An examination of the time course of training-induced skeletal muscle hypertrophy (original) (raw)
Related papers
Gross Measures of Exercise-Induced Muscular Hypertrophy
Journal of Orthopaedic & Sports Physical Therapy, 2000
Pretest-posttest, single factor design. Objectives: To compare several indices that might be used to depict muscle size. Background: The particular strategy used during heavy-resistance training may determine the magnitude of hypertrophic adaptations. At the same time, assorted measures supposedly reflecting muscle size may provide different results. Methods and Measures: Four groups of men (n = 38, mean age = 21.1 years, SD = 2.1) were exposed to conditions designed to elicit differential hypertrophic adaptations following 21 sessions of squat training. Three of the groups performed 4 sets of multiple repetitions maximum (RM): group 1,3-5 RM; group 11, 13-1 5 RM; and group 111,23-25 RM. A control (C) group did no formal physical training. Tests used to represent muscle size included body weight, thigh girth, net thigh girth, and quadriceps femoris and hamstring thicknesses via Bmode ultrasound. Results Changes in the groups subsequent to training were similar for body weight and hamstring thickness. Results differed for the remaining 3 dependent variables (mean 2 SD): thigh girth was greater in groups 11 (1.42 2 1.00) and 111 (1.35 2 1.1 6) than in group C (0.24 2 0.69); net thigh girth was greater in groups 11 (1.33 2 0.77) and 111 (1.40 2 1.03) than in group C (0.10 2 0.84); and quadriceps femoris thickness was greater in all 3 training groups (1, 0.61 2 0.54; 11, 0.43 2 0.30; 111, 0.55 2 0.39) than in group C (0.05 2 0.11). Conclusions: Observed muscle mass change following heavy-resistance training is dependent upon both the training intervention and tool used for measurement.) Orthop Sporb Phys Ther ZOOO; 3O: 143-148.
Effects of order of resistance training exercises on muscle hypertrophy in young adult men
The purpose of the present study was to analyze the effects of the order of resistance training (RT) exercises on hypertrophy in young adult men. Thirty-six young adult men (age, 21.9 ± 2.5 years; body mass, 72.6 ± 12.1 kg, height, 176.9 ± 7.4 cm; body mass index, 23.1 ± 3.3 kg/m 2) were randomly assigned to 1 of 2 training groups that performed a 6-week RT program in either (i) a traditional approach starting with multi-joint (MJ) exercises followed by single-joint exercises (SJ) (MJ-SJ, n = 19) or (ii) in reverse order (SJ-MJ, n = 17). Muscle thickness of the biceps brachii and mid-thigh were assessed by ultrasound. Lean soft tissue (LST) was assessed by dual-energy X-ray absorptiometry. Both groups similarly increased (P < 0.05) biceps brachii thickness (MJ-SJ = +14.2%, SJ-MJ = +13.8%). Alternatively, only the MJ-SJ group presented an increase in mid-thigh thickness from pre-to post-training (MJ-SJ = +7.2%, SJ-MJ = +3.9%). Upper limb LSTs (MJ-SJ = +5.2%, SJ-MJ = +7.5%) were statistically similar between conditions, and a trend for significance (P = 0.07) was found for trunk LST (MJ-SJ = +7.2%, SJ-MJ = +1.7%). Nonsignificant pre-to post-training changes were observed for lower limb LSTs (MJ-SJ = +0.7%, SJ-MJ = +1.8%). Our data suggest that both sequences are effective for increasing muscle hypertrophy over a short-term RT period; there may be a potentially beneficial hypertrophic effect for the mid-thigh by performing exercises in a manner that progresses from MJ to SJ exercises.
European Journal of Applied Physiology, 2015
muscle CSA, only T2 showed a significantly higher US echo versus T1. Additionally, TV increased at T2 and T3 versus T1, but MVC increased only at T3. Myoglobin and Interleukin-6 were elevated at T2 versus T1, and myoglobin was also higher at T2 versus T3. Conclusion We propose that early RT-induced increases in muscle CSA in untrained young individuals are not purely hypertrophy, since there is concomitant edemainduced muscle swelling, probably due to muscle damage, which may account for a large proportion of the increase. Therefore, muscle CSA increases (particularly early in an RT program) should not be labeled as hypertrophy without some concomitant measure of muscle edema/damage.
Journal of Human Sport and Exercise, 2019
The purpose of this study was to compare the temporal increase in muscle cross-sectional area (CSA) as the acute response of resistance exercise (RE) between resistance-trained and untrained groups and investigate the factors that affect the muscle CSA. Resistance-trained (n = 14) and untrained (n = 14) subjects performed four kinds of triceps brachii RE. Muscle CSA and intracellular hydration (IH), were measured prior to and 5-, 30-, and 60-minute after RE. Pearson's correlation coefficient was calculated to clarify the relationships among percent increases in muscle CSA and IH, area under the Oyx-Hb curve, blood lactate concentration, and % maximum voluntary contraction (MVC)-rootmean-square (RMS) of electromyogram (EMG). At 5-minute after RE, muscle CSA increased significantly to 120.2 ± 6.3% in the resistance-trained group and 105.5 ± 2.3% in the untrained group (p < .01). However, neither group showed a significant difference between the values before and 30-minute after RE. In the resistance-trained group, there was a significant increase in IH at 5-minute post-RH (p < .01), and correlations were found between percent increases in muscle CSA and IH (r = 0.70, p < .01), area under the Oxy-Hb curve (r = 0.77, p < .01), and % MVC-RMS of EMG (r = 0.72, p < .01). The findings of this study suggest that measurements of muscle CSA in studies of muscle hypertrophy should be performed 30-minute or more after the last resistance exercise session, and muscle pump exercises should be conducted just before participation in bodybuilding, and physique contests.
Review Article Physiological Changes in Skeletal Muscle as a Result of Strength Training
2014
Changes in shortening velocity Changes in strength (2) History of training studies (3) Specificity of the training response Task specificity Length specificity Velocity specificity Neural adaptation 241 (4) Changes in muscle strength and size during training Neural mechanisms Peripheral mechanisms Fibre type composition The angle of muscle fibre insertion Contractile material packing Connective tissue attachments Consequences for power output (5) The stimulus for increase in strength Hormonal stimuli Metabolic stimuli Mechanical factors (6) Summary 251 (7) References
Translational sports medicine, 2023
Trained individuals may require variations in training stimuli and advanced resistance training paradigms (ADV) to increase skeletal muscle hypertrophy. However, no meta-analysis has examined how ADV versus traditional (TRAD) approaches may diferentially afect hypertrophic outcomes in trained populations. Te aim of this review was to determine whether the skeletal muscle hypertrophy responses induced by TRAD difered from ADV in resistance-trained individuals. Furthermore, we sought to examine potential efects of dietary factors, participants' training status, and training loads. We searched for peer-reviewed, randomized controlled trials (published in English) conducted in healthy resistance-trained adults performing a period of TRAD and ADV with pre-to-post measurement(s) of muscle hypertrophy in PubMed, Web of Science, SPORTDiscus, and MEDLINE databases up to October 2022. A formal meta-analysis was conducted in Revman5, and risk of bias was assessed by ROB2. Ten studies met the inclusion criteria. Results indicated no diference between ADV and TRAD for muscle thickness (SMD = 0.05, 95% CI: −0.20 0.29, p = 0.70), lean mass (SMD = −0.01, 95% CI: −0.26 0.23, p = 0.92), muscle cross-sectional area (SMD = −0.07, 95% CI: −0.36 0.22, p = 0.64), or all measurements analyzed together (SMD = −0.00, 95% CI: −0.15 0.14, p = 0.95). No heterogeneity or inconsistencies were observed; however, unclear risk of bias was present in most of the studies. Short-term ADV does not induce superior skeletal muscle hypertrophy responses when compared with TRAD in trained individuals. Tis review was not previously registered.
Time Course of Resistance Training–Induced Muscle Hypertrophy in the Elderly
Journal of Strength and Conditioning Research, 2016
Extended periods of resistance training (RT) induce muscle hypertrophy. Nevertheless, to date, no study has investigated the time window necessary to observe significant changes in muscle cross-sectional area (CSA) in older adults. Therefore, this study investigated the time course of muscle hypertrophy after 10 weeks (20 sessions) of RT in the elderly. Fourteen healthy older subjects were randomly allocated in either the RT (n: 6) or control group (n: 8). The RT was composed of 4 sets 3 10 repetitions (70-80% 1 repetition maximum [1RM]) in a leg press machine. The time course of vastus lateralis muscle hypertrophy (CSA) was assessed on a weekly basis by mode-B ultrasonography. Leg press muscle strength was assessed by dynamic 1RM test. Our results demonstrated that the RT group increased leg press 1RM by 42% (p # 0.05) after 10 weeks of training. Significant increases in vastus lateralis muscle CSA were observed only after 18 sessions of training (9 weeks; p # 0.05; 7.1%). In conclusion, our training protocol promoted muscle mass accrual in older subjects, and this was only observable after 18 sessions of RT (9 weeks).
2018
Introduction: Heavy Duty resistance training (HD) is a new method that might improve muscle strength and hypertrophy. The effect of this method on thigh muscle hypertrophy is not well-known. The purpose of the present study was to examine the effects of HD versus traditional resistance training (TRT) on thigh muscle cross-sectional area (CSA). Material & Methods: Twenty untrained healthy men (age: 25.6±2.0 mean±SD) volunteered to participate in this study. The subjects were divided into HD group (n=10) or TRT group (n=10) randomly. The subjects in HD and TRT executed five resistance exercises selected to stress the thigh muscle groups in the following order: leg press, squat, leg 14 J. Mokaram Bakhtajerdi and M. Moghadasi extension, prone leg curl, and dead lift. HD and TRT consisted of 50-60 min of station weight training per day, 3 days a week, for 8 weeks. TRT training was performed in 5 stations and included 4 sets with 6-12 maximal repetitions at 70-80% of 1-RM in each station ...
THE MECHANISMS OF MUSCLE HYPERTROPHY AND THEIR APPLICATION TO RESISTANCE TRAINING
Schoenfeld, BJ. The mechanisms of muscle hypertrophy and their application to resistance training. J Strength Cond Res 24(10): 2857-2872, 2010-The quest to increase lean body mass is widely pursued by those who lift weights. Research is lacking, however, as to the best approach for maximizing exercise-induced muscle growth. Bodybuilders generally train with moderate loads and fairly short rest intervals that induce high amounts of metabolic stress. Powerlifters, on the other hand, routinely train with high-intensity loads and lengthy rest periods between sets. Although both groups are known to display impressive muscularity, it is not clear which method is superior for hypertrophic gains. It has been shown that many factors mediate the hypertrophic process and that mechanical tension, muscle damage, and metabolic stress all can play a role in exercise-induced muscle growth. Therefore, the purpose of this paper is twofold: (a) to extensively review the literature as to the mechanisms of muscle hypertrophy and their application to exercise training and (b) to draw conclusions from the research as to the optimal protocol for maximizing muscle growth.
Resistance Training Volume Enhances Muscle Hypertrophy but Not Strength in Trained Men
Medicine & Science in Sports & Exercise, 2018
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 (RM) testing for the squat and bench press. Upper-body muscle endurance was evaluated using 50% of subjects bench press 1RM performed to momentary failure. Muscle hypertrophy 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.