Different Foot Positioning During Calf Training to Induce Portion-Specific

1 34(8): 9.1%, 5 5.5%, FPI 5 J Strength Cond Res i et al. (14) observed a greater ac- amela Castro-e-Souza, Pˆ 1 Department of Physical Education, Federal 5.8%) and lateral (FPO 3 5 1 Gabriel Kunevaliki, Given the wide gap between acute muscular activation and 1 3.8%, and FPF muscle hypertrophy (29,30), long-term experimentalneeded studies to are determinetraining-induced whether effect on the gastrocnemius foot musclefore, growth. this position study There- was influences designednemius the to muscle compare the thickness changes (MT)performed in when gastroc- with the the calf-raise exercise footinward was pointed (FPI), outward or (FPO),progressive foot resistance foot training pointed in pointed young forward men.that It (FPF) the was increase hypothesized after in the 9 MTgreater of weeks the for medial the of gastrocnemius FPO would be condition,be whereas better the for FPI improving conditionwas the would expected lateral head that gastrocnemius.growth the Also, because FPO it it may condition elicit resulted intermediate activation. in intermediary feet seems to influence the(2,14,18,19). For recruitment instance, of Marcor the gastrocnemiustivation muscles of the medial heada when greater the feet activation wereHowever, pointed of these outward findings the and are lateral not universal head (18). with feet pointed inward. Methods Experimental Approach to the Problem This study is part of athe larger effects research of project whole-body designed to resistance-training analyze protocols in young 5 2347 a, Curitiba, Brazil; and 8.4%, FPI 5 and Edilson S. Cyrino 3 Witalo Kassiano, 1 ticularly important for the gas- induces portion-specific hypertrophy Leonardo S. Fortes, o Pessoa, Brazil Bruna D.V. Costa, o Pedro Nunes, [email protected]. ˜ ˜ 2 1 4 years) were selected and performed a whole-body resistance training program 3 times per week for 9 weeks, 0.05). Positioning FPO potentiated the increases in MT of the medial gastrocnemius head, whereas FPI provided ´ ıba, Joa 6 triceps surae, ankle, plantar flexion, muscle growth, muscle architecture, nonuniform muscle hypertrophy , p 6.4%) gastrocnemius heads, and significant differences for magnitude of the gains were observed between FPO and FPI 5

e L.F. Rodacki, o Pedro Nunes,

˜ The triceps surae muscle group consists of the soleus and gastroc- conditions ( greater gains for theselectively lateral for gastrocnemius gastrocnemius after head. 9 Our weeks results of suggest calf training that in head-specific young muscle male adults. hypertrophy may be obtained and FPF 2347–2351, 2020—The aim ofditions this such study as which was foot was to pointedyoung outward compare (FPO), men the foot (23 was changes pointed inward in (FPI),with or gastrocnemius foot differences was muscle pointed thickness forward in (FPF). (MT) Twenty-two thehorizontal between leg-press exercise machine, con- in specific 3 sets for ofrandomly 20–25 calves. repetitions assigned for The training for weeks calf-raise 1–3 1ultrasound and exercise 4 were of sets performed was for the weeks to performed 4–9. assess 3 Eachwere unilaterally, subject’s observed changes groups leg increases in in was in according MT MT a of of to both pin-loaded medial medial the seated and (FPO foot lateral gastrocnemius position: heads. FPO, After FPI, the training and period, FPF. there Measurements with a B-mode Abstract Nunes, JP, Costa, BDV, Kassiano,positioning W, Kunevaliki, during G, Castro-e-Souza, calf P, Rodacki, training ALF, Fortes, to LS, and induce Cyrino, ES. portion-specific Different foot gastrocnemius muscle hypertrophy. 2020 National Strength and Conditioning Association Key Words: Short Research Report Metabolism, Nutrition, and Exercise Laboratory,Department Physical of Education Physical and Education, Sport Federal Center, University Londrina of State Paran University, ´ Londrina, Brazil; Journal of Strength and Conditioning Research 34(8)/2347–2351 ª Address correspondence to Joa nemius lateral and medialflexor, heads. and The gastrocnemii are soleus multijoint muscles is thatthe a cross ankle. the If single-joint varying knee foot and plantar position of the triceps surae (20), performing differentto exercises its may development. contribute This could be par Muscle hypertrophy is oneobtained of with the repeated mainregion-specific bouts hypertrophy outcomes is of particularly that aimed by resistance may bodybuilders (1), exercise. be muscle Although growth doesmuscle not occur regions in (1,16,20,31), the(i.e., irrespective same trained magnitude of or in the untrained). all a training Varying viable strategy exercise status for choice potentiating overall seemsto muscle to a gains resistance-training in be response program (8).same In exercise addition, performing under the differentconsider joint different positions (which exercisesobtaining some region-specific muscle may as growth (1,6,7,20). well) has been proposed for Introduction trocnemius because it is deemed asstimuli difficult to (1,28). respond to Although hypertrophy flexed performing may plantar induce flexion greaterexercise with hypertrophy is executed in the with the the knee knee soleus extended (18,20), than the position when of the the 1 2 Muscle Hypertrophy Joa Andr ´ Induce Portion-Specific Gastrocnemius Different Foot Positioning During Calf Training to University of Para Copyright © 2020 National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.

Downloaded from http://journals.lww.com/nsca-jscr by BhDMf5ePHKbH4TTImqenVBaqevB2sTM0VHxvq5oSfttfNyeDNoqo9iBK/DJWAIsv on 07/31/2020 Downloaded from http://journals.lww.com/nsca-jscr by BhDMf5ePHKbH4TTImqenVBaqevB2sTM0VHxvq5oSfttfNyeDNoqo9iBK/DJWAIsv on 07/31/2020 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 2 6.2 cm; and body mass index 5 25.1 6 3.6 kg·m 2). 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 concentric 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’stestwas ments of the medial head were taken with the probe positioned in used to analyze the homogeneity of variances. These assumed

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’sposthoc 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 between FPO and FPI conditions, with a greater increase for the FPO condition (p 5 0.021). Similarly, a significant effect of the condition 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 SD †Pre-training and post-training data are presented as mean and , 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.

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 moment 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). 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