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Nutrients Mar 2018The increasing recognition of sarcopenia, the age-related loss of skeletal muscle mass and function (muscle strength and physical performance), as a determinant of poor... (Review)
Review
The increasing recognition of sarcopenia, the age-related loss of skeletal muscle mass and function (muscle strength and physical performance), as a determinant of poor health in older age, has emphasized the importance of understanding more about its aetiology to inform strategies both for preventing and treating this condition. There is growing interest in the effects of modifiable factors such as diet; some nutrients have been studied but less is known about the influence of overall diet quality on sarcopenia. We conducted a systematic review of the literature examining the relationship between diet quality and the individual components of sarcopenia, i.e., muscle mass, muscle strength and physical performance, and the overall risk of sarcopenia, among older adults. We identified 23 studies that met review inclusion criteria. The studies were diverse in terms of the design, setting, measures of diet quality, and outcome measurements. A small body of evidence suggested a relationship between "healthier" diets and better muscle mass outcomes. There was limited and inconsistent evidence for a link between "healthier" diets and lower risk of declines in muscle strength. There was strong and consistent observational evidence for a link between "healthier" diets and lower risk of declines in physical performance. There was a small body of cross-sectional evidence showing an association between "healthier" diets and lower risk of sarcopenia. This review provides observational evidence to support the benefits of diets of higher quality for physical performance among older adults. Findings for the other outcomes considered suggest some benefits, although the evidence is either limited in its extent (sarcopenia) or inconsistent/weak in its nature (muscle mass, muscle strength). Further studies are needed to assess the potential of whole-diet interventions for the prevention and management of sarcopenia.
Topics: Age Factors; Aged; Aging; Diet; Diet, Healthy; Female; Humans; Male; Middle Aged; Muscle Strength; Muscle, Skeletal; Nutritional Status; Nutritive Value; Protective Factors; Risk Factors; Risk Reduction Behavior; Sarcopenia
PubMed: 29510572
DOI: 10.3390/nu10030308 -
Sports Medicine (Auckland, N.Z.) May 2017Resistance training is an integral component of physical preparation for athletes. A growing body of evidence indicates that eccentric strength training methods induce... (Review)
Review
BACKGROUND
Resistance training is an integral component of physical preparation for athletes. A growing body of evidence indicates that eccentric strength training methods induce novel stimuli for neuromuscular adaptations.
OBJECTIVE
The purpose of this systematic review was to determine the effects of eccentric training in comparison to concentric-only or traditional (i.e. constrained by concentric strength) resistance training.
METHODS
Searches were performed using the electronic databases MEDLINE via EBSCO, PubMed and SPORTDiscus via EBSCO. Full journal articles investigating the long-term (≥4 weeks) effects of eccentric training in healthy (absence of injury or illness during the 4 weeks preceding the training intervention), adult (17-35 years), human participants were selected for the systematic review. A total of 40 studies conformed to these criteria.
RESULTS
Eccentric training elicits greater improvements in muscle strength, although in a largely mode-specific manner. Superior enhancements in power and stretch-shortening cycle (SSC) function have also been reported. Eccentric training is at least as effective as other modalities in increasing muscle cross-sectional area (CSA), while the pattern of hypertrophy appears nuanced and increased CSA may occur longitudinally within muscle (i.e. the addition of sarcomeres in series). There appears to be a preferential increase in the size of type II muscle fibres and the potential to exert a unique effect upon fibre type transitions. Qualitative and quantitative changes in tendon tissue that may be related to the magnitude of strain imposed have also been reported with eccentric training.
CONCLUSIONS
Eccentric training is a potent stimulus for enhancements in muscle mechanical function, and muscle-tendon unit (MTU) morphological and architectural adaptations. The inclusion of eccentric loads not constrained by concentric strength appears to be superior to traditional resistance training in improving variables associated with strength, power and speed performance.
Topics: Adaptation, Physiological; Adolescent; Adult; Exercise; Humans; Muscle Contraction; Muscle Fibers, Skeletal; Muscle Strength; Muscle, Skeletal; Physical Education and Training; Resistance Training
PubMed: 27647157
DOI: 10.1007/s40279-016-0628-4 -
Sports Medicine (Auckland, N.Z.) Oct 2022Whole muscle hypertrophy does not appear to be negatively affected by concurrent aerobic and strength training compared to strength training alone. However, there are... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Whole muscle hypertrophy does not appear to be negatively affected by concurrent aerobic and strength training compared to strength training alone. However, there are contradictions in the literature regarding the effects of concurrent training on hypertrophy at the myofiber level.
OBJECTIVE
The current study aimed to systematically examine the extent to which concurrent aerobic and strength training, compared with strength training alone, influences type I and type II muscle fiber size adaptations. We also conducted subgroup analyses to examine the effects of the type of aerobic training, training modality, exercise order, training frequency, age, and training status.
DESIGN
A systematic literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [PROSPERO: CRD42020203777]. The registered protocol was modified to include only muscle fiber hypertrophy as an outcome.
DATA SOURCES
PubMed/MEDLINE, ISI Web of Science, Embase, CINAHL, SPORTDiscus, and Scopus were systematically searched on 12 August, 2020, and updated on 15 March, 2021.
ELIGIBILITY CRITERIA
Population: healthy adults of any sex and age; intervention: supervised, concurrent aerobic and strength training of at least 4 weeks; comparison: identical strength training prescription, with no aerobic training; and outcome: muscle fiber hypertrophy.
RESULTS
A total of 15 studies were included. The estimated standardized mean difference based on the random-effects model was - 0.23 (95% confidence interval [CI] - 0.46 to - 0.00, p = 0.050) for overall muscle fiber hypertrophy. The standardized mean differences were - 0.34 (95% CI - 0.72 to 0.04, p = 0.078) and - 0.13 (95% CI - 0.39 to 0.12, p = 0.315) for type I and type II fiber hypertrophy, respectively. A negative effect of concurrent training was observed for type I fibers when aerobic training was performed by running but not cycling (standardized mean difference - 0.81, 95% CI - 1.26 to - 0.36). None of the other subgroup analyses (i.e., based on concurrent training frequency, training status, training modality, and training order of same-session training) revealed any differences between groups.
CONCLUSIONS
In contrast to previous findings on whole muscle hypertrophy, the present results suggest that concurrent aerobic and strength training may have a small negative effect on fiber hypertrophy compared with strength training alone. Preliminary evidence suggests that this interference effect may be more pronounced when aerobic training is performed by running compared with cycling, at least for type I fibers.
Topics: Adult; Humans; Hypertrophy; Infant; Infant, Newborn; Muscle Fibers, Skeletal; Muscle Strength; Muscle, Skeletal; Resistance Training
PubMed: 35476184
DOI: 10.1007/s40279-022-01688-x -
BMC Musculoskeletal Disorders Sep 2020Injuries to the hamstring muscles are among the most common in sports and account for significant time loss. Despite being so common, the injury mechanism of hamstring...
BACKGROUND
Injuries to the hamstring muscles are among the most common in sports and account for significant time loss. Despite being so common, the injury mechanism of hamstring injuries remains to be determined.
PURPOSE
To investigate the hamstring injury mechanism by conducting a systematic review.
STUDY DESIGN
A systematic review following the PRISMA statement.
METHODS
A systematic search was conducted using PubMed, EMBASE and the Cochrane Library. Studies 1) written in English and 2) deciding on the mechanism of hamstring injury were eligible for inclusion. Literature reviews, systematic reviews, meta-analyses, conference abstracts, book chapters and editorials were excluded, as well as studies where the full text could not be obtained.
RESULTS
Twenty-six of 2372 screened original studies were included and stratified to the mechanism or methods used to determine hamstring injury: stretch-related injuries, kinematic analysis, electromyography-based kinematic analysis and strength-related injuries. All studies that reported the stretch-type injury mechanism concluded that injury occurs due to extensive hip flexion with a hyperextended knee. The vast majority of studies on injuries during running proposed that these injuries occur during the late swing phase of the running gait cycle.
CONCLUSION
A stretch-type injury to the hamstrings is caused by extensive hip flexion with an extended knee. Hamstring injuries during sprinting are most likely to occur due to excessive muscle strain caused by eccentric contraction during the late swing phase of the running gait cycle.
LEVEL OF EVIDENCE
Level IV.
Topics: Athletic Injuries; Biomechanical Phenomena; Hamstring Muscles; Humans; Knee; Knee Joint; Muscle, Skeletal
PubMed: 32993700
DOI: 10.1186/s12891-020-03658-8 -
Journal of Science and Medicine in Sport Sep 2018Inadequate sleep (e.g., an insufficient duration of sleep per night) can reduce physical performance and has been linked to adverse metabolic health outcomes. Resistance... (Review)
Review
OBJECTIVES
Inadequate sleep (e.g., an insufficient duration of sleep per night) can reduce physical performance and has been linked to adverse metabolic health outcomes. Resistance exercise is an effective means to maintain and improve physical capacity and metabolic health, however, the outcomes for populations who may perform resistance exercise during periods of inadequate sleep are unknown. The primary aim of this systematic review was to evaluate the effect of sleep deprivation (i.e. no sleep) and sleep restriction (i.e. a reduced sleep duration) on resistance exercise performance. A secondary aim was to explore the effects on hormonal indicators or markers of muscle protein metabolism.
METHODS
A systematic search of five electronic databases was conducted with terms related to three combined concepts: inadequate sleep; resistance exercise; performance and physiological outcomes. Study quality and biases were assessed using the Effective Public Health Practice Project quality assessment tool.
RESULTS
Seventeen studies met the inclusion criteria and were rated as 'moderate' or 'weak' for global quality. Sleep deprivation had little effect on muscle strength during resistance exercise. In contrast, consecutive nights of sleep restriction could reduce the force output of multi-joint, but not single-joint movements. Results were conflicting regarding hormonal responses to resistance training.
CONCLUSION
Inadequate sleep impairs maximal muscle strength in compound movements when performed without specific interventions designed to increase motivation. Strategies to assist groups facing inadequate sleep to effectively perform resistance training may include supplementing their motivation by training in groups or ingesting caffeine; or training prior to prolonged periods of wakefulness.
Topics: Humans; Muscle Strength; Muscle, Skeletal; Resistance Training; Sleep; Sleep Deprivation
PubMed: 29422383
DOI: 10.1016/j.jsams.2018.01.012 -
Redox Report : Communications in Free... Dec 2018p53 is a tumor suppressor protein involved in regulating a wide array of signaling pathways. The role of p53 in the cell is determined by the type of imposed oxidative... (Review)
Review
BACKGROUND
p53 is a tumor suppressor protein involved in regulating a wide array of signaling pathways. The role of p53 in the cell is determined by the type of imposed oxidative stress, its intensity and duration. The last decade of research has unravelled a dual nature in the function of p53 in mediating the oxidative stress burden. However, this is dependent on the specific properties of the applied stress and thus requires further analysis.
METHODS
A systematic review was performed following an electronic search of Pubmed, Google Scholar, and ScienceDirect databases. Articles published in the English language between January 1, 1990 and March 1, 2017 were identified and isolated based on the analysis of p53 in skeletal muscle in both animal and cell culture models.
RESULTS
Literature was categorized according to the modality of imposed oxidative stress including exercise, diet modification, exogenous oxidizing agents, tissue manipulation, irradiation, and hypoxia. With low to moderate levels of oxidative stress, p53 is involved in activating pathways that increase time for cell repair, such as cell cycle arrest and autophagy, to enhance cell survival. However, with greater levels of stress intensity and duration, such as with irradiation, hypoxia, and oxidizing agents, the role of p53 switches to facilitate increased cellular stress levels by initiating DNA fragmentation to induce apoptosis, thereby preventing aberrant cell proliferation.
CONCLUSION
Current evidence confirms that p53 acts as a threshold regulator of cellular homeostasis. Therefore, within each modality, the intensity and duration are parameters of the oxidative stressor that must be analyzed to determine the role p53 plays in regulating signaling pathways to maintain cellular health and function in skeletal muscle.
ABBREVIATIONS
Acadl: acyl-CoA dehydrogenase, long chain; Acadm: acyl-CoA dehydrogenase, C-4 to C-12 straight chain; AIF: apoptosis-inducing factor; Akt: protein kinase B (PKB); AMPK: AMP-activated protein kinase; ATF-4: activating transcription factor 4; ATM: ATM serine/threonine kinase; Bax: BCL2 associated X, apoptosis regulator; Bcl-2: B cell Leukemia/Lymphoma 2 apoptosis regulator; Bhlhe40: basic helix-loop-helix family member e40; BH3: Borane; Bim: bcl-2 interacting mediator of cell death; Bok: Bcl-2 related ovarian killer; COX-IV: cytochrome c oxidase IV; cGMP: Cyclic guanosine monophosphate; c-myc: proto-oncogene protein; Cpt1b: carnitine palmitoyltransferase 1B; Dr5: death receptor 5; eNOS: endothelial nitric oxide synthase; ERK: extracellular regulated MAP kinase; Fas: Fas Cell surface death receptor; FDXR: Ferredoxin Reductase; FOXO3a: forkhead box O3; Gadd45a: growth arrest and DNA damage-inducible 45 alpha; GLS2: glutaminase 2; GLUT 1 and 4: glucose transporter 1(endothelial) and 4 (skeletal muscle); GSH: Glutathione; Hes1: hes family bHLH transcription factor 1; Hey1: hes related family bHLH transcription factor with YRPW motif 1; HIFI-α: hypoxia-inducible factor 1, α-subunit; HK2: Hexokinase 2; HSP70: Heat Shock Protein 70; HO: Hydrogen Peroxide; Id2: inhibitor of DNA-binding 2; IGF-1-BP3: Insulin-like growth factor binding protein 3; IL-1β: Interleukin 1 beta; iNOS: inducible nitric oxide synthase; IRS-1: Insulin receptor substrate 1; JNK: c-Jun N-terminal kinases; LY-83583: 6-anilino-5,8-quinolinedione; inhibitor of soluble guanylate cyclase and of cGMP production; Mdm 2/ 4: Mouse double minute 2 homolog (mouse) Mdm4 (humans); mtDNA: mitochondrial DNA; MURF1: Muscle RING-finger protein-1; MyoD: Myogenic differentiation 1; MyoG: myogenin; Nanog: Nanog homeobox; NF-kB: Nuclear factor-κB; NO: nitric oxide; NoxA: phorbol-12-myristate-13-acetate-induced protein 1 (Pmaip1); NRF-1: nuclear respiratory factor 1; Nrf2: Nuclear factor erythroid 2-related factor 2; P21: Cdkn1a cyclin-dependent kinase inhibitor 1A (P21); P38 MAPK: mitogen-activated protein kinases; p53R2: p53 inducible ribonucleotide reductase gene; P66Shc: src homology 2 domain-containing transforming protein C1; PERP: p53 apoptosis effector related to PMP-22; PGC-1α: Peroxisome proliferator-activated receptor gamma coactivator 1-alpha; PGM: phosphoglucomutase; PI3K: Phosphatidylinositol-4,5-bisphosphate 3-kinase; PKCβ: protein kinase c beta; PTEN: phosphatase and tensin homolog; PTIO: 2-phenyl-4, 4, 5, 5,-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) has been used as a nitric oxide (NO) scavenger; Puma: The p53 upregulated modulator of apoptosis; PW1: paternally expressed 3 (Peg3); RNS: Reactive nitrogen species; SIRT1: sirtuin 1; SCO2: cytochrome c oxidase assembly protein; SOD2: superoxide dismutase 2; Tfam: transcription factor A mitochondrial; TIGAR: Trp53 induced glycolysis repulatory phosphatase; TNF-a: tumor necrosis factor a; TRAF2: TNF receptor associated factor 2; TRAIL: type II transmembrane protein.
Topics: Animals; Diet; Exercise; Humans; Muscle, Skeletal; Oxidative Stress; Oxygen; Proto-Oncogene Mas; Radiation Injuries; Tumor Suppressor Protein p53
PubMed: 29298131
DOI: 10.1080/13510002.2017.1416773 -
Sports Medicine (Auckland, N.Z.) Apr 2015Maximizing the hypertrophic response to resistance training (RT) is thought to be best achieved by proper manipulation of exercise program variables including exercise... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Maximizing the hypertrophic response to resistance training (RT) is thought to be best achieved by proper manipulation of exercise program variables including exercise selection, exercise order, length of rest intervals, intensity of maximal load, and training volume. An often overlooked variable that also may impact muscle growth is repetition duration. Duration amounts to the sum total of the concentric, eccentric, and isometric components of a repetition, and is predicated on the tempo at which the repetition is performed.
OBJECTIVE
We conducted a systematic review and meta-analysis to determine whether alterations in repetition duration can amplify the hypertrophic response to RT.
METHODS
Studies were deemed eligible for inclusion if they met the following criteria: (1) were an experimental trial published in an English-language refereed journal; (2) directly compared different training tempos in dynamic exercise using both concentric and eccentric repetitions; (3) measured morphologic changes via biopsy, imaging, and/or densitometry; (4) had a minimum duration of 6 weeks; (5) carried out training to muscle failure, defined as the inability to complete another concentric repetition while maintaining proper form; and (6) used human subjects who did not have a chronic disease or injury. A total of eight studies were identified that investigated repetition duration in accordance with the criteria outlined.
RESULTS
Results indicate that hypertrophic outcomes are similar when training with repetition durations ranging from 0.5 to 8 s.
CONCLUSIONS
From a practical standpoint it would seem that a fairly wide range of repetition durations can be employed if the primary goal is to maximize muscle growth. Findings suggest that training at volitionally very slow durations (>10s per repetition) is inferior from a hypertrophy standpoint, although a lack of controlled studies on the topic makes it difficult to draw definitive conclusions.
Topics: Adaptation, Physiological; Humans; Muscle Fatigue; Muscle Strength; Muscle, Skeletal; Resistance Training; Time Factors
PubMed: 25601394
DOI: 10.1007/s40279-015-0304-0 -
Scandinavian Journal of Medicine &... Aug 2023Stretch training increases the range of motion of a joint. However, to date, the mechanisms behind such a stretching effect are not well understood. An earlier... (Meta-Analysis)
Meta-Analysis Review
Stretch training increases the range of motion of a joint. However, to date, the mechanisms behind such a stretching effect are not well understood. An earlier meta-analysis on several studies reported no changes in the passive properties of a muscle (i.e., muscle stiffness) following long-term stretch training with various types of stretching (static, dynamic, and proprioceptive neuromuscular stretching). However, in recent years, an increasing number of papers have reported the effects of long-term static stretching on muscle stiffness. The purpose of the present study was to examine the long-term (≥2 weeks) effect of static stretching training on muscle stiffness. PubMed, Web of Science, and EBSCO published before December 28, 2022, were searched and 10 papers met the inclusion criteria for meta-analysis. By applying a mixed-effect model, subgroup analyses, which included comparisons of sex (male vs. mixed sex) and type of muscle stiffness assessment (calculated from the muscle-tendon junction vs. shear modulus), were performed. Furthermore, a meta-regression was conducted to examine the effect of total stretching duration on muscle stiffness. The result of the meta-analysis showed a moderate decrease in muscle stiffness after 3-12 weeks of static stretch training compared to a control condition (effect size = -0.749, p < 0.001, I = 56.245). Subgroup analyses revealed no significant differences between sex (p = 0.131) and type of muscle stiffness assessment (p = 0.813). Moreover, there was no significant relationship between total stretching duration and muscle stiffness (p = 0.881).
Topics: Humans; Male; Muscle, Skeletal; Muscle Stretching Exercises; Range of Motion, Articular; Elasticity; Torque
PubMed: 37231582
DOI: 10.1111/sms.14402 -
Journal of Bodywork and Movement... Oct 2015Self-myofascial release (SMFR) is a type of myofascial release performed by the individual themselves rather than by a clinician, typically using a tool. (Review)
Review
BACKGROUND
Self-myofascial release (SMFR) is a type of myofascial release performed by the individual themselves rather than by a clinician, typically using a tool.
OBJECTIVES
To review the literature regarding studies exploring acute and chronic clinical effects of SMFR.
METHODS
PubMed and Google Scholar databases were searched during February 2015 for studies containing words related to the topic of SMFR.
RESULTS
Acutely, SMFR seems to increase flexibility and reduce muscle soreness but does not impede athletic performance. It may lead to improved arterial function, improved vascular endothelial function, and increased parasympathetic nervous system activity acutely, which could be useful in recovery. There is conflicting evidence whether SMFR can improve flexibility long-term.
CONCLUSION
SMFR appears to have a range of potentially valuable effects for both athletes and the general population, including increasing flexibility and enhancing recovery.
Topics: Athletic Performance; Autonomic Nervous System; Biomechanical Phenomena; Endothelium, Vascular; Humans; Muscle, Skeletal; Myalgia; Randomized Controlled Trials as Topic; Therapy, Soft Tissue; Vascular Stiffness
PubMed: 26592233
DOI: 10.1016/j.jbmt.2015.08.007 -
European Journal of Sport Science Sep 2017Although the effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy have been investigated in several studies,... (Review)
Review
Although the effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy have been investigated in several studies, the findings are equivocal and the practical implications remain unclear. In an attempt to provide clarity on the topic, we performed a systematic literature search of PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library, and Physiotherapy Evidence Database (PEDro) electronic databases. Six studies were found to have met the inclusion criteria: (a) an experimental trial published in an English-language peer-reviewed journal; (b) the study compared the use of short (≤60 s) to long (>60 s) inter-set rest intervals in a traditional dynamic resistance exercise using both concentric and eccentric muscle actions, with the only difference in resistance training among groups being the inter-set rest interval duration; (c) at least one method of measuring changes in muscle mass was used in the study; (d) the study lasted for a minimum of four weeks, employed a training frequency of ≥2 resistance training days per week, and (e) used human participants without known chronic disease or injury. Current evidence indicates that both short and long inter-set rest intervals may be useful when training for achieving gains in muscle hypertrophy. Novel findings involving trained participants using measures sensitive to detect changes in muscle hypertrophy suggest a possible advantage for the use of long rest intervals to elicit hypertrophic effects. However, due to the paucity of studies with similar designs, further research is needed to provide a clear differentiation between these two approaches.
Topics: Humans; Hypertrophy; Muscle Strength; Muscle, Skeletal; Research Design; Resistance Training; Rest; Time Factors
PubMed: 28641044
DOI: 10.1080/17461391.2017.1340524