the pelvis
and upper body towards the target (Barrentine et al., 1994;
Vad et al., 2004). The left tibialis anterior and peroneus longus
(26–28% EMG
MAX
and 35–39% EMG
MAX
, respectively) and the
three portions of the right quadriceps muscle (vastus medialis,
rectus femoris and vastus lateralis) also reached their maxi-
mum of activity (17–29% EMG
MAX
) during this phase. After
impact, the body decelerates and the muscles decrease their
levels of activity during the Early Follow-Through (6–41%
EMG
MAX
) and the Late Follow-Through (7–38% EMG
MAX
)
phases.
The results of this study can help coaches and clinicians to
better understand the relative lower limb muscle contribu-
tions associated with golf shots taken with a variety of golf
clubs. The use of longer clubs increased the muscle activation
levels, especially in the Forward Swing and Acceleration
phases. This should help to develop lower limb-specific inter-
vention programmes to improve performance and prevent
injuries. The intervention programme should increase explo-
sive muscle strength in the extensor muscles of lower limbs
joints (hip, knee and ankle), especially if longer clubs are used.
As the energy is transferred from these lower limb muscles to
the pelvis and spine, it would also be fundamental to increase
the hip dynamic stability and adequate posture and balance in
the lumbopelvic region. For that purpose, the programme
should develop the capacity of core muscles to generate and
maintain force, with special emphasis on their strength endur-
ance and control. Because optimum lower limb muscle per-
formance, particularly about the hip and knee, likely plays a
very important role in stabilising the pelvis (Watkins et al.,
1996) during periods of high activation of the trunk muscles
(Marta et al., 2013; Pink et al., 1993), inadequate lower limb
and pelvic stability may leave golfers more susceptible to
developing lower back pain.
The higher variability in the muscle activation patterns
found in the present study is probably related to the fact
that the participants were middle-aged recreational golfers.
A great variability in the muscle activation patterns in high-
handicap golfers was previously evidenced (Abernethy, Neal,
Moran, & Parker, 1990). Thus, the reduced number of partici-
pants, 14, should be pointed out as a limitation of the study.
Moreover, the study was conducted at a driving range, with
the participants hitting the ball at an image projected onto a
wall located a short distance away and protected by a net. This
Figure 2. Average percentage value of the normalised EMG (EMG
MAX
) from the anterior hip by muscle laterality on each phase by club.
Note: VM, vastus medialis; VL, vastus lateralis; RF, rectus femoris; BS, Backswing; FS, Forward Swing; ACC, Acceleration; EFT, Early Follow-Through; LFT, Late Follow-
Through; P, pitching wedge; 7i, 7-iron; 4i, 4-iron; +, significant differences between the pitching wedge and the 4-iron; #, significant differences between the
pitching wedge and the 7-iron.
6S. MARTA ET AL.
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situation is clearly different from the real golf swing and, thus,
it is another limitation of the present study.
The neuromuscular patterns are generally described by the
EMG amplitude parameters, but are limited by the muscle onset
and offset and the length of the phase. If a muscle presents low
levels of activity for a long time, it can interfere with the phase
mean values. In some cases and during some phases, an extre-
mely rapid peak occurs, but it is masked by the amplitude
analysis. Therefore, new studies that integrate the intensity
and time parameters should be considered to better under-
stand how the central nervous system activates the muscular
system during such a complex motor skill as the golf swing.
Conclusion
For middle-aged recreational golfers, significant differences
were observed between the clubs (pitching wedge, 7-iron
and the 4-iron) in the activation level of the following muscles:
left semitendinosus, right tibialis anterior, right peroneus
longus, right vastus medialis, right rectus femoris and right
gastrocnemius. More specifically, in most cases and phases,
the lower limb muscles showed higher mean values of EMG
activation when golfers performed a swing with a 4-iron club.
The differences were mainly observed in the Forward Swing,
Acceleration and Early Follow-Through.
Furthermore, we characterised the neuromuscular patterns
of the lower limb muscles during the different phases of the
golf swing in middle-aged recreational golfers. All studied
muscles developed their maximal activation levels during the
Forward Swing and Acceleration phases. The muscles that
presented higher activation levels were the right hamstrings:
the biceps femoris and semitendinosus.
Acknowledgements
The authors acknowledge CIPER (Centro Interdisciplinar de Performance
Humana) at FMH-UTL (Faculdade de Motricidade Humana –Universidade
de Lisboa) for access to the facilities.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
The project “Neuromuscular activity in the golf swing with implications for
the practice and in the prevention of overuse injuries”is supported with
funding from the FCT (Fundação para a Ciência e a Tecnologia).
Figure 3. Average percentage value of the normalised EMG (EMG
MAX
) from the posterior hip by muscle laterality on each phase by club.
Note: BF, biceps femoris; ST, semitendinosus; GM, gluteus maximus; BS, Backswing; FS, Forward Swing; ACC, Acceleration; EFT, Early Follow-Through; LFT, Late
Follow-Through; P, pitching wedge; 7i, 7-iron; 4i, 4-iron; +, significant differences between the pitching wedge and the 4-iron; #, significant differences between the
pitching wedge and the 7-iron; a) Club × Swing Phase interaction.
JOURNAL OF SPORTS SCIENCES 7
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