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Electromyographic analysis of muscle activation during pull-up variations
Article in Journal of electromyography and kinesiology: official journal of the International Society of Electrophysiological Kinesiology · November 2016
DOI: 10.1016/j.jelekin.2016.11.004
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Journal of Electromyography and Kinesiology 32 (2017) 30–36
Contents lists available at ScienceDirect
Journal of Electromyography and Kinesiology
journal homepage: www.elsevier.com/locate/jelekin
Electromyographic analysis of muscle activation during pull-up
variations
James A. Dickie a, James A. Faulkner a,b, Matthew J. Barnes a, Sally D. Lark a,⇑
a
b
School of Sport and Exercise, Massey University, Wellington, New Zealand
Department of Sport and Exercise, University of Winchester, UK
a r t i c l e
i n f o
Article history:
Received 15 March 2016
Received in revised form 1 November 2016
Accepted 27 November 2016
Keywords:
Muscle activation
Electromyography
EMG
Pull-up
Chin-up
a b s t r a c t
This study sought to identify any differences in peak muscle activation (EMGPEAK) or average rectified
variable muscle activation (EMGARV) during supinated grip, pronated grip, neutral grip and rope pullup exercises. Nineteen strength trained males (24.9 ± 5 y; 1.78 ± 0.74 m; 81.3 ± 11.3 kg;
22.7 ± 2.5 kg m 2) volunteered to participate in the study. Surface electromyography (EMG) was collected
from eight shoulder-arm-forearm complex muscles. All muscle activation was expressed as a percentage
of maximum voluntary isometric contraction (%MVIC). Over a full repetition, the pronated grip resulted
in significantly greater EMGPEAK (60.1 ± 22.5 vs. 37.1 ± 13.1%MVIC; P = 0.004; Effect Size [ES; Cohen’s d]
= 1.19) and EMGARV (48.0 ± 21.2 vs. 27.4 ± 10.7%MVIC; P = 0.001; ES = 1.29) of the middle trapezius
when compared to the neutral grip pull-up. The concentric phases of each pull-up variation resulted in
significantly greater EMGARV of the brachioradialis, biceps brachii, and pectoralis major in comparison
to the eccentric phases (P = <0.01). Results indicate that EMGPEAK and EMGARV of the shoulder-armforearm complex during complete repetitions of pull-up variants are similar despite varying hand orientations; however, differences exist between concentric and eccentric phases of each pull-up.
Ó 2016 Elsevier Ltd. All rights reserved.
1. Introduction
The pull-up is a resistance exercise widely used in a variety of
strength and conditioning settings to promote muscular endurance
or strength adaptations. However, despite familiarity with the
pull-up amongst fitness professionals to promote strength adaptation, there is a lack of evidence demonstrating muscle activation
during this exercise (Vanderburgh and Flanagan, 2000; Williams
et al., 1999). Many fitness professionals work under the assumption that variations of pull-up exercises may train different muscles to differing degrees (i.e. pronated grip pull-ups for latissimus
dorsi adaptation), however, there is little evidence to support this
assumption (Leslie and Comfort, 2013). Additionally, uniformed
services (Police, Armed Forces) commonly use pull-up variants to
train muscular strength, in different muscles required to perform
certain operational tasks, such as repelling and ladder climbing.
Hence, understanding how grip orientation may alter the level of
muscle activation is important when considering training specificity and efficiency. As there is limited evidence regarding muscle
⇑ Corresponding author at: College of Health, Massey University, Private Bag 756,
Wellington 6140, New Zealand.
E-mail address: s.lark@massey.ac.nz (S.D. Lark).
http://dx.doi.org/10.1016/j.jelekin.2016.11.004
1050-6411/Ó 2016 Elsevier Ltd. All rights reserved.
activity throughout the movements (Ricci et al., 1988; Youdas
et al., 2010), a more thorough assessment of the movement pattern
is necessary. As such, research is required to compare peak (EMGPEAK) and average rectified variable (EMGARV) muscle activation,
and/or the engagement of particular muscles, during pull-up
variations.
The pull-up can be performed with many different grip widths
and orientations, with each placing different biomechanical
demands on the associated musculature (Floyd, 2012). By observing the mechanics and anatomy of a supinated grip pull-up (commonly referred to as a chin-up) the orientation of the forearm
infers that the biceps brachii should experience greatest muscle
activation of the elbow flexors. Conversely, one would expect a
pronated grip to increase brachialis muscle activation, and neutral
grip to increase brachioradialis activation (Floyd, 2012; Ronai and
Scibek, 2014). Previous research has identified that muscle activation >50–60%MVIC is required to promote strength adaptation
(Andersen et al., 2006; Kraemer et al., 2002; Youdas et al., 2010).
Pull-up variants that result in differing levels of muscle activation
may inevitably promote different degrees of strength adaption in
particular muscles. Hence, it is important for fitness professionals
to understand the level of muscle activation in the shoulder-arm-
J.A. Dickie et al. / Journal of Electromyography and Kinesiology 32 (2017) 30–36
forearm complex when prescribing variations of the pull-up exercise (Leslie and Comfort, 2013).
Ricci et al. (1988) analysed activation of seven shoulder and arm
muscles during shoulder width supinated and pronated grip pullup exercises; results showed similar activation of muscles irrespective of hand orientation. However, muscle activity was not
normalised to a percentage of maximal voluntary isometric contraction (MVIC) as per best practice guidelines for EMG studies
(De Luca, 1997). Conversely, Youdas et al. (2010) demonstrated significantly greater activation of the lower trapezius during pronated
grip when compared to supinated grip pull-ups; while the supinated grip revealed significantly greater activation of the pectoralis
major and biceps brachii when compared to the pronated grip.
Additional muscles may contribute to different grip orientations
(Leslie and Comfort, 2013), however the latter research only analysed four muscles.
Given the methodical limitations of previous studies, the purpose of this study is to assess the relative EMGPEAK and EMGARV
of the shoulder-arm-forearm complex during supinated grip, pronated grip, neutral grip, and rope pull-up exercises. It was hypothesised that significant differences in EMGPEAK and EMGARV would
exist between pull-up variants due to differences in positioning of
the shoulder-arm-forearm complex between tasks.
2. Method
2.1. Participants
Nineteen strength trained males (24.9 ± 5 y; 1.78 ± 0.74 m;
81.3 ± 11.3 kg; 22.7 ± 2.5 kg m 2) participated in this research. Participants had engaged in regular resistance exercise (>3 days per
week) for a minimum of six months prior to testing. All participants were free from any musculoskeletal injury hindering participation in pull-up tasks. Ethical approval was provided by the
institutions Human Ethics Committee, and all participants received
verbal and written information prior to giving written consent.
2.2. EMG recording
Disposable Ag-AgCl electrodes (Ambu, BlueSensor, Denmark)
were placed in pairs over the skin and parallel to the fibres of
the biceps brachii, brachioradialis, middle deltoid, upper pectoralis
major, middle trapezius, lower trapezius, latissimus dorsi and
infraspinatus muscles; with an inter-electrode spacing of 0.02 m
(Fig. 1a and b). Prior to electrode placement each participant’s skin
was shaved of any hair with a disposable single use razor, and vigorously cleansed with alcohol wipes until erythema was attained
(Konrad, 2006). Raw EMG signals were collected with TeleMyo
DTS wireless surface EMG sensors (Noraxon, Arizona, USA). Signals
from the transmitter devices affixed to the skin were sent to a central receiver via Bluetooth. Data was collected at a sampling rate of
1000 Hz. Raw EMG signals were processed and analysed using
MyoResearch XP (Noraxon, Arizona, USA). The raw EMG data was
amplified by a gain of 1000 and filtered using a Lancosh FIR digital
bandpass filter set at 10–500 Hz and then smoothed to a 50 ms
root mean square (RMS) algorithm for EMGPEAK analysis. No data
smoothing was performed for EMGARV analysis. A high definition
camera (Logitech, HD C615, Switzerland) sampling at 30 Hz was
synchronised to the EMG recording device via the MyoResearch
XP software for analysis purposes.
The brachioradialis electrodes were positioned 0.03 m lateral,
and 0.04 m below the antecubital fossa. Electrodes for biceps brachii, middle deltoid, middle trapezius and lower trapezius were
placed over the belly of each muscle in accordance with the recommendations of Hermens et al. (1999). Similarly, placement of the
31
upper pectoralis major, latissimus dorsi and infraspinatus were
positioned using the recommendations of Bull et al. (2011),
Hibbs et al. (2011), and Waite et al. (2010), respectively. All electrode pairs were placed on the participants hand dominant side,
as motor control symmetry was assumed between both sides of
the body (McGill et al., 2014).
2.3. Normalisation
Familiarisation of all movements with visual EMG feedback was
conducted, followed by a five minute rest period prior to MVIC performed against manual resistance for each movement (Hislop et al.,
2014). This was in accordance with previously published best practice (Ekstrom et al., 2007; Lehman et al., 2004). The movements for
MVIC were adopted from Hislop et al. (2014) and are detailed in
the Supplementary Table. Participants performed three MVIC’s
per muscle; all muscles were tested in a randomised order
(Ekstrom et al., 2007; Garcia-Vaquero et al., 2012). Each MVIC
was held for five seconds, with one minute rest between each repetition (Hibbs et al., 2011; Youdas et al., 2008). Peak EMG data,
recorded during the pull-up variants was normalised to the average EMGPEAK from three MVIC’s. Additionally, EMGARV data
recorded during the pull-up variants was normalised to the average EMGARV of three, 3 s timestamps (occurring in the middle of
each MVIC) for each MVIC performed.
2.4. Pull-up protocols
Testing was completed on a purpose built pull-up device with a
bar diameter of 0.03 m. Participants were familiarised to each
pull-up exercise by performing three repetitions of each grip
orientation. Verbal instruction was provided to maintain correct
technique throughout the movement. All pull-up grip orientations
were performed in a randomised order. Each pull-up repetition
was performed with a 2:2 concentric: eccentric tempo.
The pronated grip pull-up was performed with the hands positioned on a 25° angle below the horizontal, and hands positioned
0.2 m outside the acromion processes.
The neutral grip pull-up was performed with a neutral hand orientation on two parallel bars separated 0.24 m.
The rope pull-up was performed on two lengths (0.15 m) of
rope with knotted ends, separated 0.24 m apart, with a diameter
of 0.032 m. Participants were required to grip the rope near the
knotted ends, with a neutral hand positioning.
Finally, the supinated grip pull-up was performed with the
hands separated at biacromial distance. Refer to Fig. 2a–d for
images of grip orientations.
All EMG testing sessions took place within 24 h of familiarisation; participants were instructed not to exercise 48 h prior to testing. A standardised warm up consisting of 60 s light jogging, 60 s
dynamic stretching of the shoulder girdle and glenohumearal joint,
five push ups and a further 60 s light jogging. Following five minutes of rest, participants performed five repetitions of each pullup variant (pronated, neutral grip, supinated and rope), separated
by five minutes rest between the different hand grips. Each pullup started with the elbows in full extension. Participants performed each pull-up variant, with exception of the rope pull-up,
until their nose was just superior to the horizontal bar. The upward
phase of the rope pull-up was completed when the participant’s
elbows were by the side of their torso, and pointing directly
downwards. Each pull-up repetition was completed when the
participant had lowered their body to the starting position. Each
pull-up task was performed in a randomised order. Visual inspection of the EMG signal and synchronised video were used to mark
the concentric and eccentric phases of each movement.
32
J.A. Dickie et al. / Journal of Electromyography and Kinesiology 32 (2017) 30–36
Fig. 1. Electrode postioning on (a) anterior, and (b) posterior muscles of hand-dominant shoulder and arm.
Fig. 2. Hand grip orientation for (a) wide grip pull-up, (b) neutral grip pull-up, (c) rope pull-up, and (d) chin-up.
2.5. Data analysis
From the five pull-up repetitions, and to ensure an accurate representation of EMGPEAK muscle activity, data analysis was based
upon the second, third and fourth repetition. Peak EMG for each
muscle, during each pull-up variant, was averaged over the three
consecutive repetitions; averaged data was then expressed as a
percentage of MVIC (%MVIC). Average rectified variable muscle
activity characterises changes in signal amplitude over time and
was obtained by calculating the mean area under the EMG curve,
and dividing by the elapsed time taken to perform that particular
movement. Thus providing data pertaining to the level of muscle
33
J.A. Dickie et al. / Journal of Electromyography and Kinesiology 32 (2017) 30–36
pull-up (P = 0.001; ES = 1.29; Table 3). Statistical analysis of EMGPEAK and EMGARV for all other muscles and grip orientations
revealed no significant differences (P > 0.05).
Paired T-Tests revealed that concentric phases of all four pullup variants resulted in significantly greater EMGARV of the brachioradialis, biceps brachii, and pectoralis major in comparison to
the eccentric phase (all, P < 0.01; Table 4). In addition to the three
muscles mentioned above, the concentric phase of the pronated
grip pull-up resulted in significantly greater EMGARV for the middle deltoid (P = 0.001) and lower trapezius (P = 0.001). Similarly,
the lower trapezius displayed significantly greater EMGARV during
the concentric phase of the supinated grip (P = 0.018) and rope
pull-up (P = 0.015) variants. As demonstrated in Table 4, moderate
to large effect sizes were reported between phases for a variety of
muscles during the four pull-up exercises.
activity required over an entire movement. This method of
EMGARV analysis was performed separately for the concentric
and eccentric phases, and full repetition of the pull-up variants.
Visual inspection of EMG signal and synchronised video recordings
were utilised to determine start/stop of the concentric and eccentric phases of the movement.
2.6. Statistical analysis
A series of one-way analysis of variance (ANOVA) for each muscle were used to identify differences in both the EMGPEAK and
EMGARV between the supinated grip, pronated grip, neutral grip,
and rope pull-up exercises. Where appropriate, post hoc testing
using Bonferroni multiple comparison analysis was performed to
identify the specific differences. Alpha was set to P 6 0.05. Cohen’s
d effect sizes (Cohen, 2013) were calculated for all comparisons
and reported only where moderate or large effect sizes were
revealed. Effect sizes (ES) were classified as small (ES = 0.20–
0.49), moderate (ES = 0.50–0.79), and large (ES P 0.80) (Cohen,
2013). Paired T-Tests were also performed separately for each muscle and grip to determine any differences in EMGARV between concentric and eccentric phases of each pull-up variant. All statistical
analysis was performed using SPSS version 22.0 (SPSS Inc., Chicago,
IL, USA).
To ensure consistency for MVIC the coefficient of variation (CV)
and intra-class coefficients (ICC) were reported between each participant’s three trials, for each muscle for both EMGPEAK and
EMGARV (Rouffet and Hautier, 2008). The ICC‘s were calculated
and reported using a Two-way random model, single measure form
(ICC [2, 1]). The ICC’s were interpreted as excellent (>0.75), good
(0.60–0.74) and fair (0.40–0.59) (Fleiss, 2011). The CV was calculated by dividing the standard deviation of the three MVIC’s by
the mean for each particular muscle. The closer the CV to 0 the less
variation observed between MVIC normalisation trials (Eldridge
et al., 2006).
4. Discussion
This study sought to determine whether different pull-up grips
resulted in differing levels of EMGPEAK and EMGARV for particular
muscles. With the exception of the middle trapezius, results
showed that EMGPEAK and EMGARV of the shoulder-armforearm complex was similar irrespective of hand orientation during different variations of the pull-up exercise. Accordingly, the
present study refutes the research hypothesis, and the common
belief amongst fitness professionals, that differences in muscle
activation would exist between pull-up variants (Leslie and
Comfort, 2013).
Although our results showed similar muscle activation of the
biceps brachii to that reported by Youdas et al. (2010) during supinated and pronated grip pull-ups, analysis revealed the difference
to be non-significant. Additionally, no significant differences
existed for the upper pectoralis major or lower trapezius muscles.
Previous research reports that muscle activation >50–60%MVIC is
required to promote strength adaptation (Andersen et al., 2006;
Kraemer et al., 2002; Youdas et al., 2010). Based on the observed
EMGPEAK it may be inferred that pronated grip, supinated grip,
neutral grip and rope pull-ups may not result in muscle activation
sufficient to promote strength adaptation of the middle deltoid,
upper pectoralis major and lower trapezius. Similarly, the EMGPEAK observed in the middle trapezius during supinated grip and
neutral grip pull-ups is also below the previously identified level
of activation to promote strength adaptation. Although pull-up
variants may not be suitable to promote strength adaptation in
the lower trapezius, they may be beneficial in the development
of the muscle as a stabiliser during this type of resistance training.
Interestingly, when analysing EMGARV during concentric and
eccentric phases for each pull-up variant, some significant differences were apparent. Muscle activity of the brachioradialis, biceps
brachii and pectoralis major was significantly higher during the
concentric phase in comparison to the eccentric phase. This
indicates that the aforementioned muscles undergo greater motor
unit recruitment, and therefore exercise intensity, during the
3. Results
The MVIC methods of normalisation displayed excellent reliability (ICC > 0.75) in all muscles for EMGARV. During EMGPEAK
normalisation the biceps brachii and middle trapezius displayed
good reliability (ICC 0.71 and 0.65), while all other muscles displayed excellent reliability (ICC > 0.75) for both EMGPEAK and
EMGARV. Intra-subject CV’s were lower in EMGARV normalisation
(0.09–0.13), than in the EMGPEAK normalisation (0.10–0.17). All
ICC’s and CV’s for each muscle are reported in Table 1.
One-way ANOVA revealed a significant main effect for EMGPEAK of the middle trapezius muscle (P = 0.008). Post hoc testing
revealed that the middle trapezius was activated significantly
more during the pronated grip pull-up when compared to the neutral grip pull-up (P = 0.004; ES = 1.19; Table 2). A significantly
greater EMGARV was also observed for the middle trapezius during
a full repetition of the pronated grip compared to the neutral grip
Table 1
ICC’s and CV’s for each muscle during EMGARV and EMGPEAK MVIC normalisation.
PM
BB
BR
MD
MT
LT
LD
IS
EMGARV
CV
ICC
0.09
0.93
0.10
0.83
0.11
0.97
0.13
0.93
0.12
0.83
0.09
0.91
0.12
0.93
0.12
0.85
EMGPEAK
CV
ICC
0.10
0.93
0.14
0.71
0.14
0.94
0.15
0.89
0.17
0.65
0.10
0.88
0.12
0.93
0.13
0.84
CV = coefficient of variation; ICC = intra-class coefficient; EMGARV = average rectified variable electromyography; EMGPEAK = peak electromyography; BR = brachioradialis;
BB = biceps brachii; MD = middle deltoid; PM = upper pectoralis major; MT = middle trapezius; LT = lower trapezius; LD = latissimus dorsi; IS = infraspinatus.
34
J.A. Dickie et al. / Journal of Electromyography and Kinesiology 32 (2017) 30–36
Table 2
Peak muscle activity expressed as %MVIC (±SD) of the shoulder-arm-forearm complex during four pull up variants.
BR
Pronated grip
Supinated grip
Neutral grip
Rope pull-up
97.4
89.8
93.5
96.2
BB
(24.6)
(24.6)
(21.1)
(21.7)
81.3
92.9
93.0
91.1
MD
(28.0)
(31.7)
(30.5)
(28.0)
12.7
15.8
23.4
23.1
PM
(6.9)
(13.8)
(21.4)
(14.8)
27.9
42.9
45.0
35.4
(21.9)
(24.1)
(22.0)
(21.2)
MT
LT
60.1 (22.5)
49.2 (17.2)
37.1* (16.1)
51.2 (18.7)
47.5
42.4
40.9
40.7
LD
(24.8)
(19.4)
(20.0)
(20.0)
56.1
55.6
52.1
57.8
IS
(18.6)
(23.9)
(15.6)
(21.4)
56.4
55.8
52.1
61.1
(22.7)
(22.5)
(23.0)
(25.9)
%MVIC = percentage of maximal voluntary isometric contraction; BR = brachioradialis; BB = biceps brachii; MD = middle deltoid; PM = upper pectoralis major; MT = middle
trapezius; LT = lower trapezius; LD = latissimus dorsi; IS = infraspinatus.
*
Muscle activity is significantly lower than highest reported peak EMG value for each particular muscle – P < 0.05.
Table 3
Comparison of average rectified variable muscle activity expressed as %MVIC (±SD) during a full repetition (concentric and eccentric phases) of pull-up variants.
BR
Pronated grip
Supinated grip
Neutral grip
Rope pull-up
79.4
66.4
73.1
71.4
BB
(14.0)
(19.9)
(17.1)
(12.8)
52.7
56.1
59.1
53.5
(20.2)
(26.6)
(29.1)
(27.2)
MD
PM
7.8 (3.8)
7.9 (5.0)
10.4 (7.2)
11.6 (7.7)
13.7
19.0
22.9
16.3
(9.7)
(12.1)
(12.3)
(8.7)
MT
LT
48.0 (21.2)
36.1 (12.1)
27.4* (10.7)
37.6 (13.7)
29.6
24.3
23.3
22.2
LD
(15.0)
(14.1)
(11.6)
(10.8)
40.8
36.6
33.7
42.1
IS
(12.0)
(15.3)
(9.3)
(14.2)
47.5
41.4
40.0
47.7
(17.9)
(17.5)
(16.5)
(18.2)
%MVIC = percentage of maximal voluntary isometric contraction; BR = brachioradialis; BB = biceps brachii; MD = middle deltoid; PM = upper pectoralis major; MT = middle
trapezius; LT = lower trapezius; LD = latissimus dorsi; IS = infraspinatus.
*
Muscle activity is significantly lower than highest reported ARV value for each particular muscle – P < 0.05.
Table 4
Comparison of average rectified variable muscle activity expressed as %MVIC (±SD) during concentric and eccentric phases of each pull-up variant.
BB
MD
PM
MT
LT
LD
IS
Pronated grip
CON
86.8** (17.3)
ECC
71.9 (15.7)
ES
0.90
BR
67.5** (24.7)
37.9 (18.0)
1.39
9.1** (4.6)
6.6 (3.2)
0.64
17.2** (12.4)
10.2 (7.5)
0.70
49.3 (19.9)
46.6 (25.5)
0.12
34.2** (17.2)
25.0 (13.8)
0.59
41.7 (12.1)
39.8 (15.6)
0.14
49.1 (20.9)
45.8 (18.0)
0.17
Supinated grip
CON
75.5** (20.9)
ECC
57.3 (23.2)
ES
0.83
73.5** (31.3)
38.8 (23.8)
1.26
8.0 (4.9)
7.8 (5.4)
0.04
27.4** (16.8)
10.7 (7.7)
1.36
35.1 (11.7)
35.1 (15.4)
0.00
27.3* (16.1)
21.3 (13.5)
0.41
36.7 (15.9)
36.4 (16.2)
0.02
41.8 (19.0)
40.9 (17.2)
0.05
Neutral grip
CON
82.1** (17.4)
ECC
64.1 (19.2)
ES
0.98
76.4** (33.4)
41.9 (27.9)
1.13
10.1 (7.5)
10.8 (7.3)
0.09
32.4** (17.4)
13.3 (18.1)
1.08
27.5 (12.4)
27.3 (10.4)
0.02
25.7 (16.7)
20.1 (9.3)
0.43
35.1 (8.5)
32.3 (11.4)
0.28
41.4 (18.0)
37.9 (16.1)
0.19
Rope pull-up
CON
86.9** (17.3)
ECC
55.9 (12.5)
ES
2.08
78.2** (36.3)
28.8 (19.0)
1.79
11.3 (7.9)
11.9 (8.1)
0.08
23.6** (12.5)
9.0 (5.8)
1.60
39.6 (13.9)
35.7 (14.9)
0.27
25.2* (13.6)
19.3 (9.3)
0.52
43.4 (15.0)
40.8 (16.8)
0.16
49.4 (19.6)
46.0 (17.9)
0.18
Effect sizes are calculated between the phases for each muscle for each pull up variant.
ES = effect size; %MVIC = percentage of maximal voluntary isometric contraction; CON = concentric; ECC = eccentric; BR = brachioradialis; BB = biceps brachii; MD = middle
deltoid; PM = upper pectoralis major; MT = middle trapezius; LT = lower trapezius; LD = latissimus dorsi; IS = infraspinatus.
**
Muscle activity is significantly higher for the particular movement phase – P < 0.01.
*
Muscle activity is significantly higher for the particular movement phase – P < 0.05.
concentric phase of the movement irrespective of pull-up grip.
Comparatively, the middle trapezius, latissimus dorsi and
infraspinatus work at similar levels of EMGARV during concentric
and eccentric phases of each of the pull-up variations. The biceps
brachii and brachioradialis appear to function as prime movers
during the concentric phase of each pull-up variant, whereas the
middle trapezius, latissimus dorsi and infraspinatus work consistently to control both the concentric and eccentric phases.
When considering the full repetition EMGARV of the middle
trapezius, a significant difference was only observed between the
pronated and neutral grip pull-ups. The large effect size
(ES = 1.19) indicates a biological difference between the aforementioned pull-up variants, and may be explained through differences
in the line of action of the middle trapezius during a pronated grip
pull-up. However, as motion analysis was not recorded in this
study, we can only speculate the reason for the large effect size.
Although the middle trapezius was the most common muscle that
distinguished between pronated and neutral grip pull-ups, it was
not the most highly activated muscle (Tables 1 and 2), whereas
the brachioradialis was, highlighting the importance of this muscle
during all pull-up variants.
There remains a current lack of agreement on the most reliable
method of normalisation among EMG studies (Norcross et al.,
2010). However, numerous studies have identified that MVIC normalisation results in the least variability of data when processing
EMG (Bolgla and Uhl, 2005; Burden, 2010; Burden and Bartlett,
1999). As shown in our reported ICC’s from the three MVIC trials
we are confident that this method of normalisation resulted in a
consistent measure of EMG amplitude across trials. Using the MVIC
method, normalisation facilitates comparisons between muscles,
participants and exercises; however, when comparing between
studies, the techniques used by investigators to obtain their MVIC
may remain a major delimiting factor for comparison (Burden,
2010). Regardless of this, the good to excellent ICC’s and narrow
CV’s demonstrated that the MVIC procedure used in this present
study was consistent across muscle groups and participants.
Given the methodical limitations of previous studies there is
limited research examining the degree of muscle activation during
J.A. Dickie et al. / Journal of Electromyography and Kinesiology 32 (2017) 30–36
pull-up variants. The only significant differences in observed EMGPEAK and EMGARV during an entire pull-up repetition existed in
the middle trapezius, which was not activated to a large percentage of MVIC in the researched movements.
4.1. Limitations
Previous studies have utilised different protocols to obtain
MVIC, making comparisons between studies difficult (Lehman
et al., 2004; Signorile et al., 2002; Youdas et al., 2010). In the presented research, MVIC was utilised as a reference for comparing to
dynamic activities; however, precise guidelines were followed in
order to reduce inter-individual variability and increase reliability,
as reflected in our reported ICC’s and CV’s between trials (Ekstrom
et al., 2007; Hislop et al., 2014; Konrad, 2006). This research also
required participants to use a controlled tempo, whereas muscle
activity patterns could be different had participants been able to
self-select their movement speed. Furthermore, there may be other
muscle groups not investigated in the present study but which
may demonstrate greater differences in EMG responses between
the pull-up variants. Some differences in muscle activation
between participants may have resulted from differences in limb
length. Our method required hand positioning during the pronated
grip pull-up to be 0.02 m outside the acromion process. Although
this standardisation procedure resulted in small variations of biacromial distance between participants, differences in limb length
may have resulted in a wider or narrower grip for certain subjects,
and is a limitation of this study. However, this grip width is a standard hand position that many individuals performing this exercise
would employ (Leslie and Comfort, 2013).
5. Conclusion
This research showed that pronated grip pull-ups are superior
in recruiting the middle trapezius when compared to the neutral
grip pull-up. Peak and EMGARV of the brachioradialis, biceps brachii, middle deltoid, upper pectoralis major, lower trapezius, latissimus dorsi and infraspinatus was similar across all other pull-up
variations. Furthermore, EMGPEAK muscle activation appears sufficient to promote adaptation in the brachioradialis, biceps brachii,
latissimus dorsi and infraspinatus muscles, regardless of hand orientation. The degree of middle trapezius muscle activity during the
pronated grip and rope pull-ups indicates that these grip orientations may also promote strength adaptation of the aforementioned
muscle. However, this was not evident for the supinated and neutral grip pull-ups. Based on these findings it appears all four pullup grips will elicit similar strength adaptations when implemented
in resistance training settings.
Conflict of interest
The authors declare no conflict of interest.
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.jelekin.2016.11.
004.
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J.A. Dickie et al. / Journal of Electromyography and Kinesiology 32 (2017) 30–36
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James Dickie, MSc received his Masters degree in Science from Massey University in 2015. He is currently
embarking on a PhD in Sport Science, and also works as
a strength and conditioning coach with the Wellington
Lions and Hurricanes rugby teams.
Matthew Barnes, PhD received his PhD from Massey
University in 2012 and is a Senior Lecturer in the School
of Sport and Exercise at Massey University. His research
expertise is in the field of sports performance, resistance
exercise and skeletal muscle recovery.
James Faulkner, PhD is a Senior Lecturer in Sport and
Exercise Physiology at the University of Winchester.
James attained his Bachelor’s (Hons) degree in Sport and
Exercise Sciences, and both his Master’s and Doctorate
in Sport and Health Sciences at the University of Exeter.
Prior to his arrival at the University of Winchester,
James worked as a Senior Lecturer in Sport and Exercise
Sciences at Massey University, New Zealand (20092014).
Sally Lark, PhD is a Senior Lecturer in the School of
Sport and Exercise at Massey University. She attained
two Bachelor of Science degrees from Auckland
University, and University of Salford and received a
Masters of Medical Science from Queens University
Belfast. Sally received her PhD from Manchester
Metropolitan University in 2001. Her research expertise
includes musculoskeletal physiology, clinical exercise
physiology and exercise assessment and rehabilitation.