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The purpose of this study was to compare one-repetition maximum (1-RM) and muscle activity in three chest-press exercises with different stability requirements (Smith machine, barbell, and dumbbells). Twelve healthy, resistance-trained males (age 22.7 ± 1.7 years, body mass 78.6 ± 7.6 kg, stature 1.80 ± 0.06 m) were tested for 1-RM of the three chest-press exercises in counterbalanced order with 3-5 days of rest between the exercises. One-repetition maximum and electromyographic activity of the pectoralis major, deltoid anterior, biceps, and triceps brachii were recorded in the exercises. The dumbbell load was 14% less than that for the Smith machine (P ≤ 0.001, effect size [ES] = 1.05) and 17% less than that for the barbell (P ≤ 0.001, ES = 1.11). The barbell load was ∼3% higher than that for the Smith machine (P = 0.016, ES = 0.18). Electrical activity in the pectoralis major and anterior deltoid did not differ during the lifts. Electrical activity in the biceps brachii increased with stability requirements (i.e. Smith machine <barbell <dumbbells; P ≤ 0.005; ES = 0.57, 1.46, and 2.00, respectively), while triceps brachii activity was reduced using dumbbells versus barbell (P = 0.007, ES = 0.73) and dumbbells versus Smith machine (P = 0.003, ES = 0.62). In conclusion, high stability requirements in the chest press (dumbbells) result in similar (pectoralis major and anterior deltoid), lower (triceps brachii) or higher (biceps brachii) muscle activity. These findings have implications for athletic training and rehabilitation.
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A comparison of muscle activity and 1-RM strength of three chest-press
exercises with different stability requirements
ATLE H. SAETERBAKKEN
1
, ROLAND VAN DEN TILLAAR
1
, & MARIUS S. FIMLAND
2
1
Faculty of Teacher Education and Sports, Sogn og Fjordane University College, Sogndal, Norway and
2
Norwegian University
of Science and Technology, Trondheim, Norway
(Accepted 26 November 2010)
Abstract
The purpose of this study was to compare one-repetition maximum (1-RM) and muscle activity in three chest-press exercises
with different stability requirements (Smith machine, barbell, and dumbbells). Twelve healthy, resistance-trained males (age
22.7 +1.7 years, body mass 78.6 +7.6 kg, stature 1.80 +0.06 m) were tested for 1-RM of the three chest-press exercises in
counterbalanced order with 3–5 days of rest between the exercises. One-repetition maximum and electromyographic activity
of the pectoralis major, deltoid anterior, biceps, and triceps brachii were recorded in the exercises. The dumbbell load was
14% less than that for the Smith machine (P0.001, effect size [ES] ¼1.05) and 17% less than that for the barbell
(P0.001, ES ¼1.11). The barbell load was *3% higher than that for the Smith machine (P¼0.016, ES ¼0.18). Electrical
activity in the pectoralis major and anterior deltoid did not differ during the lifts. Electrical activity in the biceps brachii
increased with stability requirements (i.e. Smith machine 5barbell 5dumbbells; P0.005; ES ¼0.57, 1.46, and 2.00,
respectively), while triceps brachii activity was reduced using dumbbells versus barbell (P¼0.007, ES ¼0.73) and dumbbells
versus Smith machine (P¼0.003, ES ¼0.62). In conclusion, high stability requirements in the chest press (dumbbells) result
in similar (pectoralis major and anterior deltoid), lower (triceps brachii) or higher (biceps brachii) muscle activity. These
findings have implications for athletic training and rehabilitation.
Keywords: Electromyography, resistance exercise, free weights, bench press, one-repetition maximum
Introduction
Bench press, also known as chest press, is a strength-
training exercise that is typically performed lying
supine on a bench using a Smith machine, barbell or
dumbbells. Unstable strength training exercises (e.g.
free weights) increase stabilization requirements of
the joints compared with the use of more stable
exercises (e.g. machines) (Garhammer, 1981). Thus,
proponents of instability resistance training claim
that unstable training modalities stress the neuro-
muscular system to a greater extent than more stable
strength-training exercises (Behm & Anderson,
2006).
Contrasting results have been reported in studies
that compared force output and muscle activation in
exercises on stable and unstable surfaces such as
Swiss balls and BOSU balls (Anderson & Behm,
2004; Marshall & Murphy, 2006; Norwood, Ander-
son, Gaetz, & Twist, 2007). For example, Kornecki
and colleagues (Kornecki, Kebel, & Siemien
´ski,
2001) and Anderson and Behm (2004) reported a
reduction in force output of about 30% and 60%,
respectively, when performing the same exercise on
an unstable surface. In contrast, Goodman and
colleagues (Goodman, Pearce, Nicholas, Gatt, &
Fairweather, 2008) reported no differences in one-
repetition maximum (1-RM) in barbell chest press
on a stable or unstable surface. Similarly, some
investigators have reported augmented electromyo-
graphy (EMG) activity in muscles that contribute to
joint stability (Kornecki et al., 2001; Marshall &
Murphy, 2006), whereas others have reported no
differences between stable and unstable surfaces
(Behm, Leonard, Young, Bonsey, & MacKinnon,
2005; Goodman et al., 2008).
A more common way of training to promote joint
stability is to employ free weights instead of machines
or dumbbells instead of a barbell. However, surpris-
ingly few studies have compared common resistance
training exercises with varying requirements of joint
stability for force output and neural drive. McCaw
and Friday (1994) reported greater neuromuscular
activity in the medial and anterior deltoid in bench
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Correspondence: A. H. Saeterbakken, Faculty of Teacher Education and Sports, Sogn og Fjordane Universi ty College, PB 133, N-6851 Sogndal, Norway.
E-mail: atle.saeterbakken@hisf.no
devia 11/12/10 10:03 RJSP_A_543916 (XML)
Journal of Sports Sciences, Month 2011; 29(0): 1–6
ISSN 0264-0414 print/ISSN 1466-447X online Ó2011 Taylor & Francis
DOI: 10.1080/02640414.2010.543916
press using free weights than machines at 60% but
not 80% of 1-RM. Welsch and colleagues (Welsch,
Bird, & Mayhew, 2005) compared barbell and
dumbbell bench press (6-RM loads) and reported
no differences in the neuromuscular activity of the
pectoralis major and anterior deltoid muscles. The
EMG activity was maintained despite the dumbbell
load being only *63% of the barbell load. This
suggests that increased neural drive was required to
stabilize the dumbbell. However, Welsch and col-
leagues did not record EMG activity of the agonist/
synergist triceps brachii and antagonist biceps brachii
muscles. Thus, it is unclear how the increased
stability requirement and the reduced absolute load
that can be lifted with dumbbells compared with
barbell chest-press influence the neuromuscular
activity of the biceps brachii and triceps brachii.
Thus the purpose of the present study was to
examine the 1-RM strength and EMG activity in
chest-press using a free barbell (conventional bench
press), a Smith machine, and dumbbells. It was
hypothesized that: (1) the increased stability require-
ment would result in lower 1-RM strength (kg) (i.e.
dumbbells 5free barbell 5Smith machine), and (2)
EMG activity would be similar in each chest-press
exercise since 1-RM was tested in each exercise.
Methods
Participants
Twelve healthy, resistance-trained males (age
22.7 +1.7 years, body mass 78.6 +7.6 kg, stature
1.80 +0.06 m) participated in the study. The
participants, none of whom was a competitive power
lifter, had 4.6 +2.2 years of strength-training ex-
perience. All participants were accustomed to the
three exercises and performed them as part of their
regular training programme. Participants were ex-
cluded from the study if they had musculoskeletal
pain, an illness or injury that might reduce maximal
effort during testing. The participants were in-
structed to refrain from any additional resistance
training exercises that targeted the chest, shoulders,
and upper arm muscle groups 72 h before testing.
Prior to the study, the participants were informed of
the test procedures and possible risks, and written
consent was obtained. Ethics approval was obtained
from the local research ethics committee and
conformed to the latest revision of the Declaration
of Helsinki.
Procedure
A within-participants crossover design was used to
examine 1-RM-related EMG activity in the barbell,
dumbbell, and Smith machine chest presses.
Two weeks before the experimental test, partici-
pants had three habituation sessions to identify 1-
RM for each of the three chest-press exercises. Each
session was separated by 3–5 days. The order in
which the exercises were performed was fully
counterbalanced. Participants 1 and 7, 2 and 8, 3
and 9, 4 and 10, 5 and 11, and 6 and 12 performed
the exercises in identical order. The exercises were
performed in the same order in the habituation
sessions and the experimental test. A 4-min rest
period was given between attempts (Schwanbeck,
Chilibeck, & Binsted, 2009). Before each 1-RM test,
a 10-min warm-up was performed on a cycle
ergometer at *60 rev min
–1
and self-selected
intensity (75–125 W) followed by four warm-up sets:
(1) 20 repetitions at 30% of 1-RM, (2) 12 repetitions
at 50% of 1-RM, (3) 6 repetitions at 70% of 1-RM,
and (4) 1 repetition at 85% of 1-RM. The percentage
of the 1-RM was estimated based on the self-
reported 1-RM of the participants in each of the
three exercises. A 3-min rest period was given
between warm-up sets (Goodman et al., 2008).
The tempo of each 1-RM lift was self-selected.
Similarly, the position of the hands on the barbell
was individually selected, but the forefinger had to be
inside the marks on the standard Olympic bar used.
Positioning of the hands was identical in the barbell
and Smith machine exercises. The position of the
arms was individually selected using the dumbbells.
The participants achieved 1-RM for the three
exercises in 3–6 attempts. The hips, shoulders, neck,
and head had to be in contact with the bench for each
of the exercises, with the feet on the floor, shoulder
width apart. Two test-leaders acted as spotters and
assisted the participants in the preload phase by
lifting the barbell or dumbbells and stabilizing the
weight until participants had fully extended arms.
On audio command, the participants lowered the
barbell to the middle of the sternum until it touched
the chest (eccentric phase). During dumbbell tests,
a 2-mm wide rubber band was placed on each
dumbbell. In the eccentric phase, the band was
stretched and had to touch the chest to make sure
the participants lowered the weights to the same
position as for the barbell. After lowering the
weights to the chest, the participants had to lift
the barbell/dumbbells back to the starting position
with fully extended elbows (concentric phase). No
bouncing of the weights was allowed. If the dumb-
bells or barbell were not lifted at the same vertical
position in the concentric phase, the lift was not
considered successful.
Recordings
A linear encoder (Ergotest Technology AS, Lange-
sund, Norway) was used to assess the vertical
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2A. H. Saeterbakken et al.
position and lifting time of the dumbbell or barbell
during all exercises. The linear encoder was syn-
chronized with the EMG recordings using a Mu-
sclelab 3010e and analysed with software V8.10
(Ergotest Technology AS, Langesund, Norway).
Before the 1-RM experimental test, the skin was
prepared (shaved, washed with alcohol, abraded) for
placement of gel-coated surface EMG electrodes.
Electrodes were placed according to the recom-
mendations of SENIAM (Hermens, Freriks, Dis-
selhorst-Klug, & Rau, 2000). The electrodes were
placed on the dominant side of the body (Marshall
& Murphy, 2006). The electrodes (11-mm contact
diameter) were placed on the belly of the muscle in
the presumed direction of the underlying muscle
fibres with a centre-to-centre distance of 2 cm. Self-
adhesive electrodes (Dri-Stick Silver circular sEMG
Electrodes AE-131, NeuroDyne Medical, USA)
were positioned at the pectoralis major, the anterior
deltoid, the triceps brachii, and biceps brachii. To
minimize noise from external sources, the raw
EMG signal was amplified and filtered using a
preamplifier located as near to the pickup point as
possible. Signals were low-pass filtered with a
maximum cut-off frequency of 8 Hz and high-pass
filtered with a minimum cut-off frequency of
600 Hz, rectified, and integrated. The raw EMG
signal was root-mean square (RMS) converted to an
RMS signal using a hardware circuit network
(frequency response 450 kHz, with a mean constant
of 12 ms, total error +0.5%). The RMS-converted
signal was sampled at a rate of 100 Hz using a 16-
bit analog-to-digital converter with a common mode
rejection rate of 100 dB. The stored data were
analysed using commercial software (Musclelab
V8.10, Ergotest Technology AS, Langesund, Nor-
way). Traces from the linear encoder and EMG
were overlaid and marked to identify the beginning
and end of the eccentric and concentric phase of
the lifts. The overall mean RMS EMG was
calculated for the entire movement as well sepa-
rately for the eccentric and concentric phases.
Statistical analysis
To assess differences in 1-RM strength, neuromus-
cular activity, and time taken in 1-RM testing
during the three chest-press exercises, a repeated-
measures one-way analysis of variance (ANOVA)
with Bonferroni post-hoc corrections to adjust for
multiple group comparisons was used (SPSS
version 17.0; SPSS, Inc., Chicago, IL). All results
are presented as means +standard deviations, and
we also report Cohen’s deffect sizes (ES). An
effect size of 0.2 was considered small, 0.5
medium, and 0.8 large. Statistical significance
was set as P0.05.
Results
The 1-RM strength was different among the three
chest-press exercises. The participants achieved the
highest 1-RM strength using the free barbell,
followed by the Smith machine and dumbbells
(Figure 1). The intra-class correlation coefficient
for the 1-RM exercises between the practice test and
the experiment was 0.947 (Smith machine), 0.947
(barbell), and 0.862 (dumbbells), respectively.
There were no differences in time spent in the
eccentric lifting phase, concentric lifting phase or in
total time taken in the three exercises (Table I).
The EMG activity for the whole movement
differed between the triceps brachii and biceps
brachii, whereas there were no differences for the
anterior deltoid and pectoralis major among
the different exercises (Figure 2). For dumbbells,
the EMG activity of the triceps brachii was lower
than for the Smith machine (P¼0.007, ES ¼0.62)
and barbell (P¼0.003, ES ¼0.73). For the biceps
brachii, the EMG activity increased with stability
requirements (i.e. dumbbells 4free barbell 4Smith
machine; Figure 2).
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Figure 1. Mean (and standard deviation) 1-RM for Smith
machine, barbell, and dumbbell chest presses. Significant differ-
ence in 1-RM between exercises:
#
P50.01, *P50.05.
Table I. Time taken (seconds) in lowering and lifting the weight
during the three chest-press exercises
Exercise Smith machine Barbell Dumbbells
Eccentric
phase
1.55 +0.38 1.55 +0.43 1.73 +0.74
Concentric
phase
3.14 +1.02 2.89 +0.88 2.75 +0.99
Total time 4.69 +1.16 4.45 +0.86 4.49 +1.39
Note: No differences were observed in time taken (P0.91) in the
different phases and total time between the three exercises.
Comparison of three chest-press exercises 3
When the EMG activity was calculated for the
eccentric phase, differences were observed between
exercises for the biceps brachii, anterior deltoid, and
pectoralis major (Figure 3a). The EMG activity was
lower when lifting with the Smith machine than with
the free barbell for the biceps brachii (P¼0.002,
ES ¼1.06), anterior deltoid (P¼0.004, ES ¼0.24),
and pectoralis major (P¼0.041, ES ¼0.33). The
EMG activity was also lower with the Smith machine
than with dumbbells for the biceps brachii
(P¼0.019, ES ¼0.94) and pectoralis major
(P¼0.012, ES ¼0.66). There were no differences
between the free barbell and dumbbells.
In the concentric phase, there were differences
between the triceps brachii and biceps brachii (Fig.
3b). Triceps brachii EMG activity was lower with
dumbbells than with the Smith machine (P¼0.005,
ES ¼0.54) and barbell (P¼0.003, ES ¼0.65). Bi-
ceps brachii EMG activity was higher with dumbbells
than with the Smith machine (P0.001, ES ¼2.32)
and barbell (P¼0.001, ES ¼1.79).
Discussion
In this study, we examined 1-RM strength and
neuromuscular activation in three chest-press ex-
ercises with different joint stability requirements.
The main findings were that 1-RM strength (i.e.
dumbbells 5Smith machine 5free barbell) and neu-
romuscular activity of the arm flexor/extensor mus-
cles, but not the pectoralis major and deltoid
anterior, differed among the three chest-press ex-
ercises.
For 1-RM strength, the dumbbells chest-press
load, which had the highest joint stability require-
ments, was substantially lower than for both Smith
machine and barbell chest-press (–14% and –17%
respectively; Figure 1). Furthermore, the load lifted
with the free barbell was slightly (*3%) higher than
with the Smith machine. The differences in 1-RM
strength between the free barbell and dumbbells in
the present study are in line with those of Welsch
et al. (2005). They reported that the maximal
dumbbells chest-press load was approximately 63%
of the maximal barbell load. Our finding of 83% is
broadly similar.
The stability requirements were lowest with the
Smith machine, which creates a guided one-dimen-
sional movement pattern, and thus the highest force
should theoretically be exerted in this exercise (Behm
& Anderson, 2006). However, contrary to the
hypothesis this was not the case in the present study.
The unnatural barbell path of the Smith machine
forced the participants to press the barbell in a linear
path similar to a novice barbell path (Madsen &
McLaughlin, 1984). Muscle use of the upper body
could be reduced and, therefore, limits the 1-RM
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405
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Figure 2. Mean (and standard deviation) root mean square
(muscle activity) of the whole movement of the triceps, biceps,
anterior deltoid, and pectoralis major during three chest-press
exercises (free barbell, in a Smith machine, and with dumbbells).
Significant difference in 1-RM between exercises:
#
P50.01,
*P50.05.
Figure 3. Mean (and standard deviation) root mean square
(muscle activity) of (a) the eccentric phase (a) and the concentric
phase (b) of the triceps, biceps, anterior deltoid, and pectoralis
major during three chest-press exercises (free barbell, in a Smith
machine, and with dumbbells). Significant difference in 1-RM
between exercises:
#
P50.01, *P50.05.
4A. H. Saeterbakken et al.
strength using the Smith machine versus a barbell
(Cotterman, Darby, & Skelly, 2005).
The difference in 1-RM strength between the free
barbell and the Smith machine is similar to that
reported by Cotterman et al. (2005) – that is, a
higher 1-RM strength with the barbell. Cotterman
et al. (2005) reported differences in 1-RM strength
both for men (*11%) and women (*22%) among
the exercises, which were much greater than in the
present study. However, these differences could
simply be because of the inexperience of the
participants. In the study of Cotterman et al.
(2005), 72% of the participants had never used a
Smith machine for bench press, whereas 97% of the
participants had used the free barbell previously. In
the present study, all participants had experience
with all three exercises, though the free barbell was
preferred by the participants for their daily training,
and the results could be attributable to training-
specific adaptation.
As regards the second hypothesis of no differences
in EMG activity, we anticipated that reduced 1-RM
strength would be compensated by increased stabi-
lization demands of the muscles. In line with the
hypothesis, EMG activity of the pectoralis major and
the anterior deltoid muscles was similar for all three
exercises when an overall mean value was taken for
both lifting phases (Figure 2). However, EMG
activity in the biceps brachii and triceps brachii
differed among exercises, indicating different de-
mands on activation patterns. The EMG activity of
the triceps brachii was lower, while that of the biceps
brachii was greater with the dumbbells than both
barbell and Smith machine (Figure 2). There was
greater biceps brachii antagonist co-activation with
the dumbbells than both the Smith machine and free
bar. This is probably attributable to the increased
stabilization demands for this exercise to maintain
the integrity of the joint (Lehman, MacMillan,
MacIntyre, Chivers, & Fluter, 2006). Furthermore,
it might be that the reduced triceps brachii EMG
activity during dumbbells lifting is a result of
reciprocal inhibition that arises from increased arm-
flexor activation (Folland & Williams, 2007). The
dumbbell chest press is typically used as a supple-
ment to more frequently used chest-press exercises,
such as the free barbell. Based on the present results,
this could have influenced the neuromuscular
activation of the biceps brachii and triceps brachii
more than the Smith machine and free barbell.
The EMG activity of the pectoralis differed in the
concentric and eccentric phases of the exercises,
whereas that of the anterior deltoid muscle differed
in the eccentric phase (Figure 3a). The activity of
these muscles was lower during the eccentric phase
for the Smith machine than for the barbell and
dumbbells. This can be explained again by the
decreased requirements of stabilization of these
muscles in the descending phase withn the Smith
machine (McCaw & Friday; 1994). Madsen and
McLaughlin (1984) reported maintenance of control
when lowering the bar as one of five factors that
affects bench-press performance. However, with
different requirements of stability, there were no
differences in time spent in the different lifting
phases and it would therefore have little influence on
the differences in neuromuscular activity (Table I).
In the concentric phase, there was no difference
for the anterior deltoid and pectoralis muscles
(Figure 3b). These two muscles are prime movers
in the three exercises, which shows that the activity of
these muscles is similar when lifting 1-RM (Schick
et al., 2010; van den Tillaar & Ettema, 2010; Welsch
et al., 2005). Differences between the concentric and
eccentric phase indicate greater neural drive to
stabilize the weights in the eccentric phase.
There were several differences in the EMG activity
of the triceps brachii and biceps brachii among the
three chest-press exercises (Figure 2). When the
eccentric and concentric phases were analysed
separately (Figures 3a and 3b), lower activity was
observed for the triceps brachii only in the concentric
phase with dumbbells. The biceps brachii stabilizes
movement during the three exercises (Lehman et al.,
2006). Thus differences in neuromuscular activity of
the biceps brachii – that is, higher activity in the
eccentric and concentric phase with dumbbells than
in the other exercises (Figures 3a and 3b) – is a result
of the increased stabilizing function of this muscle
during the exercise. However, it should be noted that
we used only one pair of electrodes on each of the
muscles (biceps and triceps). Since these muscles
have multiple heads, other parts of these muscles
could have been active during the different lifts, thus
influencing the differences observed in our study.
The present results are limited by testing only 1-
RM and cannot be generalized to other strength-
training programmes. Surface EMG has inherent
technical limitations and can provide only an
estimate of neuromuscular activation. There is an
inherent risk of crosstalk from neighbouring muscles,
even if a small inter-electrode distance were to be
used. Further research should investigate the neuro-
muscular pattern of exercises with different require-
ment of stability with loads that are more typically
employed in resistance training (e.g. 6- to 12-RM).
In conclusion, this study has shown differences in
1-RM strength (i.e. dumbbells 5Smith machine 5
free barbell) and differences in neuromuscular
activity for the arm flexor/extensor muscles, but not
for the prime movers, among the three chest-press
exercises. As the stability requirements increased, the
neuromuscular activity of the biceps brachii in-
creased. Dumbbell lifting was accompanied by
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Comparison of three chest-press exercises 5
greater biceps brachii activity, but less activity of the
triceps brachii. The prime movers showed similar
EMG activity while lifting 1-RM, but less in the
descending phase using the Smith machine than with
barbell and dumbbells chest-press. This indicates
that greater neural drive is required to stabilize
weights in the eccentric phase. During rehabilitation,
it may in some cases be beneficial to achieve high
levels of muscle activation while lifting a lighter
external load. However, strength trainers/coaches
should be aware that the dumbbell chest press does
not activate the triceps brachii to the same extent as
conventional bench press or bench press performed
in a Smith machine.
Acknowledgements
We would like to thank the participants together with
Alexander Hansen, Kjetil Myklebust, and Sigurd J.
Bergstom for assistance in participant recruitment
and data collection.
References
Anderson, K. G., & Behm, D. G. (2004). Maintenance of EMG
activity and loss of force output with instability. Journal of
Strength and Conditioning Research,18, 637–640.
Behm, D. G., & Anderson, K. G. (2006). The role of instability
with resistance training. Journal of Strength and Conditioning
Research,20, 716–722.
Behm, D. G., Leonard, A. M., Young, W. B., Bonsey, A. C., &
MacKinnon, S. N. (2005). Trunk muscle electromyography
activity with unstable and unilateral exercises. Journal of
Strength and Conditioning Research,19, 193–201.
Cotterman, M. L., Darby, L. A., & Skelly, W. A. (2005).
Comparison of muscle force production using the Smith
machine and free weights for bench press and squat exercises.
Journal of Strength and Conditioning Research,19, 169–176.
Folland, J. P., & Williams, A. G. (2007). The adaptations to
strength training: Morphological and neurological contribu-
tions to increased strength. Sports Medicine,37, 145–168.
Garhammer, J. (1981). Free weight equipment for the develop-
ment of athletic strength and power, part I. National Strength
and Conditioning Association Journal,3, 24–26.
Goodman, C. A., Pearce, A. J., Nicholes, C. J., Gatt, B. M., &
Fairweather, I. H. (2008). No difference in 1RM strength and
muscle activation during the barbell chest press on a stable and
unstable surface. Journal of Strength and Conditioning Research,
22, 88–94.
Hermens, H. J., Freriks, B., Disselhorst-Klug, C., & Rau, G.
(2000). Development of recommendations for SEMG sensors
and sensor placement procedures. Journal of Electromyogrogra-
phy and Kinesiology,10, 361–374.
Kornecki, S., Kebel, A., & Siemien
´ski, A. (2001). Muscular co-
operation during joint stabilisation, as reflected by EMG.
European Journal of Applied Physiology,84, 453–461.
Lehman, G. J., MacMillan, B., MacIntyre, I., Chivers, M., &
Fluter, M. (2006). Shoulder muscle EMG activity during push
up variations on and off a Swiss ball. Dynamic Medicine,5,7.
Madsen, N., & McLaughlin, T. (1984). Kinematic factors
influencing performance and injury risk in the bench exercise.
Medicine and Science in Sports and Exercise,16, 376–381.
Marshall, P. W., & Murphy, B. A. (2006). Increased deltoid and
abdominal muscle activity during Swiss ball bench press.
Journal of Strength and Conditioning Research,20, 745–750.
McCaw, S. T., & Friday, J. J. (1994). A comparison of muscle
activity between a free weight and machine bench press. Journal
of Strength and Conditioning Research,8, 259–264.
Norwood, J. T., Anderson, G. S., Gaetz, M. B., & Twist, P. W.
(2007). Electromyographic activity of the trunk stabilizers
during stable and unstable bench press. Journal of Strength
and Conditioning Research,21, 343–347.
Schick, E. E., Coburn, J. W., Brown, L. E., Judelson, D. A.,
Khamoui, A. V., Tran, T. T. et al. (2010). A comparison of
muscle activation between a Smith machine and free weight
bench press. Journal of Strength and Conditioning Research,24,
779–784.
Schwanbeck, S., Chilibeck, P. D., & Binsted, G. (2009). A
comparison of free weight squat to Smith machine using
electromyography. Journal of Strength and Conditioning Research,
23, 2588–2591.
van den Tillaar, R., & Ettema, G. (2010). The ‘‘sticking point’’ in
bench press. Journal of Sports Sciences,28, 529–535.
Welsch, E. A., Bird, M., & Mayhew, J. L. (2005). Electromyo-
graphic activity of the pectoralis major and anterior deltoid
muscles during three upper-body lifts. Journal of Strength and
Conditioning Research,19, 449–452.
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... dumbbell press), with both modalities proving effective for stimulating strength and hypertrophy. However, due to lower stability requirements, heavier weights can be lifted with a barbell than with dumbbells [39,40]. In a cross-over study by Saeterbakken et al. [40], resistance-trained participants were able to perform a 1RM lift with approximately 20% heavier loads during the barbell bench press compared to the dumbbell bench press. ...
... However, due to lower stability requirements, heavier weights can be lifted with a barbell than with dumbbells [39,40]. In a cross-over study by Saeterbakken et al. [40], resistance-trained participants were able to perform a 1RM lift with approximately 20% heavier loads during the barbell bench press compared to the dumbbell bench press. During the 1RM lift, comparable pectoralis and deltoideus activation was observed, but synergistic activation of the triceps brachii was considerably higher during the barbell bench press than with dumbbells. ...
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Lack of time is among the more commonly reported barriers for abstention from exercise programs. The aim of this review was to determine how strength training can be most effectively carried out in a time-efficient manner by critically evaluating research on acute training variables, advanced training techniques, and the need for warm-up and stretching. When programming strength training for optimum time-efficiency we recommend prioritizing bilateral, multi-joint exercises that include full dynamic movements (i.e. both eccentric and concentric muscle actions), and to perform a minimum of one leg pressing exercise (e.g. squats), one upper-body pulling exercise (e.g. pull-up) and one upper-body pushing exercise (e.g. bench press). Exercises can be performed with machines and/or free weights based on training goals, availability, and personal preferences. Weekly training volume is more important than training frequency and we recommend performing a minimum of 4 weekly sets per muscle group using a 6–15 RM loading range (15–40 repetitions can be used if training is performed to volitional failure). Advanced training techniques, such as supersets, drop sets and rest-pause training roughly halves training time compared to traditional training, while maintaining training volume. However, these methods are probably better at inducing hypertrophy than muscular strength, and more research is needed on longitudinal training effects. Finally, we advise restricting the warm-up to exercise-specific warm-ups, and only prioritize stretching if the goal of training is to increase flexibility. This review shows how acute training variables can be manipulated, and how specific training techniques can be used to optimize the training response: time ratio in regard to improvements in strength and hypertrophy. Graphic Abstract
... The included bench press on the Keiser Power Rack hydraulic resistance device and squats on the Keiser Squat hydraulic resistance training system. The one repetition maximum test (1RM) on the Keiser Squat and Keiser Power Rack was determined based on the protocol for the number of repetitions used by Baechle et al. [24]. After a warm-up according to the protocol used by Saeterbakken et al. [25], the participants carried out several maximum repetitions so that the number covered a range of 3 to 8 maximum repetitions. ...
... After a warm-up according to the protocol used by Saeterbakken et al. [25], the participants carried out several maximum repetitions so that the number covered a range of 3 to 8 maximum repetitions. Based on the formula, the value of 1RM was calculated and used to calculate the value of the load used by each athlete to perform tests of explosive strength and strength endurance [24]. To evaluate the explosive strength, the athletes tested performed two repetitions at maximum speed while maintaining the correct technique with a load of 50% 1RM. ...
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Background: This research aimed to identify the most significant predictors of sports level using regression modeling. Methods: This study examined 16 judokas (aged 23 (±2.5)) from four weight categories, with four athletes in each category (66 kg, 73 kg, 81 kg and 90 kg). Each athlete was a member of the Polish National Team, an international master class (IM) or national master class (M). The tests were carried out twice (every two weeks) during the pre-competitive season in the morning, after a 10-min warm-up. The tests were performed according to the following protocol: Explosive Strength Lower Limbs (ExSLL) [W], Strength Endurance Lower Limbs (SELL) [%], Explosive Strength Upper Limbs (ExSUL) [W], Strength Endurance Upper Limbs (SEUL) [%]. The relationships between the dependent variable (ranking score) and the other analyzed variables (predictors) were estimated using the one-factor ridge regression analysis. Results: There were significant intergroup and intragroup differences in the results of explosive strength and strength endurance of the lower and upper limbs. The best predictors were identified using regression modeling: ExSLL, SELL, and SEUL. Conclusions: Increasing the value of these predictors by a unit should significantly affect the scores in the ranking table. Correlation analysis showed that all variables that are strongly correlated with the Polish Judo Association (PJA) ranking table scores may have an effect on the sports performance.
... The warm-up continued in the lab with dynamic stretches for the pectoralis, anterior deltoid, and triceps brachii muscles, followed by 10 B P repetitions at 20kg, four repetitions at 50% of self-reported 1-RM, and two repetitions at 75% of self-reported 1-RM. Participants used their preferred grip-and feet-width, which were measured initially and then controlled before each subsequent lift in all sessions (Saeterbakken et al., 2011). ...
Article
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The aims of this study were to compare power output during a bench press throw (BPT) executed with (BPT bounce) and without (BPT) the barbell bounce technique, and examine the effect of cueing different barbell descent velocities on BPT power output in resistance-trained males. In total, 27 males (age 23.1 ± 2.1 years; body mass 79.4 ± 7.4 kg; height 178.8 ± 5.5 cm; and 4.6 ± 1.9 years of resistance training experience) were recruited and attended one familiarization session and two experimental sessions (EXP 1 and EXP 2). The force-velocity profile during maximal BPT and BPT bounce (randomized order) under different loads (30-60 kg) was established (EXP 1), and the effect of varying external barbell descent velocity cues "slow, medium, and as fast as possible" (i.e., "fast") on the power output for each technique (BPT and BPT bounce) was examined (EXP 2). Comparing two BPT techniques (EXP 1), BPT bounce demonstrated 7.9-14.1% greater average power (p ≤ 0.001, ES = 0.48-0.90), 6.5-12.1% greater average velocity (p ≤ 0.001, ES = 0.48-0.91), and 11.9-31.3% shorter time to peak power (p ≤ 0.001-0.05, ES = 0.33-0.83) across the loads 30-60 kg than BPT. The cueing condition "fast" (EXP 2) resulted in greater power outcomes for both BPT and BPT bounce than "slow." No statistically significant differences in any of the power outcomes were observed between "medium" and "slow" cuing conditions for BPT (p = 0.097-1.000), whereas BPT bounce demonstrated increased average power and velocity under the "medium" cuing condition, compared to "slow" (p = 0.006-0.007, ES = 0.25-0.28). No statistically significant differences were observed in barbell throw height comparing BPT and BPT bounce under each cuing condition (p = 0.225-1.000). Overall, results indicate that both bouncing the barbell and emphasizing barbell descent velocity be considered to improve upper body power in athlete and non-athlete resistance-training programs.
... While a high number of studies have analysed muscle activity patterns during bench press exercises [7][8][9][10][11][12][13], relatively little research has been done on joint kinematics and kinetics of the upper limbs for both bench press and cable pulley exercises. The authors of [14] investigated the effects of exercise intensity on trunk muscle activity during pulleybased shoulder exercises on an unstable support surface. ...
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Injuries to the shoulder are very common in sports that involve overhead arm or throwing movements. Strength training of the chest muscles has the potential to protect the shoulder from injury. Kinematic and kinetic data were acquired in 20 healthy subjects (age: 24.9 ± 2.7 years) using motion capture, force plates for the bench press exercises and load cells in the cable for the cable pulley exercises with 15% and 30% of body weight (BW). Joint ranges of motion (RoM) and joint moments at the shoulder, elbow and wrist were derived using an inverse dynamics approach. The maximum absolute moments at the shoulder joint were significantly larger for the cable pulley exercises than for the bench press exercises. The cable cross-over exercise resulted in substantially different joint angles and loading patterns compared to most other exercises, with higher fluctuations during the exercise cycle. The present results indicate that a combination of bench press and cable pulley exercises are best to train the full RoM and, thus, intra-muscular coordination across the upper limbs. Care has to be taken when performing cable cross-over exercises to ensure proper stabilisation of the joints during exercise execution and avoid joint overloading.
... On the test day, six electromyography (EMG) sensors were placed on the participant. The EMG sensors were placed on the pectoralis major (the clavicular and sternal head), anterior and lateral deltoid, biceps brachialis and triceps long head [11]. Unlike some previous studies, we also included the lateral head of the deltoid and the clavicular head of the pectoralis major in this study. ...
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The target of this study was to investigate the acute effect of a supramaximal augmented eccentric load on the kinematics and myoelectric activity during the concentric phase of the lift in a traditional bench press. Ten resistance-trained males (age 24 ± 6.4 years, height 1.80 ± 0.07 m, body-mass 87.2 ± 16.9 kg) performed two repetitions at 110/85% of the 1-RM in the dynamic accentuated external resistance (DAER) group and two repetitions at 85/85% of the 1-RM for the control group in a traditional bench press. The barbell kinematics, joint kinematics and myoelectric activity of eight muscles were measured in the eccentric phase and the pre-sticking, sticking and post-sticking regions. The main findings were that the sticking region started at a lower barbell height and that a lower barbell velocity was observed in the sticking region during the second repetition in the DAER condition compared to the control condition. Additionally, the lateral deltoid muscle and clavicle part of the pectoralis were more active during the eccentric loading compared to the control condition for the second repetition. Furthermore, higher myoelectric activity was measured during the second repetition in the sticking region for the eccentric loading condition in both pectoralis muscles, while the sternal parts of the pectoralis and anterior deltoid were more active during the second repetition of the control condition in the post-sticking region. Based on our findings, it can be concluded that the supramaximal loading in the descending phase with 110% of the 1-RM in the bench press does not have an acute and positive effect of enhanced performance in the ascending phase of the lift at 85% of 1-RM. Instead, fatigue occurs when using this eccentric load during a bench press.
... Several studies have examined the bench press exercise. For example, different chestpress exercises have been examined with regard to muscle strength, electromyographic activity (EMG) and kinematics [2,3], bench angles [4,5], biomechanics [6][7][8][9], unstable surfaces [10,11], successful and unsuccessful attempts [6], and different muscle actions (e.g., isometric, concentric only, and counter movement) [12,13]. The main focus has been the primary muscle groups (pectoralis major, deltoid anterior, and triceps brachii) in addition to the synergist and antagonist in the exercise [1,9,14,15]. ...
Article
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Background: This study compared the muscle activity and six repetition maximum (6- RM) loads in bench press with narrow, medium, and wide grip widths with sub-group comparisons of resistance-trained (RT) and novice-trained (NT) men. Methods: After two familiarization sessions, twenty-eight subjects lifted their 6-RM loads with the different grip widths with measurement of electromyographic activity. Results: Biceps brachii activity increased with increasing grip width, whereas wide grip displayed lower triceps brachii activation than medium and narrow. In the anterior deltoid, greater activity was observed using a medium compared to narrow grip. Similar muscle activities were observed between the grip widths for the other muscles. For the RT group, greater biceps brachii activity with increasing grip width was observed, but only greater activity was observed in the NT group between narrow and wide. Comparing wide and medium grip width, the RT group showed lower triceps activation using a wide grip, whereas the NT group showed lower anterior deltoid activation using a narrow compared to medium grip. Both groups demonstrated lower 6-RM loads using a narrow grip compared to the other grips. Conclusion: Grip widths affect both 6-RM loads and triceps brachii, biceps brachii, and anterior deltoid activity especially between wide and narrow grip widths.
... Several studies have determined that BBP 1RM is typically 16-17% greater than for DBP 1RM. 4,5 While peak power production in BBP has been reported to occur between 30% and 70% of 1RM 16 , this information appears to be lacking for DBP. Using equated loads for the BPP and DBP in the current study makes it difficult to draw compare with other studies using %1RM methodologies. ...
Article
Objectives: The purpose of this study was to assess differences in bench press velocity and power production with barbell and dumbbells. Design: Randomized cross-over design. Methods: College men (n = 20, age = 18-24 yrs) were measured for average and peak velocities and power during maximal effort single repetitions using barbell and bilateral dumbbells at loads equivalent to 30%, 50%, and 70% of body mass. Three repetitions were performed at each load with one-minute recovery between each repetition and 10 minutes between loads. During each repetition for each mode, average and peak velocity and power were monitored using a linear accelerometer. Results: Interclass correlation coefficients across the 3 trials for peak and average velocities were high for both barbell (ICC = 0.957 and 0.821, respectively) and dumbbells (ICC = 0.947 and 0.855, respectively). Peak power output was sig nificantly higher (p < 0.009) for barbell than dumbbells at 50% and 70% loads. Average power output was significantly different (p < 0.001) across the 3 loads but not significantly different between barbell and dumbbells (p = 0.35). Although velocity decreased as load increased, higher power outputs were produced across increases in loads. Peak power output was reached at 70% of body mass with barbell and 50% with dumbbells. Conclusion: Either barbell or bilateral dumbbell bench press exercises can be used to evaluate upper-body power with sim ilar effectiveness.
... Since the participants were resistance-trained and performed the leg press regularly, they were able to predict their 1RM very accurately. The warm-up consisted of the following procedure: 1) 20 repetitions at 30%, 2) 12 repetitions at 50%, 3) 6 repetitions at 70%, and 4) 2 repetitions at 80% (Bazyler et al., 2015;Saeterbakken et al., 2011). The high number of repetitions was chosen to ensure sufficient warm-up despite the sub-maximal loads and repetition ranges used. ...
Article
Resistance-training exercises can be classified as either single-or multi-joint exercises and differences in surface electromyography (EMG) amplitude between the two training methods may identify which muscles can benefit from either training modality. This study aimed to compare the surface EMG amplitude of five hip-and knee extensors during one multi-joint (leg press) and two single joint exercises (knee extension and kickback). Fifteen resistance trained men completed one familiarization session to determine their unilateral six repetitions maximum (6RM) in the three exercises. During the following experimental session, EMG amplitudes of the vastus lateralis, vastus medialis, rectus femoris, gluteus maximus and biceps femoris of the left leg were measured while performing three repetitions on their respective 6RM loads. The multi-joint exercise leg press produced higher EMG amplitude of the vastus lateralis (ES = 0.92, p = 0.003) than the single-joint exercise knee extension, whereas the rectus femoris demonstrated higher EMG amplitude during the knee extension (ES = 0.93, p = 0.005). The biceps femoris EMG amplitude was higher during the single-joint exercise kickback compared to the leg press (ES = 2.27, p < 0.001), while no significant differences in gluteus maximus (ES = 0.08, p = 0.898) or vastus medialis (ES = 0.056, p = 0.025 were observed between exercises. The difference in EMG amplitude between single-and multi-joint exercises appears to vary depending on the specific exercises and the muscle groups tested. Leg press is a viable and time-efficient option for targeting several hip-and knee extensors during resistance training of the lower limbs, but the single-joint exercises may be preferable for targeting the rectus femoris and biceps femoris.
Article
[Main text in Slovene] Aging is a complex multidimensional process that manifests differently in each individual. The process of ageing is characterized by many biological changes, which are reflected in weight loss, loss of muscle strength and power, loss of movement functionality and cognitive decline. These changes reduce physiological resilience and increase fall risk, risk for musculoskeletal injuries, reduce independence and thus impair the quality of life. The purpose of this paper is to review the scientific literature regarding resistance training in elderly, and provide evidence-based recommendations for resistance training in older adults. Based on the reviewed literature, it is clear that resistance training has a positive effect on the increase in muscle mass and strength, as well as on the balance capabilities. Moreover, resistance training is an effective method for improving cognitive functions, alleviating behavior problems, improving general well-being and thus positively affecting quality of life. Based on the reviewed literature we summarized the recommendations for the implementation of resistance training in older adults. Older adults should perform this type of exercise 2-3 times a week, with at least 48-hour break between individual training sessions. The intensity of the exercises should be gradually increased, while the starting intensity could be set around 50 % of maximal load. It is recommended to perform 1-3 sets with 6-12 repetitions of each exercise. Training program should be individualized according to individual's needs and abilities. Moreover, it is important to consult with medical doctor to go through the medical examination, before starting any kind of training program.
Article
Employing an arched back posture during the bench press exercise is increasingly popular. Vertical displacement of the barbell is commonly believed to be the key difference influencing strength performance between an arched and flat back bench press technique. However, comparisons between these back postures using a free weight barbell are lacking. Directly comparing performance between each posture is confounded by many variables such as proficiency and fatigue. This investigation aimed to investigate whether changing back posture alone can influence barbell kinematics, to indirectly assess potential performance differences. Twenty males performed one repetition of the bench press exercise using either an arched or flat back posture, at 25%, 50% and 75% of their one repetition maximum, in a repeated measures study design. Statistical significance was considered at p < 0.05. Changing back posture alone, reduced vertical displacement (approximately 11% average difference across all load conditions) and barbell to glenohumeral joint moment arm (approximately 20% difference) in the arched posture compared to the flat posture. These changes occurred without any specific cueing of the barbell motion and may increase the potential for lifting higher loads and decrease cumulative joint exposure. Additional cueing and training may be required to maximize the mechanical advantage available with each back posture. The arched posture appears to have an increased potential for further improvements in vertical displacement and moment arm through specific cueing. Future comparisons should consider if each back posture’s potential mechanical advantage has been maximized when assessing differences between techniques.
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The purpose of this study was to examine muscle activity and three-dimensional kinematics in the ascending phase of a successful one-repetition maximum attempt in bench press for 12 recreational weight-training athletes, with special attention to the sticking period. The sticking period was defined as the first period of deceleration of the upward movement (i.e. from the highest barbell velocity until the first local lowest barbell velocity). All participants showed a sticking period during the upward movement that started about 0.2 s after the initial upward movement, and lasted about 0.9 s. Electromyography revealed that the muscle activity of the prime movers changed significantly from the pre-sticking to the sticking and post-sticking periods. A possible mechanism for the existence of the sticking period is the diminishing potentiation of the contractile elements during the upward movement together with the limited activity of the pectoral and deltoid muscles during this period.
Article
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The bench press exercise exists in multiple forms including the machine and free weight bench press. It is not clear though how each mode differs in its effect on muscle activation. The purpose of this study was to compare muscle activation of the anterior deltoid, medial deltoid, and pectoralis major during a Smith machine and free weight bench press at lower (70% 1 repetition maximum [1RM]) and higher (90% 1RM) intensities. Normalized electromyography amplitude values were used during the concentric phase of the bench press to compare muscle activity between a free weight and Smith machine bench press. Participants were classified as either experienced or inexperienced bench pressers. Two testing sessions were used, each of which entailed either all free weight or all Smith machine testing. In each testing session, each participant's 1RM was established followed by 2 repetitions at 70% of 1RM and 2 repetitions at 90% of 1RM. Results indicated greater activation of the medial deltoid on the free weight bench press than on the Smith machine bench press. Also, there was greater muscle activation at the 90% 1RM load than at the 70% 1RM load. The results of this study suggest that strength coaches should consider choosing the free weight bench press over the Smith machine bench press because of its potential for greater upper-body muscular development.
Article
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Swiss Balls used as a platform for training provide an unstable environment for force production. The objective of this study was to measure differences in force output and electromyographic (EMG) activity of the pectoralis major, anterior deltoid, triceps, latissimus dorsi, and rectus abdominus for isometric and dynamic contractions under stable and unstable conditions. Ten healthy male subjects performed a chest press while supported on a bench or a ball. Unstable isometric maximum force output was 59.6% less than under stable conditions. However, there were no significant differences in overall EMG activity between the stable and unstable protocols. Greater EMG activity was detected with concentric vs. eccentric or isometric contractions. The decreased balance associated with resistance training on an unstable surface may force limb musculature to play a greater role in joint stability. The diminished force output suggests that the overload stresses required for strength training necessitate the inclusion of resistance training on stable surfaces.
Article
High-resistance strength training (HRST) is one of the most widely practiced forms of physical activity, which is used to enhance athletic performance, augment musculo-skeletal health and alter body aesthetics. Chronic exposure to this type of activity produces marked increases in muscular strength, which are attributed to a range of neurological and morphological adaptations. This review assesses the evidence for these adaptations, their interplay and contribution to enhanced strength and the methodologies employed. The primary morphological adaptations involve an increase in the cross-sectional area of the whole muscle and individual muscle fibres, which is due to an increase in myofibrillar size and number. Satellite cells are activated in the very early stages of training; their proliferation and later fusion with existing fibres appears to be intimately involved in the hypertrophy response. Other possible morphological adaptations include hyperplasia, changes in fibre type, muscle architecture, myofilament density and the structure of connective tissue and tendons. Indirect evidence for neurological adaptations, which encompasses learning and coordination, comes from the specificity of the training adaptation, transfer of unilateral training to the contralateral limb and imagined contractions. The apparent rise in whole-muscle specific tension has been primarily used as evidence for neurological adaptations; however, morphological factors (e.g. preferential hypertrophy of type 2 fibres, increased angle of fibre pennation, increase in radiological density) are also likely to contribute to this phenomenon. Changes in inter-muscular coordination appear critical. Adaptations in agonist muscle activation, as assessed by electromyography, tetanic stimulation and the twitch interpolation technique, suggest small, but significant increases. Enhanced firing frequency and spinal reflexes most likely explain this improvement, although there is contrary evidence suggesting no change in cortical or corticospinal excitability. The gains in strength with HRST are undoubtedly due to a wide combination of neurological and morphological factors. Whilst the neurological factors may make their greatest contribution during the early stages of a training programme, hypertrophic processes also commence at the onset of training.
Article
The experiment that was carried out consisted of subjects pushing an external object (a heavy pendulum) using stable and unstable handles of increasing mobility. Using this protocol it was possible to distinguish between the motor and stabilising functions of the muscles of the upper extremity. The motor functions were realised by the extensors of the upper extremity, whereas stabilising functions were effected by the muscles spanning the wrist joint. The experiment involved synchronised measurements of the electromyographic (EMG) activity of the muscles in question together with several mechanical quantities revealed against the external object: force, velocity and power. As a result, the instantaneous and global EMG contributions of the extensor and stabilising muscles were determined. It was found that it is the equilibrium state of the object being set in motion and not its mobility (expressed in terms of the number of degrees of freedom) that influences the forces produced by individual muscles. We also suggest that the realisation of stabilising functions by skeletal muscles is a necessary condition of performing any voluntary and co-ordinated movement.
Article
The purpose of this experiment was to determine whether free weight or Smith machine squats were optimal for activating the prime movers of the legs and the stabilizers of the legs and the trunk. Six healthy participants performed 1 set of 8 repetitions (using a weight they could lift 8 times, i.e., 8RM, or 8 repetition maximum) for each of the free weight squat and Smith machine squat in a randomized order with a minimum of 3 days between sessions, while electromyographic (EMG) activity of the tibialis anterior, gastrocnemius, vastus medialis, vastus lateralis, biceps femoris, lumbar erector spinae, and rectus abdominus were simultaneously measured. Electromyographic activity was significantly higher by 34, 26, and 49 in the gastrocnemius, biceps femoris, and vastus medialis, respectively, during the free weight squat compared to the Smith machine squat (p < 0.05). There were no significant differences between free weight and Smith machine squat for any of the other muscles; however, the EMG averaged over all muscles during the free weight squat was 43% higher when compared to the Smith machine squat (p < 0.05). The free weight squat may be more beneficial than the Smith machine squat for individuals who are looking to strengthen plantar flexors, knee flexors, and knee extensors.
Article
This study calculated IEMG values during the ascent and descent phases of the bench press and compared the values between lifts performed with free weights versus a guided weight machine. In Phase 1 of the study the 1-RM on each mode was determined for each subject. In Phase 2, EMG data were collected from five muscles of the upper extremity while each subject completed five trials at 80% of 1-RM and five trials at 60% of 1-RM for each mode. Linear envelopes were created from the EMG data of each trial, and IEMG values were calculated during the descent and ascent phases of each trial. Planned comparisons were used to compare mean IEMG values between the two loads within the same mode, and between the two modes at both the 60% and 80% loads. Results suggested greater muscle activity during the free-weight bench press, especially at the 60% 1-RM load, although there were notable differences among the patterns of individual subjects.
Article
The purpose of this research was to identify kinematic factors that could be relevant to performance and injury risk in the bench press. The methods used included: use of high-speed, 2D cinematographic procedures to record the performances of 36 subjects (19 experts and 17 novices), determination of the kinematic and kinetic differences between the groups, and identification of a rationale describing how those kinematic differences could lead to the kinetic differences. Kinematic factors so identified could influence performance and injury risk. In addition to the fact that experts were able to lift 79% more weight than the novices, the pertinent kinetic differences included the following: 1) the difference in peak force exerted while lowering the bar was only 43%; 2) the difference in peak force exerted while raising the bar was only 45%; and 3) the difference in minimum force exerted while raising the bar was 87%. There was no significant difference in torque required at the shoulder. The relevant kinematic differences were: 1) the expert group maintained a smaller bar speed while lowering the bar, 2) the expert group used a bar path closer to the shoulders; and 3) the expert group used a different sequence of bar movements. The roles of these kinematic factors in the bench press merit further investigation.
Article
The knowledge of surface electromyography (SEMG) and the number of applications have increased considerably during the past ten years. However, most methodological developments have taken place locally, resulting in different methodologies among the different groups of users.A specific objective of the European concerted action SENIAM (surface EMG for a non-invasive assessment of muscles) was, besides creating more collaboration among the various European groups, to develop recommendations on sensors, sensor placement, signal processing and modeling. This paper will present the process and the results of the development of the recommendations for the SEMG sensors and sensor placement procedures. Execution of the SENIAM sensor tasks, in the period 1996-1999, has been handled in a number of partly parallel and partly sequential activities. A literature scan was carried out on the use of sensors and sensor placement procedures in European laboratories. In total, 144 peer-reviewed papers were scanned on the applied SEMG sensor properties and sensor placement procedures. This showed a large variability of methodology as well as a rather insufficient description. A special workshop provided an overview on the scientific and clinical knowledge of the effects of sensor properties and sensor placement procedures on the SEMG characteristics. Based on the inventory, the results of the topical workshop and generally accepted state-of-the-art knowledge, a first proposal for sensors and sensor placement procedures was defined. Besides containing a general procedure and recommendations for sensor placement, this was worked out in detail for 27 different muscles. This proposal was evaluated in several European laboratories with respect to technical and practical aspects and also sent to all members of the SENIAM club (>100 members) together with a questionnaire to obtain their comments. Based on this evaluation the final recommendations of SENIAM were made and published (SENIAM 8: European recommendations for surface electromyography, 1999), both as a booklet and as a CD-ROM. In this way a common body of knowledge has been created on SEMG sensors and sensor placement properties as well as practical guidelines for the proper use of SEMG.