ArticlePDF Available

Abstract and Figures

The aim of the present study was to compare the changes in gastrocnemius muscle thickness (MT) between conditions in which foot was pointed outward (FPO), inward (FPI), or forward (FPF). Twenty-two young men (23 ± 4 years) were selected and performed a whole-body resistance training program three times per week for nine weeks, with differences in the exercise specific for calves. Calf-raise exercise was performed unilaterally, in a pin-loaded seated horizontal leg-press machine, in 3 sets of 20-25 repetitions for training weeks 1-3, and 4 sets for weeks 4-9. Each subject's leg was randomly assigned for one of the three groups according to foot position: FPO, FPI, and FPF. Measurements with a B-mode ultrasound were performed to assess changes in MT of medial and lateral gastrocnemius heads. After training period, there were observed increases in MT of both medial (FPO = 8.4%; FPI = 3.8%; FPF = 5.8%) and lateral (FPO = 5.5%; FPI = 9.1%; FPF = 6.4%) gastrocnemius, and significant differences for magnitude of the gains were observed between FPO and FPI conditions (P < 0.05). Positioning FPO potentiated the increases in MT of medial gastrocnemius, while FPI provided greater gains for the lateral head. Our results suggest that head-specific muscle hypertrophy may be obtained selectively for gastrocnemius after nine weeks of calf training in young male adults.
Content may be subject to copyright.
Downloaded from by FaGvM3YZibDyAjWzuy8nkpQbjc8F0lmSWDYSWnRyihAQowfatNL2QBhc1YloTtG3IHrf1I8UJIzFrYbnjWBMtqLyxrKgYPFdz6iA4Mfp4yUjpy4j65S/iFlNn70X55FU on 06/15/2020
Downloadedfrom by FaGvM3YZibDyAjWzuy8nkpQbjc8F0lmSWDYSWnRyihAQowfatNL2QBhc1YloTtG3IHrf1I8UJIzFrYbnjWBMtqLyxrKgYPFdz6iA4Mfp4yUjpy4j65S/iFlNn70X55FU on 06/15/2020
Short Research Report
Different Foot Positioning During Calf Training to
Induce Portion-Specific Gastrocnemius
Muscle Hypertrophy
˜o Pedro Nunes,
Bruna D.V. Costa,
Witalo Kassiano,
Gabriel Kunevaliki,
amela Castro-e-Souza,
Andr ´e L.F. Rodacki,
Leonardo S. Fortes,
and Edilson S. Cyrino
Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, Brazil;
Department of Physical Education, Federal University of Paran ´a, Curitiba, Brazil; and
Department of Physical Education, Federal
University of Para´
ıba, Joa
˜o Pessoa, Brazil
Nunes, JP, Costa, BDV, Kassiano, W, Kunevaliki, G, Castro-e-Souza, P, Rodacki, ALF, Fortes, LS, and Cyrino, ES. Different foot
positioning during calf training to induce portion-specific gastrocnemius muscle hypertrophy. J Strength Cond Res XX(X): 000–000,
2020—The aim of this study was to compare the changes in gastrocnemius muscle thickness (MT) between conditions such as
which foot was pointed outward (FPO), foot was pointed inward (FPI), or foot was pointed forward (FPF). Twenty-two young men (23
64 years) were selected and performed a whole-body resistance training program 3 times per week for 9 weeks, with differences in
the exercise specific for calves. The calf-raise exercise was performed unilaterally, in a pin-loaded seated horizontal leg-press
machine, in 3 sets of 20–25 repetitions for training weeks 1–3 and 4 sets for weeks 4–9. Each subject’s leg was randomly assigned
for 1 of the 3 groups according to the foot position: FPO, FPI, and FPF. Measurements with a B-mode ultrasound were performed to
assess changes in MT of medial and lateral gastrocnemius heads. After the training period, there were observed increases in MT of
both medial (FPO 58.4%, FPI 53.8%, and FPF 55.8%) and lateral (FPO 55.5%, FPI 59.1%, and FPF 56.4%) gastrocnemius
heads, and significant differences for magnitude of the gains were observed between FPO and FPI conditions (p,0.05).
Positioning FPO potentiated the increases in MT of the medial gastrocnemius head, whereas FPI provided greater gains for the
lateral gastrocnemius head. Our results suggest that head-specific muscle hypertrophy may be obtained selectively for gastroc-
nemius after 9 weeks of calf training in young male adults.
Key Words: triceps surae, ankle, plantar flexion, muscle growth, muscle architecture, nonuniform muscle hypertrophy
Muscle hypertrophy is one of the main outcomes that may be
obtained with repeated bouts of resistance exercise. Although
region-specific hypertrophy is particularly aimed by bodybuilders
(1), muscle growth does not occur in the same magnitude in all
muscle regions (1,16,20,31), irrespective of the training status
(i.e., trained or untrained). Varying exercise choice seems to be
a viable strategy for potentiating overall muscle gains in response
to a resistance-training program (8). In addition, performing the
same exercise under different joint positions (which some may
consider different exercises as well) has been proposed for
obtaining region-specific muscle growth (1,6,7,20).
The triceps surae muscle group consists of the soleus and gastroc-
nemius lateral and medial heads. The soleus is a single-joint plantar
flexor, and gastrocnemii are multijoint muscles that cross the knee and
the ankle. If varying foot position induces portion-specific hypertrophy
of the triceps surae (20), performing different exercises may contribute
to its development. This could be particularly important for the gas-
trocnemius because it is deemed as difficult to respond to hypertrophy
stimuli (1,28). Although performing plantar flexion with the knee
flexed may induce greater hypertrophy in the soleus than when the
exercise is executed with the knee extended (18,20), the position of the
feet seems to influence the recruitment of the gastrocnemius muscles
(2,14,18,19). For instance, Marcori et al. (14) observed a greater ac-
tivation of the medial head when the feet were pointed outward and
a greater activation of the lateral head with feet pointed inward.
However, these findings are not universal (18).
Given the wide gap between acute muscular activation and
muscle hypertrophy (29,30), long-term experimental studies are
needed to determine whether the foot position influences the
training-induced effect on gastrocnemius muscle growth. There-
fore, this study was designed to compare the changes in gastroc-
nemius muscle thickness (MT) when the calf-raise exercise was
performed with the foot pointed outward (FPO), foot pointed
inward (FPI), or foot pointed forward (FPF) after 9 weeks of
progressive resistance training in young men. It was hypothesized
that the increase in the MT of the medial gastrocnemius would be
greater for the FPO condition, whereas the FPI condition would
be better for improving the lateral head gastrocnemius. Also, it
was expected that the FPO condition resulted in intermediary
growth because it may elicit intermediate activation.
Experimental Approach to the Problem
This study is part of a larger research project designed to analyze
the effects of whole-body resistance-training protocols in young
Address correspondence to Joa
˜o Pedro Nunes,
Journal of Strength and Conditioning Research 00(00)/1–5
ª2020 National Strength and Conditioning Association
Copyright © 2020 National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.
male adults. The current investigation was executed over a period
of 11 weeks. Weeks 1 and 11 were used for ultrasound meas-
urements, whereas the progressive training program was per-
formed for 9 weeks (weeks 210). Subjects performed 7 exercises,
6 of which for the major muscle groups (e.g., bench press, lat pull-
down, triceps pushdown, biceps curl, leg press, and leg curl) in
addition to the unilateral calf-raise exercise. Subjects were
assessed before and after intervention for measures of gastroc-
nemius MT. Eight subjects were randomly chosen (
and were evaluated on 2 days of week 1 (separated by 72 hours) to
determine the reliability of the MT measurements.
Recruitment was conducted through social media and home de-
livery of flyers in the university area. Interested subjects completed
detailed health history and physical activity questionnaires and
were subsequently admitted if they met the following inclusion
criteria: 1835 years of age; male; free from cardiac, orthopedic, or
musculoskeletal disorders that could impede exercise practice; not
consume drug or supplement ergogenic aids; not be involved in the
practice of resistance training over the 4 months before the start of
the study, but should have a training experience of at least 6
months. Fromthe 52 volunteers, 29 met the criteria, were evaluated
at baseline, and initiated the training sessions.
To determine the allocation to the groups, a number was ran-
domly attributed to each subject (129) and a number to each leg of
them (1 or 2). Then, subjects were randomly selected, and each leg
was randomly assigned to 1 of the 3 groups according to foot
position for the calf-raise exercise: FPO, FPI, and FPF. During the
training period, subjects who obtained 6 absences from training
sessions (resulting in an attendance ,80% of the total number of
sessions) were asked to withdraw the program and were not
assessed on post-training measurements. Twenty-two subjects
(FPO, n516 legs; FPI, n516 legs; and FPF, n512 legs) ultimately
completed the study and were included for final analyses (age 5
23.0 63.8 years; body mass 578.1 613.7 kg; stature 5176.1 6
6.2 cm; and body mass index 525.1 63.6 kg·m
). No adverse
event occurred during the intervention period. Written informed
consent was obtained from all subjects after a detailed description
of study procedures was provided. This investigation was con-
ducted according to the Declaration of Helsinki and was approved
by the Federal University of Pernambuco Ethics Committee.
Gastrocnemius Muscle Thickness Measurement. Measures of
gastrocnemius MT were obtained at weeks 1 (before training) and
11 (after training) using a B-mode ultrasound (Logiq book; GE
Healthcare, Madison, WI), with a 7.5-MHz linear probe (8L-RS;
GE Healthcare). All procedures were performed in the morning
hours by the same experimenters in pre-training and post-training.
On arrival at the laboratory on measurement days, subjects should
verbally certify that they had been fasting for 8 hours and had not
performed vigorous exercise for the previous 48 hours. After that,
lines were drawn on the subjectsskin with a dermatographic pen
on the sites of which images were taken. Ultrasound measurements
started after subjects were lying down in the prone position for 10
minutes. Image acquisitions of the lateral gastrocnemius were
taken at the proximal third between the lateral epicondyle of the
femur and the lateral malleolus of the fibula, whereas measure-
ments of the medial head were taken with the probe positioned in
the thickest and more laterally prominent site of the lower leg (from
a posteroanterior view). A generous quantity of water-soluble
transmission gel was applied over the skin of the muscle being
assessed, with caution not to depress the skin. Images were ac-
quired with the probe placed perpendicular to the tissue interface
and were recorded at 25 Hz, with a field of view of 60100 mm
depth. Two experimenters participated in measurement procedures
so that one handled the probe (and drawn the lines on the skin as
well), and the other was responsible for freezing the images (once
the first considered that the quality was satisfactory). The MT of
both gastrocnemius heads was defined as the distance between the
superficial and deep aponeuroses. The images obtained before and
after training were overlapped (PhotoFiltre Studio; v. X10.13.1.
Houilles, France) to visually check if sites where MT would be
estimated were the same (1 image had its opacity ;4060% re-
duced). The MT length was determined using the ImageJ software
(v. 1.50; NIH, Bethesda, MD). Values of coefficient of variation,
intraclass correlation coefficient, standard error of measurement,
and minimum detectable difference were of 2.8%, 0.97 (ranging
from 0.90 to 0.99), 0.052 cm, and 0.103 cm for the medial gas-
trocnemius MT assessment and were of 3.4%, 0.98 (ranging from
0.93 to 0.99), 0.059 cm, and 0.117 cm for the lateral gastrocne-
mius, respectively (9).
Calf Training. The supervised resistance-training program was
performed 3 times per week (Mondays, Wednesdays, and Fridays)
in the afternoon period for 9 weeks. Calf-raise exercises were
performed unilaterally, in a pin-loaded seated horizontal leg-press
machine (Ipiranga; Fitness Line, Presidente Prudente, Brazil) in 3
sets of 2025 repetitions for training weeks 13 and increased to 4
sets for weeks 49. Subjects wereinstructed to perform 1 set with 1
leg, to rest a few seconds enough to self-adjust the body posture,
and then to perform 1 set with the other leg. The rest period was
6090 seconds after finishing 1 set for both legs. Subjects were
instructed to alternate the leg to begin the calf-raise exercises to
minimize potential effects of residual fatigue. Calf-raise exercises
were performed in the maximum range of motion, with the knee
extended, in a tempo of 1:1:2 seconds (concentric, concentric peak,
and eccentric phases, respectively), and subjects were cued to
squeeze the muscleon each repetition, mainly during the con-
centric peak phase (26). When near to momentary muscular failure
(last ;35 repetitions), subjects were released to carry out the
movement at a velocity that was capable of, but maintaining the
execution of the 1-second peak contraction phase, focusing on
squeezingthe targeted muscle portion. The foot was positioned
on the platform supported by metatarsals (14). For the FPO or FPI
condition, subjects positioned their foot at 45° externally or in-
ternally rotated (including both ankle and femur rotation, as nec-
essary), respectively, or when this amplitude was not achieved, at
the maximum angle according to the subjects articular mobility.
For the FPF condition, the foot was positioned forward-pointing,
with no lateral or medial rotation. Duct tapes were used in the leg-
press platform as a guide to be followed (14). The training load was
progressively increased each week by 510%, according to the
number of repetitions performed during each training session to
ensure that the subjects kept performing the sets to (or very near to)
failure in the established repetition zone (5).
Statistical Analyses
Normality was checked by Shapiro-Wilks test. Levenestestwas
used to analyze the homogeneity of variances. These assumed
Selective Gastrocnemius Muscle Hypertrophy (2020) 00:00
Copyright © 2020 National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.
differences on the effects of different foot positions (FPO vs. FPI vs.
FPF) on gastrocnemius muscle hypertrophy were examined with
analysis of covariance of the raw difference between pre-
intervention and postintervention measures with baseline values as
a covariate to eliminate any possible influence of initial score var-
iances on outcomes. Interpretation of data was based on 95%
confidence intervals (CIs) of the change score (e.g., when 95% CI of
the raw delta did not overlap the 0, there was a difference between
the baseline score). The pvalues for group comparisons were also
presented. When the F-ratio was significant, Bonferronisposthoc
test was used to identify the differences between pre-training and
post-training raw data. A p#0.05 value was accepted as statisti-
cally significant. The effect size (ES) was calculated as post-training
mean minus pre-training mean, divided by pooled pre-training SD
(3). An ES of 0.000.19 was considered as trivial, 0.200.49 was
considered as small, 0.500.79 was considered as moderate, and
$0.80 was considered as large (3). The data were expressed as
mean, SD, and 95% CIs. The data were stored and analyzed using
SPSS software, v. 23.0 (IBM Corp., Armonk, NY).
Table 1 displays the values of gastrocnemius MT before and after
training.After the training period, there were observed increases of
small-to-moderate magnitude on MT of the medial and lateral
gastrocnemius for FPO, FPI, and FPF conditions. A significant ef-
fect of the condition was observed for the increases in the medial
gastrocnemius (F54,048; p50.025), in which the Bonferroni
post hoc test revealed a significant difference occurred only be-
tween FPO and FPI conditions, with a greater increase for the FPO
condition (p50.021). Similarly, a significant effect of the condi-
tion was observed for the increases in the lateral gastrocnemius (F
54,259; p50.021), with a significant difference only between
FPO and FPI conditions, favoring the FPO condition (p50.020).
Figure 1 shows the relative changes on MT of both medial (FPO 5
8.4%; FPI 53.8%; and FPF 55.8%) and lateral (FPO 55.5%;
FPI 59.1%; and FPF 56.4%) heads of the gastrocnemius.
The main finding of this study was that the foot position can
influence the magnitude of increases in MT of the gastrocnemius,
in which the FPO induced greater gains on the medial head,
whereas the FPI potentiated the lateral head muscle growth.
Moreover, the FPF condition resulted in similar relative gains for
both heads and did not present significant differences in com-
parison with FPO and FPI conditions. This indicates that
changing the foot position can potentiate hypertrophy of a head
of the gastrocnemius without impairing the increase of the op-
posite head significantly. The initial hypotheses were confirmed,
and, based on the findings, portion-specific calf muscle hyper-
trophy is related to the ability to exercise muscle portions selec-
tively, especially when the foot is pointed outward or inward.
The relationship between muscular activation and hypertro-
phy is somewhat argued as complex and uncertain (29,30).
However, the main point that supports such a line of reasoning is
that, when comparing training intensities, high loads and low
repetitions vs. low loads and high repetitions exhibit different
muscular activations (evaluated by surface electromyography
[sEMG]), although both training protocols seem to induce similar
muscle growth (24,29,30). A possible justification for this may lie
in the method used, i.e., sEMG, which not necessarily correspond
to the mechanical stress experienced by the muscle fibers (15,30).
Indeed, a previous study showed that when measuring muscular
activation using fiber typespecific glycogen depletion obtained
by essays of muscle biopsies, high and low load performed until
failure elicited similar results (15). Regardless, the proposed poor
relationship between sEMG and hypertrophy responses (29,30),
however, possibly cannot be generalized to experimental designs
Table 1
Training effect on medial and lateral gastrocnemius muscle
thickness (cm).*†
Medial gastrocnemius MT
Pre 1.99 60.26 2.01 60.26 2.02 60.19
Post 2.15 60.27‡ 2.09 60.27‡§ 2.14 60.22‡
0.16 (0.12–0.21) 0.08 (0.03–0.12) 0.12 (0.07–017)
ES 0.69 0.33 0.50
Lateral gastrocnemius MT
Pre 2.07 60.32 2.04 60.35 2.05 60.28
Post 2.18 60.32‡ 2.22 60.37‡§ 2.18 60.31‡
0.11 (0.08–0.15) 0.18 (0.15–0.22) 0.13 (0.09–0.17)
ES 0.35 0.58 0.42
*FPO 5foot pointed outward (n516); FPI 5foot pointed inward (n516); FPF 5foot pointed
forward (n512); MT 5muscle thickness; ES 5effect size.
†Pre-training and post-training data are presented as mean and SD, whereas mean
as mean and
95% confidence intervals.
p,0.05 vs. baseline.
§p,0.05 vs. FPO.
Figure 1. Percentage changes from pre-training to post-
training period for medial and lateral gastrocnemius muscle
thickness. FPO 5foot pointed outward (n516); FPI 5foot
pointed inward (n516); and FPF 5foot pointed forward (n5
12). †p,0.05 difference between FPO and FPI conditions.
The horizontal lines represent mean and 95% confidence
intervals, whereas each circle represents a leg.
Selective Gastrocnemius Muscle Hypertrophy (2020) 00:00 |
Copyright © 2020 National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.
comparing different muscles or regions of a same muscle after the
performance of an exercise. That is, a greater activation of a given
muscle compared with the other involved ones during an exercise
seems to indicate at least that this muscle or portion is more likely to
be hypertrophied. It is worthy to note that this study did not per-
form any muscular activation analysis, and these comparisons and
inferences are based on sEMG data reported elsewhere (14,19).
Other studies have also shown that differences between the
magnitude of intramuscle-group and intermuscle-group hy-
pertrophy may be related to differences in muscular activation,
such as greater hypertrophy of the pectoral major compared with
the triceps brachii after chest-press training (17) and corre-
sponding findings in studies on muscular activation (22,27), se-
lective hypertrophy and activation of the heads of the quadriceps
femoris (7) and the triceps brachii (31), and greater hypertrophy
and activation of the quadriceps femoris compared with the
hamstrings after squat training (4,11). Nonetheless, controversies
exist (1,6,7), and there are many determinants that dictate muscle
hypertrophy so that muscular activation should not be considered
a surrogate marker for muscle growth.
The gastrocnemius is a single muscle unit but is a bipennate
muscle. Once it has 2 compartments, and each 1 has its own
innervations, this may turn it possible to increase the recruitment of
a specific portion selectively (1,14,19). Thus, the strategy used to
focus on squeezingthe muscles during each repetition might have
also contributed to current findings because this tends to increase
the activation of the targeted muscles (21,26,27). Moreover, it can
be speculated that, during the calf-raise exercises, FPO and FPI
conditions caused greater specific stretching of the medial and lat-
eral heads of the gastrocnemius, respectively. Because of neuro-
muscular compartmentalization, each gastrocnemius head has its
own moment arms and length-tension curves during ankle move-
ments (10,12,13). Therefore, based on the length-tension relation-
determined by the foot position, the activation of greater muscle
fibers was necessary to produce torque, then, under a greater
overload that ultimately caused a greater muscle growth (10). That
is, the medial gastrocnemius was at a disadvantage in the FPO
condition, as well as the lateral gastrocnemius in the FPI condition;
thus, in these conditions, each portion should be more forced to
perform the exercise (14). Previous findings have indicated that the
gastrocnemius architecture also is modulated by ankle inversion
and eversion (12). Although the present investigation did not have
measured any of these factors, when the gastrocnemius is stretched
during the calf-raise exercise, in the FPO condition, the ankle makes
aslightinversion,whereasintheFPI condition, the ankle makes an
eversion. With ankle inversion or eversion, the specific activation of
the gastrocnemius portions might have increased. This, in turn,
might have helped potentiating the stimuli for muscle growth, which
is in accordance with the present findings.
The average increase in MT observed herein was of 6.5% (ES
50.47). Although the triceps surae has been suggested as difficult
to hypertrophy (1,28), this result is equivalent to gains presented
in recent meta-analyses for other muscle groups when trained
with volumes similar to this study (23,25). However, the training
program included other exercises for the lower body, and this,
despite having a high relation to practical settings, might have
clouded the true magnitude of the effect of calf training on gas-
trocnemius MT. This study has other concerns to be addressed.
First, the use of ultrasound to assess changes in the muscle size
lacks the precision and sensitivity to detect subtle changes com-
pared with direct imaging modalities, such as MRI. Also, al-
though subjects were instructed to perform the movement at same
execution velocity and range of motion, no device was used to
monitor these factors strictly. Moreover, dietary intake and daily
physical activity levels were not assessed, and whether these fac-
tors could exert some influence on the adaptations remains un-
certain. Finally, this experiment was performed in young adult
men, and results cannot be generalized to other populations of
different sex, age, or training status.
In conclusion, the results of this study indicate that head-
specific muscle hypertrophy may be obtained for gastrocnemius
after 9 weeks of calf training in young male adults. Positioning
FPO may induce greater gains in MT of the medial gastrocnemius
head, whereas positioning FPI seems to be better suited for in-
creasing the lateral gastrocnemius head.
Practical Applications
Coaches and practitioners can choose the position of the foot
if the training aim is to induce hypertrophy of the different
portions of the gastrocnemius selectively. From the results of
our study, pointing foot straight forward may be the ideal
approach when the aim is to induce proportional improve-
ment on both heads of the gastrocnemius, whereas pointing
foot outward or inward may induce selective muscle growth,
thus correcting muscle asymmetries and improving the aes-
thetic shape of the lower leg. Combining the FPO and FPI
could maximize the gains on both heads, although future
studies are needed to test such a hypothesis.
The authors thank all subjects for their engagement in the study,
the Coordination of Improvement of Higher Education Personnel
(CAPES/Brazil) for the scholarship conferred to J.P. Nunes,
B.D.V. Costa, W. Kassiano, G. Kunevaliki, and P. Castro-e-Souza
(master), and the National Council of Technological and
Scientific Development (CNPq/Brazil) for the grants conceded
to A.L.F. Rodacki, L.S. Fortes, and E.S. Cyrino.
The authors declare that they have no conflict of interest
regarding the publication of this paper.
1. Antonio J. Nonuniform response of skeletal muscle to heavy resistance
training: Can bodybuilders induce regional muscle hypertrophy?
J Strength Cond Res 14: 102113, 2000.
2. Cibulka M, Wenthe A, Boyle Z, et al. Variation in medial and lateral
gastrocnemius muscle activity with foot position. Int J Sports Phys Ther
12: 233241, 2017.
3. Cohen J. A power primer. Psychol Bull 112: 155159, 1992.
4. Contreras B, Vigotsky AD, Schoenfeld BJ, Beardsley C, Cronin J. A
comparison of gluteus maximus, biceps femoris, and vastus lateralis
electromyography amplitude for the barbell, band, and american hip
thrust variations. J Appl Biomech 32: 254260, 2016.
5. Dankel SJ, Jessee MB, Mattocks KT, et al. Training to fatigue: The answer
for standardization when assessing muscle hypertrophy? Sport Med 47:
10211027, 2017.
6. Ema R, Akagi R, Wakahara T, Kawakami Y. Training-induced changes in
architecture of human skeletal muscles: Current evidence and unresolved
issues. J Phys Fit Sport Med 5: 3746, 2016.
7. Ema R, Kawakami Y. Quantitative profiles of the quadriceps femoris in
sport athletes. In: Sports Performance. Kanosue K, Nagami T and Tshu-
chiya J, eds. Tokyo, Japan: Springer Japan, 2015. pp. 175185.
8. Fonseca RM, Roschel H, Tricoli V, et al. Changes in exercises are more
effective than in loading schemes to improve muscle strength. J Strength
Cond Res 28: 30853092, 2014.
9. Hopkins WG. Spreadsheets for analysis of validity and reliability.
Sportscience 19: 3642, 2015.
Selective Gastrocnemius Muscle Hypertrophy (2020) 00:00
Copyright © 2020 National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.
10. Kawakami Y, Ichinose Y, Fukunaga T. Architectural and functional fea-
tures of human triceps surae muscles during contraction. J Appl Physiol
85: 398404, 1998.
11. Kubo K, Ikebukuro T, Yata H. Effects of squat training with different
depths on lower limb muscle volumes. Eur J Appl Physiol 119:
19331942, 2019.
12. Lee SSM, Piazza SJ. Inversion-eversion moment arms of gastrocnemius
and tibialis anterior measured in vivo. J Biomech 41: 33663370, 2008.
13. Maganaris CN. Force-length characteristics of the in vivo human gas-
trocnemius muscle. Clin Anat 16: 215223, 2003.
14. Marcori AJ, Moura TBMA, Okazaki VH. A Gastrocnemius muscle acti-
vation during plantar flexion with different feet positioning in physically
active young men. Isokinet Exerc Sci 25: 121125, 2017.
15. Morton RW, Sonne MW, Zuniga AF, et al. Muscle fibre activation is
unaffected by load and repetition duration when resistance exercise is
performed to task failure. J Physiol 597: 46014613, 2019.
16. Nunes JP, Schoenfeld BJ, Nakamura M, et al. Does stretch training induce
muscle hypertrophy in humans? A review of the literature. Clin Physiol
Funct Imaging 40: 148156, 2020.
17. Ogasawara R, Thiebaud RS, Loenneke JP, Loftin M, Abe T. Time course
for arm and chest muscle thickness changes following bench press train-
ing. Interv Med Appl Sci 4: 217220, 2012.
18. Pereira RS, Azevedo JB, Politti F, et al. Does feet position alter triceps surae
EMG record during heel-raise exercises in leg press machine? Man Ther
Posturol Rehabil J 15: 529, 2017.
19. Riemann BL, Limbaugh GK, Eitner JD, LeFavi RG. Medial and lateral
gastrocnemius activation differences during heelraise exercise with three
different foot positions. J Strength Cond Res 25: 634639, 2011.
20. Schoenfeld BJ. Accentuating muscular development through active in-
sufficiency and passive tension. Strength Cond J 24: 2022, 2002.
21. Schoenfeld BJ, Contreras B. Attentional focus for maximizing muscle
development: The mind-muscle connection. Strength Cond J 38: 2729,
22. Schoenfeld BJ, Contreras B, Vigotsky AD, et al. Upper body muscle acti-
vation during low-versus high-load resistance exercise in the bench press.
Isokinet Exerc Sci 24: 217224, 2016.
23. Schoenfeld BJ, Grgic J, Krieger JW. How many times per week should
a muscle be trained to maximize muscle hypertrophy? A systematic review
and meta-analysis of studies examining the effects of resistance training
frequency. J Sports Sci 37: 12861295, 2019.
24. Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW. Strength and hypertrophy
adaptations between low- versus high-load resistance training: A sys-
tematic review and meta-analysis. J Strength Cond Res 31: 35083523,
25. Schoenfeld BJ, Ogborn D, Krieger JW. Dose-response relationship be-
tween weekly resistance training volume and increases in muscle mass: A
systematic review and meta-analysis. J Sports Sci 35: 10731082, 2017.
26. Schoenfeld BJ, Vigotsky A, Contreras B, et al. Differential effects of at-
tentional focus strategies during long-term resistance training. Eur J Sport
Sci 18: 705712, 2018.
27. Snyder BJ, Fry WR. Effect of verbal instruction on muscle activity
during the bench press exercise. JStrengthCondRes26: 23942400,
28. Trappe TA, Raue U, Tesch PA. Human soleus muscle protein syn-
thesis following resistance exercise. Acta Physiol Scand 182:
189196, 2004.
29. Vigotsky AD, Beardsley C, Contreras B, et al. Greater electromyo-
graphic responses do not imply greater motor unit recruitment and
hypertrophic potentialcannot be inferred. JStrengthCondRes31:
e1e4, 2017.
30. Vigotsky AD, Halperin I, Lehman GJ, Trajano GS, Vieira TM. Inter-
preting signal amplitudes in surface electromyography studies in sport and
rehabilitation sciences. Front Physiol 8: 985, 2018.
31. Wakahara T, Fukutani A, Kawakami Y, Yanai T. Nonuniform muscle
hypertrophy: Its relation to muscle activation in training session. Med Sci
Sports Exerc 45: 21582165, 2013.
Selective Gastrocnemius Muscle Hypertrophy (2020) 00:00 |
Copyright © 2020 National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.
... Performing heel raises with the foot positioned with toes pointed inwards significantly increased GL motor unit discharge rate compared to toes neutral in healthy individuals (Hug et al. 2020). Foot position, in healthy individuals, can also selectively affect GM and GL hypertrophy (Nunes et al. 2020). Therefore, implementing different foot positions during rehabilitation could help increase GL activity during plantar flexor resistance training. ...
Full-text available
Objectives Deficits in muscle performance could be a consequence of a reduced ability of a motor neuron to increase the rate in which it discharges. This study aimed to investigate motor unit (MU) discharge properties of each triceps surae muscle (TS) and TS torque steadiness during submaximal intensities in runners with Achilles tendinopathy (AT). Methods We recruited runners with (n = 12) and without (n = 13) mid-portion AT. MU discharge rate was analysed for each of the TS muscles, using high-density surface electromyography during 10 and 20% isometric plantar flexor contractions. Results MU mean discharge rate was lower in the gastrocnemius lateralis (GL) in AT compared to controls. In AT, GL MU mean discharge rate did not increase as torque increased from 10% peak torque, 8.24 pps (95% CI 7.08 to 9.41) to 20%, 8.52 pps (7.41 to 9.63, p = 0.540); however, in controls, MU discharge rate increased as torque increased from 10%, 8.39 pps (7.25–9.53) to 20%, 10.07 pps (8.89–11.25, p < 0.001). There were no between-group difference in gastrocnemius medialis (GM) or soleus (SOL) MU discharge rates. We found no between-group differences in coefficient of variation of MU discharge rate in any of the TS muscles nor in TS torque steadiness. Conclusion Our data demonstrate that runners with AT may have a lower neural drive to GL, failing to increase MU discharge rate to adjust for the increase in torque demand. Further research is needed to understand how interventions focussing on increasing neural drive to GL would affect muscle function in runners with AT.
... Thus, the combination of a high load, several repetitions, and fatigue in maintaining an unfavorable position can generate undue stress on the shoulder complex and higher injury risk. Similarly, special attention should be paid when altering the positions of the hands and feet for higher muscle hypertrophy in the deltoid muscles or the gastrocnemius and soleus muscles, respectively [102,103]. In the case of the pectoralis major, the evidence is inconclusive as to whether different angles (incline, flat, or decline) might be better for muscle development or activation [104][105][106]; however, the wide grip should be modified to avoid excessive horizontal abduction and the externally rotated position [107]. ...
Full-text available
Weight resistance training (RT) is an essential component of physical conditioning programs to improve the quality of life and physical fitness in different ages and populations. This integrative review aimed to analyze the scientific evidence on the relationship between exercise selection and the appearance of musculoskeletal injuries in physical fitness centers (PFC). The Pub-Med or Medline, EMBASE or Science Direct, Google Scholar and PEDro databases were selected to examine the available literature using a Boolean algorithm with search terms. The review process was performed using the five-stage approach for an integrative review and it was reported according to the PRISMA in Exercise, Rehabilitation, Sport Medicine and Sports Science (PERSiST) guidelines. A total of 39 peer-reviewed articles (Price index = 71.7%) met the inclusion criteria and evaluated the link between exercise selection and the incidence of injuries in exercisers who regularly attend PFC. Most injuries occur to the shoulders, elbows, vertebrae of the spine, and knees. Although the injury etiologies are multifactorial, the findings of the reviewed articles include the impacts of overuse, short post-exercise recovery periods, poor conditioning in the exercised body areas, frequent use of heavy loads, improper technique in certain exercises, and the abuse of performance and image-enhancing drugs. Practical recommendations addressed to clinical exercise physiologists, exercise professionals, and health professionals are given in this paper. The exercise selection in RT programs requires professional supervision and adhering to proper lifting techniques and training habits that consider the anatomical and biomechanical patterns of the musculoskeletal structures, as well as genetic, pedagogical, and methodological aspects directly related to the stimulus-response process to mitigate the occurrence of RT-related injuries in PFC.
... Nevertheless, the hamstrings and plantarflexors tend not to increase with squat training. Thus, if the aim is to increase the size of these later muscles (i.e., for a "complete lower-body training"), it is necessary to add exercises that target them (35), such as leg curls (24) and calf raises (27). ...
Full-text available
The squat is one of the most widely used exercises in resistance-training programs. The aim of the present narrative review was to analyze the effect of the squat on lower-limb muscle hypertrophy. Briefly, the available literature indicates that the squat is an effective exercise for inducing hypertrophy of the quadriceps, mainly the vastii, but also the rectus femoris, although to a reduced magnitude. Multiple lines of evidence suggest little to no hamstring hypertrophy from the back squat. While the gluteus maximus clearly participates mechanically in the back squat, few longitudinal studies exist on the topic. The limited evidence available on this topic suggests deeper squats may be more hypertrophic for the gluteus maximus, and that squat depth beyond 90 degrees of knee flexion may not provide further hypertrophy of the knee flexors. Despite the popularity of the many squat variations, there are still controversies surrounding their hypertrophic potential for lower-limb musculature. Further studies are needed to investigate the hypertrophic effects of different squat variations, as well as differences in hypertrophy due to squat depth, stance, barbell position, and different squat apparatuses/machines.
... B-mode ultrasonography with an 8-MHz linear array probe was used to evaluate the muscle thickness and pennation angle of the medial and lateral gastrocnemius (LG) muscles. Longitudinal ultrasound images were obtained for the MG and LG at 30% of the lower-leg length, measured from the popliteal crease to the lateral malleolus, near the point of the maximal cross-sectional area of the lower leg (Akagi and Takahashi, 2013;Nunes et al., 2020;Yahata et al., 2021). In addition, a longitudinal ultrasound image of the soleus muscle was obtained at 50% of the lower-leg length (Kubo et al., 2014(Kubo et al., , 2017. ...
Purpose: This study aimed to compare the cross-education effect of unilateral stretching intervention programs with two different intensities (high- vs. normal-intensity) on dorsiflexion range of motion (DF ROM), muscle stiffness, and muscle architecture following a 4-week stretching intervention. Methods: Twenty-eight healthy males were randomly allocated into two groups: a high-intensity static stretching (HI-SS) intervention group (n=14; stretch intensity 6-7 out of 10) and a normal-intensity static stretching (NI-SS) intervention group (n=14; stretch intensity 0-1 out of 10). The participants were asked to stretch their dominant leg (prefer to kick a ball) for 4 weeks (3 x week for 3 x 60s). Before and after the intervention, the non-trained leg passive properties (DF ROM, passive torque, and muscle stiffness) of the plantar flexors and the muscle architecture of the gastrocnemius medialis (muscle thickness, pennation angle, and fascicle length) were measured. Results: DF ROM and passive torque at DF ROM were significantly increased in the HI-SS group (50.6% and 18.2%, respectively), but not in the NI-SS group. Moreover, there were no further significant changes in both groups. Conclusion: For rehabilitation settings, a high-intensity SS intervention is required to increase the DF ROM of the non-trained limb. However, the increases in DF ROM seem to be related to changes in stretch tolerance and not to changes in muscle architecture or muscle stiffness.
... B-mode ultrasonography (LOGIQ e V2; GE Healthcare Japan, Tokyo, Japan) with an 8 MHz linear array probe was used to evaluate the muscle thickness and the pennation angle of the medial and lateral gastrocnemius muscles (MG and LG, respectively). Longitudinal ultrasound images were obtained for the MG and LG at 30% of the lower-leg length, measured from the popliteal crease to the lateral malleolus near the point of the maximal cross-sectional area of the lower leg (Akagi and Takahashi, 2013;Nakamura et al., 2014;Nunes et al., 2020a). Additionally, a longitudinal ultrasound image of the soleus muscle was obtained at 50% of the lower-leg length (Kubo et al., 2014(Kubo et al., , 2017. ...
Full-text available
The purpose of this study was to compare two static stretching (SS) programs at high-intensity (HI-SS) and normal-intensity (NI-SS) on passive and active properties of the plantar flexor muscles. Forty healthy young men were randomly allocated into three groups: HI-SS intervention group (n=14), NI-SS intervention group (n=13), and non-training control group (n=13). An 11-point numerical scale (0-10; none to very painful stretching) was used to determine SS intensity. HI-SS and NI-SS trained at 6-7 and 0-1 intensities, respectively, both in 3 sets of 60 secs, 3x/week, for 4 weeks. Dorsiflexion range of motion (ROM), gastrocnemius muscle stiffness, muscle strength, drop jump height, and muscle architecture were assessed before and after training. The HI-SS group improved more than NI-SS in ROM (40% vs. 15%) and muscle stiffness (-57% vs. -24%), while no significant change was observed for muscle strength, drop jump height, and muscle architecture in both groups. The control group presented no significant change in any variable. Performing HI-SS is more effective than NI-SS for increasing ROM and decreasing muscle stiffness of plantar flexor muscles following a 4-week training period in young men. However, SS may not increase muscle strength or hypertrophy, regardless of the stretching discomfort intensity.
The medial (GM) and lateral gastrocnemius (GL) muscles enroll to different subparts of the Achilles tendon to form their respective subtendons. The relative gastrocnemii activations during submaximal plantarflexion contraction depend on the position of the foot in the horizontal plane: with toes-in, GL activation increases and GM activation decreases, compared to toes-out. The aim of the current study was to investigate whether horizontal foot position during submaximal isometric plantarflexion contraction differently affects the subtendons within the Achilles tendon in terms of their (i) length at rest, and (ii) elongations and distal motions. Twenty healthy subjects (12 females/8 males) participated in the study. Three-dimensional ultrasound images were taken to capture subtendon lengths at rest and during isometric contraction. Ultrasound images were recorded at the distal end of Achilles tendon (sagittal plane) during ramped contractions and analyzed using a speckle tracking algorithm. All tasks were conducted twice, ones with toes-in and ones with toes-out. At rest, subtendons were shorter with toes-out compared to toes-in. During contraction, the GM subtendon lengthened more in toes-out, compared to the GL, and vice versa (all p<.01). The relative motions within the Achilles tendon (middle minus top layers displacements) were smaller in toes-in compared to toes-out (p=.05) for higher contraction intensity. Our results demonstrated that the horizontal foot position during plantarflexion contraction impacts Achilles tendon motions. Such findings may be relevant in a clinical context, for example in pathologies affecting Achilles tendon motions such as Achilles tendinopathy.
Full-text available
Fitness professionals routinely employ a variety of resistance training exercises in program design as a strategy to enhance muscular adaptations. However, it remains uncertain whether such an approach offers advantages over a fixed-exercise selection. The objective of this paper was to review the effects of exercise variation on muscle hypertrophy and strength. A search of literature was conducted using PubMed/MEDLINE, Scopus, and Web of Science databases. Eight studies were identified as meeting inclusion criteria. The combined total sample of the studies was n = 241, comprising all young men. The methodological quality of included studies was considered "good" and "excellent" based on the PEDro Scale. The available studies indicate that varying exercise selection can influence muscle hypertrophy and strength gains. Some degree of systematic variation appears to enhance regional hypertrophic adaptations, and maximize dynamic strength, whereas excessive, random variation may compromise muscular gains. We conclude that exercise variation should be approached systematically with a focus on applied anatomical and biomechanical constructs; on the contrary, employing different exercises that provide a redundant stimulus, as well as excessive rotation of different exercises (i.e., high frequency of change), may actually hinder muscular adaptations.
Full-text available
Over time, complex interactions and a nonlinear progression among a wide range of variables contribute to improvements in the physical health and level of achievement in youth sports practitioners. Various elements, including technical skills, physical performance, environmental circumstances, and social conditioning, contribute to the development of these processes. An influencing factor of growth and physical performance is somatic maturation. The pubertal period is a critical time for skill acquisition and improvements in performance for young people, in which suitable training strategies should be adopted to preserve their state of health while avoiding risks of injury. Athletes with similar chronological ages competing in the same category levels can, in fact, show differences in maturity and, therefore, in size, function, and body structure. Physical and psychological differences related to maturity and birthdate amongst athletes of the same selection year have been identified in a variety of sports and could be linked with the dropout of youth practitioners and a reduction in the talent pool. Contemporary researchers have contributed to research on improving health and sports performance through the development of new measurement methods and training strategies in young athletes. The aim of this Special Issue of , entitled , Somatic Maturation, and Their Impact on Physical Health and Sports Performance, is to propose and evaluate new training strategies aimed at improving the health status and physical performance of young athletes while highlighting the relationship between somatic maturation, anthropometry features, education, and health-related factors via longitudinal and cross-sectional studies.
Full-text available
Stretch training is widely used in a variety of fitness-related capacities such as increasing joint range of motion, preventing contractures, and alleviating injuries. Moreover, some researches indicate that stretch training may induce muscle hypertrophy; however, studies on the topic have been primarily relegated to animal and in vitro models. The purpose of this brief review was to evaluate whether stretch training is a viable strategy to induce muscle hypertrophy in humans. An extensive literature search was performed using PubMed/MEDLINE, SciELO, and Scopus databases, using terms related to stretching and muscle hypertrophy. Only human trials that evaluated changes in measures of muscle size or architecture following training protocols that it was performed stretching exercises were selected for inclusion. Of the 10 studies identified, 3 observed some significantly positive effects of stretch training on muscle structure. Intriguingly, in these studies, the stretching was carried out with an apparatus that aided in its performance, or with an external overload. In all studies the subjects performed stretching at their own self-determined range-of-motion, no effect was observed. Of the 5 available studies that integrated stretching into a resistance-training program, 2 applied the stretching in the interset-rest period and were the ones that showed enhanced muscle growth. In conclusion, passive, low-intensity stretch does not appear to confer beneficial changes in muscle size and architecture; alternatively, albeit limited evidence suggests that when stretching is done with a certain degree of tensile strain (particularly when loaded, or added between active muscle contractions) may elicit muscle hypertrophy.
Full-text available
Purpose The purpose of this study was to compare the effects of squat training with different depths on lower limb muscle volumes. Methods Seventeen males were randomly assigned to a full squat training group (FST, n = 8) or half squat training group (HST, n = 9). They completed 10 weeks (2 days per week) of squat training. The muscle volumes (by magnetic resonance imaging) of the knee extensor, hamstring, adductor, and gluteus maximus muscles and the one repetition maximum (1RM) of full and half squats were measured before and after training. Results The relative increase in 1RM of full squat was significantly greater in FST (31.8 ± 14.9%) than in HST (11.3 ± 8.6%) (p = 0.003), whereas there was no difference in the relative increase in 1RM of half squat between FST (24.2 ± 7.1%) and HST (32.0 ± 12.1%) (p = 0.132). The volumes of knee extensor muscles significantly increased by 4.9 ± 2.6% in FST (p < 0.001) and 4.6 ± 3.1% in HST (p = 0.003), whereas that of rectus femoris and hamstring muscles did not change in either group. The volumes of adductor and gluteus maximus muscles significantly increased in FST (6.2 ± 2.6% and 6.7 ± 3.5%) and HST (2.7 ± 3.1% and 2.2 ± 2.6%). In addition, relative increases in adductor (p = 0.026) and gluteus maximus (p = 0.008) muscle volumes were significantly greater in FST than in HST. Conclusion The results suggest that full squat training is more effective for developing the lower limb muscles excluding the rectus femoris and hamstring muscles.
Full-text available
The purpose of this study was to investigate the effects of using an internal versus external focus of attention during resistance training on muscular adaptations. Thirty untrained college-aged men were randomly assigned to an internal focus group (INTERNAL) that focused on contracting the target muscle during training (n = 15) or an external focus group (EXTERNAL) that focused on the outcome of the lift (n = 15). Training for both routines consisted of 3 weekly sessions performed on non-consecutive days for 8 weeks. Subjects performed 4 sets of 8–12 repetitions per exercise. Changes in strength were assessed by six repetition maximum in the biceps curl and isometric maximal voluntary contraction in knee extension and elbow flexion. Changes in muscle thickness for the elbow flexors and quadriceps were assessed by ultrasound. Results show significantly greater increases in elbow flexor thickness in INTERNAL versus EXTERNAL (12.4% vs. 6.9%, respectively); similar changes were noted in quadriceps thickness. Isometric elbow flexion strength was greater for INTERNAL while isometric knee extension strength was greater for EXTERNAL, although neither reached statistical significance. The findings lend support to the use of a mind–muscle connection to enhance muscle hypertrophy.
Full-text available
Surface electromyography (sEMG) is a popular research tool in sport and rehabilitation sciences. Common study designs include the comparison of sEMG amplitudes collected from different muscles as participants perform various exercises and techniques under different loads. Based on such comparisons, researchers attempt to draw conclusions concerning the neuro- and electrophysiological underpinning of force production and hypothesize about possible longitudinal adaptations, such as strength and hypertrophy. However, such conclusions are frequently unsubstantiated and unwarranted. Hence, the goal of this review is to discuss what can and cannot be inferred from comparative research designs as it pertains to both the acute and longitudinal outcomes. General methodological recommendations are made, gaps in the literature are identified, and lines for future research to help improve the applicability of sEMG are suggested.
Full-text available
The purpose of this paper was to conduct a systematic review of the current body of literature and a meta-analysis to compare changes in strength and hypertrophy between low- versus high-load resistance training protocols. Searches of PubMed/MEDLINE, Cochrane Library and Scopus were conducted for studies that met the following criteria: 1) an experimental trial involving both low- (≤60% 1 RM) and high- (>60% 1 RM) load training; 2) with all sets in the training protocols being performed to momentary muscular failure; 3) at least one method of estimating changes in muscle mass and/or dynamic, isometric or isokinetic strength was used; 4) the training protocol lasted for a minimum of 6 weeks; 5) the study involved participants with no known medical conditions or injuries impairing training capacity. A total of 21 studies were ultimately included for analysis. Gains in 1RM strength were significantly greater in favor of high- versus low-load training, while no significant differences were found for isometric strength between conditions. Changes in measures of muscle hypertrophy were similar between conditions. The findings indicate that maximal strength benefits are obtained from the use of heavy loads while muscle hypertrophy can be equally achieved across a spectrum of loading ranges.
Full-text available
Background: The gastrocnemius has two heads, medial gastrocnemius (MG) and lateral gastrocnemius (LG); little is known how they contract with different foot positions. The MG is more frequently strained than the LG; and gastrocnemius activation pattern altered by foot position may play a role in injury. Leg exercises often use a toe-in versus toe-out foot position to isolate one gastrocnemius head over another. Purpose: The purpose of this study was to determine the electromyographic gastrocnemius muscle activity in the toe-out and toe-in foot positions during weight bearing and non-weight bearing activities. The hypothesis was that a toe-out foot position would elicit greater MG than LG activity; while the toe-in position would elicit greater activity in LG than MG in both weight bearing and non-weight bearing (NWB) positions. Study design: A cross-sectional study of young adults. Methods: Thirty-three participants were recruited. Surface electrodes were placed on the bellies of the MG and LG. The gastrocnemius muscle was tested in toe-in and toe-out foot positions using two different tests: a standing heel-rise and resisted knee flexion while prone. Electromyographic activity was normalized against a MVIC during a heel raise with a neutral foot position. A 2x2x2 (Foot Position x Test Position x Muscle) ANOVA was used to determine if differences exist in activity between the MG and LG for toe-in versus toe-out standing and prone test positions. Results: Significant test position main effect (F [1,32] = 86.9; p < .01), significant muscle main effect (F [1,32]=5.5; p < .01), and significant foot position x muscle interaction (F [1,32] = 14.58; p < .01) were found. Post hoc tests showed differences between MG and LG in toe-out position (t = 3.10; p < .01) but not in the toe-in for both test positions (t = 1.27; p = 0.21). Conclusions: With toe-out, the MG was more active than LG in standing and prone; no difference was noted between MG and LG in toe-in for either position. Level of evidence: Level 2.
Key points: Performing resistance exercise with heavier loads is often proposed to be necessary for the recruitment of larger motor units and activation of type II muscle fibres, leading to type II fibre hypertrophy. Indirect measures (surface electromyography - EMG) have been used to support this thesis, but we propose that lighter loads lifted to task failure (i.e., volitional fatigue) result in similar activation of type II fibres. In this study we had participants perform resistance exercise to task failure with heavier and lighter loads with both a normal and longer repetition duration (i.e., time under tension). Type I and type II muscle fibre glycogen depletion was determined by neither load nor repetition duration during resistance exercise performed to task failure. Surface EMG amplitude was not related to muscle fibre glycogen depletion or anabolic signalling; however, muscle fibre glycogen depletion and anabolic signalling were related. Performing resistance exercise to task failure, regardless of load lifted or repetition duration, necessitates the activation of type II muscle fibres. Abstract: Heavier loads (>60% of maximal strength) are believed to be necessary during resistance exercise (RE) to activate and stimulate hypertrophy of type II fibres. Support for this proposition comes from observation of higher surface electromyography (EMG) amplitudes during RE when lifting heavier vs. lighter loads. We aimed to determine the effect of RE, to task failure, with heavier versus lighter loads and shorter or longer repetition durations on: EMG-derived variables, muscle fibre activation, and anabolic signalling. Ten recreationally-trained young men performed four unilateral RE conditions randomly on two occasions (two conditions, one per leg per visit). Muscle biopsies were taken from the vastus lateralis before and one hour after RE. Broadly, total time under load, number of repetitions, exercise volume, EMG amplitude (at the beginning and end of each set), and total EMG activity were significantly different between conditions (P < 0.05); however, neither glycogen depletion (in both type I and type II fibres) nor phosphorylation of relevant signalling proteins were different between conditions. We conclude that muscle fibre activation and subsequent anabolic signalling are independent of load, repetition duration, and surface EMG amplitude, when RE is performed to task failure. Our results provide evidence that type I and type II fibres are activated when heavier and lighter loads are lifted to task failure. We propose that our results explain why RE training with higher or lower loads, when loads are lifted to task failure, result in equivalent muscle hypertrophy and occurs in both type I and type II fibres. This article is protected by copyright. All rights reserved.
Training frequency is considered an important variable in the hypertrophic response to regimented resistance exercise. The purpose of this paper was to conduct a systematic review and meta-analysis of experimental studies designed to investigate the effects of weekly training frequency on hypertrophic adaptations. Following a systematic search of PubMed/MEDLINE, Scoups, and SPORTDiscus databases, a total of 25 studies were deemed to meet inclusion criteria. Results showed no significant difference between higher and lower frequency on a volume-equated basis. Moreover, no significant differences were seen between frequencies of training across all categories when taking into account direct measures of growth, in those considered resistance-trained, and when segmenting into training for the upper body and lower body. Meta-regression analysis of non-volume-equated studies showed a significant effect favoring higher frequencies, although the overall difference in magnitude of effect between frequencies of 1 and 3+ days per week was modest. In conclusion, there is strong evidence that resistance training frequency does not significantly or meaningfully impact muscle hypertrophy when volume is equated. Thus, for a given training volume, individuals can choose a weekly frequency per muscle groups based on personal preference.
Background: muscle activation measured by electromyography provides additional insight into functional differences between movements and muscle involvement. Objective: to evaluate the electromyography of triceps surae during heel-raise exercise in healthy subjects performed at leg press machine with different feet positions. Methods: ten trained healthy male adults aged between 20 and 30 years voluntarily took part in the study. After biometric analyses the EMG signals were obtained using a 8-channel telemeterized surface EMG system (EMG System do Brazil, Brazil Ltda) (amplifier gain: 1000x, common rejection mode ratio >100 dB, band pass filter: 20 to 500 Hz). All data was acquired and processed using a 16-bit analog to digital converter, with a sampling frequency of 2kHz on the soleus (Sol), medial (GM) and lateral (GL) gastrocnemius muscles in both legs, in accordance with the recommendations of SENIAN. The root mean square (RMS) of the EMG amplitude was calculated to evaluate muscle activity of the three muscles. After being properly prepared for eletromyography procedures, all subjects were instructed to perform 3 sets of 5 repetitions during heel-raise exercise using the maximal load that enabled 10 repetitions on leg press 45° machine, each set being performed with one of the following feet positions: neutral (0º), internal and external rotation (both with 45° from neutral position). The tests were sequential and applied a 5-minute rest interval between sets. The order of the tests was randomized. Results: thought had been found interaction (F=0.27, P= 0.75) on RMS parameters and feet position, the values of Sol muscle were significantly (F=17.86, P= 0.003) lower compared with GL and GM muscles independently of feet position. Conclusion: The change in the feet position during the heel-rise exercise performed in the leg press does not influence the activation of the triceps surae, and the soleus is less activated than the gastrocnemius in that exercise.
BACKGROUND: Varying exercise parameters, such as angles of movement, can cause different activation patterns within muscle compartments. Therefore, it is expected that feet positioning variations could influence gastrocnemius activity. OBJECTIVE: Compare gastrocnemius activation during plantar flexion with feet pointing forwards (FO), inwards (IN) and outwards (OU). METHODS: Sixteen physically active men (21 ± 2 years; 1.75 ± 0.06 meters and 74.8 ± 7.2 kg), performed 3 sets of 10 repetitions in each of the following experimental conditions: plantar flexion with feet pointing FO, IN and OU. The root mean square (RMS) of the muscular activation of both gastrocnemius heads was analyzed in each set by electromyography. RESULTS: For the medial head of the gastrocnemius, the OU condition presented greater RMS values when compared to the IN (z = 3.41; p < 0.001) and FO (z = 2.37; p ≤ 0.017) conditions. For the lateral head, however, the IN condition demonstrated greatest RMS when compared with OU (z = 3.20; p = 0.001) and FO (z = 3.25; p = 0.001) conditions. CONCLUSIONS: These results suggest that it is possible to create greater activation sites in the gastrocnemius. Trainers and practitioners could use this to prescribe exercise more efficiently, possibly correcting asymmetries in athletes, especially bodybuilders.