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Variations in muscle activation levels during traditional latissimus dorsi weight training exercises: An experimental study

Authors:

Abstract

Background Exercise beliefs abound regarding variations in strength training techniques on muscle activation levels yet little research has validated these ideas. The purpose of the study is to determine muscle activation level, expressed as a percent of a normalization contraction, of the latissimus dorsi, biceps brachii and middle trapezius/rhomboids muscle groups during a series of different exercise tasks. Methods The average muscle activity during four tasks; wide grip pulldown, reverse grip pull down [RGP], seated row with retracted scapula, and seated rows with non-retracted scapulae was quantified during two 10 second isometric portions of the four exercises. A repeated measures ANOVA with post-hoc Tukey test was used to determine the influence of exercise type on muscle activity for each muscle. Results & Discussion No exercise type influenced biceps brachii activity. The highest latissimus dorsi to biceps ratio of activation occurred during the wide grip pulldown and the seated row. Highest levels of myoelectric activity in the middle trapezius/rhomboid muscle group occurred during the seated row. Actively retracting the scapula did not influence middle trapezius/rhomboid activity. Conclusion Variations in latissimus dorsi exercises are capable of producing small changes in the myoelectric activity of the primary movers.
BioMed Central
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Dynamic Medicine
Open Access
Research
Variations in muscle activation levels during traditional latissimus
dorsi weight training exercises: An experimental study.
Gregory J Lehman*
1
, Day Deans Buchan
2
, Angela Lundy
2
, Nicole Myers
2
and
Andrea Nalborczyk
2
Address:
1
Department of Graduate Studies, Canadian Memorial Chiropractic College, Toronto, ON, Canada and
2
Undergraduate Department,
Canadian Memorial Chiropractic College, Toronto, ON, Canada
Email: Gregory J Lehman* - glehman@cmcc.ca; Day Deans Buchan - daisyday7@hotmail.com; Angela Lundy - anglundy@hotmail.com;
Nicole Myers - myersnicole@hotmail.com; Andrea Nalborczyk - andrea_nal@hotmail.com
* Corresponding author
EMGexercisebacklatissimus dorsibiceps brachiirhomboidstrapezius
Abstract
Background: Exercise beliefs abound regarding variations in strength training techniques on
muscle activation levels yet little research has validated these ideas. The purpose of the study is to
determine muscle activation level, expressed as a percent of a normalization contraction, of the
latissimus dorsi, biceps brachii and middle trapezius/rhomboids muscle groups during a series of
different exercise tasks.
Methods: The average muscle activity during four tasks; wide grip pulldown, reverse grip pull
down [RGP], seated row with retracted scapula, and seated rows with non-retracted scapulae was
quantified during two 10 second isometric portions of the four exercises. A repeated measures
ANOVA with post-hoc Tukey test was used to determine the influence of exercise type on muscle
activity for each muscle.
Results & Discussion: No exercise type influenced biceps brachii activity. The highest latissimus
dorsi to biceps ratio of activation occurred during the wide grip pulldown and the seated row.
Highest levels of myoelectric activity in the middle trapezius/rhomboid muscle group occurred
during the seated row. Actively retracting the scapula did not influence middle trapezius/rhomboid
activity.
Conclusion: Variations in latissimus dorsi exercises are capable of producing small changes in the
myoelectric activity of the primary movers.
Background
Working the latissimus dorsi is considered a staple for
most weight training programs. Latissimus dorsi exercises
are advocated to provide muscle balance to chest and
shoulder press exercises. Like many strength training exer-
cises, beliefs persist regarding the influence of exercise var-
iations on muscle recruitment patterns. Anecdotally, two
beliefs assert that using a supinated grip during the per-
formance of a pulldown will preferentially activate the
biceps brachii over the latissimus dorsi when compared to
Published: 30 June 2004
Dynamic Medicine 2004, 3:4 doi:10.1186/1476-5918-3-4
Received: 06 February 2004
Accepted: 30 June 2004
This article is available from: http://www.dynamic-med.com/content/3/1/4
© 2004 Lehman et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all
media for any purpose, provided this notice is preserved along with the article's original URL.
Dynamic Medicine 2004, 3 http://www.dynamic-med.com/content/3/1/4
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the traditionally forward grip anterior pulldown. A second
belief suggests that performance of the seated row
increases activation of the middle trapezius/rhomboids
when compared with the lat pulldown. It has also been
suggested that the seated row performed with scapulae
retraction may alter middle trapezius and rhomboid activ-
ity when compared with no scapular retraction. Little
research has occurred investigating these claims.
Signoreli et al [1] investigated the influence of grip width
and line of pull during the lat pulldown on latissimus
dorsi and other muscle group's electromyographic (EMG)
activity. The authors found that using a pronated wide
grip while pulling anterior to the head resulted in the
greatest myoelectric activity of the latissimus dorsi when
compared to widegrip pulldowns pulled posterior to the
head, pulldowns using a supinated grip and pulldowns
using a close grip. This same trend was also found with the
triceps muscle. The influence of these exercises on biceps
brachii was not investigated.
Scapular retraction is often advocated during the perform-
ance of the seated row. It assumed that this position stabi-
lizes the scapula and facilitates optimal shoulder
movement. Scapula protraction is thought to tilt the gle-
noid fossa forward, influencing stability by tilting the gle-
noid fossa and changing the orientation of the inferior
glenohumeral ligament [2,3]. Protraction of the scapula
with the addition of the anterior load increases the strain
on the inferior glenohumeral ligament [3]. The influence
of scapular protraction on muscle activation patterns is
unknown. One study [4] has investigated the middle tra-
pezius activity during strength training exercises. The
authors found that the one arm row activated the middle
trapezius to 79% of its maximum [4] however, the
authors did not state whether the subject was encouraged
to retract the scapula or allow protraction.
Currently no studies have compared the influence of dif-
ferent shoulder extension/adduction exercises on lattis-
simus dorsi, biceps brachii and middle trapezius/
rhomboid myoelectric activity. This study aims to deter-
mine the influence of forearm supination, angle of pull
and scapula retraction during common latissimus dorsi
exercises on the myoelectric activity of latissimus dorsi,
middle trapezius and biceps brachii.
Methods
Subject Characteristics and Inclusion Criteria
Twelve healthy males (average age (standard deviation)
27.09 years(1.23), average height (SD) 179.08 cm(3.75),
average weight (SD)78.25 kg (5.23)), with greater than 6
months of weight training experience, with out back pain
or upper limb injuries were recruited from a convenience
sample of college students. Subjects signed an informed
consent form approved by the Internal Review Board of
the Canadian Memorial Chiropractic College (CMCC).
Study Protocol
The muscle activation level, expressed as a percentage of a
maximum voluntary contraction (MVC), of the Latis-
simus dorsi (LD), Biceps Brachii (BB) and middle trape-
zius/rhomboid muscle (MTR) groups during a series of
different exercise tasks was quantified. Four different exer-
cise tasks and three normalization procedures occurred
during one test session.
Data Collection Hardware Characteristics
Disposable bipolar Ag-AgCl disc surface electrodes with a
diameter of one cm were adhered bilaterally over the mus-
cle groups with a centre to centre spacing of 2.5 cm. For
the right biceps brachii electrodes were placed on the mid-
dle of the muscle belly when the elbow was flexed at 90
degrees. For the latissimus dorsi, electrodes were placed
one cm lateral to the inferior border of the right scapula.
A pair of electrodes was adhered superiorly to the skin
above the middle trapezius and rhomboid minor between
the spine of the scapula and the 2
nd
thoracic spinous proc-
ess. Raw EMG was amplified between 1000 and 20,000
times depending on the subject. The amplifier had a
CMRR of 10,000:1 (Bortec EMG, Calgary AB, Canada).
Raw EMG was band pass filtered (10 and 1000 Hz) and A/
D converted at 2000 Hz using a National Instruments data
acquisition system and collected using EMG acquisition
software (Delsys, Boston MA).
Normalization task procedure
Three different maximal voluntary contractions for the
three muscle groups studied were collected for each sub-
ject. Subjects performed 1–2 practice MVCs before the col-
lection of EMG. For the latissimus dorsi, subjects were
required to perform a 3 second maximal isometric Lat pull
down against an immovable resistance. For the biceps
brachii subjects were required to perform a maximum iso-
metric bicep curl (i.e. attempted elbow flexion) against an
immoveable object with the arm at 90 degrees of flexion.
The maximum voluntary contraction to recruit the Mid-
dleTrapezius/Rhomboid muscle required the participants
to perform a maximum isometric scapular retraction
against experimenter provided manual resistance. The
muscle activity during the exercise tasks was then subse-
quently expressed as a percentage of the peak activity
found during the previously described normalization
tasks.
Exercise tasks
During all exercises subjects used the same weight on a
standard lat pulldown and seated row pulley machine.
This weight was chosen by the subject based on their per-
ceived ability to perform between 10 and 12 reps until
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failure for the pronated grip lat pulldown. For each exer-
cise, two repetitions of a ten second isometric contraction
were performed. Following each repetition, a three
minute rest occurred. The two repetition protocol was
then repeated for each exercise. The exercises performed
were:
1. Wide grip pull down (WGP): From a seated position
with the thighs restricted, subjects used an overhand grip
on a straight pull down bar at 150% of the bi acromial dis-
tance (BAD). The weight was pulled into an isometric
position with the arms at 90 degrees of shoulder flexion
and elbow flexion. (Essentially a bar position which finds
the bar 1–2 inches above eye level). Subjects held this
position for 10 seconds.
2. Reverse grip pull down (RGP): From a seated position
with thighs fixed subjects used an underhand grip on a
straight bar at 100% BAD. The isometric contraction was
held at a position with 90 degrees of shoulder forward
flexion and 90 degrees of elbow flexion (Essentially a bar
position which finds the bar 1–2 inches above eye level)
3. Seated row, shoulders retracted (SRR): Subjects started
from a seated position, arms extended with forearms at a
mid pronated position 6 inches apart. The participants
pulled the weight to a position where the shoulder was at
0 degrees of flexion and 90 degrees of elbow flexion with
maximal scapular retraction. During the isometric portion
of the exercise, the subject was asked to approximate the
shoulder blades (Retraction).
4. Seated Row, shoulders slack (SRR): Subjects performed
the same movement as exercise #3 however the subject
was instructed to allow the scapula to roll forward during
the isometric hold portion of the exercise.
During all of these exercises the isometric portion (the
portion that was analysed) was preceded by a concentric
contraction that positioned the subjects arm and then fol-
lowed by an eccentric contraction where the participant
lowered the weight to the stack.
EMG Processing and data analysis
The root mean square (sliding window of 128 ms with an
overlap of 64 ms) of the raw EMG during each exercise
task and the normalization tasks was calculated using an
EMG analysis software package (Delsys, Boston USA). The
average activity was then calculated for the middle two
seconds of the isometric portion of each exercise and rep-
etition. The average of the two repetitions for each exercise
was then calculated for each subject and presented as a
percentage of the maximum activity found during the nor-
malization tasks.
Statistical Analysis
Separate repeated-measures ANOVA with post-hoc Tukey
tests were then used to determine the influence of exercise
type on muscle activity within the latissimus dorsi, biceps
brachii and middle trapezius/rhomboids.
Results
Table 1 shows the average activity found for each muscle
for the four different exercise tasks. The latissimus dorsi
musle activity was higher during the seated row with a
protracted scapulae than the activity found during a wide
grip pulldown and a reverse grip pulldown. The level of
protraction/retraction did not influence latissimus dorsi
activity during the seated row exercise. The level of fore-
arm supination had no influence on latissimus dorsi
activity during the pulldown exercise. Biceps brachii mus-
cle activity was the same across exercises.
Table 1: Average myoelectric activity (expressed as %MVC) for each muscle studied across 4 different shoulder extension exercises.
Muscle Exercise Performed
Pulldown
1
Reverse
2
Slack SR
3
Retract SR
4
Lats 26.23 [10.1] 22.37 [9.1] 30.10 [14.9] 37.08 [14.04]
Diff From*: 3 3 1,2 -
Biceps 15.20 [8.05] 19.89 [6.8] 18.21 [7.1] 19.92 [10.7]
Diff from----
MTR 22.72 [11.5] 20.51 [10.9] 29.77 [11.6] 35.50 [17.6]
Diff from:- 32-
Ratio Lats:Biceps 175.22 [84.4] 111.48 [53.2] 156.31 [81.0] 186.48 [96.0]
Diff from: 2 1,3 2 -
*This row indicates which exercise [denoted by a superscripted column number [i.e 1 = pulldown exercise] results in statistically significant [p <
.05] muscle activity. This only compares across columns [different exercises] for the same muscle group. It doesn't compare different muscle
groups within an exercise. Lats=Latissimus Dorsi, Biceps = Biceps Brachii, Ratio Lats:Biceps is the average muscle activation ratio between the
latissimus dorsi and biceps brachii for each exercise tested. Pulldown = pronated grip pulldown, Reverse = Supinated grip pulldown, Slack = Seated
row allowing scapulae protraction, Retract = Seated row with encouragement to retract the scapulae
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During the seated row the act of retracting the scapula did
not influence middle trapezius/rhomboid muscle activity.
However, performing the seated row with the scapula not
retracted resulted in an increased myoelectric activity
when compared with the reverse grip pulldown. A trend
also existed for increased activity in the middle trapezius/
rhomboids during the seated row with retraction
although this was not statistically significant.
Significant differences were found when comparing the
ratio between Latissimus Dorsi activity and Biceps Brachii
activity across exercises. This ratio is the average ratio for
each subject not the ratio of the group average. The wide
grip lat pulldown had a siginificantly higher ratio than the
reverse grip lat pulldown, as did the seated row with pro-
tracted scapula. A large variability was seen across
subjects.
Discussion
The belief that a wide grip during the lat pulldown prefer-
entially recruits the latissimus dorsi over the biceps bra-
chii does not appear to be supported. Conversely, a
supinated grip does not appear to preferentially activate
the biceps. However, there was a statistically significant
change in the latissimus dorsi: biceps brachii ratio
between the two pulldown exercises. The statistically sig-
nificant change in the latissimus dorsi to biceps ratio
occurred because of the slight non-statistically significant
decrease in latissimus dorsi activity when changing from
the wide grip to the reverse grip position of the lat pull-
down being coupled with the slight non-statistically sig-
nificant increase in biceps activity when changing from
the wide grip to the reverse grip lat pulldown exercise.
These results suggest that slight changes occur when
changing grip position but these changes are small and
may have no weight training significance. To state, as
many clinicians and personal trainers do, that the wide
grip pulldown preferentially trains the back and the close
grip supinated pulldown preferentially trains the biceps is
unsupported. While not investigated in this study, differ-
ences in strength between the exercises may be due to the
different mechanical advantages/disadvantages of one
exercise or possibly to differences in the recruitment levels
of the forearm flexors which may be most affected by grip
position. Additionally, it appeared that the seated row
slightly increased Latissimus Dorsi activity without
decreasing Biceps Brachii activity as seen by no difference
in the Latissimus Dorsi:Biceps Brachii ratio when com-
pared with the wide grip lat pulldown. A related limita-
tion to this study is that only one portion of the latissimus
dorsi was studied. Previous research has demonstrated
that functional differentiation within the latissimus dorsi
exists [5]. However, this study investigated different exer-
cises, it is possible that the muscle activation of the Latis-
simus Dorsi in our current study merely shifted to another
portion of the muscle group when moving from the wide
grip lat pulldown to the reverse grip or seated row. This
deserves further study.
A second aim of the study was to determine the influence
of scapula retraction during the seated row on Middle Tra-
pezius/Rhomboids activity. While the seated row exercise
did recruit the Middle Trapezius/Rhomboid to a greater
extent than either lat pulldown exercises, actively retract-
ing the scapula did not result in an increase activity of the
Middle Trapezius/Rhomboids. This suggests that the Mid-
dle Trapezius/Rhomboids is active regardless of the posi-
tion of the scapulae or another muscle functions to cause
scapula retraction. It is possible that deep fibres of the
rhomboid may become more active during the scapula
retraction and this increased activity was not picked up by
the electrodes or the lower trapezius may function to
cause scapula retraction. The lower trapezius has been
shown to be recruited to 74% MVC during shoulder hori-
zontal extension [4].
A limitation of the study is related to the different amount
of weight lifted by each subject. Participants were asked to
choose a weight where they would experience muscle fail-
ure between 10–12 repetitions. Ten to twelve repetitions
was chosen because this represents what is commonly
done during many strength training programs. However,
at this repetition level, the participant's muscle activity
was often less than 30–40 % of the MVC. The moderately
low level of muscle activity (30–40% MVC) during this
repetition level suggests that large fast twitch fibres (Type
II) may not be recruited during this exertion level, espe-
cially if fatigue and the associated Type II fibre recruitment
is not achieved. Having participants choose their weight
for repetitions suggest they may be cautious and underes-
timate their capabilities. This may carry over to strength
training individuals who may underestimate their
strength and lift loads at a less than optimum level for
recruiting large muscle fibres.
Additionally, it is unknown whether the changes in mus-
cle activation ratios between the latissimus dorsi and
biceps brachii occurs at higher levels of muscle activation.
Recruitment may be different near maximum exertion lev-
els. It is possible that one muscle may achieve fatigue and
maximum activation while the other does not achieve
fatigue and is not maximally stressed. It is unknown
whether it is the biceps or latissimus dorsi that is the lim-
iting factor during the performance of the lat pulldown or
seated row.
Conclusion
The wide grip lat pulldown demonstrated a small but
non-significant increase in the activity of the latissimus
dorsi compared with the supinated grip pulldown. This
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Dynamic Medicine 2004, 3 http://www.dynamic-med.com/content/3/1/4
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same small increase is seen in biceps muscle when using a
supinated grip versus the wide grip during the lat pull-
down. Due to the small changes in muscle activity there
appears to be very little difference in muscle activity
between the wide grip lat pulldown and the supinated
grip lat pulldown for the biceps and latissimus dorsi
muscles.
Additionally, the seated row while recruiting the latis-
simus dorsi and biceps brachii more or equally effectively
as the lat pulldown also recruits the middle trapezius/
rhomboid muscle group to a greater extent. Actively
retracting the scapula does not appear to increase activa-
tion levels of the middle trapezius/rhomboid muscle
group. However, from previous research this position
does appear to provide superior shoulder stability.
References
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ical Investigation of Muscle Utilization Patterns Using Vari-
ous Hand Positions During the Lat Pull-down. Journal of
Strength and Conditioning Research 2002, 16:539-546.
2. Itoi E, Motzkin NE, Morrey BF: Scapular inclination and inferior
stability of the shoulder. J Shoulder Elbow Surg 1992, 1:131-139.
3. William M, Weiser MD, Thay Q Lee, William C, McMaster MD,
Patrick J, McMahon MD: Effects of Simulated Scapular Protrac-
tion on Anterior Glenohumeral Stability. The American Journal
of Sports Medicine 1999, 27:801-805.
4. Ekstrom RA, Donatelli RA, Soderberg GL: Surface electromyo-
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anterior muscles. J Orthop Sports Phys Ther 2003, 33:247-258.
5. Paton ME, Brown JM: Functional differentiation within latis-
simus dorsi. Electromyogr Clin Neurophysiol 1995, 35:301-309.
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... In addition, another diference that may explain such discrepancies is the diferent MJ exercise performed, because we used a pull-down exercise, whereas Soares et al. [13] used a seated row. The row exercises appear to have a lower biceps brachii to latissimus dorsi ratio of muscle activation when compared to pull-downs [23], which could result in a lower strength decrease after exercise when compared to a SJ exercise. Therefore, the present results should not be extrapolated to compare other MJ and SJ exercises than those used in the present study. ...
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