Influence of bench angle on upper extremity muscular activation during bench press exercise

Abstract

This study compared the muscular activation of the pectoralis major, anterior deltoid and triceps brachii during a free-weight barbell bench press performed at 0°, 30°, 45° and -15° bench angles. Fourteen healthy resistance trained males (age 21.4 ± 0.4 years) participated in this study. One set of six repetitions for each bench press conditions at 65% one repetition maximum were performed. Surface electromyography (sEMG) was utilised to examine the muscular activation of the selected muscles during the eccentric and concentric phases. In addition, each phase was subdivided into 25% contraction durations, resulting in four separate time points for comparison between bench conditions. The sEMG of upper pectoralis displayed no difference during any of the bench conditions when examining the complete concentric contraction, however differences during 26-50% contraction duration were found for both the 30° [122.5 ± 10.1% maximal voluntary isometric contraction (MVIC)] and 45° (124 ± 9.1% MVIC) bench condition, resulting in greater sEMG compared to horizontal (98.2 ± 5.4% MVIC) and -15 (96.1 ± 5.5% MVIC). The sEMG of lower pectoralis was greater during -15° (100.4 ± 5.7% MVIC), 30° (86.6 ± 4.8% MVIC) and horizontal (100.1 ± 5.2% MVIC) bench conditions compared to the 45° (71.9 ± 4.5% MVIC) for the whole concentric contraction. The results of this study support the use of a horizontal bench to achieve muscular activation of both the upper and lower heads of the pectoralis. However, a bench incline angle of 30° or 45° resulted in greater muscular activation during certain time points, suggesting that it is important to consider how muscular activation is affected at various time points when selecting bench press exercises.

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Influence of bench angle on upper extremity muscular
activation during bench press exercise
Jakob D. Lauvera, Trent E. Cayota & Barry W. Scheuermanna
a Department of Kinesiology, Cardiopulmonary and Metabolic Research Laboratory,
University of Toledo, Toledo, OH, USA
Published online: 23 Mar 2015.
To cite this article: Jakob D. Lauver, Trent E. Cayot & Barry W. Scheuermann (2015): Influence of bench angle
on upper extremity muscular activation during bench press exercise, European Journal of Sport Science, DOI:
10.1080/17461391.2015.1022605
To link to this article: http://dx.doi.org/10.1080/17461391.2015.1022605
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ORIGINAL ARTICLE
Influence of bench angle on upper extremity muscular
activation during bench press exercise
JAKOB D. LAUVER, TRENT E. CAYOT, & BARRY W. SCHEUERMANN
Department of Kinesiology, Cardiopulmonary and Metabolic Research Laboratory, University of Toledo, Toledo, OH, USA
Abstract
This study compared the muscular activation of the pectoralis major, anterior deltoid and triceps brachii during a free-
weight barbell bench press performed at 0°, 30°, 45° and –15° bench angles. Fourteen healthy resistance trained males (age
21.4 ± 0.4 years) participated in this study. One set of six repetitions for each bench press conditions at 65% one repetition
maximum were performed. Surface electromyography (sEMG) was utilised to examine the muscular activation of the
selected muscles during the eccentric and concentric phases. In addition, each phase was subdivided into 25% contraction
durations, resulting in four separate time points for comparison between bench conditions. The sEMG of upper pectoralis
displayed no difference during any of the bench conditions when examining the complete concentric contraction, however
differences during 26–50% contraction duration were found for both the 30° [122.5 ± 10.1% maximal voluntary isometric
contraction (MVIC)] and 45° (124 ± 9.1% MVIC) bench condition, resulting in greater sEMG compared to horizontal
(98.2 ± 5.4% MVIC) and –15 (96.1 ± 5.5% MVIC). The sEMG of lower pectoralis was greater during –15° (100.4 ± 5.7%
MVIC), 30° (86.6 ± 4.8% MVIC) and horizontal (100.1 ± 5.2% MVIC) bench conditions compared to the 45° (71.9 ±
4.5% MVIC) for the whole concentric contraction. The results of this study support the use of a horizontal bench to achieve
muscular activation of both the upper and lower heads of the pectoralis. However, a bench incline angle of 30° or 45°
resulted in greater muscular activation during certain time points, suggesting that it is important to consider how muscular
activation is affected at various time points when selecting bench press exercises.
Keywords: Resistance training, electromyography, muscular activation
Introduction
Exercise selection is one component of a resistance-
training programme that is vital to the principle of
specificity (Baechle, Earle, & National Strength &
Conditioning Association (U.S.), 2008), with differ-
ent exercises eliciting different muscular activation.
Muscular activation is important during an exercise
programme as it has been shown to be an important
stimulus for the development of muscle strength and
mass (Trebs, Brandenburg, & Pitney, 2010). Bench
press is one of the most commonly prescribed upper-
body exercises aimed at increasing strength and
specifically targeting the pectoralis major (Barnett
et al., 1995; Welsch, Bird, & Mayhew, 2005). The
main actions of the two heads of the pectoralis major
when working in combination is horizontal adduction
and medial rotation of the humerus (Moore & Agur,
2007). However, when acting alone, the upper head
aids in flexion of the shoulder and the lower head aids
in extension of the shoulder from the flexed position
(Moore & Agur, 2007). Based on these actions and
the ability of the shoulder joint to move through a
wide range of motion (ROM), several variations
have been made to the bench angle during bench
press exercises in an effort to optimise the activation
of the two different heads of the pectoralis major
(Baechle et al., 2008; Barnett et al., 1995). Therefore,
a greater understanding of the effect that bench angle
has on muscle activation will aid in the design of
effective upper extremity exercise programmes.
Barnett, Kippers, and Turner (1995) examined the
activity of the upper and lower heads of the pectoralis
major during bench press exercise performed at
various bench angles. The authors found that hori-
zontal bench (0°) exercise resulted in the greatest
activation of the lower pectoralis major, but found
no difference in upper pectoralis activation between
horizontal bench and 40° (Barnett et al., 1995).
Correspondence: Barry W. Scheuermann, Department of Kinesiology, Cardiopulmonary and Metabolic Research Laboratory, University of
Toledo, Mail Stop 119, 2801 W. Bancroft Street, Toledo, OH 43606, USA. E-mail: barry.scheuermann@utoledo.edu
European Journal of Sport Science, 2015
http://dx.doi.org/10.1080/17461391.2015.1022605
© 2015 European College of Sport Science
Downloaded by [University of Toledo], [Jakob Lauver] at 06:03 26 March 2015

More recently, Trebs et al. (2010) found that com-
pared to horizontal bench press, a bench angle of 44°
and 56° resulted in greater activation of the upper
pectoralis. However, Trebs et al. (2010) found no
difference in upper pectoralis activation between 28°
and horizontal bench, and similar to Barnett et al.
(1995) observed the highest activation of the lower
pectoralis during horizontal bench (Trebs et al.,
2010). Although the methodological approaches of
previous investigations (Barnett et al., 1995; Glass &
Armstrong, 1997; Trebs et al., 2010) vary slightly
(i.e., bench angles and equipment) participants were
tested using the same relative resistance load during
all bench conditions. Muscle activation may be
effected with a change in the absolute resistance load
(Basmajian & De Luca, 1985) regardless of change in
bench angle and/or body position, which is an
important consideration as alterations in the bench
angle during bench press are utilised in an effort to
elicit the greatest muscle activation of either the upper
or lower pectoralis major.
While previous investigations have systematically
examined muscle activation during various bench
press conditions they have examined activation throu-
ghout the complete lift. During any resistance exercise
a complete ROM is important, however throughout
the ROM there may be potential differences in the
level of muscle activation. This could have the poten-
tial to attenuate any difference in muscle activation
observed during the complete lift between bench
angle conditions as differences in activation may
have been evident throughout different time points
of contractions. Therefore, it was the primary pur-
pose of the present investigation to compare the
changes in muscle activation at various time points
across contraction phases (concentric, eccentric)
during free-weight barbell bench press at varying
bench angles (–15°, 0°, 30°, 45°) while maintaining
the same absolute resistance load. The results of the
present investigation will lead to a better understand-
ing of the effect of bench angle on muscle activation
during bench press exercise and thus will aid in
selection of variations in bench press exercise to deve-
lop upper extremity strength and musculature.
Methods
Participants
Fourteen healthy resistance trained males (age =
21.4 ± 0.4 years, height = 1.76 ± 0.03 m and weight
= 86.2 ± 3.36 kg, 8.7 ± 0.97% body fat) participated
in this study. All participants provided written infor-
med consent after having the experimental proce-
dures, exercise protocol and possible risks associated
with participation explained. The experimental pro-
tocol was approved by the University’s Institutional
Review Board and was in accordance with guide-
lines set forth by the Declaration of Helsinki. All
participants were free of neuromuscular disorders
prior to participation. Similar inclusion criteria
were employed from a previous investigation (Trebs
et al., 2010) as participants had to be able to com-
plete a one repetition maximum (1 RM) greater
than their body weight during horizontal barbell
bench press, have resistance-training experience
(≥12 months) and be free of any injuries within the
last 12 months.
Procedures
Participants reported to the laboratory on two sep-
arate occasions with at least 48 hours between
sessions. Participants were asked to refrain from
any upper extremity resistance training for 48 hours
and any strenuous exercise for 24 hours prior to each
session (Trebs et al., 2010). During the first session
anthropometric data were collected. Body fat com-
position percentage was determined utilising a three-
site (chest, abdominal, thigh) skin-fold measurement
technique (Jackson & Pollock, 1978). In addition,
the typical barbell grip width used when performing
resistance exercise was recorded for each participant.
The participants then performed a five-minute
warm-up on a stationary cycle (Body Solid, BFSB
10, Forest Park, IL; Glass & Armstrong, 1997;
Trebs et al., 2010). Two sets (10 repetitions, 6
repetitions) of horizontal barbell bench press at self-
selected intensities were completed (Trebs et al.,
2010). Following the warm-up, participants were
asked to complete a 1 RM. One RM was defined as
the successful completion of one repetition of hori-
zontal barbell bench press throughout a full ROM
with the greatest amount of external load (Baechle
et al., 2008). The participants were provided three to
five minutes of recovery between 1 RM attempts
(Baechle et al., 2008; Trebs et al., 2010). All
participants obtained their 1 RM within five
attempts. Once the 1 RM was determined all
participants performed a familiarisation set (six
repetitions) at each of the bench conditions (–15°,
0°, 30°, 45°) in order to familiarise participants with
the procedure for the second session.
During the second session surface electromyogra-
phy (sEMG) electrodes were used to assess muscular
activation. To evaluate kinematics during each of the
bench press conditions, two video cameras (Micro-
soft Life Cam Studio, Redmond, WA; Sony Handy
Cam DCR-SX45, Tokyo, Japan) were arranged to
record the sagittal and frontal planes of movement at
a rate of 25 frames per second. The participants
completed a warm-up utilising the procedure from
session 1. The participants then performed two max-
imal voluntary isometric contractions [5 s contraction
2J. D. Lauver et al.
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and 2 min recovery; maximal voluntary isometric
contraction (MVIC)] for each of the target muscles.
The MVIC testing order was randomised between
participants. MVIC was performed in order to
normalise the exercising sEMG data. Following the
final MVIC attempt, five minutes of recovery was
provided prior to the bench press exercise.
Participants completed one set of six repetitions
for each of the barbell bench press conditions (–15°,
0°, 30° and 45°) at a resistance equivalent to 65% 1
RM. Bench conditions were randomised between
participants and five minutes of recovery was pro-
vided between sets to minimise fatigue (Baechle
et al., 2008). The duty cycle for each repetition
included a two-second eccentric phase followed by a
two-second concentric phase (Barnett et al., 1995).
In agreement with previous studies (Barnett et al.,
1995; Glass & Armstrong, 1997; Trebs et al., 2010),
standard contraction duration methods were used by
setting a metronome to provide the participants with
an audible cue for the intended duty cycle. The
participants were asked to maintain a barbell grip
width of 150% of their measured biacromial width
and complete a full ROM. Grip width was controlled
as it may effect muscular activation (Lehman, 2005)
and 150% of biacromial width was utilised as it was
not significantly different than self-selected grip width.
Surface electromyography (sEMG) techniques
sEMG was obtained from the primary movers inclu-
ding the upper and lower pectoralis major, anterior
deltoid and lateral triceps brachii using dual silver/
silver-chloride electrodes (Product #272, Noraxon,
Scottsdale, AZ) with a fixed inter-electrode spa-
cing of 2 cm. Each of the sEMG electrodes was
connected to a Telemyo 8-Channel Transmitter
(Telemyo 900, Noraxon, Scottsdale, AZ) which
transmitted the signal wirelessly to a Telemyo
Receiver (Telemyo 900, Noraxon, Scottsdale, AZ).
The skin was shaved and cleansed with an alcohol
pad in order to reduce inter-electrode resistance.
The sEMG electrodes for the upper and lower
pectoralis major were placed on the midclavicular
line, midway between the acromioclavicular joint of
the shoulder and the sternoclavicular joint of the
sternum, over the second and fifth intercostals spaces,
respectively (Glass & Armstrong, 1997; Trebs et al.,
2010). The sEMG electrode for the anterior deltoid
was placed over the mid-belly of the muscle approxi-
mately 4 cm below the clavicle (Cram, Kasman, &
Holtz, 1998). The sEMG electrode for the lateral
triceps brachii was placed over the mid-belly of the
lateral head midway between the acromion process of
the scapula and the olecranon process of the ulna
(Cram et al., 1998). A ground electrode was placed on
the seventh cervical spinous process.
Raw sEMG signals were collected at a sampling
frequency of 1000 Hz. During signal processing a
band-pass filter (10 Hz–500 Hz) and root means
square (RMS) smoothing (50-millisecond window)
was utilised (Myoresearch XP 1.07 Master Edition,
Noraxon, Scottsdale, AZ). The sEMG signal was
divided into concentric and eccentric phases with the
use of the frontal plane video, which was simulta-
neously collected, and time aligned with the sEMG
signal in Myoresearch. Each phase was further sub-
divided into 25% contraction duration bins, result-
ing in four separate time points per contraction
phase. This was done in order to observe any possible
differences in muscle activation at different time
points throughout the completion of each contraction
between bench conditions. The RMS values were
normalised using the averaged MVIC amplitudes of
each respective muscle.
Maximal voluntary isometric contraction (MVIC)
assessment
For each of the randomised MVIC attempts the
participant lied in a supine position on a horizontal
bench. A strap was placed across the hips to reduce
any movement during the MVIC attempts. The par-
ticipant was asked to provide maximal force against
manual resistance for a five-second duration and
completed two MVIC attempts for each movement.
Strong verbal encouragement was provided to the
subject during each of the MVIC attempts. Two
minutes of recovery was provided following each
MVIC attempt.
For the upper and lower pectoralis major MVIC
the participant was asked to horizontally abduct with
the shoulder and elbow flexed at 90°. The particip-
ant provided maximal force while attempting to
horizontally adduct the arm (Chopp, Fischer, &
Dickerson, 2010; Hodder & Keir, 2013). During
the anterior deltoid MVIC the participant was asked
to flex the elbow to 90° so that his hand was pointed
upwards. The participant was then asked to make a
closed fist with the hand of the flexed arm and
provide maximal force against manual resistance,
Table I. Mean kinematic data (±SD)
Bench
condition
Initial shoulder
angle (degrees)
Concentric
contraction
duration (sec)
Eccentric phase
duration (sec)
−15° 62.7 ± 4.9*** 1.52 ± .23*
,
** 1.88 ± .24
0° 76.29 ± 5.5*** 1.67 ± .19* 1.85 ± .20
30° 105.17 ± 4.9*** 1.86 ± .33 1.78 ± .16
45° 117.88 ± 6.1*** 2.03 ± .49 1.77 ± .17
*Significantly different than 45°; **significantly different than 30°;
***significant difference between all conditions.
Influence of bench angle on the muscular activation 3
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attempting to produce shoulder flexion (Chopp et al.,
2010; Hodder & Keir, 2013). During the triceps
brachii MVIC the participant was asked to flex the
elbow to 90°. The participant was then asked to
provide maximal force attempting to extend the
elbow while manual resistance was provided.
Kinematics
Markers were utilised to locate the points of interest
in the sagittal plane of movement. Markers were
placed on the participants via two-sided tape after
palpating the following anatomical landmarks: olecr-
anon process of the ulna, acromion process of the
scapula and greater trochanter of the femur. In
addition markers where placed on the barbell to track
motion in the sagittal plane. The shoulder flexion
angle was measured prior to each eccentric con-
traction utilising Dartfish Connect 5.5 (Dartfish,
Alpharetta, GA). The shoulder angle was defined as
the angle made by olecranon process, acromion
process and greater trochanter markers (Table I).
Statistical analyses
All data were analysed using NCSS statistical soft-
ware (NCSS, LLC, Kaysville, Utah). Three-way
analysis of variance (ANOVA) with repeated mea-
sures was used to examine the effects of bench
condition (–15°, 0°, 30°, 45°), contraction duration
(0–25%, 26–50%, 51–75%, 76–100%) and contrac-
tion phase (concentric, eccentric) on the muscle
activation of the upper pectoralis major, lower
pectoralis major, anterior deltoid and lateral triceps
brachii. In addition, two-way ANOVA with repeated
measures was utilised to examine the effects of bench
condition (–15°, 0°, 30°, 45°) and contraction phase
(concentric, eccentric) on the muscle activation of
the upper pectoralis major, lower pectoralis major,
anterior deltoid and lateral triceps brachii during the
entire contraction duration. All significant ANOVAs
were followed by Tukey post hoc tests in order to
locate significantly different means. Differences in
the participants’normal grip width and 150% bia-
cromial grip width were compared using a paired
ttest. The level of significance was set priori at p≤
0.05. All values are presented as the mean ± stan-
dard deviation (SD).
Results
Upper pectoralis major sEMG
The upper pectoralis major displayed significantly
greater muscle activation during the concentric
phase compared to the eccentric phase during the
complete contraction for all tested bench conditions
(–15°, 0°, 30°, 45°) (Figure 1a,1b). During the
concentric phase of the contraction the muscle
activation of the upper pectoralis major was greater
during 30° (117.5 ± 49.2% MVIC) compared to –
15° (102.6 ± 27.7% MVIC). However, during 26–
50% of the contraction duration, both the 30° (122.5
± 38.0% MVIC) and 45° (124.8 ± 34.2% MVIC)
bench conditions resulted in greater upper pectoralis
major activation compared to horizontal (98.2 ±
20.2% MVIC) and –15° (96.1 ± 20.6% MVIC)
(Figure 1b).
Figure 1. (a) Activation of the upper pectoralis across eccentric phase durations. (b) Activation of the upper pectoralis across concentric
contraction durations.
*Significantly greater muscular activation compared to 45° bench condition; +significantly greater muscular activation compared to –15°
bench condition; ◊significantly greater muscular activation compared to 0° bench condition.
4J. D. Lauver et al.
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During the eccentric phase, the upper pectoralis
major elicited greater muscle activation during –15°
(72.5 ± 27.3% MVIC) and horizontal (76.4 ± 21.2%
MVIC) bench conditions compared to 45° (56.5 ±
21.2% MVIC) during the entire phase (Figure 1b).
The horizontal bench condition resulted in greater
muscle activation than 45° across entire the eccentric
phase, while the –15 was greater than 45° during 0–
25% (54.0 ± 18.1% MVIC, 41.1 ± 13.8% MVIC)
and 76–100% (71.8 ± 22.3% MVIC, 56.1 ± 24.8%
MVIC) contraction duration (Figure 1a).
Lower pectoralis major sEMG
The lower pectoralis major displayed significantly
greater muscle activation during the concentric
phase compared to the eccentric phase during the
complete contraction for all test bench conditions
(–15°, 0°, 30°, 45°). Compared to the 45° bench
(71.6 ± 4.5% MVIC), the muscle activation of lower
pectoralis was greater during –15° (99.6 ± 22.5%
MVIC), horizontal (98.4 ± 19.9% MVIC) and 30°
(85.9 ± 19.0% MVIC) bench conditions when
examining the whole concentric contraction and
remained evident across all contraction durations
(0–25%, 26–50%, 51–75%, 76–100%). The muscle
activation during horizontal and –15° were both
greater than the 30° bench condition during the whole
contraction. The observed difference in muscle activa-
tion between horizontal and 30° was evident during
0–25% (0° = 119.1 ± 26.7% MVIC; 30° = 101.3 ±
28.3% MVIC) and 76–100% (0° = 108.9 ± 45.3%
MVIC; 30° = 83.1 ± 39.4% MVIC) of the contraction
duration, whereas the difference between –15° (112.3
± 47.2% MVIC) and 30° was only present during 76–
100% of the contraction duration.
The lower pectoralis major displayed similar results
during the entire eccentric phase, as –15° (72.7 ±
19.5% MVIC), horizontal (68.5 ± 15.3% MVIC) and
30° (39.3 ± 10.7% MVIC) bench conditions resulted
in greater muscle activation compared to 45°(27.7 ±
9.5% MVIC). These differences observed between –
15°, horizontal and 45° remained across the entire
contraction duration (0–25%, 26–50%, 51–75%,
76–100%). The 30° bench condition (48.2 ± 21.5%
MVIC) resulted in greater muscle activation com-
pared to 45° (31.3 ± 12.4% MVIC) during 25–50%
contraction duration (Figure 2b).
Anterior deltoid sEMG
The anterior deltoid displayed significantly greater
muscle activation during the concentric phase com-
pared to the eccentric phase during the complete
contraction for the 30° and 45° bench conditions.
The muscle activation of anterior deltoid was less
during –15° (58.3 ± 30.7% MVIC) compared to
both horizontal (76.0 ± 37.0% MVIC) and incline
bench conditions [90.9 ± 44.3% MVIC (30°), 97.5
± 39.3% MVIC (45°)] when examining the whole
concentric contraction. In addition, greater muscle
activation of the anterior deltoid resulted from the
incline conditions (30°, 45°) compared to horizontal
during the whole concentric contraction. The differ-
ence between horizontal and –15° occurred at 51–
75% and 76–100% of the contraction duration. The
difference between 45° and horizontal was apparent
Figure 2. (a) Activation of the lower pectoralis across eccentric phase durations. (b) Activation of the upper lower across concentric
contraction durations.
*Significantly greater muscular activation compared to 45° bench condition; #significantly greater muscular activation compared to 30°
bench condition.
Influence of bench angle on the muscular activation 5
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across all contraction durations; however, the differ-
ence between horizontal and 30° occurred at 0–25%
and 26–50% of the contraction duration (Figure 3b).
Examining the entire eccentric phase, the muscle
activation of anterior deltoid was greater during 45°
(74.7 ± 31.2% MVIC), 30° (68.0 ± 32.0% MVIC)
and horizontal (56.4 ± 28.9% MVIC) compared to –
15° (39.2 ± 19.0% MVIC). Furthermore, the 45°
bench condition resulted in greater muscle activation
of the anterior deltoid compared to the horizontal
condition. The difference between 45° and horizontal
was evident during 26–50%, 51–75%, 76–100% of
the contraction duration, while 30° resulted in greater
activation compared to horizontal during 76–100%
of the contraction duration. In addition the hori-
zontal bench condition resulted in greater activation
compared to the –15° during 26–50, 51–75% and
76–100% of the contraction duration (Figure 3a).
Lateral triceps brachii sEMG
The lateral triceps brachii displayed significantly
greater muscle activation during the concentric
phase compared to the eccentric phase during the
complete contraction for all test bench conditions
(–15°, 0°, 30°, 45°). During the concentric contrac-
tion, the incline conditions (30°, 45°) resulted in
greater muscle activation (30° = 114.3 ± 26.3%
MVIC; 45° = 117.8 ± 28.5% MVIC) of the lateral
triceps brachii compared to the –15° (102.2 ± 26.5%
MVIC) bench condition. Furthermore, 45° elicited a
greater lateral triceps brachii muscle activation com-
pared to horizontal (106.0 ± 28.7% MVIC) during
the entire concentric contraction. The difference
between the incline conditions (30°, 45°) and –15°
occurred during 26–50%, 51–75% and 76–100% of
the contraction duration. The difference between
45° and horizontal was present during 51–75% and
76–100% of the contraction duration, while the
difference between 30° and horizontal occurred at
76–100% of the contraction duration. There was no
difference in muscle activation of the lateral triceps
brachii during the eccentric contraction at any tested
bench angles.
Kinematic data
The normal handgrip width (0.63 ± 0.02 m) utilised
by the experienced resistance trained subjects was not
significantly different from the experimental handgrip
width (0.65 ± 0.01 m) used in the present study.
Discussion
The lack of a difference in the concentric muscular
activation of the upper pectoralis between the
horizontal, –15°, 30° and 45° bench conditions
found in the present study is in agreement with
previous studies (Barnett et al., 1995; Glass &
Armstrong, 1997). However, Trebs et al. (2010)
found that bench angles of 44° and 56° resulted in
greater activation of the upper pectoralis compared to
a horizontal bench, which is in contrast to the
findings of this study. This may be explained by the
use of a Smith machine in the study conducted by
Trebs et al. (2010), where as a free-weight barbell
was utilised in this study. When utilising a Smith
machine the path of the bar is restricted in the vertical
plane during movement due to the guides of the
Smith machine (Trebs et al., 2010), thereby prevent-
ing the normal “S”or reverse “C”pattern that the bar
usually takes during a free-weight bench press (Cot-
terman, Darby, & Skelly, 2005; Trebs et al., 2010).
In addition to examining the activation over the
complete concentric phase we examined the activa-
tion at four separate contraction duration time points
to examine the possible differences in muscular
activation throughout different time points of the
lift. There was no difference in upper pectoralis
activation over the whole concentric phase but there
were differences during 26–50% completion of the
concentric phase (Figure 1b). This difference may
have occurred during this interval due to the increase
in shoulder flexion (Table I), which is also supported
by the finding of increased activation of the anterior
deltoid. The anterior deltoid activation was greater
during 45° compared to both horizontal and –15°,
while 30° was only greater than –15°. However,
during the first 50% of the concentric phase the 30°
bench resulted in greater anterior deltoid activation
than the horizontal (Figure 3b).
In contrary to Barnett et al. (1995) we did not find
any difference in activation between horizontal and –
15° bench conditions for lower perctoralis activation.
When the bench angle increased from horizontal,
the level of activation of the lower pectoralis decreased
which is in agreement with previous research (Barnett
et al., 1995; Glass & Armstrong, 1997; Trebs et al.,
2010). However, when examining the different time
points the difference between horizontal and 30°
bench condition was not evident across all times
points. These results demonstrate that even though
muscle activation is different when examining the
whole contraction that there are differences through-
out the contraction or lift. These differences between
conditions and time points are important to consider
since muscle activation is an important stimulus for
the development of muscle strength and mass (Trebs
et al., 2010).
Interestingly, during the eccentric phase the hori-
zontal bench resulted in greater activation of both
the lower and upper pectoralis compared to 45°.
This could have interesting applications as eccentric
6J. D. Lauver et al.
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training has been shown to result in greater gains
in both muscle strength and muscle mass (Roig
et al., 2009). Eccentric training is of interest from a
mechanical perspective as muscles are capable of
achieving higher absolute forces when contracting
eccentrically compared to concentrically (Hather,
Tesch, Buchanan, & Dudley, 1991; Roig et al., 2009).
In this study, the concentric muscular activation of
the lateral triceps brachii was greater at the 45° bench
compared to the horizontal bench, which is in con-
trast to Barnett et al. (1995). One possible reason for
this difference is hand space or grip width. Lehman
(2005) showed that moving from a wide grip to a
narrow grip width increased neuromuscular activa-
tion of the triceps brachii and decreased the muscular
activation of the lower head of the pectoralis major.
Handgrip was controlled to 150% of biacromial width
in the present study which was different from Barnett
et al. (1995) who controlled grip width at 100% and
200% biacromial width, as well as previous studies
that did not control grip width (Glass & Armstrong,
1997; Trebs et al., 2010).
When examining the differences in activation it is
important to consider that in any exercise that invo-
lves the activation of multiple muscles in a complex
movement pattern the muscular activation of a single
muscle will be dependent on the activation of
synergistic muscles. It is also important to remember
that the activation of a muscle will depend on factors
such as the movement being performed, joint angle
and the muscle architecture (Freund & Budingen,
1978). During the horizontal bench press the prim-
ary movement at the shoulder joint is horizontal
adduction, which in this study resulted in the
greatest activation of the lower pectoralis. This could
suggest that horizontal bench press results in the
greatest demand on the lower pectoralis. However, it
is important to consider the joint angle and position
as this can effect muscle architecture and therefore,
the ability to generate force. Lower activation of the
upper pectoralis and the anterior deltoid during a
horizontal bench press could be due to the joint
angle and movement since these muscles are more
proficient at performing shoulder flexion rather
than horizontal adduction (Moore & Agur, 2007;
Trebs et al., 2010). In contrast, as the bench angle
increased from –15° to 45° there was a decrease in
activation of the lower pectoralis while the activation
of the anterior deltoid increased. These findings
could suggest that as the bench angle increases there is
less horizontal adduction and more flexion occurring
at the glenohumeral joint. This is further supported by
the significant increase in the initial shoulder flexion
angle that occurred as the bench angle increased in
this study (Table I).
A primary factor that will affect the activation level
of a muscle is the force requirement. In the current
study, the same absolute load was lifted at each
bench angle in an effort to eliminate the differences
in external load as a confounding factor affecting the
amplitude of the sEMG signal. This is in contrast to
previous studies that used different absolute loads
(i.e., same relative loads) at each tested bench angle
(Barnett et al., 1995; Glass & Armstrong, 1997;
Trebs et al., 2010). Change in the absolute load
between bench conditions could have affected the
muscular activation regardless of the change in
bench angle as it would have changed the force
Figure 3. (a) Activation of the anterior deltoid across eccentric phase durations. (b) Activation of the anterior deltoid across concentric
contraction durations.
+Significantly greater muscular activation compared to –15° bench condition; ◊significantly greater muscular activation compared to 0°
bench condition.
Influence of bench angle on the muscular activation 7
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requirement. Previous studies found that as the
incline angle increased, the absolute 1 RM load
achieved decreased (Trebs et al., 2010). This reduc-
tion in absolute force between bench conditions
could have contributed to the decrease in muscular
activation of the lower head of the pectoralis major
that was found as the bench angle increased (Barnett
et al., 1995; Glass & Armstrong, 1997; Trebs et al.,
2010). In agreement with previous investigations
(Barnett et al., 1995; Glass & Armstrong, 1997; Trebs
et al., 2010), the present study found a similar trend of
decreasing activation of the lower pectoralis activation
as the bench angle increased demonstrating that
bench angle, joint position and movement may play
a more significant role in muscle activation of the
lower pectoralis than the load lifted. Interestingly, the
study conducted by Trebs et al. (2010) demonstrated
greater activation of the upper pectoralis during the
44° and 56° conditions compared to horizontal even
with the reduction in absolute load.
The results of this study support the use of a hori-
zontal bench position to achieve muscular activation
of both the upper and lower heads of the pectoralis
major during both the concentric and eccentric
phases of the lift. However, a bench incline angle of
30° or 45° resulted in greater muscular activation
during specific time points throughout the contrac-
tion. The results suggest that an incline bench angle
of 30° is more beneficial than 45° as it resulted in the
same upper pectoralis activation but 30° resulted in
great lower pectoralis activation. In addition, a –15°
bench did not result in greater activation of either
head of the pectoralis, thus there is no added benefit
of include a –15° bench press in conjunction with a
horizontal bench. The results of the present invest-
igation demonstrate the importance of considering
the effects of muscle activation throughout different
time points of the contraction/lift as variations may
be evident. These results suggest that in an effort to
optimise a resistance-training programme with the
goal of improving muscle strength and development
of the pectoralis major, it would be beneficial to
include horizontal bench press and an incline bench
of 30°. The use of a decline or 45° incline bench
would have little or no added benefit.
Acknowledgements
The authors would like to thank the subjects for
volunteering to participate in this study.
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