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Short Research Report
Different Foot Positioning During Calf Training to
Induce Portion-Specific Gastrocnemius
Muscle Hypertrophy
Joa
˜o Pedro Nunes,
1
Bruna D.V. Costa,
1
Witalo Kassiano,
1
Gabriel Kunevaliki,
1
Pˆamela Castro-e-Souza,
1
Andr ´e L.F. Rodacki,
2
Leonardo S. Fortes,
3
and Edilson S. Cyrino
1
1
Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, Brazil;
2
Department of Physical Education, Federal University of Paran ´a, Curitiba, Brazil; and
3
Department of Physical Education, Federal
University of Para´
ıba, Joa
˜o Pessoa, Brazil
Abstract
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
Introduction
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.
Methods
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, joaonunes.jpn@hotmail.com.
Journal of Strength and Conditioning Research 00(00)/1–5
ª2020 National Strength and Conditioning Association
1
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 2–10). 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 (random.org)
and were evaluated on 2 days of week 1 (separated by 72 hours) to
determine the reliability of the MT measurements.
Subjects
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: 18–35 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 (1–29) 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
22
). 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.
Procedures
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 subjects’skin 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 60–100 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 ;40–60% 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 20–25 repetitions for training weeks 1–3 and increased to 4
sets for weeks 4–9. 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
60–90 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 muscle”on each repetition, mainly during the con-
centric peak phase (26). When near to momentary muscular failure
(last ;3–5 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
“squeezing”the 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 subject’s 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 5–10%, 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-Wilk’s test. Levene’stestwas
used to analyze the homogeneity of variances. These assumed
Selective Gastrocnemius Muscle Hypertrophy (2020) 00:00
2
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, Bonferroni’sposthoc
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 0.00–0.19 was considered as trivial, 0.20–0.49 was
considered as small, 0.50–0.79 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).
Results
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.
Discussion
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 type–specific 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).*†
FPO FPI FPF
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‡
Mean
diff
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‡
Mean
diff
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
diff
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 |www.nsca.com
3
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 intra–muscle-group and inter–muscle-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 “squeezing”the 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-
ship,wheneachheadwasexercisedinamoreelongatedcondition,
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.
Acknowledgments
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.
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