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Asian J Sports Med. 2015 March; 6(1): e24057. DOI: 10.5812/asjsm.24057
Published online 2015 March 22. Research Article
Single vs. Multi-Joint Resistance Exercises: Effects on Muscle Strength and
Hypertrophy
Paulo Gentil 1,*; Saulo Soares 1; Martim Bottaro 1
1Department of Physical Education, University of Brasilia, Brasilia, Brazil
*Corresponding author: Paulo Gentil, Department of Physical Education, University of Brasilia, Brasilia, Brazil, Tel: +55-613202-4731, E-mail: paulogentil@hotmail.com
Received: October 4, 2014; Accepted: October 4, 2014
Background: Some authors suggest that single joint (SJ) exercises promote greater muscle hypertrophy because they are easier to be
learned and therefore have less reliance on neural factors. On the other hand, some authors recommend an emphasis on multi-joint (MJ)
exercises for maximizing muscle strength, assuming that MJ exercises are more effective than SJ exercises because they enable a greater
magnitude of weight to be lifted.
Objectives: The present study aimed to compare the effects of MJ vs. SJ exercises on muscle size and strength gains in untrained young
men.
Patients and Methods: Twenty-nine young men, without prior resistance training experience, were randomly divided into two groups.
One group performed (n = 14) only MJ exercises involving the elbow flexors (lat. pull downs), while the other (n = 15) trained the elbow
flexors muscles using only SJ exercises (biceps curls). Both groups trained twice a week for a period of ten weeks. The volunteers were
evaluated for peak torque of elbow flexors (PT) in an isokinetic dynamometer and for muscle thickness (MT) by ultrasonography.
Results: There were significant increases in MT of 6.10% and 5.83% for MJ and SJ, respectively; and there were also significant increases in PT
for MJ (10.40%) and SJ (11.87%). However, the results showed no difference between groups pre or post training for MT or PT.
Conclusions: In conclusion, the results of the present study suggest that MJ and SJ exercises are equally effective for promoting increases
in upper body muscle strength and size in untrained men. Therefore, the selection between SJ and MJ exercises should be based on
individual and practical aspects, such as, equipment availability, movement specificity, individual preferences and time commitment.
Keywords:Resistance Training; Ultrasonography; Muscles; Hypertrophy
Copyright © 2015, Sports Medicine Research Center. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommer-
cial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages,
provided the original work is properly cited.
1. Background
Resistance training (RT) has been recommended by
many authors and scientists as an important compo-
nent of physical activity programs, specifically because
of its capacity to promote increases in muscle size and
strength (1-3). However, in order to ensure optimal re-
sults, the design of RT programs should be based on sci-
entific principles that consider the manipulation and
combination of several variables, such as rest interval,
movement velocity, training load, number of sets and ex-
ercise selection (3, 4). Although exercise selection is one
of the most questioned variables, it has received surpris-
ingly little attention by the scientific community.
In general, it is common to classify resistance exercises
as multi-joint (MJ) or single-joint (SJ), depending on how
many joints are involved in the movement. Some authors
suggest that SJ exercises promote greater muscle hyper-
trophy because they are easier to be learned and there-
fore have less reliance on neural factors than MJ exer-
cises (5, 6). On the other hand, some authors recommend
an emphasis on MJ exercises for maximizing muscle
strength, assuming that MJ exercises are more effective
than SJ exercises because they enable a greater magni-
tude of weight to be lifted (1, 3). However, evidences for
these claims are limited because of the lack of studies
comparing muscle hypertrophy and strength gains be-
tween SJ and MJ exercises, which make it difficult to cor-
rectly choose an exercise when designing a RT program.
A study of Giannakopoulos et al. (7) compared the ef-
fects of SJ and MJ exercises on shoulder cuff muscular
performance and reported greater increases in internal
and external rotation peak torque for the MJ group. How-
ever, the SJ group performed a lower number of sets and
at a lower intensity, which may limit the comparisons.
A previous study investigated the effects of adding SJ
exercises to a MJ protocol on muscle size and strength
of young men and reported no differences in changes
of elbow flexors’ muscle strength and size between the
groups that performed only MJ and the group that per-
formed MJ + SJ (8). However, since there was not a group
performing only SJ exercises, the study may be valuable
for analyzing training volume rather than exercise selec-
tion and the question remains whether an RT program
with only SJ exercise would be as efficient as a program
involving only MJ exercises.
Gentil P et al.
Asian J Sports Med. 2015;6(1):e240572
2. Objectives
Due to the importance of adequate exercise selection
for the design of effective RT programs and the lack of
studies comparing the chronic effects of SJ and MJ exer-
cises, the purpose of the present study was to compare
the effects of MJ and SJ exercises on the gains of muscle
size and strength of the elbow flexors in untrained young
men. Our hypothesis is that there is no difference in mus-
cle adaptations between the groups that perform MJ and
SJ exercises.
3. Patients and Methods
3.1. Experimental Procedures
Twenty-nine college aged young men, without prior
resistance training experience, were randomly divided
into two groups. One group performed only MJ exercises
(lat. pull downs) involving the elbow flexors, while the
other group trained the elbow flexor muscles using only
SJ exercises (arm curls). Both groups trained twice a week
with at least 48 hours between training sessions, for a
period of ten weeks. All exercises were carried out with
three sets of eight to 12 maximum repetitions (3). The vol-
unteers were evaluated for peak torque of elbow flexors
(PT) in an isokinetic dynamometer and for muscle thick-
ness (MT) by ultrasonography.
3.2. Participants
Thirty-four young men volunteered for the study. The
volunteers were recruited through folders and advertis-
ing banners around the university campus. To be accept-
ed, participants should be at least 18 years of age, have not
been participating in any resistance training program
over the past six months and be free of health problems
that could be aggravated by the experimental proce-
dures. To be included in the analysis, the participants
had to attend at least 80% of the training sessions (9).
The volunteers were instructed to not change their nu-
tritional habits and, if any relevant change was detected
(e.g. becoming a vegetarian, being on caloric restriction,
use of nutritional supplements or ergogenic substances,
etc.) the data of the participants were excluded from the
analysis. Data of five volunteers were excluded for failing
to meet the inclusion criteria, the exclusions occurred
due to low attendance (2), low adhesion to training pro-
tocol (2) and changes in nutritional habits (1). The charac-
teristics of the excluded participants did not differ from
the others. All volunteers were notified about the experi-
mental procedures, benefits and risks before signing the
informed consent form. An Institutional Research Ethics
Committee granted approval for the study.
3.3. Muscle Thickness
In the present study MT was assessed by an ultrasound
equipment. Ultrasound is a quick, reliable and cost-effec-
tive method to measure muscle size (10, 11). Participants
were tested before and after the 10-week training period
for MT of the elbow flexors of the right arm. All tests were
conducted at the same time of the day, and participants
were instructed to hydrate normally 24 hours before the
tests. Measures were taken 3 - 5 days after the last train-
ing session to prevent any swelling from contributing to
the MT measurement (12). During this time, participants
were oriented not to participate in any other exercise ses-
sions or intense activity involving the upper body. MT was
measured at 10 cm from the cubital fossa using B-Mode
ultrasound (Philips-VMI, Ultra Vision Flip, model BF). A
water soluble transmission gel was applied to the mea-
surement site and a 7.5 MHz ultrasound probe was placed
perpendicular to the tissue interface while not depress-
ing the skin. Once the technician was satisfied with the
quality of the image produced, the image on the monitor
was frozen. With the image frozen, a cursor was enabled
in order to measure MT, which was taken as the distance
from the subcutaneous adipose tissue-muscle interface
to muscle-bone interface (13). A trained technician per-
formed all analyses (14). The coefficients of variation for
elbow flexor MTs were less than 3.0%. Baseline test and
retest intraclass correlation coefficient (ICC) for elbow
flexors MT was 0.95.
3.4. Peak Torque
The concentric PT of the dominant arm’s elbow flexors
was tested on an isokinetic dynamometer Biodex System
3 (Biodex Medical, Inc., Shirley, NY) with two sets of four
repetitions at 60° s-1, and 60 seconds rest interval be-
tween sets. According to Feiereisen et al. (15), isokinetic
measurements should be preferentially used to evaluate
strength gains and limit bias between measurements
at different times. Calibration of the dynamometer was
performed before each testing session according to the
manufacturer’s specifications. Participants were seated
with their elbow on a Scott bench and aligned with the
axis of rotation of the dynamometer’s lever arm. The fore-
arm remained in a supinated position throughout the
test. Verbal encouragement was given throughout the
test, and all tests were administered by the same inves-
tigator. Baseline test and retest ICC and standard error of
the mean values for PT were 0.96 and 2.4%, respectively.
3.5. Resistance Training Protocol
Participants were randomly assigned to two groups.
The MJ group performed leg press, knee flexion; bench
press and lat. pull down. The SJ group also performed
leg press, knee flexion and bench press but, instead of
lat. pull down, they performed standing barbell biceps
curls. The lat. pull down was performed with a pronated
wide grip as defined previously by Lusk et al. (16) and no
specific instructions were given on how to emphasize
the latissimus dorsi or the biceps brachii. The standing
Gentil P et al.
3
Asian J Sports Med. 2015;6(1):e24057
barbell biceps curls was performed at a shoulder-width
supinated grip.
Training protocols followed the recommendations of
the American College of Sports and Medicine (3). All exer-
cises were performed with three sets of 8 - 12 maximum
repetitions (RM). Subjects were instructed to perform
the concentric and eccentric phases each in two seconds,
without pause between them. During the training ses-
sions, music tracks with 120 bpm were played in order to
facilitate control of movement speed. Participants were
oriented to perform all sets until concentric failure. If
necessary, loads were adjusted from set to set to main-
tain the designated number of repetitions. Training ses-
sions were closely supervised by experienced trainers,
because previous research has demonstrated greater
gains in supervised vs. unsupervised training (17). Train-
ing was conducted two days a week, with a minimum of
48 hours between sessions. Rest interval between sets
ranged from 1.5 to 2.5 minutes. Each participant filled
a training log for each workout, containing the loads
used, the number of repetitions performed in each set
and any relevant information (illness, pain, sleep depri-
vation), and all training logs were verified by a supervi-
sor following each exercise session.
3.6. Statistical Analysis
All values were reported as means and standard devia-
tions. Two way ANOVA 2 x 2 (group by time) with a be-
tween-within design was used to compare means. When
necessary, multiple comparisons with confidence inter-
vals adjusted by the Bonferroni procedure were used for
post hoc analysis. The significance level was established
as P ≤ 0.05. The statistical program SPSS version 16.0 was
used for statistical analysis.
4. Results
The characteristics of participants are presented in
Table 1. Table 2 presents the values of MT and PT pre and
post training. The ANOVA found no statistically signifi-
cant difference (P > 0.05) between groups pre or post
training for MT or PT. However, with respect to time (pre
vs. post), there were significant increases in MT of 6.10%
and 5.83% for MJ and SJ, respectively (P ≤ 0.05). PT also
significantly increases for MJ (10.40%, P ≤ 0.05) and SJ
(11.87%, P ≤ 0.05).
Table 1. Characteristics of the Subjects a
Variable Multi Joint
Group (n = 14)
Single Joint
Group (n = 15)
Age, y 23.4 ± 2.6 22.4 ± 2.1
Body weight, kg 73.1 ± 13.6 69.3 ± 5.8
Height, cm 171.9 ± 8.2 175.8 ± 5.9
a Data are presented as Mean ± SD.
Table 2. Muscle Thickness and Peak Torque Before and After 10
Weeks of Training a
Variable Multi Joint
Group
Single Joint
Group
Muscle thickness,
mm
Pre-training 31.80 ± 3.76 28.79 ± 2.76
Post-training 33.74 ± 3.40 b30.47 ± 4.67 b
Delta 6.10 5.83%
Peak Torque, N m
Pre-training 49.26 ± 9.49 49.69 ± 10.50
Post-training 54.38 ± 10.08 b55.59 ± 10.61 b
Delta 10.40 11.87
a Data are presented as Mean ± SD or %.
b P < 0.05, post vs. Pre.
5. Discussion
The major find of the present study was that there is
no significant difference on elbow flexor strength gains
and hypertrophy between MJ and SJ exercise. Exercise
selection is a crucial step when designing RT programs.
However, there are many controversies when choosing
an exercise, especially when deciding between SJ or MJ
exercises. Some authors suggest that SJ exercises would
promote greater increases in muscle size, because they
would have less reliance on neural factors (5, 6). On the
other hand, some authors (1, 3) suggest that MJ exercises
are more effective because they enable a greater mag-
nitude of weight to be lifted. This leads some people to
prefer SJ exercises while others give preference to MJ exer-
cises. However, the controversy remains because studies
comparing the chronic effects of MJ and SJ exercises on
strength gains and muscle hypertrophy are scarce.
In a previous study, Chilibeck et al. (6) reported that
the lean mass in the upper-body of women performing
RT increases more than in the lower-body. The authors
suggested that the more prolonged neural adaptation re-
lated to the more complex leg press exercise may have de-
layed muscle hypertrophy in the legs, while the arm curl
exercise promoted higher muscle hypertrophy due to
faster neural adaptation. However, the training program
also contained SJ exercises for the legs (knee extension
and knee flexion), as well as, MJ exercises that involved
the arms (bench press and lat. pull downs). Therefore, it
is not possible to make a direct comparison between SJ
and MJ exercises.
Recently, Gentil et al. (8) examined the effect of add-
ing SJ exercises to a MJ exercise program on upper body
muscle size and strength of young men. In the study, one
group performed only upper body MJ exercises (lat. pull
down and bench press) while the other performed the
same MJ exercises plus SJ exercises (elbow flexion and el-
bow extension). According to the results, there were no
differences in muscle size and strength gains between
Gentil P et al.
Asian J Sports Med. 2015;6(1):e240574
groups. However, since there was not a group that per-
formed only SJ exercises, the question remains whether
an RT program with only SJ exercise would be as efficient
as a program involving only MJ exercises.
We did not find studies comparing muscle hypertro-
phy responses between SJ and MJ exercises. One of the
few studies to compare the chronic effects of MJ and SJ
exercises on muscle performance was the study of Gi-
annakopoulos et al. (7) that analyzed the effects of two
training modes on shoulder cuff muscular performance.
The participants of the study were divided into 3 groups:
one group performed SJ exercises (internal and external
shoulder rotation using 2 kg dumbbells); one trained
with MJ exercises (lat. pull down, overhead press, reverse
pull up and push-up exercises); and the other had no
training. According to the results, the group that trained
with MJ exercises achieved greater increases in internal
and external rotation peak torque than the groups that
trained with SJ exercises.
Comparison between our study and the study of Gi-
annakopoulos et al. (7) are limited due to methodologi-
cal differences, and the difference between the results is
probably due to the differences in training volume and
intensity between protocols. In the study of Giannako-
poulos et al. (7) the SJ group performed a lower number of
sets compared to the MJ group. Additionally, the SJ group
trained at a constant load, with no load progression,
which may have limited the results. In the present study
the SJ and MJ groups performed an equal number of sets
of progressive resistance training and both trained with
maximal repetitions.
The results of the present study on muscle hypertro-
phy are unique and important for practical purposes.
Increase or maintaining muscle mass is an important
goal for health, fitness and performance. It has been
shown that muscle hypertrophy is dependent on the me-
chanical tension, muscle damage and metabolic stress
produced by the strength exercise (18, 19). Thus, accord-
ing to the results of the present study we may presume
that muscle strain and muscle damage caused by the MJ
and SJ exercise for the EF muscles was somewhat similar.
However, one of the limitations of the present study was
that the mechanisms involved in muscle hypertrophy
between MJ and SJ exercise were not evaluated. Further-
more, the finding that MJ exercises are as efficient as SJ in
muscle hypertrophy and strength may be valuable when
designing an RT program. In order to save time, strength
and conditioning, specialists can choose exercises that
target a higher number of muscle groups at a time. This
strategy can increase training volume and reduce the
time commitment, which, in turn, may improve exercise
adherence since lack of time is the most cited barrier for
an individual engaging in any exercise program (20-23).
The results of the present study shows that MJ and SJ
exercises are equally effective for promoting increases
in muscle strength and size in untrained men, confirm-
ing our hypothesis. It is well established that muscles in-
terpret environmental stimuli through mechanical and
metabolic changes (18, 19, 24-26) and it seems that these
responses will not differ if the movement is performed
alone (biceps curl, which involves only elbow flexion) or
accompanied by the movement of another joints (lat.
pull down, which involves elbow flexion and shoulder ex-
tension). Based on the present results, it can be suggested
that the selection between SJ and MJ exercises should be
based on individual and practical aspects, such as equip-
ment availability, individual preferences, movement
specificity, time commitment etc. Further studies are
required to test if the results will be the same in trained
people and other muscle groups.
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