Different Foot Positioning During Calf Training to Induce Portion-Specific Gastrocnemius Muscle Hypertrophy
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Short Research Report
Different Foot Positioning During Calf Training to
Induce Portion-Specific Gastrocnemius
Muscle Hypertrophy
João Pedro Nunes,1 Bruna D.V. Costa,1 Witalo Kassiano,1 Gabriel Kunevaliki,1 Pâmela Castro-e-Souza,1
André L.F. Rodacki,2 Leonardo S. Fortes,3 and Edilson S. Cyrino1
1
Metabolism, Nutrition, and Exercise Laboratory, Physical Education and Sport Center, Londrina State University, Londrina, Brazil;
2
Department of Physical Education, Federal University of Paraná, Curitiba, Brazil; and 3Department of Physical Education, Federal
University of Paraı´ba, João Pessoa, Brazil
Abstract
Downloaded from http://journals.lww.com/nsca-jscr by BhDMf5ePHKbH4TTImqenVBaqevB2sTM0VHxvq5oSfttfNyeDNoqo9iBK/DJWAIsv on 07/31/2020
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 34(8):
2347–2351, 2020—The aim of this study was to compare the changes in gastrocnemius muscle thickness (MT) between con-
ditions such as which foot was pointed outward (FPO), foot was pointed inward (FPI), or foot was pointed forward (FPF). Twenty-two
young men (23 6 4 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 5 8.4%, FPI 5 3.8%, and FPF 5 5.8%) and lateral (FPO 5 5.5%, FPI 5 9.1%,
and FPF 5 6.4%) 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 gastrocnemius 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 feet seems to influence the recruitment of the gastrocnemius muscles
(2,14,18,19). For instance, Marcori et al. (14) observed a greater ac-
Muscle hypertrophy is one of the main outcomes that may be
tivation of the medial head when the feet were pointed outward and
obtained with repeated bouts of resistance exercise. Although
a greater activation of the lateral head with feet pointed inward.
region-specific hypertrophy is particularly aimed by bodybuilders
However, these findings are not universal (18).
(1), muscle growth does not occur in the same magnitude in all
Given the wide gap between acute muscular activation and
muscle regions (1,16,20,31), irrespective of the training status
muscle hypertrophy (29,30), long-term experimental studies are
(i.e., trained or untrained). Varying exercise choice seems to be
needed to determine whether the foot position influences the
a viable strategy for potentiating overall muscle gains in response
training-induced effect on gastrocnemius muscle growth. There-
to a resistance-training program (8). In addition, performing the
fore, this study was designed to compare the changes in gastroc-
same exercise under different joint positions (which some may
nemius muscle thickness (MT) when the calf-raise exercise was
consider different exercises as well) has been proposed for
performed with the foot pointed outward (FPO), foot pointed
obtaining region-specific muscle growth (1,6,7,20).
inward (FPI), or foot pointed forward (FPF) after 9 weeks of
The triceps surae muscle group consists of the soleus and gastroc-
progressive resistance training in young men. It was hypothesized
nemius lateral and medial heads. The soleus is a single-joint plantar
that the increase in the MT of the medial gastrocnemius would be
flexor, and gastrocnemii are multijoint muscles that cross the knee and
greater for the FPO condition, whereas the FPI condition would
the ankle. If varying foot position induces portion-specific hypertrophy
be better for improving the lateral head gastrocnemius. Also, it
of the triceps surae (20), performing different exercises may contribute
was expected that the FPO condition resulted in intermediary
to its development. This could be particularly important for the gas-
growth because it may elicit intermediate activation.
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 Methods
Address correspondence to João Pedro Nunes, joaonunes.jpn@hotmail.com. Experimental Approach to the Problem
Journal of Strength and Conditioning Research 34(8)/2347–2351 This study is part of a larger research project designed to analyze
ª 2020 National Strength and Conditioning Association the effects of whole-body resistance-training protocols in young
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Copyright © 2020 National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.Selective Gastrocnemius Muscle Hypertrophy (2020) 34:8
male adults. The current investigation was executed over a period the thickest and more laterally prominent site of the lower leg (from
of 11 weeks. Weeks 1 and 11 were used for ultrasound meas- a posteroanterior view). A generous quantity of water-soluble
urements, whereas the progressive training program was per- transmission gel was applied over the skin of the muscle being
formed for 9 weeks (weeks 2–10). Subjects performed 7 exercises, assessed, with caution not to depress the skin. Images were ac-
6 of which for the major muscle groups (e.g., bench press, lat pull- quired with the probe placed perpendicular to the tissue interface
down, triceps pushdown, biceps curl, leg press, and leg curl) in and were recorded at 25 Hz, with a field of view of 60–100 mm
addition to the unilateral calf-raise exercise. Subjects were depth. Two experimenters participated in measurement procedures
assessed before and after intervention for measures of gastroc- so that one handled the probe (and drawn the lines on the skin as
nemius MT. Eight subjects were randomly chosen (random.org) well), and the other was responsible for freezing the images (once
and were evaluated on 2 days of week 1 (separated by 72 hours) to the first considered that the quality was satisfactory). The MT of
determine the reliability of the MT measurements. 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.
Subjects Houilles, France) to visually check if sites where MT would be
estimated were the same (1 image had its opacity ;40–60% re-
Recruitment was conducted through social media and home de-
livery of flyers in the university area. Interested subjects completed duced). The MT length was determined using the ImageJ software
detailed health history and physical activity questionnaires and (v. 1.50; NIH, Bethesda, MD). Values of coefficient of variation,
were subsequently admitted if they met the following inclusion intraclass correlation coefficient, standard error of measurement,
criteria: 18–35 years of age; male; free from cardiac, orthopedic, or and minimum detectable difference were of 2.8%, 0.97 (ranging
musculoskeletal disorders that could impede exercise practice; not from 0.90 to 0.99), 0.052 cm, and 0.103 cm for the medial gas-
consume drug or supplement ergogenic aids; not be involved in the trocnemius MT assessment and were of 3.4%, 0.98 (ranging from
practice of resistance training over the 4 months before the start of 0.93 to 0.99), 0.059 cm, and 0.117 cm for the lateral gastrocne-
the study, but should have a training experience of at least 6 mius, respectively (9).
months. From the 52 volunteers, 29 met the criteria, were evaluated
at baseline, and initiated the training sessions. Calf Training. The supervised resistance-training program was
To determine the allocation to the groups, a number was ran- performed 3 times per week (Mondays, Wednesdays, and Fridays)
domly attributed to each subject (1–29) and a number to each leg of in the afternoon period for 9 weeks. Calf-raise exercises were
them (1 or 2). Then, subjects were randomly selected, and each leg performed unilaterally, in a pin-loaded seated horizontal leg-press
was randomly assigned to 1 of the 3 groups according to foot machine (Ipiranga; Fitness Line, Presidente Prudente, Brazil) in 3
position for the calf-raise exercise: FPO, FPI, and FPF. During the sets of 20–25 repetitions for training weeks 1–3 and increased to 4
training period, subjects who obtained 6 absences from training sets for weeks 4–9. Subjects were instructed to perform 1 set with 1
sessions (resulting in an attendance ,80% of the total number of leg, to rest a few seconds enough to self-adjust the body posture,
sessions) were asked to withdraw the program and were not and then to perform 1 set with the other leg. The rest period was
assessed on post-training measurements. Twenty-two subjects 60–90 seconds after finishing 1 set for both legs. Subjects were
(FPO, n 5 16 legs; FPI, n 5 16 legs; and FPF, n 5 12 legs) ultimately instructed to alternate the leg to begin the calf-raise exercises to
completed the study and were included for final analyses (age 5 minimize potential effects of residual fatigue. Calf-raise exercises
23.0 6 3.8 years; body mass 5 78.1 6 13.7 kg; stature 5 176.1 6 were performed in the maximum range of motion, with the knee
6.2 cm; and body mass index 5 25.1 6 3.6 kg·m22). No adverse extended, in a tempo of 1:1:2 seconds (concentric, concentric peak,
event occurred during the intervention period. Written informed and eccentric phases, respectively), and subjects were cued to
consent was obtained from all subjects after a detailed description “squeeze the muscle” on each repetition, mainly during the con-
of study procedures was provided. This investigation was con- centric peak phase (26). When near to momentary muscular failure
ducted according to the Declaration of Helsinki and was approved (last ;3–5 repetitions), subjects were released to carry out the
by the Federal University of Pernambuco Ethics Committee. 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
Procedures on the platform supported by metatarsals (14). For the FPO or FPI
condition, subjects positioned their foot at 45° externally or in-
Gastrocnemius Muscle Thickness Measurement. Measures of ternally rotated (including both ankle and femur rotation, as nec-
gastrocnemius MT were obtained at weeks 1 (before training) and essary), respectively, or when this amplitude was not achieved, at
11 (after training) using a B-mode ultrasound (Logiq book; GE the maximum angle according to the subject’s articular mobility.
Healthcare, Madison, WI), with a 7.5-MHz linear probe (8L-RS; For the FPF condition, the foot was positioned forward-pointing,
GE Healthcare). All procedures were performed in the morning with no lateral or medial rotation. Duct tape was used in the leg-
hours by the same experimenters in pre-training and post-training. press platform as a guide to be followed (14). The training load was
On arrival at the laboratory on measurement days, subjects ver- progressively increased each week by 5–10%, according to the
bally certified that they had been fasting for 8 hours and had not number of repetitions performed during each training session to
performed vigorous exercise for the previous 48 hours. After that, ensure that the subjects kept performing the sets to (or very near to)
lines were drawn on the subjects’ skin with a dermatographic pen failure in the established repetition zone (5).
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
Statistical Analyses
taken at the proximal third between the lateral epicondyle of the
femur and the lateral malleolus of the fibula, whereas measure- Normality was checked by Shapiro-Wilk’s test. Levene’s test was
ments of the medial head were taken with the probe positioned in used to analyze the homogeneity of variances. These assumed
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differences on the effects of different foot positions (FPO vs. FPI vs. in which the FPO induced greater gains on the medial head,
FPF) on gastrocnemius muscle hypertrophy were examined with whereas the FPI potentiated the lateral head muscle growth.
analysis of covariance of the raw difference between pre- Moreover, the FPF condition resulted in similar relative gains for
intervention and postintervention measures with baseline values as both heads and did not present significant differences in com-
a covariate to eliminate any possible influence of initial score var- parison with FPO and FPI conditions. This indicates that
iances on outcomes. Interpretation of data was based on 95% changing the foot position can potentiate hypertrophy of a head
confidence intervals (CIs) of the change score (e.g., when 95% CI of of the gastrocnemius without impairing the increase of the op-
the raw delta did not overlap the 0, there was a difference between posite head significantly. The initial hypotheses were confirmed,
the baseline score). The p values for group comparisons were also and, based on the findings, portion-specific calf muscle hyper-
presented. When the F-ratio was significant, Bonferroni’s post hoc trophy is related to the ability to exercise muscle portions selec-
test was used to identify the differences between pre-training and tively, especially when the foot is pointed outward or inward.
post-training raw data. A p # 0.05 value was accepted as statisti- The relationship between muscular activation and hypertro-
cally significant. The effect size (ES) was calculated as post-training phy is somewhat argued as complex and uncertain (29,30).
mean minus pre-training mean, divided by pooled pre-training SD However, the main point that supports such a line of reasoning is
(3). An ES of 0.00–0.19 was considered as trivial, 0.20–0.49 was that, when comparing training intensities, high loads and low
considered as small, 0.50–0.79 was considered as moderate, and repetitions vs. low loads and high repetitions exhibit different
$0.80 was considered as large (3). The data were expressed as muscular activations (evaluated by surface electromyography
mean, SD, and 95% CIs. The data were stored and analyzed using [sEMG]), although both training protocols seem to induce similar
SPSS software, v. 23.0 (IBM Corp., Armonk, NY). 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).
Results Indeed, a previous study showed that when measuring muscular
Table 1 displays the values of gastrocnemius MT before and after activation using fiber type–specific glycogen depletion obtained
training. After the training period, there were observed increases of by essays of muscle biopsies, high and low load performed until
small-to-moderate magnitude on MT of the medial and lateral failure elicited similar results (15). Regardless, the proposed poor
gastrocnemius for FPO, FPI, and FPF conditions. A significant ef- relationship between sEMG and hypertrophy responses (29,30),
fect of the condition was observed for the increases in the medial however, possibly cannot be generalized to experimental designs
gastrocnemius (F 5 4,048; p 5 0.025), 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 (p 5 0.021). Similarly, a significant effect of the condi-
tion was observed for the increases in the lateral gastrocnemius (F
5 4,259; p 5 0.021), with a significant difference only between
FPO and FPI conditions, favoring the FPO condition (p 5 0.020).
Figure 1 shows the relative changes on MT of both medial (FPO 5
8.4%; FPI 5 3.8%; and FPF 5 5.8%) and lateral (FPO 5 5.5%;
FPI 5 9.1%; and FPF 5 6.4%) 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,
Table 1
Training effect on medial and lateral gastrocnemius muscle
thickness (cm).*†
FPO FPI FPF
Medial gastrocnemius MT
Pre 1.99 6 0.26 2.01 6 0.26 2.02 6 0.19
Post 2.15 6 0.27‡ 2.09 6 0.27‡§ 2.14 6 0.22‡
Meandiff 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 6 0.32 2.04 6 0.35 2.05 6 0.28
Post 2.18 6 0.32‡ 2.22 6 0.37‡§ 2.18 6 0.31‡
Meandiff 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 Figure 1. Percentage changes from pre-training to post-
training period for medial and lateral gastrocnemius muscle
*FPO 5 foot pointed outward (n 5 16); FPI 5 foot pointed inward (n 5 16); FPF 5 foot pointed thickness. FPO 5 foot pointed outward (n 5 16); FPI 5 foot
forward (n 5 12); MT 5 muscle thickness; ES 5 effect size. pointed inward (n 5 16); and FPF 5 foot pointed forward (n 5
†Pre-training and post-training data are presented as mean and SD, whereas meandiff as mean and 12). †p , 0.05 difference between FPO and FPI conditions.
95% confidence intervals. The horizontal lines represent mean and 95% confidence
‡p , 0.05 vs. baseline. intervals, whereas each circle represents a leg.
§p , 0.05 vs. FPO.
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comparing different muscles or regions of a same muscle after the execution velocity and range of motion, no device was used to
performance of an exercise. That is, a greater activation of a given monitor these factors strictly. Moreover, dietary intake and daily
muscle compared with the other involved ones during an exercise physical activity levels were not assessed, and whether these fac-
seems to indicate at least that this muscle or portion is more likely to tors could exert some influence on the adaptations remains un-
be hypertrophied. It is worthy to note that this study did not per- certain. Finally, this experiment was performed in young adult
form any muscular activation analysis, and these comparisons and men, and results cannot be generalized to other populations of
inferences are based on sEMG data reported elsewhere (14,19). different sex, age, or training status.
Other studies have also shown that differences between the In conclusion, the results of this study indicate that head-
magnitude of intra–muscle-group and inter–muscle-group hy- specific muscle hypertrophy may be obtained for gastrocnemius
pertrophy may be related to differences in muscular activation, after 9 weeks of calf training in young male adults. Positioning
such as greater hypertrophy of the pectoral major compared with FPO may induce greater gains in MT of the medial gastrocnemius
the triceps brachii after chest-press training (17) and corre- head, whereas positioning FPI seems to be better suited for in-
sponding findings in studies on muscular activation (22,27), se- creasing the lateral gastrocnemius head.
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 Practical Applications
hamstrings after squat training (4,11). Nonetheless, controversies
exist (1,6,7), and there are many determinants that dictate muscle Coaches and practitioners can choose the position of the foot
hypertrophy so that muscular activation should not be considered if the training aim is to induce hypertrophy of the different
a surrogate marker for muscle growth. portions of the gastrocnemius selectively. From the results of
The gastrocnemius is a single muscle unit but is a bipennate our study, pointing foot straight forward may be the ideal
muscle. It may be possible to increase the recruitment of a specific approach when the aim is to induce proportional improve-
portion selectively once it has 2 compartments and one has its own ment on both heads of the gastrocnemius, whereas pointing
innervations (1,14,19). Thus, the strategy used to focus on foot outward or inward may induce selective muscle growth,
“squeezing” the muscles during each repetition might have also thus correcting muscle asymmetries and improving the aes-
contributed to current findings because this tends to increase the thetic shape of the lower leg. Combining the FPO and FPI
activation of the targeted muscles (21,26,27). Moreover, it can be could maximize the gains on both heads, although future
speculated that, during the calf-raise exercises, FPO and FPI con- studies are needed to test such a hypothesis.
ditions caused greater specific stretching of the medial and lateral
heads of the gastrocnemius, respectively. Because of neuromuscular
Acknowledgments
compartmentalization, each gastrocnemius head has its own mo-
ment arms and length-tension curves during ankle movements The authors thank all subjects for their engagement in the study,
(10,12,13). Therefore, based on the length-tension relationship, the Coordination of Improvement of Higher Education Personnel
when each head was exercised in a more elongated condition, de- (CAPES/Brazil) for the scholarship conferred to J.P. Nunes,
termined by the foot position, the activation of greater muscle fibers B.D.V. Costa, W. Kassiano, G. Kunevaliki, and P. Castro-e-Souza
was necessary to produce torque, then, under a greater overload (master), and the National Council of Technological and
that ultimately caused a greater muscle growth (10). That is, the Scientific Development (CNPq/Brazil) for the grants conceded
medial gastrocnemius was at a disadvantage in the FPO condition, to A.L.F. Rodacki, L.S. Fortes, and E.S. Cyrino.
as well as the lateral gastrocnemius in the FPI condition; thus, in The authors declare that they have no conflict of interest
these conditions, each portion should be more forced to perform the regarding the publication of this paper.
exercise (14). Previous findings have indicated that the gastrocne-
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