Hypertrophy
Randomized Controlled Trial
2019
Resistance Training Volume Enhances Muscle Hypertrophy but Not Strength in Trained Men
By Brad J. Schoenfeld, Bret Contreras, James Krieger, Jozo Grgic, Kenneth Delcastillo, Ramon Belliard and Andrew Alto
Medicine & Science in Sports & Exercise, 51(1), pp. 94-103
Abstract
<h2>Abstract</h2> <p>Purpose: The purpose of this study was to evaluate muscular adaptations between low-, moderate-, and high-volume resistance training protocols in resistance-trained men. Methods: Thirty-four healthy resistance-trained men were randomly assigned to one of three experimental groups: a low-volume group performing one set per exercise per training session (n = 11), a moderate-volume group performing three sets per exercise per training session (n = 12), or a high-volume group performing five sets per exercise per training session (n = 11). Training for all routines consisted of three weekly sessions performed on nonconsecutive days for 8 wk. Muscular strength was evaluated with one repetition maximum (<a href="/terms/repetition-maximum/" class="term-link" data-slug="repetition-maximum" title="RM">RM</a>) testing for the squat and bench press. Upper-body muscle endurance was evaluated using 50% of subjects' bench press <a href="/terms/one-repetition-maximum/" class="term-link" data-slug="one-repetition-maximum" title="1RM">1RM</a> performed to momentary failure. <a href="/terms/muscle-hypertrophy/" class="term-link" data-slug="muscle-hypertrophy" title="Muscle hypertrophy">Muscle hypertrophy</a> was evaluated using B-mode ultrasonography for the elbow flexors, elbow extensors, mid-thigh, and lateral thigh. Results: Results showed significant preintervention to postintervention increases in strength and endurance in all groups, with no significant between-group differences. Alternatively, while all groups increased muscle size in most of the measured sites from preintervention to postintervention, significant increases favoring the higher-volume conditions were seen for the elbow flexors, mid-thigh, and lateral thigh. Conclusions: Marked increases in strength and endurance can be attained by resistance-trained individuals with just three 13-min weekly sessions over an 8-wk period, and these gains are similar to that achieved with a substantially greater time commitment. Alternatively, muscle hypertrophy follows a dose–response relationship, with increasingly greater gains achieved with higher training volumes.</p>Introduction
<h2>Introduction</h2> <p>Resistance training (RT) is the primary exercise intervention for increasing muscle mass in humans. It is theorized that the volume of training performed in a RT bout—herein determined by the formula: repetitions × sets [1]—plays a significant role in chronic muscular adaptations such as muscle size and strength [2]. As compared with single-set routines, acute studies indicate that performing multiple sets augments the phosphorylation of p70S6 kinase and <a href="/terms/muscle-protein-synthesis/" class="term-link" data-slug="muscle-protein-synthesis" title="muscle protein synthesis">muscle protein synthesis</a> (MPS), suggesting that higher volumes of training are warranted for maximizing the hypertrophic response [3, 4]. However, although acute signaling and MPS studies can help to generate hypotheses as to potential long-term RT responses, longitudinal studies directly assessing hallmark adaptations, such as muscular strength and <a href="/terms/muscle-hypertrophy/" class="term-link" data-slug="muscle-hypertrophy" title="muscle hypertrophy">muscle hypertrophy</a>, are necessary to draw evidence-based conclusions for exercise prescription [5].</p> <p>When evaluating the results of longitudinal research on the topic, many of the studies have failed to show statistically significant differences in hypertrophy between lower and higher RT volumes. However, low sample sizes in these studies raise the potential for type II errors, invariably confounding the ability to draw conclusive inferences regarding probability. A recent meta-analysis showed a dose–response relationship between the total number of weekly sets and increases in muscle growth [6]. However, the analysis was only able to determine dose–response effects up to 10 total weekly sets per muscle group due to the paucity of research on higher-volume RT programs. Thus, it remains unclear whether training with even higher volumes would continue to enhance hypertrophic adaptations and, if so, at what point these results would plateau. An added limitation to these findings is that only two of the 15 studies that met inclusion criteria were carried out in individuals with previous RT experience. There is compelling evidence that resistance-trained individuals respond differently than those who are new to RT [7]. A "ceiling effect" makes it progressively more difficult for trained lifters to increase muscle mass, thereby necessitating more demanding RT protocols to elicit further muscular gains. Indeed, there is emerging evidence that consistent RT can alter anabolic intracellular signaling [8], indicating an attenuated hypertrophic response. Thus, findings from untrained individuals cannot necessarily be generalized to a resistance-trained population.</p> <p>A dose–response pattern has also been proposed for RT volume and muscular strength gains. A recent meta-analysis on the topic by Ralston et al. [9] showed that moderate to high weekly training volumes (defined as set volume) are more effective for strength gains as compared with lower training volumes. It should be noted, however, that only two of the included studies used a dose–response study design among trained individuals. In a sample of 32 resistance-trained men, Marshall et al. [10] demonstrated that higher-volume training produces both faster and greater strength gains as compared with lower-volume training. In contrast to these results, Ostrowski et al. [11] conducted a study among 27 trained men and reported similar changes in muscular strength between low-, moderate- and high-volume training groups. Both of these studies included resistance-trained men, yet they observed different findings. It, therefore, is evident that further work among trained individuals is warranted to better elucidate this topic.</p> <p>Given the existing gaps in the current literature, the purpose of this study was to evaluate muscular adaptations between low-, moderate-, and high-volume RT protocols in resistance-trained men. This design afforded the ability to glean insight into the benefits of the respective training protocols while taking into account the time efficiency of training. Based on previous research and meta-analytical data, we hypothesized that there would be a graded response to outcomes, with increasing gains in muscular strength and hypertrophy seen in low-, moderate-, and high-volume programs, respectively.</p>Methods
<h2>Methods</h2> <h3>Subjects</h3> <p>Subjects were 45 healthy male volunteers (height, 175.0 ± 7.9 cm; weight, 82.5 ± 13.8 kg; age, 23.8 ± 3.8 yr; RT experience, 4.4 ± 3.9 yr) recruited from a university population. This sample size was justified by a priori power analysis in G*power using a target <a href="/terms/effect-size/" class="term-link" data-slug="effect-size" title="effect size">effect size</a> (ES) of f = 0.25, alpha of 0.05 and power of 0.80, which determined that 36 subjects were required for participation; the additional recruitment accounted for the possibility of dropouts. Subjects were required to meet the following inclusion criteria: 1) males between the ages of 18 to 35 yr, 2) no existing musculoskeletal disorders, 3) claimed to be free from consumption of anabolic steroids or any other legal or illegal agents known to increase muscle size for the previous year, 4) experienced with RT, defined as consistently lifting weights at least three times per week for a minimum of 1 yr.</p> <p>Subjects were randomly assigned to one of three experimental groups: a low-volume group (1SET) performing one set per exercise per training session (n = 15), a moderate-volume group (3SET) performing three sets per exercise per training session (n = 15), or a high-volume group (5SET) performing five sets per exercise per training session (n = 15). Using previously established criteria [12], this translated into a total weekly number of sets per muscle group of six and nine sets for 1SET, 18 and 27 sets for 3SET, and 30 and 45 sets for 5SET in the upper and lower limbs, respectively. Approval for the study was obtained from the Lehman College Institutional Review Board. Informed consent was obtained from all subjects before beginning the study.</p> <h3>RT Procedures</h3> <p>The RT protocol consisted of seven exercises per session targeting all major muscle groups of the body. The exercises performed were: flat barbell bench press, barbell military press, wide grip lateral pulldown, seated cable row, barbell back squat, machine leg press, and unilateral machine leg extension. To prevent confounding, subjects were instructed to refrain from performing any additional resistance-type or high-intensity anaerobic training for the duration of the study.</p> <p>Training for all routines consisted of three weekly sessions performed on nonconsecutive days for 8 wk. Sets consisted of 8 to 12 repetitions carried out to the point of momentary <a href="/terms/momentary-muscular-failure/" class="term-link" data-slug="momentary-muscular-failure" title="concentric failure">concentric failure</a>, that is, the inability to perform another concentric repetition while maintaining proper form. The cadence of repetitions was carried out in a controlled fashion, with a concentric action of approximately 1 s and an eccentric action of approximately 2 s. Subjects were afforded 90-s rest between sets. The time between exercises was prolonged to approximately 120 s given the additional time required for the setup of the equipment used in the subsequent resistance exercise. The load was adjusted for each exercise as needed on successive sets to ensure that subjects achieved momentary failure in the target repetition range. All routines were directly supervised by the research team to ensure proper performance of the respective routines. Before training, subjects underwent 10 repetition maximum (<a href="/terms/repetition-maximum/" class="term-link" data-slug="repetition-maximum" title="RM">RM</a>) testing to determine individual initial training loads for each exercise.</p> <h3>Dietary Adherence</h3> <p>To avoid potential dietary confounding of results, subjects were advised to maintain their customary nutritional regimen and to avoid taking any supplements other than those provided in the course of the study. Dietary adherence was assessed by self-reported food records using a nutritional tracking application (http://www.myfitnesspal.com), which was collected for 5-d periods twice during the study: 1 wk before the first training session (i.e., baseline) and during the final week of the training protocol. To help ensure that dietary protein needs were met, subjects consumed a supplement on <a href="/terms/training-frequency/" class="term-link" data-slug="training-frequency" title="training days">training days</a> containing 24 g protein and 1 g carbohydrate (Iso100 Hydrolyzed <a href="/terms/whey-protein/" class="term-link" data-slug="whey-protein" title="Whey Protein">Whey Protein</a> Isolate; Dymatize Nutrition) under the supervision of the research staff.</p> <h3>Measurements</h3> <p><strong>Anthropometry.</strong> Subjects were told to refrain from eating for 12 h before testing, eliminate alcohol consumption for 24 h, abstain from strenuous exercise for 24 h, and void immediately before the test. Height was measured to the nearest 0.1 cm using a stadiometer. Body mass was measured to the nearest 0.1 kg on a calibrated scale.</p> <p><strong>Muscle thickness.</strong> Ultrasound imaging was used to obtain measurements of muscle thickness (MT), which shows a high correlation with RT-induced changes in muscle <a href="/terms/cross-sectional-area/" class="term-link" data-slug="cross-sectional-area" title="cross-sectional area">cross-sectional area</a> as determined by the "gold standard" magnetic resonance imaging [16]. The lead researcher, a trained ultrasound technician, performed all testing using a B-mode ultrasound imaging unit. Measurements were taken on the right side of the body at four sites: 1) elbow flexors, 2) elbow extensors, 3) mid-thigh (a composite of the rectus femoris and vastus intermedius), and 4) lateral thigh (a composite of the vastus lateralis and vastus intermedius). Images were obtained 48 to 72 h before commencement of the study, as well as after the final RT session, to ensure that swelling from training did not obscure results. Three images were obtained for each site and then averaged to obtain a final value.</p> <p><strong>Maximal strength.</strong> Upper- and lower-body strength was assessed by <a href="/terms/one-repetition-maximum/" class="term-link" data-slug="one-repetition-maximum" title="1RM">1RM</a> testing in the barbell parallel back squat (1RM-SQUAT) and flat barbell bench press (1RM-BENCH). Subjects reported to the laboratory having refrained from any exercise other than activities of daily living for at least 48 h before baseline testing and at least 48 h before testing at the conclusion of the study. All 1RM determinations were made within five trials.</p> <p><strong>Muscle endurance.</strong> Upper-body muscular endurance was assessed by performing the bench press using 50% of the subject's initial 1RM in the bench press (50% BP) for as many repetitions as possible to momentary failure with proper form. Muscular endurance testing was carried out after assessment of muscular strength to minimize effects of <a href="/terms/metabolic-stress/" class="term-link" data-slug="metabolic-stress" title="metabolic stress">metabolic stress</a> interfering with performance of the latter.</p> <h3>Statistical Analyses</h3> <p>Data were modeled using both a frequentist and Bayesian approach. The frequentist approach involved using an ANCOVA on the change scores, with group (one, three, or five sets) as the factor and with the baseline value as a covariate. The Bayesian approach involved a JZS Bayes Factor ANCOVA with default prior scales. In the case of a significant ANCOVA effect, control for the familywise error rate of multiple testing was performed using a Holm–Bonferroni correction. Analyses were performed using JASP 0.8.6. Effects were considered significant at P ≤ 0.05. Bayes factors for effects were interpreted as "weak," "<a href="/terms/concentric-contraction/" class="term-link" data-slug="concentric-contraction" title="positive">positive</a>," "strong," or "very strong" according to Raftery [20]. Data are reported as mean ± SD unless otherwise specified.</p>Results
<h2>Results</h2> <p>Eleven subjects dropped out during the course of the study, resulting in a total sample of 34 subjects (1SET, n = 11; 3SET, n = 12; 5SET, n = 11). Reasons for dropouts were as follows: personal reasons, 4; noncompliance, 3; training-related injury, 2; injury unrelated to training, 2. Thus, the study was slightly underpowered based on initial power analysis. All subjects included in the final statistical analysis completed ≥80% of sessions with an overall average attendance of 94%. Average training time per session was approximately 13 min for 1SET, approximately 40 min for 3SET, and approximately 68 min for 5SET.</p> <p><strong>Squat <a href="/terms/one-repetition-maximum/" class="term-link" data-slug="one-repetition-maximum" title="1RM">1RM</a>.</strong> There was no significant difference between groups in squat 1RM improvement, and evidence favored the null model (P = 0.22; BF10 1).</p> <p><strong>Bench 1RM.</strong> There was no significant difference between groups in bench 1RM improvement, and there was weak evidence favoring a difference in pretest bench 1RM over a group difference in bench press improvement (P = 0.15; BF10 1 for group differences).</p> <p><strong>Bench endurance.</strong> There was no significant difference between groups in bench endurance improvement, and evidence favored the null model (P = 0.52; BF10 1).</p> <p><strong>Elbow flexor thickness.</strong> There was a significant difference between groups in improvements in bicep thickness, and <a href="/terms/concentric-contraction/" class="term-link" data-slug="concentric-contraction" title="positive">positive</a> evidence in favor of a group effect over the null (P = 0.02; BF10 = 3.04). Post hoc comparisons showed a significant difference between one and five sets. There was positive evidence in favor of five sets compared with one set (BF10 = 4.71) and weak evidence in favor of three sets compared with one set (BF10 = 1.30). Evidence did not favor three sets versus five sets (BF10 = 0.60).</p> <p><strong>Elbow extensor thickness.</strong> There was no significant difference between groups in the improvement in triceps thickness, and evidence favored the null model (P = 0.19; BF10 1).</p> <p><strong>Mid-thigh thickness.</strong> There was a significant difference between groups in improvements in rectus femoris thickness, and positive evidence in favor of a group effect over the null (P = 0.02; BF10 = 8.51). Post hoc comparisons showed a significant difference between one and five sets. There was positive evidence in favor of five sets compared to one set (BF10 = 13.65) and weak evidence in favor of five sets compared with three sets (BF10 = 2.34). Evidence did not favor one set versus three sets (BF10 = 0.51).</p> <p><strong>Lateral thigh thickness.</strong> There was a significant difference between groups in improvements in vastus lateralis thickness, and strong evidence in favor of both a group effect and pretest effect over the null (P = 0.006; BF10 = 63.87). Post hoc comparisons showed a significant difference between one and five sets. There was strong evidence in favor of five sets compared to one set (BF10 = 38.14) and weak evidence in favor of three sets compared with one set (BF10 = 1.42) and five sets compared to three sets (BF10 = 2.25).</p> <p><strong>Diet.</strong> There were no significant differences between groups in changes in self-reported kilocalorie or macronutrient intake. There was positive evidence in favor of baseline differences in self-reported kilocalorie intake (BF10 = 10.26), but only weak evidence in favor of baseline differences in self-reported macronutrient intake.</p>Discussion
<h2>Discussion</h2> <p>The present study provided several important findings that further our knowledge of the effect of RT volume on muscular adaptations in resistance-trained individuals. Specifically, changes in muscle strength and muscle endurance were similar regardless of the volume performed when training in a moderate loading range (8–12 repetitions per set); alternatively, higher volumes of training in this loading range were associated with greater increases in markers of <a href="/terms/muscle-hypertrophy/" class="term-link" data-slug="muscle-hypertrophy" title="muscle hypertrophy">muscle hypertrophy</a>.</p> <h3>Muscle Strength</h3> <p>Contrary to our initial hypothesis, gains in muscular strength were strikingly similar across conditions, with volume showing no differential effects on <a href="/terms/one-repetition-maximum/" class="term-link" data-slug="one-repetition-maximum" title="1RM">1RM</a>-SQUAT or 1RM-BENCH. Indeed, the results presented herein indicate that the 1SET training condition may be similarly effective at increasing muscular strength as performing three or five sets per exercise. These findings indicate that resistance-trained individuals can markedly enhance levels of strength by performing only ~39 min of weekly RT, with gains equal to that achieved in a fivefold greater time commitment.</p> <p>Our results are somewhat in contrast to the meta-analysis by Ralston et al. [9]. The authors reported that for strength in multijoint exercises (as used in this study), moderate-to-high weekly set volume routines (defined as six or more sets per week) are more effective than low weekly set volume routines (defined as five sets or less per week). Although in this study, the 1SET group did perform the least amount of volume, their total <a href="/terms/training-volume/" class="term-link" data-slug="training-volume" title="weekly volume">weekly volume</a> of six to nine sets per muscle group would be classified as a moderate volume in the Ralston et al. [9] review, making direct comparison difficult.</p> <p>Three individual studies thus far have used a comparable study design. Radaelli et al. [21] compared the effects of 6, 18, and 30 weekly sets per muscle group and showed that for the bench press and lat-pulldown exercises, the 30 weekly set group experienced greater increases than the two other groups. However, given that their subjects did not have any RT experience, greater strength gains in the 30 weekly set group may be partially attributed to enhanced "learning" effects [22]. Marshall et al. [10] found that the 16 weekly sets group increased strength significantly greater than the two weekly sets group; however, this intervention lasted 6 wk with twice-<a href="/terms/training-frequency/" class="term-link" data-slug="training-frequency" title="weekly frequency">weekly frequency</a>, differing from the present study. Ostrowski et al. [11] reported that after 10 wk of training, all groups increased upper and lower-body strength with no significant between-group differences. Taken together, our results would imply that for strength improvements, there is a certain threshold of volume that can be used in a training program, over which further increases in volume are not advantageous and might only delay recovery from exercise.</p> <h3>Muscle Hypertrophy</h3> <p>The results of the present study show a graded dose–response relationship between training volume and muscle hypertrophy in a sample of resistance-trained men. Our findings essentially mirror recent meta-analytic data showing a dose–response relationship between volume and hypertrophy [6]. The present study indicates that substantially greater training volumes may be beneficial in enhancing muscle growth in those with previous RT experience, at least over an 8-wk training period. Hypertrophy for three of the four measured muscles was significantly greater for the highest versus lowest volume condition. Only the elbow extensors did not show statistically greater increases in MT between conditions. However, only the 5SET condition showed a significant prestudy to poststudy increase in elbow extensor growth, and a dose–response relationship was seen for the magnitude of effect in elbow extensor thickness changes, with <a href="/terms/effect-size/" class="term-link" data-slug="effect-size" title="ES">ES</a> values of 0.12, 0.30, and 0.55 for the low-, moderate-, and high-volume conditions, respectively.</p> <p>Most previous researches investigating the effects of varying RT volumes on muscular adaptations have been carried out in those without RT experience. Only one previous study endeavored to examine the dose–response relationship (i.e., a minimum of three different set volumes) between training volume and muscle growth in resistance-trained individuals using site-specific measures of hypertrophy [11]. In the 10-wk study by Ostrowski et al. [11], results showed that percent changes and ES for muscle growth in the elbow extensors and quadriceps femoris favored the high-volume group, although no statistically significant differences were noted. When comparing with the present study, there were notable similarities: changes in triceps brachii MT in Ostrowski et al. [11] were 2.2% for the lowest volume condition (seven sets per muscle per week) and 4.7% for the highest-volume condition (28 sets per muscle per week). Our study showed comparable changes in elbow extensor MT of 1.1% versus 5.5% for the lowest (six sets per muscle per week) versus highest (30 sets per muscle per week) volume conditions, respectively.</p> <h3>Muscle Endurance</h3> <p>All conditions showed similar improvements in the test used for assessing muscular endurance (i.e., the 50%BP test). Similar to the findings presented for strength, all groups increased muscular endurance from pre-to-post with no significant between-group differences. These findings indicate that training for improvements in muscular abilities such as strength and muscular endurance warrants a different volume prescription than when the training goal is muscular hypertrophy. Differences in the dose–response curves might be because muscular abilities such as endurance have a significant skill component; adaptations such as muscular endurance are, to a certain extent, influenced by motor learning [25].</p> <h3>Limitations</h3> <p>The study had several limitations. First, all subjects reported performing multiset routines before the onset of the study and a majority did not regularly train to momentary failure; the novelty of altering these variables may have affected the respective groups differentially. Second, the upper-body musculature was trained exclusively with multijoint exercises. Third, measurements of MT were obtained only at the mid-portion of the muscle belly, which may not capture regional hypertrophy. Fourth, subjects may not have fully complied with instructions to refrain from additional exercise training. Fifth, the study had a relatively small sample size and thus may have been somewhat underpowered. Finally, findings are specific to young resistance-trained men and cannot necessarily be generalized to other populations, including adolescents, women, and older adults.</p>Conclusions
<h2>Conclusions</h2> <p>The present study shows that marked increases in strength can be attained by resistance-trained individuals with just three 13-min sessions per week, and that gains are similar to that achieved with a substantially greater time commitment when training in a moderate loading range (8–12 repetitions per set). This finding has important implications for those who are time-pressed, allowing the ability to get stronger in an efficient manner, and may help to promote greater exercise adherence in the general public. Alternatively, we show that increases in <a href="/terms/muscle-hypertrophy/" class="term-link" data-slug="muscle-hypertrophy" title="muscle hypertrophy">muscle hypertrophy</a> follow a dose–response relationship, with increasingly greater gains achieved with higher training volumes. Thus, those seeking to maximize muscular growth need to allot a greater amount of weekly time to achieve this goal. Further research is warranted to determine how these findings apply to resistance individuals in other populations, such as women and the elderly. Volume does not appear to have any differential effects on measures of upper-body muscular endurance.</p>관련 논문
근비대
2017
주간 저항 훈련 볼륨과 근육량 증가 사이의 용량-반응 관계: 체계적 문헌고찰 및 메타분석
11개 공유 용어
생체역학
2020
저항 훈련 중 가동 범위가 근육 발달에 미치는 효과: 체계적 문헌고찰
13개 공유 용어
근비대
2021
운동할 시간이 없다고? 시간 효율적인 근력 및 근비대 훈련 프로그램 설계: 내러티브 리뷰
14개 공유 용어
근비대
2022
저항 훈련에서 실패 근접도가 골격근 비대에 미치는 영향: 메타분석을 포함한 체계적 문헌고찰
10개 공유 용어
영양학
2018
건강한 성인에서 단백질 보충이 저항 훈련으로 인한 근육량 및 근력 증가에 미치는 효과: 체계적 문헌고찰, 메타분석 및 메타회귀
12개 공유 용어