Pimental_2016_Smitch vs barbell EMG_JEP

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Journal of Exercise Physiologyonline 
 
 
October 2016 
Volume 19 Number 5 
 
 
Editor-in-Chief 
Tommy Boone, PhD, MBA 
Review Board 
Todd Astorino, PhD 
Julien Baker, PhD 
Steve Brock, PhD 
Lance Dalleck, PhD 
Eric Goulet, PhD 
Robert Gotshall, PhD 
Alexander Hutchison, PhD 
M. Knight-Maloney, PhD 
Len Kravitz, PhD 
James Laskin, PhD 
Yit Aun Lim, PhD 
Lonnie Lowery, PhD 
Derek Marks, PhD 
Cristine Mermier, PhD 
Robert Robergs, PhD 
Chantal Vella, PhD 
Dale Wagner, PhD 
Frank Wyatt, PhD 
Ben Zhou, PhD 
 
 
 
 
Official Research Journal 
of the American Society of 
Exercise Physiologists 
 
ISSN 1097-9751 
 
Official Research Journal of 
the American Society of 
Exercise Physiologists 
 
ISSN 1097-9751 
 
 
 
 
 
 
 
 
JEPonline 
 
Smith Machine vs. Barbell: Ten Repetition Maximum 
Loads and Muscle Activation Pattern during Upper 
Body Exercises 
 
Iago Pimentel2, Ewertton Bezerra1.2,3, De Angelys de Ceselles2,3, 
Mateus Rossato1,2, João Machado2, Caetano Lazzari1, Gabriel Paz3, 
Humberto Miranda3, Antonio Moro1 
 
1Biomechanics Laboratory – Federal University of Santa Catarina, SC, 
Brazil, 2Human Performance Laboratory – Federal University of 
Amazonas, AM, Brazil, 3Strength Training Laboratory, Federal University of 
Rio de Janeiro, RJ, Brazil 
 
ABSTRACT 
 
Pimentel I, Bezerra E, Ceselles D, Rossato M, Machado J, 
Lazarri C, Paz G, Miranda H, Moro A. Smith Machine vs. Barbell: 
Ten Repetition Maximum Loads and Muscle Activation Pattern 
during Upper Body Exercises. JEPonline 2016;19(5):86-92. The aim 
of this study was to investigate muscle activation performance and 
maximum repetition test for the bench press, military press and the 
close-grip bench press exercises with the barbell and the Smith 
Machine. Twelve recreationally trained men (mean ± SD: 21.83 ± 4.5 
yrs; 1.72 ± 0.1 cm; 80.3 ± 9.2 kg; 25.1 ± 2.96 kg·m-2; 17.3 ± 6.85 
%Fat) underwent a within-subject, randomized and counterbalanced 
repeated-measures to analyze the 10-RM strength and muscle 
activation in the bench press, military press, and the close-grip 
bench press. Electromyographic signals were collected for the 
pectoralis major, anterior deltoid, biceps brachii, and triceps brachii 
during 1 set of each exercise with the barbell and smith machine. No 
difference was observed in muscle activity for pectoralis major, 
anterior deltoid, biceps brachii, and triceps brachii when comparing 
the barbell and the Smith Machine (P>0.05). However, significant 
differences in 10-RM loads were observed between the barbell and 
the Smith Machine for the close-grip bench press and military press 
exercises. These finding should be important when considering the 
determination of training loads. 
 
Key Words: Exercise, Electromyography, Resistance Training 
 
 
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INTRODUCTION 
 
The process of individualizing workout is important. Before choosing parameters such as 
exercise intensity, numbers of repetitions, speed of execution, rest intervals, and weekly 
frequency, exercise physiologists and other healthcare professionals involved with strength 
training should choose the type of exercise to be performed. Exercise selection should be a 
priority because the focus of the strength training program depends on making the right 
decision. Is the purpose of the strength training program to develop hypertrophy and 
maximum strength or muscular endurance and, if so, for which muscles? For example, the 
standard upper body resistance exercises for the development of anterior shoulders muscles 
are the bench press, military press, and close-grip bench press. 
 
In addition to specific exercises for specific muscle groups, there are different ways to 
execute free weight (i.e., barbell or dumbbells) exercises versus using machines (i.e., cables 
or the Smith Machine) and there are different effects as well. For example, when Krosshaug 
(6) analyzed the bench press exercise using dumbbells and barbell, it was found that during 
the execution of the bench press with the barbell, the external reactive forces had a medial-
lateral factor due to friction. This outcome did not happen with the dumbbells execution, 
where the external reaction forces were transmitted through the grip straight downward due 
to gravitational pulling. Furthermore, it seemed to change the triceps brachii activation during 
the barbell bench press (4,10), perhaps, due to the fact that the barbell bench press exercise 
required less stabilization of the shoulder musculature since the vertical force was distributed 
at the midpoint of the bar (5). 
 
Saeterbakken et al. (10) observed the greatest values for maximal strength during the barbell 
bench press exercise when compared with the same exercise executed with dumbells and 
the Smith Machine. These data corroborate with Krosshaugm (6), when the author showed 
lower activation levels for the triceps brachii during dumbbells execution. Several researches 
were made related to the bench press, but the same have not happened to the others 
exercises. Paoli et al. (8) observed the influence of different range of motion in shoulder 
muscle activity during military press exercise. They suggested changes in muscle activity of 
trapezius (upper and middle) during incomplete range of motion. Nevertheless, according our 
research, there is no study about muscle activity during the close-grip bench press when 
performed with dumbbells and the Smith Machine. 
 
Literature is narrow concerning the influence of different types of execution (barbell or Smith 
Machine) for distinct exercises involving shoulder and elbow muscle activation patterns. 
Furthermore, there is a lack of information about how to combine exercises in different 
phases of a periodized exercise program. No studies to date have analyzed and compared 
muscle activation patterns over different sorts of execution (barbell or Smith Machine) for the 
bench press, military press, and close-grip bench press. We hypothesized that barbell will be 
more effective for shoulder and elbow muscles than the Smith Machine for all exercises, but 
for maximum strength performance. 
 
Hence, the purpose of this study was to investigate muscle activation and ten repetition 
maximum load determination for exercises (bench press, military press, and close-grip bench 
press) performance between barbell and the Smith Machine with recreationally trained men. 
 
 
 
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METHODS 
 
Subjects 
Twelve recreational trained men (mean ± SD: 21.83 ± 4.5 yrs; 1.72 ± 0.1 cm; 80.3 ± 9.2 kg; 
25.1 ± 2.96 kg·m-2; 17.3 ± 6.85 %Fat), nonprofessional bodybuilders, training 3 times·wk-1 
during less than one year participated in this study. Subjects reported no shoulder injury or 
pathology at the moment of the experiments and during the previous six months. The study 
was approved by the Ethics committee of the Federal University of Amazonas – Brazil 
(CAAE: 15313413.4.00005020). All participants were asked to read and sign an informed 
consent about the tests. 
 
Procedures 
A within-subject, randomized and counterbalanced repeated-measures design was used to 
analyze the 10-RM strength and muscle activation in the bench press, military press, and the 
close-grip bench press. Two types of exercise execution were adopted (barbell and Smith 
Machine) for three upper body exercises: bench press, military press, and the close-grip 
bench press. 10-RM load was determined for each subject for the exercises in three 
sessions, with 48 hrs between sessions, and in randomized order: two exercises for 
sessions, with 20 min between exercises. All machine-based exercises were performed on a 
RS-Rotech equipment (Rotech Company, Goiás, Goiânia, BRA). During 10-RM testing, 
subjects were given a maximum of three attempts for each exercise a day, with a 5-min rest 
between attempts (9). Ametronome conducted the exercise execution speed at a constant 
rhythm of four seconds per repetition (2 sec for concentric phase and 2 sec for eccentric 
phase) (5). 
 
Electromyographic (EMG) data for the pectoralis major, anterior deltoid, triceps brachii, and 
biceps brachii were collected during all exercises with the barbell and the Smith Machine. 
Electrodes were placed according to the recommendations of Cram and colleagues (2). For 
the pectoralis major muscle, the electrodes were placed midway between the axilla and the 
areola. For anterior deltoid, the electrodes were placed approximately 4 cm below the clavicle 
parallel to the muscle fibers. For the biceps brachii, the electrodes were positioned on the 
midpoint of the muscle belly, in the longitudinal direction of the fibers. For triceps brachii, the 
electrodes were placed parallel to the muscle fibers, about 2 cm laterally from the midline of 
the arm (i.e., half way between the acromion process and the olecranon process). 
 
Before the experimental procedure, epilation and antisepsis procedures were performed on 
the areas the bipolar surface electrodes were to be placed (Kendal Medi Trace 200; Tyco 
Healthcare, Pointe-Claire, Canada). The electrodes were placed on the subjects’ right side of 
the body. After electrode positioning, impedance measures were assessed and accepted with 
less than 5 kΩ. The impedance was observed using a signal frequency of 25 Hz. 
 
For acquisition of muscle activity, EMG signals were collected using a MyoSystemTM 1400A 
with 8 input channels. The EMG signal was filtered with a band pass between 20 and 450 Hz. 
The sampling rate of the signal was 1000 Hz. For proper comparisons, the RMS value (Root 
Mean Square) obtained for each muscle (pectoralis major, anterior deltoid, biceps brachii, 
and triceps brachii) was normalized to the peak values obtained relative to all exercise 
modes. The signal intensity was presented as a percentage of the peak (11). 
 
 
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Statistical Analyses 
 
The Shapiro-Wilk test and homogeneity (Levene´s test) showed that all variables presented 
normal distribution and homogeneity. The intraclass correlation coefficient showed high 
relation between test and retest for all exercise and different execution modes (ICC>0.9). 
Paired t-student test compared the muscle action between BA and SM for all exercises. The 
level of statistical significance was set at P≤0.05 for all tests. The statistical analysis was 
performed with SPSS version 20.0 (Chicago, IL, USA). 
 
RESULTS 
 
There were statistical differences between the barbell and the Smith Machine for the military 
press and the close-grip bench press during the 10-RM test (P=0.006; P=0.030), 
respectively. However, the same did not happen for bench press (P=0.32), Figure 1. 
 
Figure 1. Ten Repetition Maximum Loads for Bench Press (BP), Military Press (MP), and Closed Grip 
Bench Press (CGBP) during Performance on the Smith Machine (gray) and the Barbell (black). *P<0.05 
for Barbell. 
 
 
No significant differences on muscle activity were observed for the pectoralis major, anterior 
deltoid, triceps brachii, and the biceps brachii when comparing the exercises performed with 
the barbell and the Smith Machine (P>0.05). The pectoralis major showed activity with values 
above 50% (RMS normalized) for the bench press [barbell, (54.77 ± 11; Smith Machine 
(51.24 ± 11)] and the close-grip bench press [barbell, (53.14 ± 10)]. The anterior deltoid 
showed similar muscle activity values of the pectoralis major for the bench press [Smith 
Machine, 52.25 ± 19) and the military press [barbell (58.19 ± 13); Smith Machine (60.74 ± 
.2)]. The triceps brachii showed more activity (50%, RMS normalized) than the biceps brachii 
during the bench press and the military press, but similar values in the close-grip bench press 
(refer to Figure 2). 
 
 
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Figure 2. %RMS Normalized of the Pectoralis Major (PM), Anterior Deltoid (AD), Triceps Brachii (TB), and 
Biceps Brachii (BB) during Performance on the Smith Machine (gray) and the Barbell (black). 
 
 
DISCUSSION 
 
The purpose of this study was to investigate maximum 10-RM loads determination and 
muscle activation for bench press, military press, and close-grip bench press performance 
using the barbell and the Smith Machine with recreationally trained men. We hypothesized 
that barbell would be more effective for shoulder and elbow muscles than the Smith Machine 
for all exercises, but for maximum strength performance. Our hypothesis for maximum 
strength performance during 10-RM was confirmed, because the military press and the close-
grip bench press showed higher values while using the Smith Machine than when using the 
barbell. For 10-RM strength, the military press and the close-grip bench press executed with 
the Smith Machine, which had the lowest joint stability requirements, showed higher results 
than the same exercises when using the barbell, 6% and 5%, respectively. However, the load 
lifted in the bench press was similar between the analyzed conditions. 
 
In agreement with our findings are Behm and Kenneth (1). They reported that during the 
Smith Machine performance, the stability requirements were lower, which required a greater 
application of force. Also, the subjects’ experience in strength training may have had an 
influence on our results. On the other hand, Saeterbakken et al. (10) disagree with the 
present study. Their findings showed lower performance when comparing the Smith Machine 
and the barbell. Here again, though, their subjects were more experienced (~4 yrs) than the 
subjects in the present study. 
 
The second part of our hypothesis was rejected since the findings showed that the possible 
instability did not induce higher muscle activation during the barbell exercise. The pectoralis 
major and the anterior deltoid muscles did not show a difference for the bench press. Similar 
results were presented by McCaw and Friday (7), who found no significant differences in the 
integrated electromyographic activity (iEMG) of the pectoralis major and the anterior deltoid 
muscles when comparing 80% 1-RM for the bench press exercise using the barbell and the 
Smith machine. 
 
During the military press, greater shoulder abduction promoted higher activity of the anterior 
deltoid (~60%). These results corroborate with Paoli et al. (8). The researchers examined the 
effect of ROM [the first one with a final elbow angle of 90o (R1); the second with 135o (R2), 
and the last one with a final elbow angle of 180o (R3)] at different loads (no load, 30% of one 
 
 
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repetition maximum [1-RM], and 70% of 1-RM) on the electromyographic (EMG) activity of 
the pectoralis major, anterior deltoid, and triceps brachii. The results showed that the use of 
the widest ROM increased the EMG activity of all the muscles selected with respect to the 
closest one; whereas, this effect is not totally confirmed with the employment of R2. The 
lower activity of the pectoralis major (~40%) can be explained by the fact that the sternal 
portion evaluated is not involved with shoulder abduction. 
 
However, during the close-grip bench press performance, greater shoulder flexion was 
evident with involvement from both the anterior deltoid and the pectoralis major. Both the 
biceps brachii (a shoulder flexor) and the triceps brachii (an elbow extensor) were at ~50%. 
Saeterbakken et al. (10) investigated the influence the dumbbell exercise in addition to the 
barbell and Smith Machine and Dumbbell. They found a difference in the biceps brachii and 
triceps brachii involvement only between the barbell and the Smith Machine when compared 
with dumbbells, in which the muscle activity of triceps brachii was lower and the biceps 
brachii was higher than the others. 
 
CONCLUSIONS 
 
No difference was observed in muscle activityfor the pectoralis major, anterior deltoid, biceps 
brachii, and triceps brachii when comparing the barbell and the Smith Machine. However, 
significant differences in 10-RM loads were observed between the barbell and the Smith 
Machine for the close-grip bench press and the military press exercises. These finding should 
be important when considering the determination of training loads. 
 
 
 
ACKNOWLEDGMENTS 
Foundation for Research Support of the State of Amazonas (FAPEAM/Brazil) providing 
financial support PhD scholarship (Ewertton Bezerra and Mateus Rossato) and for scientific 
initiation scholarship (Iago Pimentel). 
 
Address for correspondence: Ewertton Bezerra, Federal University of Amazonas, General 
Rodrigo Otávio Jordão Ramos Av; 6200 - Coroado I, Manaus - AM, 69067-005. Email: 
esbezerra@gmail.com 
 
 
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