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European Journal of Sport Science
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/tejs20
Partial range of motion training elicits favorable
improvements in muscular adaptations when
carried out at long muscle lengths
Gustavo F. Pedrosa, Fernando V. Lima, Brad J. Schoenfeld, Lucas T. Lacerda,
Marina G. Simões, Mariano R. Pereira, Rodrigo C.R. Diniz & Mauro H. Chagas
To cite this article: Gustavo F. Pedrosa, Fernando V. Lima, Brad J. Schoenfeld, Lucas T. Lacerda,
Marina G. Simões, Mariano R. Pereira, Rodrigo C.R. Diniz & Mauro H. Chagas (2021): Partial
range of motion training elicits favorable improvements in muscular adaptations when carried out at
long muscle lengths, European Journal of Sport Science, DOI: 10.1080/17461391.2021.1927199
To link to this article: https://doi.org/10.1080/17461391.2021.1927199
View supplementary material Published online: 23 May 2021.
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Partial range of motion training elicits favorable improvements in muscular
adaptations when carried out at long muscle lengths
Gustavo F. Pedrosa
a,b
, Fernando V. Lima
a
, Brad J. Schoenfeld
c
, Lucas T. Lacerda
a,d,e,f
, Marina G. Simões
a
,
Mariano R. Pereira
a
, Rodrigo C.R. Diniz
a
and Mauro H. Chagas
a
a
Weight Training Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Federal University of Minas Gerais, Belo
Horizonte, Brazil;
b
Brazilian Air Force, Aeronautical Instruction and Adaptation Center, Lagoa Santa, Brazil;
c
Department of Health Sciences,
CUNY Lehman College, Bronx, NY, USA;
d
Department of Physical Education and Sports, Technological Education Federal Center of Minas
Gerais, Belo Horizonte, Brazil;
e
Pontifical Catholic University of Minas Gerais, Belo Horizonte, Brazil;
f
State University of Minas Gerais,
Divinópolis, Brazil
ABSTRACT
The study compared changes in strength and regional muscle hypertrophy between different
ranges of motion (ROM) in the knee extension exercise. Forty-five untrained women were
randomized to either a control group or to perform the exercise in one of the following 4
groups (0°=extended knee): Full ROM (FULL
ROM
: 100°−30° of knee flexion); Initial Partial ROM
(INITIAL
ROM
: 100°−65°); Final Partial ROM (FINAL
ROM
: 65°−30°); Varied ROM (VAR
ROM
: daily
alternation between the ROM of INITIAL
ROM
and FINAL
ROM
). Pre- and post-training assessments
included one repetition maximum (1RM) testing in the ROM corresponding to the initial, final
and full ROM, and measurement of cross-sectional areas of the rectus femoris and vastus
lateralis muscles at 40%, 50%, 60% and 70% of femur length in regard to regional muscle
hypertrophy. Results showed that the INITIAL
ROM
group presented a greater relative increase
than all groups at 70%, and at 50% and 60% the increases were greater than FINAL
ROM
,
FULL
ROM
, and non-training control (CON) groups. Moreover, FINAL
ROM
group presented similar
changes compared to the CON group at 60% and 70%. In regard to 1RM, FINAL
ROM
and
INITIAL
ROM
groups presented greater relative increases at the ROM trained, and no group
showed greater increases than VAR
ROM
or INITIAL
ROM
, regardless the ROM tested. In conclusion,
partial ROM training in the initial phase of the knee extension exercise promoted greater
relative hypertrophy in certain muscle regions than training in other ROM configurations, and
no group promoted a greater 1RM increase than VAR
ROM
group, which showed similar 1RM
increases in the different ROMs tested.
KEYWORDS
Muscle hypertrophy;
resistance exercise; partial
range of motion; excursion
Introduction
Regional muscle hypertrophy is an adaptive response to
resistance training that occurs when the size of given
muscle region increases to a greater extent than other
muscle regions (Zabaleta-Korta, Fernández-Peña, &
Santos-Concejero, 2020). It has been speculated that train-
ing in different joint ranges of motion (ROM) may indeed
promote such non-uniform adaptations (Newmire & Wil-
loughby, 2018; Zabaleta-Korta et al., 2020). Studies by
Bloomquistetal.(2013) and McMahon, Morse, Burden,
Winwood, and Onambélé (2014a) demonstrated that train-
ing in a full ROM (FULL
ROM
) elicited greater muscle hyper-
trophy at distal muscle regions than training in the final
partial ROM (FINAL
ROM
:i.e.final half of the angles of a
FULL
ROM
, taking the concentric action as reference). Of
note, both studies observed similar hypertrophic responses
between conditions at the proximal muscle regions. These
findings suggest that training in a FINAL
ROM
preferentially
induces greater muscle hypertrophy at proximal regions
than in other regions, while training with FULL
ROM
equally hypertrophies the muscle across the regions.
However, neither study compared the hypertrophy
responses between muscle regionswithineachtraining
condition, nor did they compare the hypertrophy of
different muscle regions between different muscles.
These inter- and intramuscular analyses would provide
greater insight as to whether, and the extent to which,
ROM may influence a regional hypertrophic response.
The apparent hypertrophic superiority of FULL
ROM
training may be specific to contractions at angles in
which the muscle is elongated (Alegre, Ferri-Morales,
Rodriguez-Casares, & Aguado, 2014; Maeo et al., 2020;
Noorkõiv, Nosaka, & Blazevich, 2014). Previous research
© 2021 European College of Sport Science
CONTACT Mauro H. Chagas mauroufmg@hotmail.com Weight Training Laboratory, School of Physical Education, Physiotherapy and Occupational
Therapy, Federal University of Minas Gerais, Av. Antônio Carlos, 6627, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil
Supplemental data for this article can be accessed https://doi.org/10.1080/17461391.2021.1927199.
EUROPEAN JOURNAL OF SPORT SCIENCE
https://doi.org/10.1080/17461391.2021.1927199
reports greater metabolic stress, IGF-1 release, and acti-
vation of proteins Akt/mTOR and p70S6 K after contrac-
tions at longer vs shorter muscle lengths (McMahon,
Morse, Burden, Winwood, & Onambélé, 2014b; Rindom,
Kristensen, Overgaard, Vissing, & de Paoli, 2019; Russ,
2008), all of which have been associated with muscle
hypertrophy. This raises the possibility that training
exclusively in the initial half of the angles of a FULL
ROM
(INITIAL
ROM
, taking the concentric action as reference),
where the muscle is in a lengthened state, may
promote a hypertrophic response even greater than
training throughout a FULL
ROM
.
Recently, researchers have speculated that training
through a variety of ROMs (VAR
ROM
) may enhance
muscle growth (Schoenfeld & Grgic, 2020). One such
variation strategy could be to alternate between training
with INITIAL
ROM
and FINAL
ROM
from session to session.
This undulating model resembles the muscle length vari-
ations that occur during FULL
ROM
training, but allows the
ability to focus on the individual components of the
ROM which conceivably may enhance muscular adap-
tations. However, this hypothesis has yet to be tested.
ROM also has potential implications for the strength-
related response to resistance training. Consistent with
the principle of specificity (McCafferty & Horvath, 1977),
current evidence indicates greater strength increases are
achieved at the ROM trained (Martínez-Cava et al., 2019;
Pallarés, Cava, Courel-Ibáñez, González-Badillo, & Morán-
Navarro, 2020;Weiss,Fry,Wood,Relyea,&Melton,2000).
For example, Bloomquist et al. (2013) found that training
exclusively in the FINAL
ROM
resulted in a greater strength
increase in the one maximum repetition (1RM) test per-
formed at the ROM trained. Thus, the question remains
as to whether strength gains also would be specificto
the ROM tested when training is performed in the
INITIAL
ROM
. Moreover, it is undetermined as to what
effect using a VAR
ROM
would have on specificstrength
changes over time.
To address the aforementioned gaps in the literature,
the present study aimed to compare the effects of train-
ing with INITIAL
ROM,
FINAL
ROM,
FULL
ROM
, and VAR
ROM
on
regional muscle hypertrophy and the 1RM strength
response performed in different ROMs. In addition, we
aimed to assess the relationship between the strength
increases in different ROMs with the muscle growth in
different muscle regions.
Methods
Overview
Participants equally comprised 4 experimental groups
and 1 control group (CON) over a 12-week study
period. The experimental groups trained in one of 4
different ROM configurations in the knee extension
machine (INITIAL
ROM:,
FINAL
ROM,
FULL
ROM
, and VAR
ROM
)
for 36 training sessions separated by 48–72 h (Figure 1).
To assess regional changes in hypertrophy of the
rectus femoris (RF) and vastus lateralis (VL) muscles,
pre- and post-training measures of muscle cross-sec-
tional area (CSA) were obtained via b-mode ultrasound
at 4 longitudinal regions along the femur (40%, 50%,
60%, and 70% of femur length). Changes in dynamic
muscular strength were assessed via 3 different bilateral
1RM tests in the knee extension corresponding to the
INITIAL
ROM
, FINAL
ROM
, and FULL
ROM
.
Subjects
Forty-five non-trained women with an age range of 18–
30 years old (mean ± SD: age = 22.7 ± 2.8 years; weight =
61.5 ± 9.0 kg; height = 1.61 ± 0.01 m; body fat percen-
tage = 25.9 ± 5.1%) participated in the study. The local
ethics committee approved this study, which complied
with international standards. In addition, each subject
was instructed not to perform any physical activity on
the testing session’s days.
Procedures
Pre-training session 1
Height, body mass, and fat percentage (skinfold thickness)
measurements were performed. Thereafter, ultrasound
images were obtained to measure CSA of the RF and VL
muscles. Initially, participants remained still on a stretcher
in the supine position for 15 min. During this period, the
anterior regions of the right thigh were marked to identify
the points of image acquisition. For the marking pro-
cedure, femur length was measured as the distance
between the major trochanter and lateral epicondyle.
From the proximal extremity, mark points were made on
the volunteer’s thigh at 40%, 50%, 60%, and 70% of
femur length using a tape measure. A laser device was
used to mark the other points and verify their axial align-
ment. This device was placed over the volunteeŕsthigh,
and the lasers indicated points axially aligned across the
thigh (check supplementary material). The procedures
used to acquire images in the pre-training were the
same for the post-training, which was completed
between 72–96 h after the last training session.
A b-mode ultrasound device (MindRay DC-7, Shenz-
hen, China) with a 4-cm linear transducer was used in
extended-field-of-view mode to assess muscle CSA.
The equipment was configured following Lacerda et al.
(2021) and adjusted for each individual participant and
muscle region to produce the clearest possible images.
The same trained evaluator performed the acquisition
2G. F. PEDROSA ET AL.
of 2 images at each percentage of femur length (40%,
50%, 60%, and 70%). The probe was placed transversely
in parallel to the intercondylar line using a coupled
guide on the volunteer’s thigh. A set of sixteen images
per volunteer were obtained for RF and VL CSA analysis
(8 pre-training + 8 post-training). After obtaining the
images, the CSA of each muscle scan was manually esti-
mated by a blinded examiner using specific software
(OsiriX MD 6.0, Bernex, Switzerland). The RF and VL
CSA regional values were determined by calculating
the mean values of the 2 images acquired at each per-
centage of femur length (Figure 2).
Reliability of CSA measurements was assessed by
analysis of the intraclass correlation coefficient (ICC
3,1
)
for both intra- and inter-evaluator. For intra-evaluator,
the 2 CSA measures of each region of the RF and VL
demonstrated ICC
3,1
values between 0.98–0.99. For
inter-evaluator reliability, an invited radiology technician
measured the CSA of 1/3 of all images. The inter-evalua-
tor reliability showed ICC
3,1
values ranging from 0.94–
0.99 along the 4 muscle regions of the two muscles.
We also measured muscle thickness at 50% of length
of the RF muscle, determined as the distance between
the deeper and upper RF muscle aponeurosis (Miyatani,
Kanehisa, Kuno, Nishijima, & Fukunaga, 2002). The
muscle thickness measurement was ranked in order of
size and used as a criterion for the balanced
randomization of the participants into the groups. We
opted to use muscle thickness for randomizing the par-
ticipants because of its ease of measurement compared
to the CSA and given the need to complete the ran-
domization process prior to the ensuing pre-training
session.
Pre-training sessions 2, 3, 4, and 5
During pre-training session 2, participants were familiar-
ized with the bilateral 1RM tests corresponding to the 3
ROM tests (INITIAL
ROM
, FINAL
ROM
, and FULL
ROM
group).
First, the participants were positioned in the knee exten-
sion machine with 110° of hip flexion (trunk and thigh)
and the medial malleolus of the tibia positioned 2 cm
below the machine pad. To minimize accessory move-
ments, participants were restrained in the machine by
a four-point seat belt. In addition, a metallic structure
was placed in front of the machine to serve as a refer-
ence (mechanical stop) to the desired knee extension
angle (65° or 30° of knee flexion) (see supplementary
material). Also, a potentiometer, coupled to the
rotational axis of the mechanical arm of the knee exten-
sion machine, provided real-time biofeedback on a com-
puter screen as to the ROM excursed by each volunteer.
The use of a potentiometer to analyze the ROMs
excursed during tests and training were described in
previous studies of our group (Diniz et al., 2020;
Lacerda et al., 2021).
The familiarization to 1RM tests was determined
within a maximum of 6 attempts, with 3-minute rest
periods provided between attempts. A 30-minute rest
period was given between the tests (order balanced
between the participants) for familiarization.
In the third, fourth, and fifth sessions at pre-training, a
sole 1RM test was performed in each session, which fol-
lowed the procedures, and order of the ROM tested in
familiarization. The data of these 3 sessions were used
for statistical analysis. The range of ICC
3,1
values
between the performance on familiarizations and tests
were 0.94–0.97.
Training
After the initial testing period, participants carried out a
12-week training programme using their designated
ROM. The experimental protocol consisted of 3–6 sets
of 7 repetitions (each repetition carried out with 2-
Figure 1. Training groups. VAR
ROM
group daily alternated the ROM between INITIAL
ROM
and FINAL
ROM
.
EUROPEAN JOURNAL OF SPORT SCIENCE 3
second concentric and 2-second eccentric actions, with
the tempo controlled by a metronome) at 60% 1RM
with 3-minute rest periods between sets. The 1RM per-
centage was obtained specific to the ROM performed
in a given group. All training groups started the training
period performing 3 sets. This training load configur-
ation was based on a pilot study, which indicated that
most individuals (similar to the present study) were
unable to perform more than 7 repetitions across 3
sets (intensity at 60% of 1RM, specific to each ROM
with 2-second concentric and 2-second eccentric
actions, and a 180-second rest interval between sets).
During the 3rd to 5th week of training, the women per-
formed 4 sets. Between the 6th and 8th week 5 sets were
performed, and between the 9th and 12th week of train-
ing the participants performed 6 sets. The mechanical
stops used during the 1RM tests to delimitate the ROM
desired and the potentiometer were also used in the
training period. The data provided by the potentiometer
allowed the participants to assess the duration and ROM
data of each muscle action on a laptop screen during all
training sessions and tests. To verify that groups trained
according to their prescribed muscle action duration
and ROM, we randomly analyzed 1/6 of all training ses-
sions. No statistical difference was observed in the
mean muscle action duration among groups (one-way
ANOVA –p>0.05). Also, no difference was observed
among groups with similar start or end angles (one-
way ANOVA –p>0.05).
Every 2 weeks of training, the participants performed
a 1RM test in the ROM trained to maintain the intensity
of load programmed throughout the 12 weeks of train-
ing. These tests occurred before the start of the training
session; a 10-minute rest period separated the com-
pletion of 1RM testing and the onset of the training
session. Assessment of rating of perceived exertion
found that this protocol elicited a mean rating of 15
on the Borg category scale (range of 6–20) across all
sets, corresponding to a “hard”level of perceived
effort; the final set tended to be rated as “very hard,”
Figure 2. Example of extended-field-of-view of four regions of rectus femoris and vastus lateralis muscles from the same volunteer.
CSA = Cross-sectional area. a) = pre-training. b) = post-training.
4G. F. PEDROSA ET AL.
indicating that workouts were sufficiently challenging
for all groups.
Post-training sessions 1, 2, and 3
In the first post-training session, which occurred
between 72–96 h after the final training session, all par-
ticipants were submitted to ultrasound assessment of
the same muscles, regions, and procedures as con-
ducted in pre-training. Afterward, the participants per-
formed the first 1RM test following the order and
procedures determined at pre-training. In the second
and third sessions of post-training (48 h apart between
sessions) the other two 1RM tests were performed with
the same order and procedures of the pre-training
sessions.
Statistical analyses
Statistical analysis was performed with Sisvar version 5.7
software. We carried out analyses of variance (ANOVA) to
test for differences in absolute baseline values for all
variables analyzed, with no differences identified
between groups. To verify the change caused by training
protocols performed by ROM manipulation, we trans-
formed the CSA and 1RM test performance data into
relative responses ((Post –Pre)/Pre x 100). The normality
and homogeneity of variances were verified using
Shapiro–Wilk and Levene’s tests, respectively. Eta-
squared (η
2
) was calculated for the main significant
effect (Fritz, Morris, & Richler, 2012), with the following
interpretation: small<0.06; medium=0.06–0.14;
large>0.14 (Cohen, 1988). To compare the CSA relative
responses, a three-way ANOVA was performed (Group
x Muscle x Region). Moreover, the 1RM relative
responses were compared with a two-way ANOVA
(Group x ROM). To verify whether the results of the
1RM tests were different among groups and ROMs
tested at pre-training, we employed a two-way ANOVA
(Group x ROM). In the case of statistical differences, the
Scott-Knott post hoc test was employed to determine
which groups differed (Scott & Knott, 1974). Pearson cor-
relation coefficient was used to verify the relationship
between the regions CSA relative changes and 1RM
tests performance relative changes. Data are presented
as mean ± SD. Probability was set at α≤0.05 for statistical
significance for all responses.
Results
Cross-sectional area
The three-way ANOVA showed a significant interaction
effect between the factors Group x Muscle (p=0.0154;
η
2
=0.04). For the RF, INITIAL
ROM
and VAR
ROM
groups pre-
sented a greater change than the other groups, and the
FULL
ROM
group presented a greater change than
FINAL
ROM
and CON groups, which showed similar
changes. For the VL, the INITIAL
ROM,
FULL
ROM
, and
VAR
ROM
groups presented similar responses, which
were greater than FINAL
ROM
and CON groups; the
FINAL
ROM
group presented a greater increase than the
CON group. Furthermore, INITIAL
ROM
and VAR
ROM
groups presented a greater increase for the RF than
the VL. For the other groups, both muscles presented
similar changes.
A significant interaction effect was found between
the factors Group x Region (p=0.0349; η
2
=0.01). The
post hoc test revealed similar changes between the
training groups, which were all greater than the
CON group at 40% of femur length. INITIAL
ROM
and
VAR
ROM
groups presented similar changes and
greater than the other groups at 50%, whereas
FULL
ROM
and FINAL
ROM
groups presented similar
increases, which were greater than the CON group.
INITIAL
ROM
and VAR
ROM
groups presented similar
changes and greater than the other groups at 60%,
followed by the FULL
ROM
. Moreover, FINAL
ROM
and
CON groups showed similar responses. INITIAL
ROM
group presented greater responses than other
groups at 70%. Additionally, FULL
ROM
and VAR
ROM
groups showed similar increases and greater than
FINAL
ROM
and CON groups, which showed similar rela-
tive responses. The CSA changes among the 4 muscle
regions were similar for the INITIAL
ROM
, FULL
ROM
,
VAR
ROM
and CON groups. However, for the FINAL
ROM
group, the CSA changes at 40%, 50% and 60% were
greater than at 70% (Figure 3).
1RM Tests
Two-way ANOVA found an interaction between the
factors Group x ROM (p=0.0394; η
2
=0.14). The post
hoc test revealed that in 1RM testing performed at
the initial ROM, INITIAL
ROM
and VAR
ROM
groups
showed greater changes than the other groups,
and FINAL
ROM
and FULL
ROM
groups showed similar
changes, which were greater than CON group. For
the 1RM test performed at the final ROM, the train-
ing groups showed similar increases, all of which
were greater than the CON group. In the 1RM test
performed at the full ROM, INITIAL
ROM
, FULL
ROM
,
and VAR
ROM
groups presented similar relative
increases, which were greater than FINAL
ROM
and
CON groups; FINAL
ROM
showed greater changes
than CON group. Additionally, INITIAL
ROM
and
FINAL
ROM
groups presented a greater increase in
EUROPEAN JOURNAL OF SPORT SCIENCE 5
the 1RM test at the respective ROM trained, and the
other groups did not show differences between the
tests (Figure 4).
From a loading standpoint, two-way ANOVA only
found a main effect for ROM whereby a similar amount
of weight was lifted at the INITIAL
ROM
and FINAL
ROM
,
and at these two ROMs, a greater amount of weight
was lifted than at the full ROM (p=0.034; η
2
=0.05).
Pearson correlation coefficient
For the INITIAL
ROM
group, the Pearson correlation
coefficient indicated a significant, and positive associ-
ation between relative CSA changes of the VL at
60% and 70% and the 1RM tests at the initial and
full ROM (r=0.73–0.80; p=0.01–0.02). For the FINAL
ROM
group, a positive and significant relationship was
observed between the changes of CSA of VL at
Figure 3. The relative increase of cross-sectional area at 40%, 50%, 60%, and 70% of femur length. INITIAL = INITIAL
ROM
; FINAL =
FINAL
ROM
; FULL = FULL
ROM
; VAR = VAR
ROM
. *Greater increase than the other groups; &Greater increase than the FINAL
ROM
and CON
groups; #Greater increase than CON group; $Different than at other regions for the same group.
6G. F. PEDROSA ET AL.
40%, 50% and 60% with the 1RM tests at the final
and full ROM (r=0.72–0.98; p<0.001–0.020), and at
70% with the 1RM test at full ROM (r=0.70;
p=0.037). For the VAR
ROM
group, the CSA increases
of the RF at 60% and 70% presented a significant
correlation with the 1RM test increase at the initial
ROM (r=0.68–0.76; p=0.044–0.018). For the FULL
ROM
and CON groups, no significant correlation was
found.
Discussion
Muscle hypertrophy
The INITIAL
ROM
, FULL
ROM
, and VAR
ROM
groups elicited
similar CSA changes across the muscle regions. Although
these groups excursed the initial ROM (100°−35° of knee
flexion), only the INITIAL
ROM
group exclusively excursed
this ROM. Therefore, excursing a full ROM may not be
causal for inducing homogenous muscle growth across
Figure 4. 1RM tests in different ROM. INITIAL = INITIAL
ROM
; FINAL = FINAL
ROM
; FULL = FULL
ROM
; VAR = VAR
ROM
. *Greater than the
other groups at the respective ROM; &greater than groups FINAL
ROM
and CON at the respective ROM; # only greater than CON
Group at the respective ROM. $ different than the other ROM for the same group. L = lower values. U = upper values.
EUROPEAN JOURNAL OF SPORT SCIENCE 7
muscle regions, as previously hypothesized (Helms,
Fitschen, Aragon, Cronin, & Schoenfeld, 2014), but
rather due to training at a long muscle length in the
initial ROM. McMahon et al. (2014b) showed that after
8 weeks of training with the knee extension, the
INITIAL
ROM
group presented a greater VL change at the
distal region than the FINAL
ROM
group. This result casts
doubt as to whether the INITIAL
ROM
training does in
fact promote a greater distal muscle change compared
to other regions and raises the alternative possibility
that FINAL
ROM
training elicits less change in the distal
region than at other regions. Overall, the present
results suggest that excursing the initial ROM during
knee extension exercise elicits similar growth across
the muscle regions, while training with final ROM may
not significantly hypertrophy the distal muscle regions,
at least in the muscles analyzed. However, the present
study analyzed only four muscle regions of two quadri-
ceps femoris muscles, thus preventing the extrapolation
of these results to other regions and muscles of the
quadriceps femoris.
When considering regional hypertrophic changes
between groups, the INITIAL
ROM
group achieved
greater relative increases in CSA at 50% and 60% com-
pared to FINAL
ROM
, FULL
ROM
, and CON groups, and at
70% adaptations were greater than all groups. Given
that the protocol for FINAL
ROM
, FULL
ROM
, and VAR
ROM
groups included at least some training at shorter
muscle lengths, it is possible a concentrated focus on
training at a longer muscle length by the INITIAL
ROM
group was more advantageous for muscle development.
Indeed, previous research shows a hypertrophic super-
iority to training at longer versus shorter muscle
lengths (Alegre et al., 2014; McMahon et al., 2014b; Noor-
kõiv, Nosaka, & Blazevich, 2015). Our results expand
upon these findings to indicate that excursing shorter
muscle lengths may be detrimental to hypertrophic
changes even when some of the training is carried out
at longer muscle lengths. Intriguingly, analysis of the
1RM training loads showed that both partial groups
(INITIAL
ROM
and FINAL
ROM
) employed heavier loads
than the FULL
ROM
group, yet the INITIAL
ROM
group
achieved greater increases in CSA than the other two
groups. Since the magnitude of load was similar for
the INITIAL
ROM
and FINAL
ROM
groups, this would seem
to indicate that mechanical stress alone was not respon-
sible for the observed differences; rather, muscular
development appears to be driven via an interaction
between mechanical stress and muscle length, the
mechanisms of which are not clear.
It is worth noting that the higher relative increases in
CSA between groups occurred at the distal muscle
region (∼30% for RF and ∼18% for VL) for the INITIAL
ROM
group, which is in line with prior studies that investi-
gated muscle hypertrophy in different regions (proximal,
middle and distal) via ultrasound imaging (McMahon
et al., 2014a;2014b). McMahon et al. (2014b) found
that knee extension training in the initial ROM promoted
a∼50% CSA increase of the distal VL (75% of femur
length). In another study by the same group,
McMahon et al. (2014a) reported a 40.1% CSA increase
of the distal VL (75% of femur length) after training in
a full ROM using a variety of different knee extension
exercises. In both studies, these hypertrophic increases
were relatively greater than that achieved proximally,
and were superior at longer versus shorter muscle
lengths.
Considering the hypertrophic differences between
the INITIAL
ROM
and FULL
ROM
groups, it seems the combi-
nation of training with a longer time under tension at a
longer muscle length with higher loads (ascertained by
greater pre- 1RM test values at the partial ROMs than
at full ROM) for the INITIAL
ROM
group provided a
greater stimulus for hypertrophy than training in full
ROM, which likely occurred with greater mechanical
work (greater angular displacement). Previous studies
indicate that metabolic stress (Fouré, Ogier, Guye,
Gondin, & Bendahan, 2020; Kooistra, Blaauboer, Born,
de Ruiter, & de Haan, 2005; Ng, Agre, Hanson, Harring-
ton, & Nagle, 1994) and activation of the proteins Akt/
mTOR and p70S6 K (Rindom et al., 2019; Russ, 2008)
can occur to a greater magnitude when performing con-
tractions at longer versus shorter muscle lengths. This
evidence suggests a heightened anabolic milieu at
longer compared to shorter muscle length contractions,
which conceivably may help to explain the discrepancy
of results, as the FULL
ROM
group trained in both a
shorter and longer muscle length, while the INITIAL
ROM
group exclusively trained at a longer muscle length.
However, the mechanisms underpinning regional hyper-
trophy due to contractions at longer and shorter muscle
lengths are still poorly characterized and warrant further
research.
INITIAL
ROM
and VAR
ROM
groups showed similar
regional hypertrophic responses at 40%, 50%, and
60%. We speculated that hypertrophy would be similar
between VAR
ROM
and FULL
ROM
, which excursed of the
spectrum of initial and final ROMs during each rep-
etition. Contrary to this hypothesis, regional muscular
gains were generally greater in VAR
ROM
than FULL
ROM.
A possible explanation could be related to the fact
that the VAR
ROM
group trained with a higher load than
the FULL
ROM
group at a longer muscle length. Conceiva-
bly, the greater mechanical stress imposed under the
condition of a stretched muscle may therefore
promote a synergistic anabolic stimulus.
8G. F. PEDROSA ET AL.
Regarding the individual muscles investigated, the RF
and VL presented similar relative increases in the
FINAL
ROM
and FULL
ROM
groups. Alternatively, the RF
muscle increased to a greater magnitude than the VL
in the INITIAL
ROM
and VAR
ROM
groups. These results
suggest that training at longer muscle lengths may
promote greater hypertrophy for the RF compared to
the VL. This result runs counter to that of Noorkõiv
et al. (2014), who reported similar increases in muscle
volume between the RF and VL when training isometri-
cally at a longer muscle length. Further investigation is
needed to clarify whether training at long muscle
lengths does in fact promote a greater hypertrophy
response for the RF than for the VL.
In regard to the regional muscle hypertrophy within
groups, The FINAL
ROM
group presented greater regional
muscle growth at more proximal regions (40% and 50%)
than at more distal regions (60% and 70%). These results
may help to clarify findings of previous research, in
which the FINAL
ROM
groups showed a lower hyper-
trophic response at distal regions compared to
FULL
ROM
(Bloomquist et al., 2013; McMahon et al.,
2014a) and INITIAL
ROM
groups (McMahon et al., 2014b).
Bloomquist et al. (2013), despite not having performed
comparisons among muscle regions within each training
group (FINAL
ROM
x FULL
ROM
), performed paired t-tests to
compare longitudinal CSA of pre x post values in 6
regions across the anterior part of the thigh after squat-
ting training. For the FINAL
ROM
group, the results
showed that only the two most proximal muscle
regions increased after training. These data reinforce
our findings, which suggest that training at shorter
muscle lengths may not promote significant muscle
hypertrophy at more distal regions in the RF and VL
muscles. On the other hand, training at a longer
muscle length seems to promote a homogeneous
hypertrophic response across the muscle regions, as
occurred for the INITIAL
ROM
FULL
ROM
and VAR
RO.
However, our data are limited to four regions of two
quadriceps femoris muscles. Future studies should
seek to investigate more muscle regions within a given
muscle as well as muscles other than the quadriceps
femoris to enhance our understanding of the effect of
ROM on the regional muscle hypertrophy response.
Dynamic strength
Based on the principle of specificity (McCafferty &
Horvath, 1977), we expected that greater increases in
dynamic strength would occur in the ROM trained.
This hypothesis was partially confirmed, as the FINAL
ROM
and INITIAL
ROM
groups achieved a greater strength
increase in the respective ROM tested; the result of the
FINAL
ROM
group is consistent with those reported in pre-
vious studies (Bloomquist et al., 2013; Martínez-Cava
et al., 2019; Rhea et al., 2016). Although no study to
date has investigated strength changes in the
INITIAL
ROM
, the results of study that investigated iso-
metric torque production across angles after training
with partial ROM corroborate the present findings, due
to increases in isometric torque occurred near or at the
training angles (Graves, Pollock, Jones, Colvin, &
Leggett, 1989,1992). Additionally, the strength gains
from training at a longer muscle length may also occur
further along the training angle (Noorkõiv et al., 2015;
Thepaut-Mathieu, Van Hoecke, & Maton, 1988). These
results support the present findings, as the INITIAL
ROM
group demonstrated strength increases similar to the
groups that showed a greater strength increase in the
1RM test at the final and full ROM.
Previous research suggests that neural adaptations
help to explain joint-angle-specific strength increases,
with increasing muscle activation observed at or near
the angles trained (Alegre et al., 2014; Noorkõiv et al.,
2014; Thepaut-Mathieu et al., 1988). Nevertheless,
regional muscle hypertrophy may also play a role in
this phenomenon (Narici, Roi, Landoni, Minetti, & Cerre-
telli, 1989; Noorkõiv et al., 2014). Noorkõiv et al. (2014)
found positive and significant correlations between the
relative changes of regional CSA and the torque at
angles near the angle trained during isometric knee
extension exercise. However, these results account
only for the group that trained isometrically at a
longer muscle length, as no significant correlation was
found when training at a shorter muscle length. Based
on these results, Noorkõiv et al. (2014) speculated that
specific regional CSA increases may be associated with
increasing torque production at or near the angles
trained after training in longer muscle length.
However, the group that trained at a shorter muscle
length in the Noorkõiv et al. (2014) did not show signifi-
cant hypertrophy in any muscle analyzed after 6 weeks
of training, but this group did display isometric strength
increases near the training angles. The present study
partly corroborates the findings of Noorkõiv et al.
(2014), as INITIAL
ROM
and FINAL
ROM
groups presented
positive and significant correlations between regional
CSA increases and 1RM increases at the ROM trained.
Collectively, the present study suggests that the muscu-
lature can remodel regionally to enhance strength pro-
duction, but this variation seems to be dependent on
the ROM trained.
FULL
ROM
and VAR
ROM
were the unique training
groups that presented similar 1RM test increases
among the ROM tested. These results are consistent
with previous studies, in which the FULL
ROM
group
EUROPEAN JOURNAL OF SPORT SCIENCE 9
showed uniform improvements in 1RM test performance
at the different ROM tested (Martínez-Cava et al., 2019;
Pallarés et al., 2020; Weiss et al., 2000). Since both
FULL
ROM
and VAR
ROM
groups excursed the spectrum of
angles investigated (100°−30° of knee flexion), we
hypothesize that the overload imposed at each joint
angle may have been sufficient to promote adaptations
leading to similar strength increases in all ROMs investi-
gated, which would be in accordance with Rhea et al.
(2016). However, VAR
ROM
presented a greater 1RM
increase than FULL
ROM
in the initial ROM, but not in
the final or full ROM. Despite the observation that the
FULL
ROM
group likely trained with greater mechanical
work across the repetitions, the VAR
ROM
group trained
with a higher load across the angles trained by the
FULL
ROM
group. These data suggest that knee extension
training with a higher load in the initial ROM was more
advantageous to strength increases in the initial ROM
as opposed to training with greater mechanical work
across a full ROM. These findings possibly may be
explained by the hypertrophic adaptations experienced
by each training group. The VAR
ROM
group presented a
greater muscle hypertrophy increase than FULL
ROM
group at 50% and 60%, and some evidence suggests
that region-specific increases of muscle mass may be
associated with dynamic strength increases at certain
training angles (Noorkõiv et al., 2015). Thus, the
greater muscle hypertrophy increase may have
accounted for the VAR
ROM
group to achieve a greater
1RM increase in the INITIAL
ROM
compared to the
FULL
ROM
. In support of this line of reasoning, the CSA
increases at 60%, and 70% of RF in the VAR
ROM
group
significantly correlated with the 1RM test increases in
the initial ROM. The implications of these findings
require further investigation as our analysis is limited
to four muscle regions of two quadriceps muscles.
Intriguingly, despite the fact that the VAR
ROM
group
also trained with a higher load than FULL
ROM
group in
the final ROM, the 1RM increase in the final ROM was
similar between these groups. It seems the impact of train-
ing with higher loads in the final and initial ROMs com-
pared to training in a full ROM induces different strength
responses; these findings require further study as to the
associated morphological and neural adaptations.
VAR
ROM
group was the only group that presented a
relative increase similar to the INITIAL
ROM
group in the
initial 1RM test. Moreover, the VAR
ROM
group presented
similar relative increases in dynamic strength across the
employed 1RM tests. These results indicate that daily
undulating training between the initial and final ROMs
can promote similar increases in dynamic strength
across both partial and full ROMs. Moreover, these
strength gains are equivalent to the groups that
trained exclusively in one of these ROMs. Further
research is needed to better characterize potential
mechanisms and the application of undulating training
between different partial ROMs.
Conclusion
The present study indicates that training in different ROM
configurations may lead to regional changes in muscle
CSA and dynamic strength performance. Resistance train-
ing at the initial ROM generally showed superiority in
comparison to final, full, and varied ROM training. In
addition, maximum strength performance is affected by
the ROM trained, and a joint-angle specific strength
increase may occur after partial ROM training. Further-
more, alternating sessions between the initial and final
ROMs may increase the maximum strength uniformly
among different ROMs, reaching values similar to that
achieved from partial ROM training.
Disclosure statement
No potential conflict of interest was reported by the author(s).
ORCID
Fernando V. Lima http://orcid.org/0000-0001-9293-7340
Brad J. Schoenfeld http://orcid.org/0000-0003-4979-5783
Lucas T. Lacerda http://orcid.org/0000-0002-0735-8131
Rodrigo C.R. Diniz http://orcid.org/0000-0001-9425-4447
Mauro H. Chagas http://orcid.org/0000-0002-1955-8990
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