Comparison among the EMG Activity of the Anterior Deltoid and Medial Deltoid During Two Variations of Dumbbell Shoulder Press Exercise

Abstract

Objective: To analyze the muscle activation of anterior and medial deltoid muscles while performing two different grip variations of dumbbell shoulder press. Methodology: Ten healthy male participants (age = 20.9 ± 1.449 years, height = 1.71 ± .038 m, weight=69.65 ± 2.92 kg) from Lakshmi Bai National Institute of Physical Education (Gwalior, M.P, India) were recruited as a sample of the study. The participants performed 5 repetitions of two different grip variations of dumbbell shoulder press. The exercises were Arnold Dumbbell Press (ADP) and Overhead Dumbbell Press (ODP). Surface Electromyography (SEMG) was used to record the muscle activation and for measuring muscle electrical activity that occurs during muscle contraction. Results: Paired t–test was used to detect mean differences between the two variations of dumbbell shoulder press. It was found that Anterior and Medial Deltoid muscles were more active while performing ADP (AD-1346.4292.495; MD – 827.5 146.426) as compared to ODP (AD - 1043.4 141.299; MD – 725.4 100.4). Also while performing both the exercises, the muscle activation of anterior deltoid was found to be much higher than Medial Deltoid. Conclusions: Arnold dumbbell press was more effective exercise for the activation of Anterior and Medial deltoid muscles as compared to the Overhead Dumbbell Press. Anterior deltoid acts as primary muscle while performing both the exercises, as the muscle activation is much higher as compared to medial deltoid. © 2017, Indian Journal of Public Health Research and Development. All rights reserved.

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Comparison among the EMG Activity of the Anterior Deltoid
and Medial Deltoid During Two Variations of Dumbbell
Shoulder Press Exercise
Shiny Raizada1, Amritashish Bagchi2
1Assistant Professor, Department of Physical Education, Santa Cruz East, Mumbai, India;
2Assistant Professor, Symbiosis School of Sports Sciences,
Symbiosis International University, Lavale, Pune, India
ABSTRACT
Objective: To analyze the muscle activation of anterior and medial deltoid muscles while performing two
dierentgripvariationsofdumbbellshoulderpress.
Methodology:Tenhealthymaleparticipants (age=20.9± 1.449years,height= 1.71 ±.038m,weight
=69.65±2.92kg)fromLakshmiBaiNationalInstituteofPhysicalEducation(Gwalior,M.P,India)were
recruitedasasampleofthestudy.Theparticipantsperformed5repetitionsoftwodierentgripvariationsof
dumbbellshoulderpress.TheexerciseswereArnoldDumbbellPress(ADP)andOverheadDumbbellPress
(ODP).SurfaceElectromyography(SEMG) wasusedto recordthemuscleactivation andformeasuring
muscle electrical activity that occurs during muscle contraction.
Results:Pairedt–testwasusedtodetectmeandierencesbetweenthetwovariationsofdumbbellshoulder
press.ItwasfoundthatAnteriorandMedialDeltoidmusclesweremoreactivewhileperformingADP(AD-
1346.4292.495;MD–827.5146.426)ascomparedtoODP(AD-1043.4141.299;MD–725.4100.4).
Alsowhileperformingboththeexercises,themuscleactivationofanteriordeltoidwasfoundtobemuch
higher than Medial Deltoid.
Conclusions:ArnolddumbbellpresswasmoreeectiveexercisefortheactivationofAnteriorandMedial
deltoidmusclesascomparedtotheOverheadDumbbellPress.Anteriordeltoidactsasprimarymusclewhile
performingboththeexercises,asthemuscleactivationismuchhigherascomparedtomedialdeltoid.
Keywords: Anterior Deltoid, Dumbbell shoulder press, Electromyography, Medial Deltoid and Muscle
activation
INTRODUCTION
The shoulders are used in many daily life activities
and it’s a key to many full-bodied movements. The
shoulder muscles always come into play while throwing,
pushing, pulling or lifting1.
Deltoids are the most important muscles of the
shoulders to produce shoulder joint movements.
Anatomically deltoids are divided into three dierent
portions: anterior, medial and posterior. For developing
itsstrength,eachportioncanbeworkedseparately.Each
oftheseportionshasadierentroleofplay.Theanterior
deltoids plays dominant role in lifting the arms forward,
similarly the middle deltoids lift the arms sideways and
theposteriordeltoidsliftthearmsbackward.
Symmetrical development of each portion of the deltoids
canbeassuredbytheuseofindividualexercisesthatcan
beaccomplishedwiththeuseofdumbbells.Thestrength,
protection against shoulder injury, and a powerful upper
bodyforparticipationinsportsaresomeofthebenets
of well-developed deltoid2.
Thedumbbellshoulderpressisoneofthepopular
exercises for the shoulders. While doing vertical press,
dumbbellsaretheperfecttoolforaseveralreasons.In
dumbbellshoulderpresstheweightispressedupwards,
it allows the Gleno-humeral joint to follow a natural
path, which is well suited to the anatomy of the shoulder.
As compare to dumbbell press, in barbell Press the
movementoftheshoulderislimitedbythatoftheother
shoulderandthe placementofthe bar3.Thedumbbell
DOI Number: 10.5958/0976-5506.2017.00411.9

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shoulder press is also more eective for producing
shoulder muscles hypertrophy. Dumbbells allow more
freedom as compare to barbells but it also requires
coordination. As compare to barbell, during the last
phaseof thepress, dumbbellsallow thearms tocome
closer that result in greater range of motion4. A twisting
variationoftheoverheaddumbbellshoulderpress(also
knownasbasicshoulderpress)istheArnolddumbbell
press. During this press, the range of motion increases at
thestartingpositionof thedumbbells,withoutaltering
the target muscles. The target muscles for both i.e.
overhead shoulder press and the Arnold press are the
front and side shoulder muscles5. Choosing the best
exercise for developing the shoulder becomes really
dicult due to the dierent portions of the shoulder
muscles.Oneway to determinethisisbycheckingthe
level of muscle activation associated with a particular
exercise,throughtheuseofelectromyography(EMG).
Electromyography measures the electrical activity
of the muscles tissues during muscle contraction and
relaxation cycles. Apart from rehabilitation it is also
used in many sports techniques and is an essential
tool in physiological, biomechanical and biomedical
assessments for performance enhancement in sports6,7,8,9.
The purpose of the study was to analyze the muscle
activity of anterior and medial deltoid during two
dierentgripvariationsofdumbbellshoulderpress.
METHODOLOGY
Subjects:Tenhealthy maleparticipants (age= 20.9±
1.449years, height =1.71 ±.038 m,weight =69.65±
2.92kg)fromLakshmibaiNationalInstituteofPhysical
Education (Gwalior, M.P, India) were recruited as a
sample to be included in the study. More specically,
each subject met our stringent requirement of at least
1yearofexperienceintheirregular(i.e.atleastthrice
a week) weight training programs. Simple Random
Sampling technique was used for the selection of the
subjects. All subjects were free from injuries which
wouldhavelimitedtheirabilitytoperformthetechnique
correctly.Eachsubjectprovidedinformedconsentprior
to participation in any testing procedures.
Experimental Approach to the Problem: To compare
theEMGresponsebetweenthetwovariationofDumbbell
ShoulderPress(DSP),subjectsperformed5repetitionof
ArnoldDumbbellPress(ADP)andOverheadDumbbell
Press(ODP),withsurfaceelectrodespositionedoverthe
2muscle(i.e.AnteriorDeltoid;ADandMedialDeltoid;
MD).Afamiliarizationsessionwascarriedout2weeks
beforetesting for knowing 10 RM of thesubjects. At
thebeginningofthesession,thesubjectswereaskedto
warmup(jogging)for3–5minutes.Their10repetition
maximum(10RM)wasdeterminedbyhavingthesubjects
liftapproximatelythreetove sets ofeachexerciseat
increasing loads until they reach their maximum load for
10 repetitions. They were allowed to rest for 5 minutes
between the sets, or until they felt suciently rested,
andthentheywereaskedtorepeattheabovesteps(after
twodays)fordetermining10RM,thistimeperforming
theothervariation.SurfaceElectroMyoGraphy(SEMG)
was used for measuring muscle electrical activity that
occurs during muscle contraction and relaxation cycles.
The SEMG signal generated by the muscle bers is
capturedby the electrodes, thenamplied and ltered
bythesensorbeforebeingconvertedtoadigitalsignal
bythe encoder.It isthen sent (by optical ber) to the
computer to be processed, displayed and recorded by
theInnitisoftware.TheMyoScan-Pro sensor’sactive
range is from 20 to 500 Hz. It can record SEMG signals
of up to 1600 microvolts (μV), RMS. A/D Converter
(Encoder;ProCompInniti)has 2channels(C and D)
samplingat256samplespersecond.
Data collection:Biographinnityversion5.0wasusedto
record muscle activation of Anterior and Medial Deltoid.
Before placing the electrodes on the target muscles, an
abrasivecreamwasappliedtothe electrodes.Thenthe
EMGelectrodeswereplacedparalleltothemuscleber
on two locations (i.e. channel C for Anterior Deltoid
and channel D for Medial Deltoid). A 15 foot optic
berwirewasusedforrecordingthemusclesactivation
(RawEMGsignals),whichisdirectlyconnectedtoA/C
encoder. A 20 mega pixels extended video camera was
synchronizedwiththeEMGsoftware(Biographinnity
version5.0),tondoutthemuscleactivationvalueofthe
selected muscles at the time of performing the exercises.
Myoscan-pro sensor with triode electrode was used.
Theparticipantsperformed 5 repetitions(of10RM) of
eachvariationof dumbbellshoulderpress one byone.
Toknowthedierencesbetweenthemusclesactivation
in the Arnold dumbbell press and overhead dumbbell
press,the amountof weightfor theboth theexercises
waskept same. Sucient recovery timewas provided
to the participants after completing each exercise. The
meanvalueof5repetitionswasrecordedasanalscore
foreachsubject.
Statistics: For testing the assumption of normality and
toknowthenatureofdatadierentdescriptivestatistics

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such as mean, standard deviation, skewness, kurtosis,
normalprobability plots andShapiro–Wilk’stestwere
used. All data are presented as mean with standard
deviations. Paired t – test was used to detect mean
dierences between the two variations of dumbbell
shoulder press. For this purpose Statistical Package for
SocialScience(SPSS)version21wasused.Thelevelof
signicancewassetat0.05.
RESULTS AND DISCUSSION
Adeviationfrom symmetry can be indicated,if a
skewness value is more than twice its standard error. As
noneofthevariables’skewnessisgreaterthantwiceits
standarderror,henceallthevariablesaresymmetrically
distributed.Similarly,thevalueofkurtosisforthedata
tobenormalofanyofthevariableisnotmorethantwice
its standard error of kurtosis hence none of the kurtosis
valuesaresignicant.Inotherwords,thedistributionof
allthevariablesismeso-kurtic.
Further for testing the normality Shapiro–Wilks
test was used. It compares the scores in the sample to
anormallydistributedsetofscoreswiththesamemean
andstandard deviation. If the test is non– signicant
(p>.05)ittellsthatthedistributionofthesampleisnot
signicantlydierentfromanormaldistribution(i.e.it
isprobablynormal)and vice–versa.Herefromtable-1
wecanseethatnoneofthevariables’p–valueisless
than.05,hencethedataisnormallydistributed.
Table 1: Descriptive Statistics and Test of Normality
Exercise Arnold Dumbbell Press Vertical Dumbbell Press
Muscles Anterior
Deltoid
Medial
Deltoid
Anterior
Deltoid
Medial
Deltoid
Mean 1346.40 827.50 1043.40 725.40
Std. Error
of Mean 92.495 46.304 44.682 31.751
Std.
Deviation 292.495 146.426 141.299 100.407
Skewness .597 -.581 .223 .194
Std.
Error of
Skewness
.687 .687 .687 .687
Kurtosis -.884 -1.295 -1.932 -.636
Std. Error
of Kurtosis 1.334 1.334 1.334 1.334
Shapiro
– Wilk
(p-value)
.402 .103 .086 .872
Figure 1: Mean and S.D value of muscles activation
(Anterior Deltoid and Medial Deltoid) in Two
Variations of Dumbbell Shoulder Press.
Theabovegureshowsthatthemusclesactivation
ofAnteriorDeltoidandMedialDeltoidmusclesinboth
theexerciseswere notsimilar.ArnoldDumbbell Press
shows greater muscle activation in both Anterior and
Medial Deltoid as compared to Overhead Dumbbell
Press.Tosee whether these dierencesare signicant
pairedt–testwasused.
Table 2: A summary of the paired t - test
Muscles Pair Paired Dierences t Sig. (2-tailed)
Mean Std. Deviation Std. Error Mean
AD ADP-ODP 303 296.5854 93.78853 3.231 0.01
MD ADP-ODP 102.1 105.5256 33.37013 3.06 0.014
ADP AD - MD 518.90 276.98795 87.59128 5.924 .000
ODP AD - MD 318.00 197.72427 62.52591 5.086 .001
*Signicantat0.05level Degreeoffreedom=9
Arnolddumbbellpress found tobebetter exercise
thanoverheaddumbbellpressassignicantdierences
shows higher muscles activation in both the muscles
i.e. anterior and medial deltoid. In case of pairwise
comparison between Anterior and Medial Deltoid
muscleactivationforeachofthetwoexercises(i.e.ADP
&ODP);signicantdierenceswerefoundinanterior
deltoid muscle. This indicates that while performing
ADPandODP,anteriordeltoidactsasprimarymuscle
forboththeexercises,asthemuscleactivationismuch
higher as compared to medial deltoid.

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In the initial position of Arnold dumbbell press
the elbows drop in front of the body, activates the
anterior deltoid muscles to a great extent as compared
to overhead dumbbell press. And as the dumbbell
movesupward,themedialdeltoidsbecomeincreasingly
engagedbutnotuntiltheanteriordeltoidinitiatemostof
the movements10.Duetodierentmovementpatternsor
thepath,theArnolddumbbellpressismoreeectivefor
producingshouldermuscle(ADand MD)hypertrophy
ascomparedtoOverheadDumbbellPress.
CONCLUSION
The purpose of the study was to analyze the muscle
activity of anterior and medial deltoid during two
dierentgripvariationsofdumbbellshoulderpress.Due
togreaterrange ofmotionArnolddumbbellpress was
moreeectiveexercisefortheactivationofAnteriorand
Medial deltoid muscles as compared to the Overhead
DumbbellPress.Whileperformingboththeexercisesit
hasbeenconcludedthatanteriordeltoidmuscleactsasa
primarymuscleasthemusclesactivationissignicantly
higher than the medial deltoid, which means both the
exercises are more eective for developing anterior
deltoid than medial deltoid.
Ethical clearance: No need
Source of funding: Self
Conict of Interest: Nil
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