Search

Integrating strength and endurance training in a single exercise session, even on separate days, can be physically demanding and time- consuming. Therefore, there is a growing interest in identifying efficient training methods that can concurrently enhance cardio- vascular and neuromuscular performance through a singular training modality. This study conducted a systematic review and meta- analysis to explore the effects of aerobic training with blood flow restriction (AT + BFR) on muscle hypertrophy and strength gains in healthy individuals. Our study was registered at PROSPERO and used multiple databases (PubMed, Embase, Scopus, and Web of Science), seeking clinical trials that examined AT + BFR influence on muscle hypertrophy and strength gains in individuals aged 18-60 years and comparing with aerobic training without BFR. The risk of bias and method quality were assessed using the ROB2.0 tool and PEDro scale, respectively, and the quality of evidence was evaluated with the GRADE method. A random-effects model was used for meta-analysis, and standardized mean difference (SMD) was calculated for each outcome. Of 4,462 records, 29 full texts were assessed for eligibility, with 7 articles meeting the inclusion criteria. The results indicated that AT + BFR was more beneficial for inducing muscle hypertrophy than aerobic training without BFR (SMD [95% CI] = 0.86 [0.37-1.35]; I² = 42%). Furthermore, AT + BFR was associated with greater improvements in muscle strength (SMD [95% CI] = 0.41 [0.10-0.72]; I² = 0%). Despite the generally high risk of bias for both outcomes, these encouraging findings underscore the clinical significance of AT + BFR as a compelling tool for enhancing neuromuscular parameters. [ABSTRACT FROM AUTHOR]

BACKGROUND Despite the widespread use of botulinum toxin (BTX) injection for the treatment of masseter muscle hypertrophy (MMH), there is no standard treatment option. OBJECTIVE We report the efficacy and safety for BTX in MMH over a period of 48 weeks. METHODS In double-blinded, placebo-controlled phase 3 trials, 180 patients (randomized 1:1) received treatment with placebo (normal saline) or prabotulinumtoxinA (48 units). Masseter muscle thickness (at maximal clenching and resting positions), 3D imaging analysis, and masseter muscle hypertrophy scale grades were analyzed at each time point. After the 24-week CORE study, all patients who met the same criteria of the CORE study at week 24 (n 5 114) received only prabotulinumtoxinA, regardless of previous treatment, for an additional 24 weeks (48 weeks in total) for the open-label extension study. RESULTS The largest differences in mean and percent changes from baseline in masseter muscle thickness were observed at 12 weeks, and there were significant differences between the 2 groups at all time points (all p, .001). The effect was independent of the number of injections. No serious adverse event was observed. CONCLUSION PrabotulinumtoxinA could effectively ameliorate MMH without major complications. [ABSTRACT FROM AUTHOR]

To systematically review and analyze the effects of resistance-based exercise programs and potential moderators of change in body fat percentage, whole-body fat and lean mass, muscle hypertrophy, muscle strength, and muscle power/rapid force in healthy young women (between 18 and 35 years). A systematic search was undertaken in 7 databases from inception to May 2022. Eligible randomized controlled trials examined the effects of resistance-based exercise programs on outcomes of interest in healthy young women. Meta-analysis was undertaken with a 3-level mixed-effects model. Associations between standardized mean difference (SMD) and potential moderators (number of sessions, weekly volume, and intensity) were tested by meta-regression models. Statistical significance was set at an a level of 0.05, whereas an a level of 0.05-0.10 was also considered for potential moderators of resistance training effects. Forty articles (n = 1,312) were included. Resistance-based exercise programs resulted in a significant improvement of 0.4 SMD (95% confidence intervals [95% CI]: 0.2 to 0.5, p < 0.001) in lean mass/muscle hypertrophy and 1.2 SMD (95% CI: 0.9 to 1.5, p < 0.001) in muscle strength. A higher number of sessions was associated with changes in lean mass/muscle hypertrophy (β = 0.01 ± 0.00, p = 0.009), whereas a higher weekly volume approached statistical significance to moderate changes in muscle strength (β = 0.01 ± 0.01, p = 0.053). Body fat percentage (-0.4 SMD, 95% CI: -0.6 to -0.1, p = 0.006) and muscle power/rapid force (0.6 SMD, 95% CI: 0.2 to 1.1, p = 0.011) were significantly improved. In conclusion, a higher resistance training volume was associated with greater improvements in lean mass/muscle hypertrophy, muscle strength, and body fat percentage, whereas muscle power/rapid force improvements were observed irrespective of prescription characteristics. These findings may help in designing resistance training programs for muscle hypertrophy, strength and power, and body fat percentage in healthy women. [ABSTRACT FROM AUTHOR]

Different methods can be used to assess muscle hypertrophy, but the effects of training on regional changes in muscle size can be detected only using direct muscle measurements such as muscle thickness, cross-sectional area, or volume. Importantly, muscle size increases vary across regions within and between muscles after resistance training programs (i.e., heterogeneous, or nonuniform, muscle hypertrophy). Muscle architectural changes, including fascicle length and pennation angle, after resistance and stretch training programs are also region-specific. In this paper, we show that the literature indicates that a single-site measure of muscle shape does not properly capture the effects achieved after exercise training interventions and that conclusions concerning the magnitude of muscle adaptations can vary substantially depending on the muscle site to be examined. Thus, we propose that measurements of muscle size and architecture should be completed at multiple sites across regions between the agonist muscles within a muscle group and along the length of the muscles to provide an adequate picture of training effects. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the effect of progressively adding sets for the lower limb every 2 wk versus performing a constant set volume in resistance-trained males. Methods: Thirty-one resistance-trained males (age = 24.4 ± 2.9 yr, height = 175.5 ± 6.5 cm, body mass = 80.1 ± 9.4 kg, body fat = 14.4% ± 3.1%, resistance training [RT] experience = 5.1 ± 2.2 yr; one-repetition maximum [1RM] barbell back squat: body mass ratio = 1.7 ± 0.1 a.u.) were randomly allocated into a constant group (CG, n = 10), a four-set progression group (4SG, n = 10) or a six-set progression group (6SG, n = 11). After a 2-wk washout period and another 2-wk familiarization period, participants performed a lower-limb training program twice a week for 12 wk. Maximum dynamic strength (1RM) in the barbell back squat, vastus lateralis cross-sectional area, and the sum of lateral thigh muscle thickness at 30%, 50%, and 70% of the femur length were assessed at baseline and after the 12-wk training program. Results: Regarding 1RM, multiple comparisons revealed that 6SG elicited higher muscle strength gains than 4SG (P = 0.002) and CG (P < 0.0001), and 4SG had greater improvements than CG (P = 0.023). Cross-sectional area and sum of lateral thigh muscle thickness showed no between-group differences (P = 0.067 and P = 0.076, respectively). However, an inspection of 95% confidence intervals suggests a potential dose–response relationship, with results appearing to plateau in the higher volume conditions. Conclusions: Our results suggest that progressively adding four or six sets per week every 2 wk elicited greater lower-limb strength in resistance-trained individuals over a 12-wk training period. Although our findings indicate a possible small benefit for higher volume conditions regarding hypertrophic adaptations in this population, the limited certainty of our findings warrants caution. [ABSTRACT FROM AUTHOR]

BACKGROUND: Cardiac metabolic dysfunction is a hallmark of heart failure (HF). Estrogen-related receptors ERRα and ERRγ are essential regulators of cardiac metabolism. Therefore, activation of ERR could be a potential therapeutic intervention for HF. However, in vivo studies demonstrating the potential usefulness of ERR agonist for HF treatment are lacking, because compounds with pharmacokinetics appropriate for in vivo use have not been available. METHODS: Using a structure-based design approach, we designed and synthesized 2 structurally distinct pan-ERR agonists, SLUPP-332 and SLU-PP-915. We investigated the effect of ERR agonist on cardiac function in a pressure overload-induced HF model in vivo. We conducted comprehensive functional, multi-omics (RNA sequencing and metabolomics studies), and genetic dependency studies both in vivo and in vitro to dissect the molecular mechanism, ERR isoform dependency, and target specificity. RESULTS: Both SLU-PP-332 and SLU-PP-915 significantly improved ejection fraction, ameliorated fibrosis, and increased survival associated with pressure overload-induced HF without affecting cardiac hypertrophy. A broad spectrum of metabolic genes was transcriptionally activated by ERR agonists, particularly genes involved in fatty acid metabolism and mitochondrial function. Metabolomics analysis showed substantial normalization of metabolic profiles in fatty acid/lipid and tricarboxylic acid/oxidative phosphorylation metabolites in the mouse heart with 6-week pressure overload. ERR agonists increase mitochondria oxidative capacity and fatty acid use in vitro and in vivo. Using both in vitro and in vivo genetic dependency experiments, we show that ERRγ is the main mediator of ERR agonism-induced transcriptional regulation and cardioprotection and definitively demonstrated target specificity. ERR agonism also led to downregulation of cell cycle and development pathways, which was partially mediated by E2F1 in cardiomyocytes. CONCLUSIONS: ERR agonists maintain oxidative metabolism, which confers cardiac protection against pressure overload-induced HF in vivo. Our results provide direct pharmacologic evidence supporting the further development of ERR agonists as novel HF therapeutics. [ABSTRACT FROM AUTHOR]

It is unclear whether human tendon adapts to moderate-intensity, high-volume long-term eccentric exercise, e.g., downhill running (DR) training. This study aimed to investigate the time course of patellar tendon (PT) adaptation to short-term DR training and to determine whether changes in PT properties were related to changes in mechanical stress or loading history. Twelve untrained, young, healthy adults (5 women and 7 men) took part in 4 weeks' DR training, comprising 10 sessions. Running speed was equivalent to 60-65% VÌO2max, and session duration increased gradually (15-30 minutes) throughout training. Isometric knee extensor maximal voluntary torque (MVT), vastus lateralis (VL) muscle physiological cross-sectional area (PCSA) and volume, and PT CSA, stiffness, and Young's modulus were assessed at weeks 0, 2, and 4 using ultrasound and isokinetic dynamometry. Patellar tendon stiffness (+6.4 ± 7.4%), Young's modulus (+6.9 ± 8.8%), isometric MVT (+7.5 ± 12.3%), VL volume (+6.6 ± 3.2%), and PCSA (+3.8 ± 3.3%) increased after 4 weeks' DR (p < 0.05), with no change in PT CSA. Changes in VL PCSA correlated with changes in PT stiffness (r = 0.70; p = 0.02) and Young's modulus (r = 0.63; p = 0.04) from 0 to 4 weeks, whereas changes in MVT did not correlate with changes in PT stiffness and Young's modulus at any time point (p > 0.05). To conclude, 4 weeks' DR training promoted substantial changes in PT stiffness and Young's modulus that are typically observed after high-intensity, low-volume resistance training. These tendon adaptations seemed to be driven primarily by loading history (represented by VL muscle hypertrophy), whereas increased mechanical stress throughout the training period did not seem to contribute to changes in PT stiffness or Young's modulus. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to compare the effects of free-weight andmachine-based resistance training on strength, hypertrophy, and joint discomfort. Methods: Thirty-eight resistance-trained men participated in an 8-wk resistance program allocated into free-weight (n = 19) or machine-based (n = 19) groups. Training variables were identical for both modalities, so they only differed in the use of barbells or machines to execute the full squat, bench press, prone bench pull, and shoulder press exercises. The velocity-based method was implemented to accurately adjust the intensity throughout the program. Strength changes were evaluated using eight velocity-monitored loading tests (four exercises two modalities) and included the relative one-repetition maximum (1RMRel), as well as the mean propulsive velocity against low (MPVLow) and high (MPVHigh) loads. Ultrasound-derived cross-sectional area of quadriceps (proximal and distal regions), pectoralis major, and rectus abdominis was measured to examine hypertrophy. Complementarily, Western Ontario and McMaster Universities and Disabilities of the Arm, Shoulder and Hand questionnaires were administrated to assess changes in lower- and upper-limb joint discomfort. Outcomes were compared using ANCOVA and percentage of change (Δ) statistics. Results: Each group significantly ( P < 0.001) increased 1RMRel, MPVLow, and MPVHigh for both modalities tested, but especially in the one they trained.When considering together the eight exercises tested, strength changes for both modalities were similar (Δ differences ≤1.8%, P ≥ 0.216). Likewise, the cross-sectional area of all the muscles evaluated was significantly increased by both modalities, with no significant differences between them (Δ difference ≤2.0%, P ≥ 0.208). No between-group differences ( P ≥ 0.144) were found for changes in stiffness, pain, and functional disability levels, which were reduced by both modalities. Conclusions: Free-weight and machine-based modalities are similarly effective to promote strength and hypertrophy without increasing joint discomfort. [ABSTRACT FROM AUTHOR]

BACKGROUND: Proper nuclear organization is critical for cardiomyocyte function, because global structural remodeling of nuclear morphology and chromatin structure underpins the development and progression of cardiovascular disease. Previous reports have implicated a role for DNA damage in cardiac hypertrophy; however, the mechanism for this process is not well delineated. AMPK (AMP-activated protein kinase) family of proteins regulates metabolism and DNA damage response (DDR). Here, we examine whether a member of this family, SNRK (SNF1-related kinase), which plays a role in cardiac metabolism, is also involved in hypertrophic remodeling through changes in DDR and structural properties of the nucleus. METHODS: We subjected cardiac-specific Snrk-/- mice to transaortic banding to assess the effect on cardiac function and DDR. In parallel, we modulated SNRK in vitro and assessed its effects on DDR and nuclear parameters. We also used phosphoproteomics to identify novel proteins that are phosphorylated by SNRK. Last, coimmunoprecipitation was used to verify Destrin (DSTN) as the binding partner of SNRK that modulates its effects on the nucleus and DDR. RESULTS: Cardiac-specific Snrk-/- mice display worse cardiac function and cardiac hypertrophy in response to transaortic banding, and an increase in DDR marker pH2AX (phospho-histone 2AX) in their hearts. In addition, in vitro Snrk knockdown results in increased DNA damage and chromatin compaction, along with alterations in nuclear flatness and 3-dimensional volume. Phosphoproteomic studies identified a novel SNRK target, DSTN, a member of F-actin depolymerizing factor proteins that directly bind to and depolymerize F-actin. SNRK binds to DSTN, and DSTN downregulation reverses excess DNA damage and changes in nuclear parameters, in addition to cellular hypertrophy, with SNRK knockdown. We also demonstrate that SNRK knockdown promotes excessive actin depolymerization, measured by the increased ratio of G-actin to F-actin. Last, jasplakinolide, a pharmacological stabilizer of F-actin, rescues the increased DNA damage and aberrant nuclear morphology in SNRK-downregulated cells. CONCLUSIONS: These results indicate that SNRK is a key player in cardiac hypertrophy and DNA damage through its interaction with DSTN. This interaction fine-tunes actin polymerization to reduce DDR and maintain proper cardiomyocyte nuclear shape and morphology. [ABSTRACT FROM AUTHOR]

This study investigated the effects of low-intensity torque-matched isometric training on muscle hypertrophy and strengthening at long (LL) and short muscle lengths (SL). Twentyeight young subjects completed an 8-week hamstring isometric training program (30% of maximal voluntary contraction (MVC)35 s x 20 repetitions x 5 sets x 3 times/week) at 30° knee flexion (LL) or 90° knee flexion (SL). The cross-sectional area (CSA) of the hamstrings and MVC were measured before and after the intervention. The active torque because of muscle contraction was calculated by subtracting the passive torque at rest from the total torque (30% MVC). The active torque was significantly lower in the LL training group than in the SL training group (p < 0.01), whereas there was no between-group difference in total torque during training. For CSA and MVC at 30° knee flexion, the split-plot analysis of variance (ANOVA) showed no significant time 3 group interaction; however, it did show a significant main effect of time (p < 0.05), indicating a significant increase after training intervention. As for MVC at 90° knee flexion, there was a significant time3group interaction (p < 0.05) and a significant simple main effect of time in both the LL (p < 0.01; Cohen's d effect size [ES] = 0.36) and SL (p < 0.01; ES = 0.64) training groups. Therefore, low-intensity isometric training at LL can induce hypertrophy and strengthening, even in cases where the active torque production is lower than that at SL, whereas the training at SL may be more effective for muscle strengthening at SL. [ABSTRACT FROM AUTHOR]

Introduction: Athletes use their skeletal muscles to demonstrate performance. Muscle force generating capacity is correlated with volume, meaning that variations in sizes of different muscles may be indicative of how athletes meet different demands in their sports. Medical imaging enables in vivo quantification ofmuscle volumes; however, muscle volume distribution has not been compared across athletes of different sports. Purpose: The goal of this work was to define "muscular phenotypes" in athletes of different sports and compare these using hierarchical clustering. Methods: Muscle volumes normalized by body mass of athletes (football, baseball, basketball, or track) were compared with control participants to quantify size differences using z-scores. z-Scores of 35 muscles described the pattern of volume deviation within each athlete's lower limb, characterizing their muscular phenotype. Data-driven high-dimensional clustering analysis was used to group athletes presenting similar phenotypes. Efficacy of clustering to identify similar phenotypes was demonstrated by grouping athletes' contralateral limbs before other athletes' limbs. Results: Analyses revealed that athletes did not tend to cluster with others competing in the same sport. Basketball players with similar phenotypes grouped by clustering also demonstrated similarities in performance. Clustering also identified muscles with similar volume variation patterns across athletes, and principal component analysis revealed specific muscles that accounted for most of the variance (gluteus maximus, sartorius, semitendinosus, vastus medialis, vastus lateralis, and rectus femoris). Conclusions: Athletes exhibit heterogeneous lower limb muscle volumes that can be characterized and compared as individual muscular phenotypes. Clustering revealed that athletes with the most similar phenotypes do not always play the same sport such that patterns of muscular heterogeneity across a group of athletes reflect factors beyond their specific sports. [ABSTRACT FROM AUTHOR]

BACKGROUND: In hypertrophic cardiomyopathy (HCM), myocyte disarray and microvascular disease (MVD) have been implicated in adverse events, and recent evidence suggests that these may occur early. As novel therapy provides promise for disease modification, detection of phenotype development is an emerging priority. To evaluate their utility as early and disease-specific biomarkers, we measured myocardial microstructure and MVD in 3 HCM groups--overt, either genotype-positive (G+LVH+) or genotype-negative (G-LVH+), and subclinical (G+LVH-) HCM--exploring relationships with electrical changes and genetic substrate. METHODS: This was a multicenter collaboration to study 206 subjects: 101 patients with overt HCM (51 G+LVH+ and 50 G-LVH+), 77 patients with G+LVH-, and 28 matched healthy volunteers. All underwent 12-lead ECG, quantitative perfusion cardiac magnetic resonance imaging (measuring myocardial blood flow, myocardial perfusion reserve, and perfusion defects), and cardiac diffusion tensor imaging measuring fractional anisotropy (lower values expected with more disarray), mean diffusivity (reflecting myocyte packing/interstitial expansion), and second eigenvector angle (measuring sheetlet orientation). RESULTS: Compared with healthy volunteers, patients with overt HCM had evidence of altered microstructure (lower fractional anisotropy, higher mean diffusivity, and higher second eigenvector angle; all P<0.001) and MVD (lower stress myocardial blood flow and myocardial perfusion reserve; both P<0.001). Patients with G-LVH+ were similar to those with G+LVH+ but had elevated second eigenvector angle (P<0.001 after adjustment for left ventricular hypertrophy and fibrosis). In overt disease, perfusion defects were found in all G+ but not all G-patients (100% [51/51] versus 82% [41/50]; P=0.001). Patients with G+LVH-compared with healthy volunteers similarly had altered microstructure, although to a lesser extent (all diffusion tensor imaging parameters; P<0.001), and MVD (reduced stress myocardial blood flow [P=0.015] with perfusion defects in 28% versus 0 healthy volunteers [P=0.002]). Disarray and MVD were independently associated with pathological electrocardiographic abnormalities in both overt and subclinical disease after adjustment for fibrosis and left ventricular hypertrophy (overt: fractional anisotropy: odds ratio for an abnormal ECG, 3.3, P=0.01; stress myocardial blood flow: odds ratio, 2.8, P=0.015; subclinical: fractional anisotropy odds ratio, 4.0, P=0.001; myocardial perfusion reserve odds ratio, 2.2, P=0.049). CONCLUSIONS: Microstructural alteration and MVD occur in overt HCM and are different in G+ and G-patients. Both also occur in the absence of hypertrophy in sarcomeric mutation carriers, in whom changes are associated with electrocardiographic abnormalities. Measurable changes in myocardial microstructure and microvascular function are early-phenotype biomarkers in the emerging era of disease-modifying therapy. [ABSTRACT FROM AUTHOR]

Whether there is an optimal range of motion (ROM) to induce muscle hypertrophy remains elusive, especially for gastrocnemius. This study aimed to compare the changes in gastrocnemius muscle thickness between calf raise exercise performed with full ROM (FULLROM), partial ROM performed in the initial (INITIALROM), and final (FINALROM) portions of the ROM. Forty-two young women performed a calf training program for 8 weeks, 3 days⋅week-1, with differences in the calf raise ROM configuration. The calf raise exercise was performed in a pin-loaded, horizontal, leg-press machine, in 3 sets of 15-20 repetition maximum. The subjects were randomly assigned to 1 of the 3 groups: FULLROM (ankle: -25° to +25°), INITIALROM (ankle: -25° to 0°), and FINALROM (ankle: 0°to +25°), where 0° was defined as an angle of 90° of the foot with the tibia. The muscle thickness measurements of medial and lateral gastrocnemius were taken by means of B-mode ultrasound. INITIALROM elicited greater medial gastrocnemius increases than FULLROM and FINALROM (INITIALROM = +15.2% vs. FULLROM = +6.7% and FINALROM = +3.4%; p ≤ 0.009). Furthermore, INITIALROM elicited greater lateral gastrocnemius increases than FINALROM (INITIALROM = +14.9% vs. FINALROM = +6.2%; p < 0.024) but did not significantly differ from FULLROM (FULLROM = +7.3%; p = 0.060). The current results suggest that calf training performed at longer muscle lengths may optimize gastrocnemius muscle hypertrophy in young women. Therefore, when prescribing hypertrophy-oriented training, the inclusion of the calf raise exercise performed with partial ROM in the initial portion of the excursion should be considered. [ABSTRACT FROM AUTHOR]

Purpose: The optimal intensity of resistance training (RT) to improve muscular, physical performance, and metabolic adaptations still needs to be well established for older adults. Based on current position statements, we compared the effects of two different RT loads on muscular strength, functional performance, skeletal muscle mass, hydration status, and metabolic biomarkers in older women. Methods: One hundred one older women were randomly allocated to perform a 12-wk whole-body RT program (eight exercises, three sets, three nonconsecutive days a week) into two groups: 8-12 repetitions maximum (RM) and 10-15RM. Muscular strength (1RM tests), physical performance (motor tests), skeletal muscle mass (dual-energy X-ray absorptiometry), hydration status (bioelectrical impedance), and metabolic biomarkers (glucose, total cholesterol, HDL-c, HDL-c, triglycerides, and C-reactive protein) were measured at baseline and posttraining. Results: Regarding muscular strength, 8-12RM promoted higher 1RM increases in chest press (+23.2% vs +10.7%, P < 0.01) and preacher curl (+15.7% vs +7.4%, P < 0.01), but not in leg extension (+14.9% vs +12.3%, P > 0.05). Both groups improved functional performance (P <0.05) in gait speed (4.6%-5.6%), 30 s chair stand (4.6%-5.9%), and 6 min walking (6.7%-7.0%) tests, with no between-group differences (P > 0.05). The 10-15RM group elicited superior improves in the hydration status (total body water, intracellular and extracellular water; P < 0.01), and higher gains of skeletal muscle mass (2.5% vs 6.3%, P < 0.01), upper (3.9% vs 9.0%, P < 0.01) and lower limbs lean soft tissue (2.1% vs 5.4%, P < 0.01). Both groups improved their metabolic profile. However, 10-15RM elicited greater glucose reductions (-0.2% vs -4.9%, P < 0.05) and greater HDL-c increases (-0.2% vs +4.7%, P < 0.01), with no between-group differences for the other metabolic bio-markers (P > 0.05). Conclusions: Our results suggest that 8-2RM seems more effective than 10-15RM for increasing upper limbs' muscular strength, whereas the adaptative responses for lower limbs and functional performance appear similar in older women. In contrast, 10-15RM seems more effective for skeletal muscle mass gains, and increased intracellular hydration and improvements in metabolic profile may accompany this adaptation. [ABSTRACT FROM AUTHOR]

Resistance exercise range of motion (ROM) influences muscular adaptations. However, there are no consistent practical guidelines about the optimal ROM for maximizing muscle hypertrophy. The objective of this article was to systematically review the literature for studies that compared the effects of full ROM (fROM) and partial ROM (pROM) on muscle hypertrophy. PubMed/MEDLINE, Scopus, and Web of Science databases were searched to identify articles from the earliest record up to and including April 2022. We calculated the effect size (ES) scores of the variables of interest. Eleven studies were included in the review. Full ROM and pROM performed in the initial part of the ROM elicited greater muscle hypertrophy of the rectus femoris, vastus lateralis, biceps brachii, and brachialis distal sites (between-groups ES: 0.20–0.90) than pROM performed in the final part of the ROM. fROM elicited greater muscle growth on the gluteus maximus and adductors than pROM in the final part of the ROM (between-groups ES: 0.24–0.25). Initial pROM produced more favorable proximal rectus femoris hypertrophy than fROM (between-groups ES: 0.35–0.38). pROM in the middle part of the ROM elicited greater triceps brachii hypertrophy than fROM (between-group ES: 1.21). In conclusion, evidence suggests that when training at a longer muscle length—through either pROM or fROM—some muscles, such as quadriceps femoris, biceps brachii, and triceps brachii, tend to experience optimal growth. Thus, the use pROM in the initial part of the excursion in combination with fROM training should be considered when prescribing hypertrophy-oriented resistance training programs. [ABSTRACT FROM AUTHOR]

This project examined the differences between a single set (SS) compared to multiple sets (MS) of resistance exercise on the Akt/protein kinase B (PKB) signaling pathway, the expression of insulin-like growth factor-1 (IGF-1), and the receptor for IGF-1 (IGF-1R) to better understand the types of resistance training protocols that are most beneficial in stimulating the muscle hypertrophic response. Sixteen healthy men were randomly selected into 2 groups of 8. Subjects in each group received 3 biopsies: (a) before exercise, (b) 15 minutes postexercise, and (c) 180 minutes postexercise. Subjects in the SS group performed 1 set of leg press to failure at 80% of their predetermined 1 repetition maximum (1RM). Subjects in the MS group performed 2 sets of 10 repetitions and 1 set to failure at 80% of their predetermined 1RM, with 3 minutes of rest between each set. Our results indicated no group 3 time interactions in the concentration of Akt signaling proteins. Furthermore, there were no group 3 time interactions in IGF-1 or IGF-1R expression. However, phosphorylated 4E-binding protein 1 levels increased 150% from pre to 180 minutes post (p = 0.005). In addition, there was a significantly greater increase in IGF-1R expression in the SS group compared with the MS group (7.99±10.07 vs. 4.41 ± 6.28; p = 0.026). Collectively, we found that a SS of resistance training evokes a similar acute Akt/PKB pathway response as MS in recreationally active men. [ABSTRACT FROM AUTHOR]

Study Design.: We performed histologic, immunohistochemical, immunoblot examination and suspension array analyses of cytokine expression in cultured cells derived from human cervical ossification of the posterior longitudinal ligament (OPLL). Objective.: To determine the roles of interleukin-6 (IL-6) during the maturation of osteoblasts and chondrocytes associated with the development of OPLL. Summary of Background Data.: Ectopic OPLL affects ~3% of the general population, with a higher incidence in Asian ethnic groups. Alterations in cytokine profiles may influence osteoblast differentiation, but the mechanisms and signaling pathways associated with the ossification process remain unclear. Methods.: Samples were collected from 14 patients with OPLL who had undergone spinal surgery and seven with cervical spondylotic myelopathy without OPLL. Tissue sections were used for histologic and immunohistochemical studies, and primary cells from ligamentum samples were used for cytokine array and immunoblotting. A suspension array was used to measure the concentrations of 27 inflammatory cytokines or growth factors. Results.: Suspension array and immunoblot analyses revealed significantly elevated levels of IL-6 in OPLL patients. Alterations in IL-6 concentrations were found to alter the expression of the genes Sox9 , Runx2 , and SIRT1. In addition, immunohistochemical analysis revealed that these factors are present in mesenchymal cells within the degenerative portion of the ligament matrix that is adjacent to the ossification front. Conclusions.: IL-6 plays a profound role in the osteoblast differentiation process along with the induction of chondrocyte hypertrophy and cell apoptosis in the early stages of ossification in OPLL. These changes in cytokine profiles are essential factors for regulation of the ectopic ossified plaque in OPLL. [ABSTRACT FROM AUTHOR]

The purpose of this systematic review with meta-analysis was to explore the effects of concurrent resistance and endurance training (CT) incorporating continuous or intermittent endurance training (ET) on whole-muscle and type I and II muscle fiber hypertrophy compared with resistance training (RT) alone. Randomized and nonrandomized studies reporting changes in cross-sectional area at muscle fiber and whole-muscle levels after RT compared with CT were included. Searches for such studies were performed in Web of Science, PubMed, Scopus, SPORTDiscus, and CINAHL electronic databases. The data reported in the included studies were pooled in a random-effects meta-analysis of standardized mean differences (SMDs). Twenty-five studies were included. At the whole-muscle level, there were no significant differences for any comparison (SMD < 0.03). By contrast, RT induced greater type I and type II muscle fiber hypertrophy than CT when high-intensity interval training (HIIT) was incorporated alone (SMD > 0.33) or combined with continuous ET (SMD > 0.27), but not compared with CT incorporating only continuous ET (SMD < 0.16). The subgroup analyses of this systematic review and meta-analysis showed that RT induces greater muscle fiber hypertrophy than CT when HIIT is included. However, no CT affected whole-muscle hypertrophy compared with RT. [ABSTRACT FROM AUTHOR]

Purpose: Sprinters exhibit inhomogeneous muscularity corresponding to musculoskeletal demand for sprinting execution. An inhomogeneous morphology would affect the mass distribution, which in turn may affect the mechanical difficulty in moving from an inertia perspective; however, the morphological characteristics of sprinters from the inertia perspective have not been examined. Here we show no corresponding differences in the normalized mass and normalized moment of inertia between the sprinters and untrained nonsprinters. Methods: We analyzed fat- and water-separated magnetic resonance images from the lower limbs of 11 male sprinters (100 m best time of 10.44–10.83 s) and 12 untrained nonsprinters. We calculated the inertial properties by identifying the tissue of each voxel and combining the literature values for each tissue density. Results: The lower-limb relative mass was significantly larger in sprinters (18.7% ± 0.7% body mass) than in nonsprinters (17.6% ± 0.6% body mass), whereas the normalized moment of inertia of the lower limb around the hip in the anatomical position was not significantly different (0.044 ± 0.002 vs 0.042 ± 0.002 [a. u.]). The thigh relative mass in sprinters (12.9% ± 0.4% body mass) was significantly larger than that in nonsprinters (11.9% ± 0.4% body mass), whereas the shank and foot relative masses were not significantly different. Conclusions: We revealed that the mechanical difficulty in swinging the lower limb is not relatively larger in sprinters in terms of inertia, even though the lower-limb mass is larger, reflecting their muscularity. We provide practical implications that sprinters can train without paying close attention to the increase in lower-limb mass and moment of inertia. [ABSTRACT FROM AUTHOR]

Purpose: Resistance exercise training (RET) attenuates age-related muscle and strength loss ("sarcopenia"). However, compared with machine-based RET, the efficacy of cost-effective, accessible elastic band RET (EB-RET) for muscle adaptive remodeling lacks supporting mechanistic evidence. Methods: Eight young (YM; 24 ± 4 yr) and eight older (OM; 68 ± 6 yr) untrained males consumed an oral stable isotope tracer (D2O) combined with serial vastus lateralis muscle biopsies to measure integrated myofibrillar protein synthesis (iMyoPS) and regulatory signaling over ~48 h before (habitual) and after an acute bout of EB-RET (6 × 12 repetitions at ~70% of one-repetition maximum). iMyoPS was determined via gas chromatography–pyrolysis–isotope ratio mass spectroscopy and regulatory signaling expression by immunoblot. Results: Habitual iMyoPS did not differ between YM and OM (1.62% ± 0.21% vs 1.43% ± 0.47%·d−1, respectively, P = 0.128). There was a significant increase in iMyoPS after EB-RET in YM (2.23% ± 0.69%·d−1, P = 0.02), but not OM (1.75% ± 0.54%·d−1, P = 0.30). EB-RET increased the phosphorylation of key anabolic signaling proteins similarly in YM and OM at 1 h postexercise, including p-IRS-1Ser636/639, p-AktSer473, p-4EBP-1Thr37/46, p-P70S6KThr389, and p-RPS6Ser240/244, whereas p-TSC2Thr1462 and p-mTORSer2448 increased only in YM (all P < 0.05). There were no differences in the expression of amino acid transporters/sensors or proteolytic markers after EB-RET. Conclusions: iMyoPS was elevated after EB-RET in YM but not OM. However, the increase in acute anabolic signaling with EB-RET was largely similar between groups. In conclusion, the capacity for EB-RET to stimulate iMyoPS may be impaired in older age. Further work may be necessary to optimize prescriptive programming in YM and OM. [ABSTRACT FROM AUTHOR]

Background: Mechanical stress on the heart, such as high blood pressure, initiates inflammation and causes hypertrophic heart disease. However, the regulatory mechanism of inflammation and its role in the stressed heart remain unclear. IL-1β (interleukin-1β) is a proinflammatory cytokine that causes cardiac hypertrophy and heart failure. Here, we show that NLRP3 (neural signals activate the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing 3) inflammasome for IL-1β production to induce adaptive hypertrophy in the stressed heart.Methods: C57BL/6 mice, knockout mouse strains for NLRP3 and P2RX7 (P2X purinoceptor 7), and adrenergic neuron-specific knockout mice for SLC17A9, a secretory vesicle protein responsible for the storage and release of ATP, were used for analysis. Pressure overload was induced by transverse aortic constriction. Various animal models were used, including pharmacological treatment with apyrase, lipopolysaccharide, 2'(3')-O-(4-benzoylbenzoyl)-ATP, MCC950, anti-IL-1β antibodies, clonidine, pseudoephedrine, isoproterenol, and bisoprolol, left stellate ganglionectomy, and ablation of cardiac afferent nerves with capsaicin. Cardiac function and morphology, gene expression, myocardial IL-1β and caspase-1 activity, and extracellular ATP level were assessed. In vitro experiments were performed using primary cardiomyocytes and fibroblasts from rat neonates and human microvascular endothelial cell line. Cell surface area and proliferation were assessed.Results: Genetic disruption of NLRP3 resulted in significant loss of IL-1β production, cardiac hypertrophy, and contractile function during pressure overload. A bone marrow transplantation experiment revealed an essential role of NLRP3 in cardiac nonimmune cells in myocardial IL-1β production and cardiac phenotype. Pharmacological depletion of extracellular ATP or genetic disruption of the P2X7 receptor suppressed myocardial NLRP3 inflammasome activity during pressure overload, indicating an important role of ATP/P2X7 axis in cardiac inflammation and hypertrophy. Extracellular ATP induced hypertrophic changes of cardiac cells in an NLRP3- and IL-1β-dependent manner in vitro. Manipulation of the sympathetic nervous system suggested sympathetic efferent nerves as the main source of extracellular ATP. Depletion of ATP release from sympathetic efferent nerves, ablation of cardiac afferent nerves, or a lipophilic β-blocker reduced cardiac extracellular ATP level, and inhibited NLRP3 inflammasome activation, IL-1β production, and adaptive cardiac hypertrophy during pressure overload.Conclusions: Cardiac inflammation and hypertrophy are regulated by heart-brain interaction. Controlling neural signals might be important for the treatment of hypertensive heart disease. [ABSTRACT FROM AUTHOR]

This exploratory secondary data analysis compared the effects of a percentage of 1 repetition maximum (%1RM) and a repetition zone (RM Zone) progression model carried out to muscle failure on volume load progression (VLPro), muscle strength, and cross-sectional area (CSA). The sample comprised 24 untrained men separated in 2 groups: %1RM (n = 14) and RM Zone (n = 10). Muscle CSA and muscle strength (1RM) were assessed before and after 24 training sessions, and an analysis of covariance was used. Volume load progression and accumulated VL (VLAccu) were compared between groups. The relationships between VLProg, VLAccu, 1RM, and CSA increases were also investigated. A significance level of p = 0.05 was adopted for all statistical procedures. Volume load progression was greater for RM Zone compared with %1RM (2.30 ± 0.58% per session vs. 1.01 ± 0.55% per session; p < 0.05). Significant relationships were found between 1RM and VLProg (p < 0.05) and CSA and VLProg (p < 0.05). No between-group differences were found for VLAccu (p > 0.05). Analysis of covariance revealed no between-group differences for 1RM absolute (p < 0.05) or relative changes (p < 0.05). However, post hoc testing revealed greater absolute and relative changes in CSA for the RM Zone group compared with the %1RM group (p < 0.001). In conclusion, RM Zone resulted in a greater VLPro rate and muscle CSA gains compared with %1RM, with no differences in VLAccu and muscle strength gains between progression models. [ABSTRACT FROM AUTHOR]

Coratella, G, Beato, M, Bertinato, L, Milanese, C, Venturelli, M, and Schena, F. Including the eccentric phase in resistance training to counteract the effects of detraining in women: a randomized controlled trial. J Strength Cond Res 36(11): 3023–3031, 2022—The current study compared the effects of concentric-based (CONC), eccentric-based (ECC), and traditional concentric-eccentric (TRAD) resistance training on muscle strength, mass, and architecture and the postdetraining retention of the training-induced effects in women. Sixty women were randomly assigned to unilateral volume-equated CONC, ECC, or TRAD knee extension training or control (N = 15 per group). Before training, after an 8-week intervention period, and after an 8-week detraining period, isokinetic concentric, eccentric, and isometric torque were measured. In addition, thigh lean mass was assessed by dual X-ray absorptiometry and vastus lateralis thickness, pennation angle, and fascicle length by ultrasound. After training, concentric and isometric torque increased (p < 0.05) similarly in all groups, whereas eccentric torque increased more in ECC than that in CONC (+13.1%, effect size (ES): 0.71 [0.04–1.38]) and TRAD (+12.6%, ES: 0.60 [0.12–1.08]). Thigh lean mass increased in ECC (+6.1%, ES: 0.47 [0.27–0.67]) and TRAD (+3.1%, ES: 0.33 [0.01–0.65]). Vastus lateralis thickness and pennation angle increased (p < 0.05) similarly in all groups, whereas fascicle elongation was visible in ECC (+9.7%, ES: 0.92 [0.14–1.65]) and TRAD (+7.1%, ES: 0.64 [0.03–1.25]). After detraining, all groups retained (p < 0.05) similar concentric torque. ECC and TRAD preserved eccentric torque (p < 0.05), but ECC more than TRAD (+17.9%, ES: 0.61 [0.21–1.21]). All groups preserved isometric torque (p < 0.05), but ECC more than CONC (+14.2%, ES: 0.71 [0.04–1.38]) and TRAD (+13.8%, ES: 0.65 [0.10–1.20]). Thigh lean mass and vastus lateralis fascicle length were retained only in ECC (p < 0.05), pennation angle was preserved in all groups (p < 0.05), and thickness was retained in CONC and ECC (p < 0.05). Including the eccentric phase in resistance training is essential to preserve adaptations after detraining. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. BACKGROUND: Aesthetic muscle stimulation (AMS) using high-intensity electromagnetic field (HIFEM) targets skeletal muscle neurons, causing muscle hypertrophy and loss of adipose tissue, thereby cultivating a sculpted physique. Many studies have evaluated AMS for noninvasive body contouring; however, the efficacy, safety, and long-term data remain unclear. OBJECTIVE: To critically evaluate the current literature on the use of electromagnetic muscle stimulation for body contouring and provide a consensus on patient selection and long-term efficacy of AMS. MATERIALS AND METHODS: PubMed and Embase were searched using the terms: "HIFEM," "Electromagnetic therapy," and "muscle" or "Electrical stimulation muscle treatments" and "aesthetics." Studies involving the use of muscle stimulation for nonaesthetic/dermatologic, in vitro studies or studies involving animals were excluded. RESULTS: Twenty studies in total were included [9 moderate-quality, 8 low-quality, and 3 very low‒quality studies] based on the Grading of Recommendations, Assessment, Development, and Evaluation scale, representing 521 patients. Body sites evaluated included the abdomen (378 patients), buttock (156 patients), arms (22 patients), and calves (15 patients). CONCLUSION: Electromagnetic muscle stimulation represents an effective therapeutic intervention for abdominal contouring that yields increased muscle thickness, and reduced abdominal fat thickness, for up to 1 year after treatment. Larger, controlled studies are needed to determine the efficacy of electromagnetic muscle stimulation alone for contouring of buttocks, thighs, arms, and calves. [ABSTRACT FROM AUTHOR]

Objectives: Blood flow restriction (BFR) training is an increasingly applied tool with potential benefits in muscular hypertrophy, strength, and endurance. This study investigates the effectiveness of BFR training relative to other forms of training on muscle strength, hypertrophy, and endurance. Data sources: We performed systematic searches of MEDLINE, Embase, and PubMed and assessed the methodological quality of included studies using the Cochrane risk of bias tool. Main results: We included 53 randomized controlled trials with 31 included in meta-analyses. For muscular strength comparing low-intensity BFR (LI-BFR) training with high-intensity resistance training (HIRT), the pooled mean difference (MD) for 1 repetition maximum was 5.34 kg (95% CI, 2.58-8.09; P < 0.01) favoring HIRT. When comparing LI-BFR training with HIRT for torque, the MD was 6.35 N·m (95% CI, 0.5-12.3; P = 0.04) also favoring HIRT. However, comparing LI-BFR with low-intensity resistance training (LIRT) for torque, there was a MD of 9.94 N·m (95% CI, 5.43-14.45; P < 0.01) favoring BFR training. Assessing muscle hypertrophy, the MD in cross-sectional area was 0.96 cm2 (95% CI, 0.21-1.7; P = 0.01) favoring pooled BFR training compared with nonocclusive training. Assessing endurance, V̇ o 2 maximum demonstrated a greater mean increase of 0.37 mL/kg/min (95% CI, −0.97 to 3.17; P = 0.64) in BFR endurance training compared with endurance training alone. Conclusion: Blood flow restriction training produced increases in muscular strength, hypertrophy, and endurance. Comparing LI-BFR training with HIRT, HIRT was a significantly better training modality for increasing muscle hypertrophy and strength. However, LI-BFR was superior when compared with a similar low-intensity protocol. Blood flow restriction training is potentially beneficial to those unable to tolerate the high loads of HIRT; however, better understanding of its risk to benefit ratio is needed before clinical application. Level of evidence: Level 1. [ABSTRACT FROM AUTHOR]

Diniz, RCR, Tourino, FD, Lacerda, LT, Martins-Costa, HC, Lanza, MB, Lima, FV, and Chagas, MH. Does the muscle action duration induce different regional muscle hypertrophy in matched resistance training protocols? J Strength Cond Res 36(9): 2371–2380, 2022—The manipulation of the muscle action duration (MAD) can influence the instantaneous torque along the range of motion, which can lead to adaptations of regional muscle hypertrophy. The aim of this study was to compare the effects of matched resistance training (RT) on the knee extension machine with different MAD in the cross-sectional area (CSA) responses within the quadriceps femoris (QF) and its muscles. Forty-four subjects were allocated into a control and 3 experimental groups. For a period of 10 weeks, subjects in the experimental groups performed the training protocols that were different only by the MAD: group 5c1e (5s concentric action [CON] and 1s eccentric action [ECC]; group 3c3e (3s CON and 3s ECC) and group 1c5e (1s CON and 5s ECC). Magnetic resonance imaging was performed (before and after the intervention) to determine the relative change (%) in CSA of the QF muscles along proximal (30%), middle (50%), and distal regions (70% distal of the femur). The change in CSA of the rectus femoris at the middle region are greater in 5c1e (6.8 ± 6.5%) and 1c5e (7.4 ± 6.0%) groups than 3c3e (3.4 ± 6.6%) and control groups (0.2 ± 1.8%). In addition, vastus lateralis at the distal region (5c1e = 15.9 ± 11.8%; 1c5e = 14.4 ± 10.0%) presenting greater increases in change of CSA than the others vastus only 5c1e (vastus lateralis [VI] = 5.0 ± 4.7%; vastus medialis [VM] = 4.2 ± 3.2%) and 1c5e groups (VI = 4.7 ± 3.6%; VM = 3.4 ± 3.1%). In conclusion, this study showed that matched RT protocols with different MAD resulted in different region-specific muscle hypertrophic across the individual muscles of QF. [ABSTRACT FROM AUTHOR]

Davies, TB, Halaki, M, Orr, R, Mitchell, L, Helms, ER, Clarke, J, and Hackett, DA. Effect of set structure on upper-body muscular hypertrophy and performance in recreationally trained men and women. J Strength Cond Res 36(8): 2176–2185, 2022—This study explored the effect of volume-equated traditional-set and cluster-set structures on muscular hypertrophy and performance after high-load resistance training manipulating the bench press exercise. Twenty-one recreationally trained subjects (12 men and 9 women) performed a 3-week familiarization phase and were then randomized into one of two 8-week upper-body and lower-body split programs occurring over 3 and then progressing to 4 sessions per week. Subjects performed 4 sets of 5 repetitions at 85% one repetition maximum (1RM) using a traditional-set structure (TRAD, n = 10), which involved 5 minutes of interset rest only, or a cluster-set structure, which included 30-second inter-repetition rest and 3 minutes of interset rest (CLUS, n = 11). A 1RM bench press, repetitions to failure at 70% 1RM, regional muscle thickness, and dual-energy x-ray absorptiometry were used to estimate changes in muscular strength, local muscular endurance, regional muscular hypertrophy, and body composition, respectively. Velocity loss was assessed using a linear position transducer at the intervention midpoint. TRAD demonstrated a significantly greater velocity loss magnitude (g = 1.50) and muscle thickness of the proximal pectoralis major (g = −0.34) compared with CLUS. There were no significant differences between groups for the remaining outcomes, although a small effect size favoring TRAD was observed for the middle region of the pectoralis major (g = −0.25). It seems that the greater velocity losses during sets observed in traditional-set compared with cluster-set structures may promote superior muscular hypertrophy within specific regions of the pectoralis major in recreationally trained subjects. [ABSTRACT FROM AUTHOR]

Martins-Costa, HC, Lacerda, LT, Diniz, RCR, Lima, FV, Andrade, AGP, Peixoto, GH, Gomes, MC, Lanza, MB, Bemben, MG, and Chagas, MH. Equalization of training protocols by time under tension determines the magnitude of changes in strength and muscular hypertrophy. J Strength Cond Res 36(7): 1770–1780, 2022—The aim of this study was to investigate the effects of 2 training protocols equalized by tension (TUT) on maximal strength (1 repetition maximum [RM]), regional cross-sectional areas (proximal, middle, and distal), and total cross-sectional areas (sum of the regional cross-sectional areas) of the pectoralis major and triceps brachii muscles. Thirty-eight men untrained in resistance training participated in the study and were allocated under 3 conditions: Protocol 3s (n = 11; 12 repetitions; 3s repetition duration), Protocol 6s (n = 11; 6 repetitions; 6s repetition duration), and Control (n = 11; no training). Training protocols (10 weeks; bench press exercise) were equated for TUT (36 seconds per set), number of sets (3–4), intensity (50–55% of 1RM), and rest between sets (3 minutes). Analysis of variance was used to examine a percentage change in variables of interest across the 3 groups with an alpha level of 0.05 used to establish statistical significance. Protocols 3s and 6s showed no differences in the increase of total and regional muscle cross-sectional areas. There were no differences in regional hypertrophy of the pectoralis major muscle. In the triceps brachii muscle, the increase in distal cross-sectional area was greater when compared with the middle and proximal regions. Both experimental groups had similar increases in the 1RM test. In conclusion, training protocols with the same TUT promote similar strength gains and muscle hypertrophy. Moreover, considering that the protocols used different numbers of repetitions, the results indicate that training volumes cannot be considered separately from TUT when evaluating neuromuscular adaptations. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Kassiano, W, Nunes, JP, Costa, B, Ribeiro, AS, Schoenfeld, BJ, and Cyrino, ES. Does varying resistance exercises promote superior muscle hypertrophy and strength gains? A systematic review. J Strength Cond Res 36(6): 1753–1762, 2022—Fitness professionals routinely employ a variety of resistance training exercises in program design as a strategy to enhance muscular adaptations. However, it remains uncertain whether such an approach offers advantages over a fixed-exercise selection. The objective of this review was to review the effects of exercise variation on muscle hypertrophy and strength. A search of the literature was conducted using PubMed/MEDLINE, Scopus, and Web of Science databases. Eight studies were identified as meeting inclusion criteria. The combined total sample of the studies was N = 241, comprising all young men. The methodological quality of included studies was considered "good" and "excellent" based on the Physiotherapy Evidence Database Scale. The available studies indicate that varying exercise selection can influence muscle hypertrophy and strength gains. Some degree of systematic variation seems to enhance regional hypertrophic adaptations and maximize dynamic strength, whereas excessive, random variation may compromise muscular gains. We conclude that exercise variation should be approached systematically with a focus on applied anatomical and biomechanical constructs; on the contrary, employing different exercises that provide a redundant stimulus, as well as excessive rotation of different exercises (i.e., high frequency of change), may actually hinder muscular adaptations. [ABSTRACT FROM AUTHOR]

Longo, AR, Silva-Batista, C, Pedroso, K, de Salles Painelli, V, Lasevicius, T, Schoenfeld, BJ, Aihara, AY, de Almeida Peres, B, Tricoli, V, and Teixeira, EL. Volume load rather than resting interval influences muscle hypertrophy during high-intensity resistance training. J Strength Cond Res 36(6): 1554–1559, 2022—Interset rest interval has been proposed as an important variable for inducing muscle mass and strength increases during resistance training. However, its influence remains unclear, especially when protocols with differing intervals have equalized volume. We aimed to compare the effects of long (LI) vs. short rest interval (SI) on muscle strength (one repetition maximum [1RM]) and quadriceps cross-sectional area (QCSA), with or without equalized volume load (VL). Twenty-eight subjects trained twice a week for 10 weeks. Each subject's leg was allocated to 1 of 4 unilateral knee extension protocols: LI, SI, SI with VL -matched by LI (VLI-SI), and LI with VL-matched by SI (VSI-LI). A 3-minute rest interval was afforded in LI and VSI-LI protocols, while SI and VLI-SI employed a 1-minute interval. All subjects trained with a load corresponding to 80% 1RM. One repetition maximum and QCSA were measured before and after training. All protocols significantly increased 1RM values in post-training (p < 0.0001; LI: 27.6%, effect size [ES] = 0.90; VLI-SI: 31.1%, ES = 1.00; SI: 26.5%, ES = 1.11; and VSI-LI: 31.2%, ES = 1.28), with no significant differences between protocols. Quadriceps cross-sectional area increased significantly for all protocols in post-training (p < 0.0001). However, absolute changes in QCSA were significantly greater in LI and VLI-SI (13.1%, ES: 0.66 and 12.9%, ES: 0.63) than SI and VSI-LI (6.8%, ES: 0.38 and 6.6%, ES: 0.37) (both comparisons, p < 0.05). These data suggest that maintenance of high loads is more important for strength increases, while a greater VL plays a primary role for hypertrophy, regardless of interset rest interval. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Terada, K, Kikuchi, N, Burt, D, Voisin, S, and Nakazato, K. Full title: Low-load resistance training to volitional failure induces muscle hypertrophy similar to volume-matched, velocity fatigue. J Strength Cond Res 36(6): 1576–1581, 2022—We investigated how resistance training (RT) to failure at low load affects acute responses and chronic muscle adaptations compared with low-load RT to velocity fatigue at equal work volume. Twenty-seven subjects performed 8 weeks of bench press twice weekly. Subjects were randomly assigned to one of 3 groups: low-load volitional failure (LVoF, n = 9), low-load velocity fatigue (LVeF, n = 8), and high-load (HL, n = 10). Resistance training comprised 3 sets to failure at 40% one repetition maximum (1RM) in the LVoF group, 3 sets to velocity fatigue (20% lifting velocity loss) at 40% 1RM in the LVeF group, and 3 sets of 8 repetitions at 80% 1RM in the HL group. We measured muscle strength, hypertrophy, endurance, and power at baseline and after the RT program. We also measured muscle swelling and blood lactate after each RT bout to investigate the acute response. There were no differences in total work volume between the LVoF and LVeF groups. Responses to RT were similar between LVoF and LVeF, whether looking at acute muscle swelling, increase in blood lactate, chronic hypertrophy, and strength gain. However, LVoF and LVeF RT triggered different responses to muscle function in comparison with HL training: LVoF and LVeF showed enhanced acute responses and greater chronic endurance gains, but lower chronic strength gains than HL. In conclusion, low-load RT to volitional failure induces muscle hypertrophy similar to volume-matched velocity fatigue. [ABSTRACT FROM AUTHOR]

Purpose: Resistance training induces skeletal muscle hypertrophy via the summated effects of postexercise elevations in myofibrillar protein synthesis (MyoPS) that persist for up to 48 h, although research in females is currently lacking. MyoPS is regulated by mTOR translocation and colocalization; however, the effects of resistance training on these intracellular processes are unknown. We hypothesized that MyoPS would correlate with hypertrophy only after training in both sexes and would be associated with intracellular redistribution of mTOR. Methods: Recreationally active males and females (n = 10 each) underwent 8 wk of whole-body resistance exercise three times a week. Fasted muscle biopsies were obtained immediately before (REST) and 24 and 48 h after acute resistance exercise in the untrained (UT) and trained (T) states to determine integrated MyoPS over 48 h (D2O ingestion) and intracellular mTOR colocalization (immunofluorescence microscopy). Results: Training increased (P < 0.01) muscle strength (~20%–126%), muscle thickness (~8%–11%), and average fiber cross-sectional area (~15%–20%). MyoPS increased above REST in UT (P = 0.032) and T (P < 0.01), but to a greater extent in males (~23%; P = 0.023), and was positively (P < 0.01) associated with muscle thickness and fiber cross-sectional area at T only in both males and females. mTOR colocalization with the cell periphery increased (P < 0.01) in T, irrespective of sex or acute exercise. Training increased (P ≤ 0.043) total mTOR, LAMP2 (lysosomal marker), and their colocalization (P < 0.01), although their colocalization was greater in males at 24 and 48 h independent of training status (P < 0.01). Conclusions: MyoPS during prolonged recovery from exercise is greater in males but related to muscle hypertrophy regardless of sex only in the trained state, which may be underpinned by altered mTOR localization. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effect of protein and/or amino acid supplementation on muscle mass and strength in a healthy population. A structured literature search was conducted from database inception up to October 23, 2019, using PubMed and Scopus. Data were collected from randomized controlled trials and weighted mean difference, and its 95% confidence interval was calculated by using a random-effects model. Risk of bias was assessed using the Cochrane tool. Data were included from 46 randomized controlled trials, totaling 2049 participants. Protein but not amino acid supplementation resulted in significant positive effects on muscle mass (weighted mean difference, 0.47 kg; 95% confidence interval, 0.18-0.75 kg; P <.001) and upper body strength. The significant effect of protein supplementation on muscle mass persisted in the subgroups with and without resistance training, in young (<30 years) and older (≥59 years) adults, and across either gender. This review suggests that dietary protein and/or amino acid supplementation may promote muscle mass hypertrophy and/or maintenance, as well as some measures of muscular strength in a healthy population. [ABSTRACT FROM AUTHOR]

Nascimento de Oliveira Júnior, G, de Freitas Rodrigues de Sousa, J, Augusto da Silva Carneiro, M, Martins, FM, Santagnello, SB, Campos Souza, MV, and Orsatti, FL. Resistance training volume enhances muscle hypertrophy, but not strength in postmenopausal women: a randomized controlled trial. J Strength Cond Res 36(5): 1216–1221, 2022—Among several possible resistance training (RT) variables to be manipulated, the training volume has been considered as a critical variable to maximize RT-induced hypertrophy. Many of the studies that compared one set of RT with 3 sets have failed to show a difference in muscle hypertrophy in older adults. However, it is not clear whether further increases in RT volume (i.e., 6 sets) would result in even greater RT-related hypertrophy than 3 sets in older adults. This study aimed to investigate whether higher-volume RT (HV-RT) maximizes gains in lean body mass and muscle strength (MS) when compared with lower-volume RT (LV-RT) in postmenopausal women (PW). Fifty-eight PW were randomized into 1 of the 3 groups: control group (CT, no exercise), HV-RT (6 sets per exercise), and LV-RT (3 sets per exercise). Volunteers took part in a supervised training program (leg press 45°, leg extension, leg curl and standing calf raises) and were assessed for leg lean mass (LLM; dual X-ray absorptiometry) and lower limb MS (leg press and leg extension; 1 repetition maximum [1RM]) before and after 12 weeks of RT. Both HV-RT and LV-RT groups increased (p < 0.05) LLM and MS when compared with the CT group. Higher increases in LLM gains were observed for the HV-RT group when compared with the LV-RT group (6.1 and 2.3%, p < 0.001). Both HV-RT and LV-RT groups similarly increased 1RM in the leg press and leg extension. Thus, there seems to be a dose-response relationship between RT volume and muscle hypertrophy, but not for MS gains in PW. [ABSTRACT FROM AUTHOR]

Hackett, DA. Training, supplementation, and pharmacological practices of competitive male bodybuilders across training phases. J Strength Cond Res 36(4): 963-970, 2022-Bodybuilding involves the pursuit of muscularity and leanness primarily through the use of progressive resistance training in combination with other practices such as manipulation of diet and use of ergogenic aids. This study aimed to compare the training practices and ergogenic aids used by competitive male bodybuilders across training phases. An online survey was completed by 235 competitive male bodybuilders with a median age of 26.0 (interquartile range 23.0-31.3) years. Results showed that most respondents performed split-routines (85.5%), 4-7 sessions per week (95.7%), trained major muscle groups twice a week (>50%), and session duration being 60-90 minutes (55.7%). Off-season resistance training sessions mostly comprised of targeting 2-3 muscle groups (56%), 2-3 exercises per muscle group (60.4%), 3-4 sets per exercise (73.2%), 7-12 repetition maximum (RM) per set (71.6%), and 61-180 seconds recovery between sets and exercises (80.5%). At the precompetition phase (6 weeks before competition), there was a decrease in the number of muscle groups trained per session (p = 0.027) and a greater number of repetitions performed per set (p < 0.001). A significant increase in the reported aerobic exercise volume was found during precompetition (<0.001). Performance enhancing drugs were used by 53.6% of respondents who did not compete in natural bodybuilding competitions. Dietary supplements were used by 95.7% of respondents with the most common being creatine monohydrate (80.4%) and whey protein (65.8%). Findings suggest that competitive bodybuilders follow resistance training practices consistent with the broad muscular hypertrophy recommendations but a notable shift in practices occur in the weeks before competition. [ABSTRACT FROM AUTHOR]

Scarpelli, MC, Nobrega, SR, Santanielo, N, Alvarez, IF, Otoboni, GB, Ugrinowitsch, C, and Libardi, CA. Muscle hypertrophy response is affected by previous resistance training volume in trained individuals. J Strength Cond Res 36(4): 1153-1157, 2022-The purpose of this study was to compare gains in muscle mass of trained individuals after a resistance training (RT) protocol with standardized (i.e. nonindividualized) volume (N-IND), with an RT protocol using individualized volume (IND). In a within-subject approach, 16 subjects had one leg randomly assigned to N-IND (22 sets[middle dot]wk-1, based on the number of weekly sets prescribed in studies) and IND (1.2 x sets[middle dot]wk-1 recorded in training logs) protocols. Muscle cross-sectional area (CSA) was assessed by ultrasound imaging at baseline (Pre) and after 8 weeks (Post) of RT, and the significance level was set at p < 0.05. Changes in the vastus lateralis CSA (difference from Pre to Post) were significantly higher for the IND protocol (p = 0.042; mean difference: 1.08 cm2; confidence interval [CI]: 0.04-2.11). The inferential analysis was confirmed by the CI of the effect size (0.75; CI: 0.03-1.47). Also, the IND protocol had a higher proportion of individuals with greater muscle hypertrophy than the typical error of the measurement (chi-square, p = 0.0035; estimated difference = 0.5, CI: 0.212-0.787). In conclusion, individualizing the weekly training volume of research protocols provides greater gains in muscle CSA than prescribing a group standard RT volume. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Hirono, T, Ikezoe, T, Taniguchi, M, Tanaka, H, Saeki, J, Yagi, M, Umehara, J, and Ichihashi, N. Relationship between muscle swelling and hypertrophy induced by resistance training. J Strength Cond Res 36(2): 359–364, 2022—Muscle swelling immediately after resistance exercise may be induced by metabolic stress. The accumulation of metabolic stress is considered to promote muscle hypertrophy after several weeks of resistance training (RT). The purpose of this study was to determine the relationship between muscle swelling immediately after the first session of RT and muscle hypertrophy after a 6-week RT using ultrasonography. Twenty-two untrained young men performed knee extension resistance exercise consisting of 3 sets with 8 repetitions at a load of 80% of one repetition maximum for 6 weeks (3 d·wk−1). Muscle thickness of the quadriceps femoris was measured using ultrasonography device at 3 anatomical sites (proximal, medial, and distal sites) of the middle, lateral, and medial part of the anterior thigh. The sum of the muscle thickness at 9 measurement sites was used for analysis. Acute change in muscle thickness immediately after the first session of RT was used as an indicator of muscle swelling. Chronic change in muscle thickness after the 6-week RT was used as an indicator of muscle hypertrophy. A significant increase in muscle thickness was observed immediately after the first session of RT (8.3 ± 3.2%, p < 0.001). After the 6-week RT, muscle thickness increased significantly (2.9 ± 2.6%, p < 0.001). A significant positive correlation was found between muscle swelling and muscle hypertrophy (ρ = 0.443, p = 0.039). This study suggests that the greater the muscle swelling immediately after the first session of RT, the greater the muscle hypertrophy after RT. [ABSTRACT FROM AUTHOR]

Lasevicius, T, Schoenfeld, BJ, Silva-Batista, C, Barros, TdS, Aihara, AY, Brendon, H, Longo, AR, Tricoli, V, Peres, BdA, and Teixeira, EL. Muscle failure promotes greater muscle hypertrophy in low-load but not in high-load resistance training. J Strength Cond Res 36(2): 346–351, 2022—The purpose of this study was to investigate the effects of an 8-week resistance training program at low and high loads performed with and without achieving muscle failure on muscle strength and hypertrophy. Twenty-five untrained men participated in the 8-week study. Each lower limb was allocated to 1 of 4 unilateral knee extension protocols: repetitions to failure with low load (LL-RF; ∼34.4 repetitions); repetitions to failure with high load (HL-RF; ∼12.4 repetitions); repetitions not to failure with low load (LL-RNF; ∼19.6 repetitions); and repetitions not to failure with high load (HL-RNF; ∼6.7 repetitions). All conditions performed 3 sets with total training volume equated between conditions. The HL-RF and HL-RNF protocols used a load corresponding to 80% 1 repetition maximum (RM), while LL-RF and LL-RNF trained at 30% 1RM. Muscle strength (1RM) and quadriceps cross-sectional area (CSA) were assessed before and after intervention. Results showed that 1RM changes were significantly higher for HL-RF (33.8%, effect size [ES]: 1.24) and HL-RNF (33.4%, ES: 1.25) in the post-test when compared with the LL-RF and LL-RNF protocols (17.7%, ES: 0.82 and 15.8%, ES: 0.89, respectively). Quadriceps CSA increased significantly for HL-RF (8.1%, ES: 0.57), HL-RNF (7.7%, ES: 0.60), and LL-RF (7.8%, ES: 0.45), whereas no significant changes were observed in the LL-RNF (2.8%, ES: 0.15). We conclude that when training with low loads, training with a high level of effort seems to have greater importance than total training volume in the accretion of muscle mass, whereas for high load training, muscle failure does not promote any additional benefits. Consistent with previous research, muscle strength gains are superior when using heavier loads. [ABSTRACT FROM AUTHOR]

Brigatto, FA, Lima, LEdM, Germano, MD, Aoki, MS, Braz, TV, and Lopes, CR. High resistance-training volume enhances muscle thickness in resistance-trained men. J Strength Cond Res 36(1): 22–30, 2022—This study investigated the effects of different volumes of resistance training (RT) (8 weeks of 16, 24, and 32 weekly sets per muscle group) on muscular strength and hypertrophy. Subjects were pair-matched according to baseline strength and then randomly assigned to 1 of 3 experimental groups: 16 weekly sets per muscle group (G16, n = 9), 24 weekly sets per muscle group (G24, n = 9), or 32 weekly sets per muscle group (G32, n = 9). All other RT variables (e.g., exercise performed, exercise order, weekly frequency, range of repetitions, rest interval between sets and exercises, etc.) were maintained constant. The total load lifted was calculated for every RT session to compare the accumulated external training load among experimental groups across the intervention period. Testing was conducted before intervention (pre) and after 8-week (post-8) periods for maximal voluntary muscle strength (1 repetition maximum [1RM] test for bench press and parallel back squat exercises) and muscle thickness (MT) of the biceps brachii, triceps brachii, and vastus lateralis. The major findings were as follows: (a) all RT volumes increased bench press and parallel back squat 1RM and (b) all RT volumes increased the biceps brachii, triceps brachii, and vastus lateralis MT. The magnitude of increase in 1RM and MT of the lower body when training with 32 weekly sets per muscle group was higher than for 16 weekly sets per muscle group. The magnitude of the increase in MTTB was higher when training with 32 weekly sets than for 16 weekly sets. [ABSTRACT FROM AUTHOR]

Drummond, MDM, Couto, BP, Oliveira, MP, and Szmuchrowski, LA. Effects of local vibration on dynamic strength training. J Strength Cond Res 35(11): 3028–3034, 2021—The study aim was to compare the chronic effects of maximal dynamic strength training with and without the addition of local vibration (LV) on maximal force generation and hypertrophy of the elbow flexor muscles in trained subjects. Twenty men were divided into 2 groups (conventional training [CT] group and vibration training [VT] group). The CT group performed conventional maximal dynamic strength training, and the VT group performed maximal dynamic strength training with mechanical vibrations (frequency of 26 Hz and amplitude of 6 mm). CT and VT groups performed 5 sets of 3–4 repetitions, with 2-minute rest intervals between sets. The subjects trained 3 times per week for 12 weeks. After the training period, the CT group presented a significant increase in the mean 1 repetition maximum (1RM) value in the elbow flexion exercise in the orthostatic position (EFO) (7.2 ± 1.5%) (p < 0.0001) and elbow flexion exercise using the Scott bench (EFSB) (6.3 ± 1.8%) (p < 0.0001). The VT group also showed significant increases in 1RM values in the EFO (6.87 ± 0.8%) (p < 0.0001) and EFSB (6.56 ± 1.4%) (p < 0.0001). The CT group presented a significant increase in the mean maximal voluntary isometric contraction (MVIC) value after the training period (8.2 ± 2.3%) (p < 0.0001). The VT group also showed a significant increase in the mean MVIC value after training (9.1 ± 2.4%) (p < 0.0001). After the training period, both groups presented a significant increase in the mean value of elbow flexor thickness (CT = 5.6 ± 3.5%, VT = 5.1 ± 2.8%) (p = 0.001). The increases in 1RM, MVIC, and muscle thickness were statically similar between groups. Therefore, the addition of LV does not represent an additional stimulus for individuals trained in dynamic maximal strength training. [ABSTRACT FROM AUTHOR]

Spiliopoulou, P, Zaras, N, Methenitis, S, Papadimas, G, Papadopoulos, C, Bogdanis, GC, and Terzis, G. Effect of concurrent power training and high-intensity interval cycling on muscle morphology and performance. J Strength Cond Res 35(9): 2464-2471, 2021--The aim of the study was to examine the effect of performing high-intensity interval cycling on muscle morphology and performance immediately after power training (PT). Twenty healthy female physical education students were assigned into 2 training groups. One group performed PT, and the other group performed the same PT followed by high-intensity interval aerobic training on a cycle ergometer (PTC). Training was performed 3 days per week for 6 weeks. Countermovement jump (CMJ) height and CMJ power, half-squat maximal strength (1 repetition maximum), maximum aerobic power, vastus lateralis muscle fiber composition, and cross-sectional area (CSA) were evaluated before and after the intervention. Countermovement jump height increased after PT (10.1 6 6.6%, p 5 0.002) but not after PTC (25.1 6 10.5%, p 5 0.099), with significant difference between groups (p 5 0.001). Countermovement jump power increased after PT (4.5 6 4.9%, p 5 0.021) but not after PTC (22.4 6 6.4, p 5 0.278), with significant difference between groups (p 5 0.017). One repetition maximum increased similarly in both groups. Muscle fiber composition was not altered after either PT or PTC. Vastus lateralis muscle fiber CSA increased significantly and similarly after both PT (I: 16.9 6 16.2%, p 5 0.035, IIA: 12.7 6 10.9%, p 5 0.008, IIX: 15.5 6 17.1%, p 5 0.021) and PTC (I: 18.0 6 23.7%, p 5 0.033, IIA: 18.2611.4%, p50.001, IIX: 25.5619.6%, p50.003). These results suggest that the addition of high-intensity interval cycling to PT inhibits the anticipated increase in jumping performance induced by PT per se. This inhibition is not explained by changes in muscle fiber type composition or vastus lateralis muscle fiber CSA adaptations. [ABSTRACT FROM AUTHOR]

Background: Cardiac hypertrophy is an important prepathology of, and will ultimately lead to, heart failure. However, the mechanisms underlying pathological cardiac hypertrophy remain largely unknown. This study aims to elucidate the effects and mechanisms of HINT1 (histidine triad nucleotide-binding protein 1) in cardiac hypertrophy and heart failure.Methods: HINT1 was downregulated in human hypertrophic heart samples compared with nonhypertrophic samples by mass spectrometry analysis. Hint1 knockout mice were challenged with transverse aortic constriction surgery. Cardiac-specific overexpression of HINT1 mice by intravenous injection of adeno-associated virus 9 (AAV9)-encoding Hint1 under the cTnT (cardiac troponin T) promoter were subjected to transverse aortic construction. Unbiased transcriptional analyses were used to identify the downstream targets of HINT1. AAV9 bearing shRNA against Hoxa5 (homeobox A5) was administrated to investigate whether the effects of HINT1 on cardiac hypertrophy were HOXA5-dependent. RNA sequencing analysis was performed to recapitulate possible changes in transcriptome profile.Coimmunoprecipitation assays and cellular fractionation analyses were conducted to examine the mechanism by which HINT1 regulates the expression of HOXA5.Results: The reduction of HINT1 expression was observed in the hearts of hypertrophic patients and pressure overloaded-induced hypertrophic mice, respectively. In Hint1-deficient mice, cardiac hypertrophy deteriorated after transverse aortic construction. Conversely, cardiac-specific overexpression of HINT1 alleviated cardiac hypertrophy and dysfunction. Unbiased profiler polymerase chain reaction array showed HOXA5 is 1 target for HINT1, and the cardioprotective role of HINT1 was abolished by HOXA5 knockdown in vivo. Hoxa5 was identified to affect hypertrophy through the TGF-β (transforming growth factor β) signal pathway. Mechanically, HINT1 inhibited PKCβ1 (protein kinase C β type 1) membrane translocation and phosphorylation via direct interaction, attenuating the MEK/ERK/YY1 (mitogen-activated protein kinase/extracellular signal-regulated kinase kinase/yin yang 1) signal pathway, downregulating HOXA5 expression, and eventually attenuating cardiac hypertrophy.Conclusions: HINT1 protects against cardiac hypertrophy through suppressing HOXA5 expression. These findings indicate that HINT1 may be a potential target for therapeutic interventions in cardiac hypertrophy and heart failure. [ABSTRACT FROM AUTHOR]

Introduction: Resistance exercise training (RET) induces muscle hypertrophy that, when combined with co-temporal protein ingestion, is enhanced. However, fewer studies have been conducted when RET is combined with multi-ingredient supplements. Purpose: We aimed to determine the effect of a high-quality multi-ingredient nutritional supplement (SUPP) versus an isonitrogenous (lower protein quality), isoenergetic placebo (PL) on RET-induced gains in lean body mass (LBM), muscle thickness, and muscle cross-sectional area (CSA). We hypothesized that RET-induced gains in LBM and muscle CSA would be greater in SUPP versus PL. Methods: In a double-blind randomized controlled trial, 26 (13 male, 13 female) healthy young adults (mean ± SD, 22 ± 2 yr) were randomized to either the SUPP group (n = 13; 20 g whey protein, 2 g leucine, 2.5 g creatine monohydrate, 300 mg calcium citrate, 1000 IU vitamin D) or the PL group (n = 13; 20 g collagen peptides, 1.4 g alanine, 0.6 g glycine) groups, ingesting their respective supplements twice daily. Measurements were obtained before and after a 10-wk linear progressive RET program. Results: Greater increases in LBM were observed for SUPP versus PL (SUPP: +4.1 ± 1.3 kg, PL: +2.8 ± 1.7 kg, P < 0.05). No additive effect of the supplement could be detected on vastus lateralis muscle CSA, but SUPP did result in increased biceps brachii muscle CSA and thickness (P < 0.05). Conclusions: We conclude that when combined with RET, the consumption of SUPP increased LBM and upper-body CSA and thickness to a greater extent than to that observed in the PL group of healthy young adults. [ABSTRACT FROM AUTHOR]

The aim of the study was to compare skeletal muscle morphological and functional outcomes after low-load resistance training using 2 differing blood flow restriction (BFR) protocols. Recreationally active men and women (n 5 42 [f 5 21], 24.4 6 4.4 years) completed 21 sessions over 7 weeks of load-matched and volume-matched low-load resistance training (30% 1 repetition maximum [1RM]) with either (a) no BFR (CON), (b) continuous BFR (BFR-C, 60% arterial occlusion pressure [AOP]), or (c) intermittent BFR (BFR-I, 60% AOP). Muscle mass was assessed using peripheral quantitative computed tomography before and after training. Muscular strength, endurance, and power were determined before and after training by assessing isokinetic dynamometry, 1RM, and jump performance. Ratings of pain and effort were taken in the first and final training session. An alpha level of p,0.05 was used to determine significance. There were no between-group differences for any of the morphological or functional variables. The muscle cross sectional area (CSA) increased pre-post training (p 5 0.009; CON: 1.6%, BFR-C: 1.1%, BFR-I: 2.2%). Maximal isometric strength increased pre-post training (p, 0.001; CON: 9.6%, BFR-C: 14.3%, BFR-I: 19.3%). Total work performed during an isokinetic endurance task increased pre-post training (p, 0.001, CON: 3.6%, BFR-C: 9.6%, BFR-I: 11.3%). Perceptions of pain (p50.026) and effort (p50.033) during exercise were higher with BFR-C; however, these reduced with training (p 5 0.005–0.034). Overall, these data suggest that when 30% 1RM loads are used with a frequency of 3 times per week, the addition of BFR does not confer superior morphological or functional adaptations in recreationally active individuals. Furthermore, the additional metabolic stress that is proposed to occur with a continuous BFR protocol does not seem to translate into proportionally greater training adaptations. The current findings promote the use of both intermittent BFR and low-load resistance training without BFR as suitable alternative training methods to continuous BFR. These approaches may be practically applicable for those less tolerable to pain and discomfort associated with ischemia during exercise. [ABSTRACT FROM AUTHOR]

This study investigated differences in individual responses to muscle hypertrophy during strength training and detraining. Ten weeks of resistance training was followed by 6 weeks of detraining in men (n = 24). Bilateral leg press (LP) one-repetition maximum (1RM) and maximal electromyography (EMGs) of vastus lateralis (VL) and vastus medialis, maximal voluntary activation (VA), transcranial magnetic stimulation for corticospinal excitability (CE), cross-sectional area of VL (VLCSA), selected serum hormone concentrations were measured before and repeatedly during training and detraining. In the total group, VLCSA increased by 10.7% (p = 0.025) and LP 1RM by 16.3% (p < 0.0001) after training. The subjects were split into 3 groups according to increases in VLCSA: high responders (HR).15% (n = 10), medium responders (MR) 15-4.5% (n = 7), and low responders (LR) < 4.5% (n = 7). Vastus lateralis CSA in HRandMRincreased statistically significantly from pre to posttraining but not in LR. Only HR increased LP 1RM statistically significantly from pre to post. Maximal EMG activity increased 21.3 ± 22.9% from pre- to posttraining for the total group (p = 0.009) and for MR(p < 0.001). No significant changes occurred in VA and CE or serum hormone concentrations. During detraining, HR showed a decrease of 210.5% in VLCSA, whereas MR and LR did not. None of the subgroups decreased maximal strength during the first 3 weeks of detraining, whereas HR showed a slight (by 2.5%) rebound in strength. The present results suggest that strength gains and muscle activation adaptations may take place faster in HR and decrease also faster compared with other subgroups during detraining. [ABSTRACT FROM AUTHOR]

The purpose of the present investigation was to compare the effects of total body (TB) versus split routine (SR) resistance training workouts on maximal strength and muscle hypertrophy in trained men. Twenty-one resistance-trained men were randomly assigned to either a TB (TB: age = 24.1 ± 4.4 years; body mass = 78.7 ± 11.3 kg; body height = 177.0 ± 3.9 cm) or the SR group (SR: age = 24.9 ± 4.2 years; body mass = 79.2 ± 9.5 kg; body height = 175.2 ± 6.0 cm). Both groups performed a 10-week resistance training program. Isokinetic bench press at 75 and 25 cm·s-1 (ISOK75 and ISOK25, respectively), isometric bench press (ISOBP), isometric squat (ISOSQ), and one repetition maximum BP and SQ assessments were performed before and after training. Muscle thickness of the pectoralis major (PECMT), superior part of trapezius (TRAPMT), and vastus lateralis (VLMT) muscles was also evaluated at the same timepoints using ultrasonography. Improvements were observed in both groups for all strength assessments and muscle thicknesses. Only changes in ISOK25 were significantly (p = 0.015) greater in TB than in SR, while significantly greater (p = 0.037) changes in VLMT were detected in SR compared with TB. Results indicated that a TB training paradigm may be more appropriate for maximal strength improvement, while an SR training protocol may be more optimal in stimulating muscle growth in experienced, resistance-trained men. [ABSTRACT FROM AUTHOR]

Supplemental digital content is available in the text. Purpose: This study aimed to analyze the effect of resistance training (RT) performed until volitional failure with low, moderate, and high loads on muscle hypertrophy and muscle strength in healthy adults and to assess the possible participant-, design-, and training-related covariates that may affect the adaptations. Methods: Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, MEDLINE, CINAHL, EMBASE, SPORTDiscus, and Web of Science databases were searched. Including only studies that performed sets to volitional failure, the effects of low- (>15 repetitions maximum (RM)), moderate- (9–15 RM), and high-load (≤8 RM) RTs were examined in healthy adults. Network meta-analysis was undertaken to calculate the standardized mean difference (SMD) between RT loads in overall and subgroup analyses involving studies deemed of high quality. Associations between participant-, design-, and training-related covariates with SMD were assessed by univariate and multivariate network meta-regression analyses. Results: Twenty-eight studies involving 747 healthy adults were included. Although no differences in muscle hypertrophy between RT loads were found in overall (P = 0.113–0.469) or subgroup analysis (P = 0.871–0.995), greater effects were observed in untrained participants (P = 0.033) and participants with some training background who undertook more RT sessions (P = 0.031–0.045). Muscle strength improvement was superior for both high-load and moderate-load compared with low-load RT in overall and subgroup analysis (SMD, 0.60–0.63 and 0.34–0.35, respectively; P < 0.001–0.003), with a nonsignificant but superior effect for high compared with moderate load (SMD, 0.26–0.28, P = 0.068). Conclusions: Although muscle hypertrophy improvements seem to be load independent, increases in muscle strength are superior in high-load RT programs. Untrained participants exhibit greater muscle hypertrophy, whereas undertaking more RT sessions provides superior gains in those with previous training experience. [ABSTRACT FROM AUTHOR]

Study Design: Experimental animal study.Objective: The aim of this study was to clarify chronological effects of mechanical stress on ligamentum flavum (LF) using a long-term fusion rabbit model.Summary Of Background Data: LF hypertrophy is a major pathology of lumbar spinal stenosis (LSS), but its mechanism remains unclear. We previously demonstrated mechanical-stress-induced LF hypertrophy with a rabbit model. However, we only investigated LFs at a single time point in the short-term; the effects of long-term mechanical stress have not been elucidated.Methods: Eighteen-week-old male New Zealand White rabbits were randomly divided into two groups: the mechanical stress group underwent L2-3 and L4-5 posterolateral fusion and resection of the L3-4 supraspinal muscle, whereas the control group underwent only surgical exposure. Rabbits were sacrificed 16 and 52 weeks after the procedure. Axial specimens of LFs at L3-4 were evaluated histologically. Immunohistochemistry for alpha-smooth muscle actin (α-SMA) was performed to assess the numbers of vessels and myofibroblasts.Results: In the mechanical stress group, LFs at the L3-4 level exhibited hypertrophy with elastic fiber disruption and cartilage matrix production at 16 and 52 weeks. A trend test indicated that mechanical stress induced LF hypertrophy, elastic fiber disruption, and cartilage matrix production in a time-dependent manner, with the lowest levels before treatment and the highest at 52 weeks. Immunostaining for α-SMA showed similar numbers of vessels in both groups, whereas the percentage of myofibroblasts was significantly larger at 16 and 52 weeks in the mechanical stress group than in the control group.Conclusion: We demonstrated that long-term mechanical stress caused LF hypertrophy with progressive elastic fiber disruption and cartilage matrix production accompanied by enhanced myofibroblasts. In addition, the reported rabbit model could be extended to elucidate the mechanism of LF hypertrophy and to develop new therapeutic strategies for LSS by preventing LF hypertrophy.Level of Evidence: SSSSS. [ABSTRACT FROM AUTHOR]

The aim of this review was to summarize the evidence from longitudinal studies assessing the effects induced by resistance training (RT) performed to failure (RTF) vs. not to failure (RTNF) on muscle strength, hypertrophy, and power output in adults. Three electronic databases were searched using terms related to RTF and RTNF. Studies were eligible if they met the following criteria: randomized and nonrandomized studies comparing the effects of RTF vs. RTNF on muscle hypertrophy, maximal strength, and muscle power in adults, and RT intervention >6 weeks. Results were presented as standardized mean differences (SMDs) between treatments with 95% confidence intervals, and calculations were performed using random effects models. Significance was accepted when p < 0.05. Thirteen studies were included in this review. No difference was found between RTF and RTNF on maximal strength in overall analysis (SMD: -0.08; p = 0.642), but greater strength increase was observed in RTNF considering nonequalized volumes (SMD: -0.34; p = 0.048). Resistance training performed to failure showed a greater increase in muscle hypertrophy than RTNF (SMD: 0.75; p = 0.005), whereas no difference was observed considering equalized RT volumes. No difference was found between RTF and RTNF on muscle power considering overall analysis (SMD: -0.20; p = 0.239), whereas greater improvement was observed in RTNF considering nonequalized RT volumes (SMD: -0.61; p = 0.025). Resistance training not to failure may induce comparable or even greater improvements in maximal dynamic strength and power output, whereas no difference between RTF vs. RTNF is observed on muscle hypertrophy, considering equalized RT volumes. [ABSTRACT FROM AUTHOR]