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Circulation Jan 2024Hypertrophic cardiomyopathy (HCM) is characterized by unexplained left ventricular hypertrophy and is classically caused by pathogenic or likely pathogenic variants... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Hypertrophic cardiomyopathy (HCM) is characterized by unexplained left ventricular hypertrophy and is classically caused by pathogenic or likely pathogenic variants (P/LP) in genes encoding sarcomere proteins. Not all subclinical variant carriers will manifest clinically overt disease because penetrance (proportion of sarcomere or sarcomere-related P/LP variant carriers who develop disease) is variable, age dependent, and not reliably predicted.
METHODS
A systematic search of the literature was performed. We used random-effects generalized linear mixed model meta-analyses to contrast the cross-sectional prevalence and penetrance of sarcomere or sarcomere-related genes in 2 different contexts: clinically-based studies on patients and families with HCM versus population or community-based studies. Longitudinal family/clinical studies were additionally analyzed to investigate the rate of phenotypic conversion from subclinical to overt HCM during follow-up.
RESULTS
In total, 455 full-text manuscripts and articles were assessed. In family/clinical studies, the prevalence of sarcomere variants in patients diagnosed with HCM was 34%. The penetrance across all genes in nonproband relatives carrying P/LP variants identified during cascade screening was 57% (95% CI, 52%-63%), and the mean age at HCM diagnosis was 38 years (95% CI, 36%-40%). Penetrance varied from ≈32% for (myosin light chain 3) to ≈55% for (myosin-binding protein C3), ≈60% for (troponin T2) and (troponin I3), and ≈65% for (myosin heavy chain 7). Population-based genetic studies demonstrate that P/LP sarcomere variants are present in the background population but at a low prevalence of <1%. The penetrance of HCM in incidentally identified P/LP variant carriers was also substantially lower at ≈11%, ranging from 0% in Atherosclerosis Risk in Communities to 18% in UK Biobank. In longitudinal family studies, the pooled phenotypic conversion across all genes was 15% over an average of ≈8 years of follow-up, starting from a mean of ≈16 years of age. However, short-term gene-specific phenotypic conversion varied between ≈12% for and ≈23% for .
CONCLUSIONS
The penetrance of P/LP variants is highly variable and influenced by currently undefined and context-dependent genetic and environmental factors. Additional longitudinal studies are needed to improve our understanding of true lifetime penetrance in families and in the community and to identify drivers of the transition from subclinical to overt HCM.
Topics: Humans; Adult; Penetrance; Mutation; Cross-Sectional Studies; Pedigree; Cardiomyopathy, Hypertrophic; Troponin T
PubMed: 37929589
DOI: 10.1161/CIRCULATIONAHA.123.065987 -
Physiological Reports Sep 2020This study aimed to review the effects of ladder-based resistance training (LRT) on muscle hypertrophy and strength in rodents through a systematic review with... (Meta-Analysis)
Meta-Analysis
This study aimed to review the effects of ladder-based resistance training (LRT) on muscle hypertrophy and strength in rodents through a systematic review with meta-analysis. We systematically searched PubMed/Medline, SportDiscuss, Scopus, Google Scholar, Science Direct, and Scielo database on May 18, 2020. Thirty-four studies were included measuring total (mCSA) or mean muscle fibers cross-sectional area (fCSA) or maximum load-carrying capacity (MLCC) or muscle mass (MM). About the main results, LRT provides sufficient mechanical stimulation to increase mCSA and fCSA. Meta-analysis showed a significant overall effect on the fCSA (SMD 1.89, 95% CI [1.18, 2.61], p < .00001, I = 85%); however, subgroup analysis showed that some muscle types might not be hypertrophied through the LRT. Meta-analysis showed a significant training effect on the MM (SMD 0.92, 95% CI [0.52, 1.32], p < .00001, I = 72%). Sub-group analysis revealed that soleus (SMD 1.32, 95% CI [0.11, 2.54], p = .03, I = 86%) and FHL (SMD 1.92, 95% CI [1.00, 2.85], p < .0001, I = 71%) presented significant training effects, despite moderate heterogeneity levels (I = 72%). MLCC increases considerably after a period of LRT, regardless of its duration and the characteristics of the protocols (SMD 12.37, 95% CI [9.36, 15.37], p < .00001, I = 90%). Through these results, we reach the following conclusions: (a) LRT is efficient to induce muscle hypertrophy, although this effect varies between different types of skeletal muscles, and; (b) the ability of rodents to carry load increases regardless of the type and duration of the protocol used.
Topics: Animals; Hypertrophy; Mice; Muscle Strength; Muscle, Skeletal; Physical Conditioning, Animal; Rats
PubMed: 32889774
DOI: 10.14814/phy2.14502 -
Journal of Cachexia, Sarcopenia and... Oct 2022One aspect of skeletal muscle memory is the ability of a previously trained muscle to hypertrophy more rapidly following a period of detraining. Although the molecular... (Meta-Analysis)
Meta-Analysis Review
One aspect of skeletal muscle memory is the ability of a previously trained muscle to hypertrophy more rapidly following a period of detraining. Although the molecular basis of muscle memory remains to be fully elucidated, one potential mechanism thought to mediate muscle memory is the permanent retention of myonuclei acquired during the initial phase of hypertrophic growth. However, myonuclear permanence is debated and would benefit from a meta-analysis to clarify the current state of the field for this important aspect of skeletal muscle plasticity. The objective of this study was to perform a meta-analysis to assess the permanence of myonuclei associated with changes in physical activity and ageing. When available, the abundance of satellite cells (SCs) was also considered given their potential influence on changes in myonuclear abundance. One hundred forty-seven peer-reviewed articles were identified for inclusion across five separate meta-analyses; (1-2) human and rodent studies assessed muscle response to hypertrophy; (3-4) human and rodent studies assessed muscle response to atrophy; and (5) human studies assessed muscle response with ageing. Skeletal muscle hypertrophy was associated with higher myonuclear content that was retained in rodents, but not humans, with atrophy (SMD = -0.60, 95% CI -1.71 to 0.51, P = 0.29, and MD = 83.46, 95% CI -649.41 to 816.32, P = 0.82; respectively). Myonuclear and SC content were both lower following atrophy in humans (MD = -11, 95% CI -0.19 to -0.03, P = 0.005, and SMD = -0.49, 95% CI -0.77 to -0.22, P = 0.0005; respectively), although the response in rodents was affected by the type of muscle under consideration and the mode of atrophy. Whereas rodent myonuclei were found to be more permanent regardless of the mode of atrophy, atrophy of ≥30% was associated with a reduction in myonuclear content (SMD = -1.02, 95% CI -1.53 to -0.51, P = 0.0001). In humans, sarcopenia was accompanied by a lower myonuclear and SC content (MD = 0.47, 95% CI 0.09 to 0.85, P = 0.02, and SMD = 0.78, 95% CI 0.37-1.19, P = 0.0002; respectively). The major finding from the present meta-analysis is that myonuclei are not permanent but are lost during periods of atrophy and with ageing. These findings do not support the concept of skeletal muscle memory based on the permanence of myonuclei and suggest other mechanisms, such as epigenetics, may have a more important role in mediating this aspect of skeletal muscle plasticity.
Topics: Animals; Atrophy; Humans; Hypertrophy; Muscle Fibers, Skeletal; Muscle, Skeletal; Sarcopenia
PubMed: 35961635
DOI: 10.1002/jcsm.13043 -
Journal of Clinical Medicine Feb 2024Sarcopenia is a significant health concern primarily affecting old adult individuals, characterized by age-related muscle loss, and decreased strength, power, and... (Review)
Review
Sarcopenia is a significant health concern primarily affecting old adult individuals, characterized by age-related muscle loss, and decreased strength, power, and endurance. It has profound negative effects on overall health and quality of life, including reduced independence, mobility, and daily activity performance, osteoporosis, increased fall and fracture risks, metabolic issues, and chronic diseases like diabetes and cardiovascular conditions. Preventive strategies typically involve a combination of proper nutrition and regular physical activity. Among strength training exercises, high-intensity interval training (HIIT) stands out as the most effective approach for improving muscle function in older adults with sarcopenia. The current review identifies and summarizes the studies that have examined the effects of HIIT on muscle strength in older adults as an element of the prevention and treatment of sarcopenia. A systematic search using several computerized databases, namely, MEDLINE/PubMed, Scopus, SPORTDiscus, and Web of Science, was performed on 12 January 2023, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 224 studies were initially retrieved. A total of five studies met the selection criteria. HIIT training shows improvements in body composition and functional and cardiorespiratory capacity, has benefits on muscle strength, increases muscle quality and architecture, and is associated with muscle hypertrophy in healthy older adults. Nonetheless, given the shortcomings affecting primary research in terms of the limited number of studies and the high risk of bias, further research is warranted.
PubMed: 38592165
DOI: 10.3390/jcm13051299 -
American Journal of Translational... 2021MicroRNAs (miRNAs) are small non-coding RNAs that participate in gene expression regulation. It has been observed that circulating levels of miRNAs may fluctuate during... (Review)
Review
MicroRNAs (miRNAs) are small non-coding RNAs that participate in gene expression regulation. It has been observed that circulating levels of miRNAs may fluctuate during exercise, showing numerous cardiac biological and physiological effects such as structural and functional adaptations. We aimed to provide an overview of the currently available information concerning the role of circulating miRNAs in cardiovascular adaptations in response to acute and/or chronic exercise training. Relevant studies published were searched in three databases: PubMed, Web of Science and Scopus. A combination of the following keywords was used: ("microRNA" OR "miRNA" OR "miR" AND "exercise" OR "training" OR "physical activity") AND "(heart hypertrophy" OR "cardiac remodeling" OR "cardiac muscle mass" OR "cardiac hypertrophy"). Only experimental studies, written in English and conducted in healthy individuals were included. Five articles met the inclusion criteria and were finally included in this systematic review after reviewing both title, abstract and full-text. A total of thirty-six circulating cardiac-related miRNAs were analyzed, but only five of them (miR-1, miR-133a, miR-146a, miR-206 and miR-221) were directly associated with cardiac adaptations parameters, while two of them (miR-1 and miR-133a) were related to cardiac hypertrophy. Most of them were upregulated immediately after a marathon and returned to basal levels at longer times. Therefore, we conclude that, although evidence is still limited, and long-term studies are needed to obtain more robust evidence, exercise is more likely to affect circulating cardiac-related miRNAs levels.
PubMed: 35035676
DOI: No ID Found -
Annals of Plastic Surgery Feb 2023Energy-based treatments include ultrasound, lasers, cryolipolysis, and radiofrequency. The most recent energy treatment for noninvasive body contouring is...
BACKGROUND
Energy-based treatments include ultrasound, lasers, cryolipolysis, and radiofrequency. The most recent energy treatment for noninvasive body contouring is electromagnetic treatments-a hot topic in plastic surgery today. A systematic review to assess efficacy and safety has not been published.
METHODS
An electronic search was performed using PubMed to identify the literature describing electromagnetic treatments. Measurements from imaging studies were tabulated and compared.
RESULTS
Fourteen clinical studies were evaluated. Two studies included simultaneous radiofrequency treatments. In 11 studies, the Emsculpt device was used; in 2 studies, the Emsculpt-Neo device was used. One study included a sham group of patients. The usual protocol was 4 treatments given over a 2-week period. No complications were reported. Eight studies included abdominal measurement data obtained using magnetic resonance imaging, computed tomography, or ultrasound. Photographic results were typically modest. Photographs showing more dramatic results also showed unexplained reductions in untreated areas.Measurement variances were high. The mean reduction in fat thickness was 5.5 mm. The mean increment in muscle thickness was 2.2 mm. The mean decrease in muscle separation was 2.9 mm (P = 0.19). Early posttreatment ultrasound images in 1 study showed an echolucent muscle layer, compared with a more echodense layer at the baseline, consistent with tissue swelling after exercise. Almost all studies were authored by medical advisors for the device manufacturer.
DISCUSSION
Measurement data show small reductions in fat thickness, occurring almost immediately after the treatments. Adipocyte removal without tissue swelling would be unique among energy-based treatments. Similarly, muscle hypertrophy is not known to occur acutely after exercise; muscle swelling likely accounts for an early increment in muscle thickness. Any improvement in the diastasis recti is likely fictitious.
CONCLUSIONS
Electromagnetic treatments, either administered alone or in combination with radiofrequency, are safe. However, the evidence for efficacy is tenuous. Measured treatment effects are very small (<5 mm). Conflict of interest and publication bias are major factors in studies evaluating energy-based alternatives. The evidence-based physician may not be satisfied that an equivocal treatment benefit justifies the time and expense for patients.
Topics: Humans; Body Contouring; Follow-Up Studies; Patient Satisfaction; Lipectomy; Electromagnetic Phenomena
PubMed: 36688862
DOI: 10.1097/SAP.0000000000003387 -
Sports Medicine - Open Apr 2024Increases in maximal strength and muscle volume represent central aims of training interventions. Recent research suggested that the chronic application of stretch may...
BACKGROUND
Increases in maximal strength and muscle volume represent central aims of training interventions. Recent research suggested that the chronic application of stretch may be effective in inducing hypertrophy. The present systematic review therefore aimed to syntheisize the evidence on changes of strength and muscle volume following chronic static stretching.
METHODS
Three data bases were sceened to conduct a systematic review with meta-analysis. Studies using randomized, controlled trials with longitudinal (≥ 2 weeks) design, investigating strength and muscle volume following static stretching in humans, were included. Study quality was rated by two examiners using the PEDro scale.
RESULTS
A total of 42 studies with 1318 cumulative participants were identified. Meta-analyses using robust variance estimation showed small stretch-mediated maximal strength increases (d = 0.30 p < 0.001) with stretching duration and intervention time as significant moderators. Including all studies, stretching induced small magnitude, but significant hypertrophy effects (d = 0.20). Longer stretching durations and intervention periods as well as higher training frequencies revealed small (d = 0.26-0.28), but significant effects (p < 0.001-0.005), while lower dosage did not reach the level of significance (p = 0.13-0.39).
CONCLUSIONS
While of minor effectiveness, chronic static stretching represents a possible alternative to resistance training when aiming to improve strength and increase muscle size. As a dose-response relationship may exist, higher stretch durations and frequencies as well as long program durations should be further elaborated.
PubMed: 38637473
DOI: 10.1186/s40798-024-00706-8 -
Journal of Functional Morphology and... Apr 2023Emerging evidence indicates that the use of low-load resistance training in combination with blood flow restriction (LL-BFR) can be an effective method to elicit... (Review)
Review
Emerging evidence indicates that the use of low-load resistance training in combination with blood flow restriction (LL-BFR) can be an effective method to elicit increases in muscle size, with most research showing similar whole muscle development of the extremities compared to high-load (HL) training. It is conceivable that properties unique to LL-BFR such as greater ischemia, reperfusion, and metabolite accumulation may enhance the stress on type I fibers during training compared to the use of LLs without occlusion. Accordingly, the purpose of this paper was to systematically review the relevant literature on the fiber-type-specific response to LL-BFR and provide insights into future directions for research. A total of 11 studies met inclusion criteria. Results of the review suggest that the magnitude of type I fiber hypertrophy is at least as great, and sometimes greater, than type II hypertrophy when performing LL-BFR. This finding is in contrast to HL training, where the magnitude of type II fiber hypertrophy tends to be substantially greater than that of type I myofibers. However, limited data directly compare training with LL-BFR to nonoccluded LL or HL conditions, thus precluding the ability to draw strong inferences as to whether the absolute magnitude of type I hypertrophy is indeed greater in LL-BFR vs. traditional HL training. Moreover, it remains unclear as to whether combining LL-BFR with traditional HL training may enhance whole muscle hypertrophy via greater increases in type I myofiber cross-sectional area.
PubMed: 37218848
DOI: 10.3390/jfmk8020051 -
Journal of Sport and Health Science Mar 2022One of the most life-threatening comorbidities in elderly cancer patients is cancer cachexia, which is characterized by the ongoing loss of skeletal muscular strength... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
One of the most life-threatening comorbidities in elderly cancer patients is cancer cachexia, which is characterized by the ongoing loss of skeletal muscular strength and mass and is also associated with aging. There is a lack of recommendations for optimal resistance training (RT) for those patients. The purpose of this study was to systematically review and quantify the effects of RT on muscular strength and hypertrophy in elderly cancer patients.
METHODS
Five electronic databases were searched (until January 2020) for studies that met the following criteria: (i) cancer patients aged ≥60 years; (ii) structured and supervised RT intervention for ≥6 weeks; and (iii) measured muscular strength and/or hypertrophy.
RESULTS
Thirteen studies (717 participants, average age = 66 years) met the inclusion criteria. RT significantly increased muscular strength (mean effect size = 0.87, 95% confidence interval (95%CI): 0.43-1.32, p < 0.001) and did not significantly induce muscle hypertrophy (mean effect size = 0.09, 95%CI: -0.14 to 0.31, p = 0.45). In subgroup analyses for muscle strength, higher weekly frequency was significantly associated with larger effect size. Egger's test showed no significant publication bias for the 2 outcomes.
CONCLUSION
The results suggest that RT improves muscular strength but does not significantly induce muscle hypertrophy in elderly cancer patients.
Topics: Aged; Humans; Hypertrophy; Middle Aged; Muscle Strength; Muscle, Skeletal; Neoplasms; Resistance Training
PubMed: 33592324
DOI: 10.1016/j.jshs.2021.02.002 -
Journal of Clinical Medicine Dec 2022There is clinical interest in determining the effects of low-load blood flow restriction (LL-BFR) resistance training on muscle strength and hypertrophy compared with... (Review)
Review
Effects of Low-Load Blood Flow Restriction Resistance Training on Muscle Strength and Hypertrophy Compared with Traditional Resistance Training in Healthy Adults Older Than 60 Years: Systematic Review and Meta-Analysis.
BACKGROUND
There is clinical interest in determining the effects of low-load blood flow restriction (LL-BFR) resistance training on muscle strength and hypertrophy compared with traditional high- and low-load (HL and LL) resistance training in healthy older adults and the influence of LL-BFR training cuff-pressure on these outcomes.
METHODS
A search was performed on the MEDLINE, PEDro, CINHAL, Web of Science, Science Direct, Scopus, and CENTRAL databases.
RESULTS
The analysis included 14 studies. HL resistance training produces a small increase in muscle strength (eight studies; SMD, -0.23 [-0.41; -0.05]) but not in muscle hypertrophy (six studies; (SMD, 0.08 [-0.22; 0.38]) when compared with LL-BFR resistance training. Compared with traditional LL resistance training, LL-BFR resistance training produces small-moderate increases in muscle strength (seven studies; SMD, 0.44 [0.28; 0.60]) and hypertrophy (two studies; SMD, 0.51 [0.06; 0.96]). There were greater improvements in muscle strength when higher cuff pressures were applied versus traditional LL resistance training but not versus HL resistance training.
CONCLUSIONS
LL-BFR resistance training results in lower muscle strength gains than HL resistance training and greater than traditional LL resistance training in healthy adults older than 60 years. LL-BFR resistance training promotes a similar muscle hypertrophy to HL resistance training but is greater than that of traditional LL resistance training. Applying cuff pressures above the limb occlusion pressure could enhance the increases in muscle strength compared with traditional LL resistance training.
PubMed: 36556004
DOI: 10.3390/jcm11247389