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Sports Medicine (Auckland, N.Z.) Mar 2023The current literature on the chronic effects of static stretching (SS) exercises on muscle strength and power is unclear and controversial. (Meta-Analysis)
Meta-Analysis
Chronic Effects of Static Stretching Exercises on Muscle Strength and Power in Healthy Individuals Across the Lifespan: A Systematic Review with Multi-level Meta-analysis.
BACKGROUND
The current literature on the chronic effects of static stretching (SS) exercises on muscle strength and power is unclear and controversial.
OBJECTIVE
We aimed to examine the chronic effects of SS exercises on muscle strength and power as well as flexibility in healthy individuals across the lifespan.
DESIGN
Systematic review with meta-analysis of (randomized) controlled trials.
DATA SOURCES
A systematic literature search was conducted in the databases PubMed, Web of Science, Cochrane Library, and SPORTDiscus up to May 2022.
ELIGIBILITY CRITERIA FOR SELECTING STUDIES
We included studies that investigated the chronic effects of SS exercises on at least one muscle strength and power outcome compared to an active/passive control group or the contralateral leg (i.e., using between- or within-study designs, respectively) in healthy individuals, irrespective of age, sex, and training status.
RESULTS
The main findings of 41 studies indicated trivial-to-small positive effects of chronic SS exercises on muscle strength (standardized mean difference [SMD] = 0.21, [95% confidence interval 0.10-0.32], p = 0.001) and power (SMD = 0.19, 95% confidence interval 0.12-0.26], p < 0.001). For flexibility, moderate-to-large increases were observed (SMD = 0.96, [95% confidence interval 0.70-1.22], p < 0.001). Subgroup analyses, taking the participants' training status into account, revealed a larger muscle strength improvement for sedentary (SMD = 0.58, p < 0.001) compared with recreationally active participants (SMD = 0.16, p = 0.029). Additionally, larger flexibility gains were observed following passive (SMD = 0.97, p < 0.001) compared with active SS exercises (SMD = 0.59, p = 0.001). The chronic effects of SS on muscle strength were moderated by the proportion of female individuals in the sample (β = 0.004, p = 0.042), with higher proportions experiencing larger gains. Other moderating variables included mean age (β = 0.011, p < 0.001), with older individuals showing larger muscle strength gains, and the number of repetitions per stretching exercise and session (β = 0.023, p = 0.004 and β = 0.013, p = 0.008, respectively), with more repetitions associated with larger muscle strength improvements. Muscle power was also moderated by mean age (β = 0.006, p = 0.007) with larger gains in older individuals. The meta-regression analysis indicated larger flexibility gains with more repetitions per session (β = 0.094, p = 0.016), more time under stretching per session (β = 0.090, p = 0.026), and more total time under stretching (β = 0.078, p = 0.034).
CONCLUSIONS
The main findings indicated that chronic SS exercises have the potential to improve muscle strength and power. Such improvements appear to benefit sedentary more than recreationally active participants. Likewise, chronic SS exercises result in a marked enhancement in flexibility with larger effects of passive, as compared with active, SS. The results of the meta-regression analysis for muscle strength indicated larger benefits of chronic SS exercises in samples with higher proportions of female, older participants, and a higher number of repetitions per stretching exercise and session. For muscle power, results suggested larger gains for older participants. Regarding flexibility, findings indicated larger benefits following a higher number of repetitions per exercise and a longer time under stretching per session as well as a longer total time under stretching.
Topics: Humans; Female; Aged; Muscle Stretching Exercises; Longevity; Muscle Strength; Resistance Training
PubMed: 36719536
DOI: 10.1007/s40279-022-01806-9 -
Magnesium Research Nov 2017Increasing evidence supports a role of magnesium (Mg) in skeletal muscle function. However, no systematic review or meta-analysis has summarized data on Mg... (Meta-Analysis)
Meta-Analysis Review
Increasing evidence supports a role of magnesium (Mg) in skeletal muscle function. However, no systematic review or meta-analysis has summarized data on Mg supplementation in relation to muscle fitness in humans. Thus, this study aimed to quantitatively assess the effect of Mg supplementation on muscle fitness. A meta-analysis and systematic review. Medline database and other sources were searched for randomized clinical trials through July 2017. Studies that reported results regarding at least one of the following outcomes: leg strength, knee extension strength, peak torque, muscle power, muscle work, jump, handgrip, bench press weights, resistant exercise, lean mass, muscle mass, muscle strength, walking speed, Repeated Chair Stands, and TGUG were included. Measurements of the association were pooled using a fixed-effects model and expressed as weighted mean differences (WMDs) with 95% confidence intervals (95% CIs). Fourteen randomized clinical trials targeting 3 different populations were identified: athletes or physically active individuals (215 participants; mean age: 24.9 years), untrained healthy individuals (95 participants; mean age: 40.2 years), and elderly or alcoholics (232 participants; mean age: 62.7 years). The beneficial effects of Mg supplementation appeared to be more pronounced in the elderly and alcoholics, but were not apparent in athletes and physically active individuals. The results of the meta-analysis suggested that no significant improvements in the supplementation group were observed regarding isokinetic peak torque extension [WMD = 0.87; 95% CI = (-1.43, 3.18)], muscle strength [WMD = 0.87; 95% CI = (-0.12, 1.86)] or muscle power [WMD = 3.28; 95% CI = (-14.94, 21.50)]. Evidence does not support a beneficial effect of Mg supplementation on muscle fitness in most athletes and physically active individuals who have a relatively high Mg status. But Mg supplementation may benefit individuals with Mg deficiency, such as the elderly and alcoholics.
Topics: Adult; Aged; Alcoholism; Athletes; Dietary Supplements; Exercise; Female; Humans; Magnesium; Male; Muscle Strength
PubMed: 29637897
DOI: 10.1684/mrh.2018.0430 -
Journal of Cachexia, Sarcopenia and... Feb 2023Probiotics have shown potential to counteract sarcopenia, although the extent to which they can influence domains of sarcopenia such as muscle mass and strength in... (Meta-Analysis)
Meta-Analysis Review
Probiotics have shown potential to counteract sarcopenia, although the extent to which they can influence domains of sarcopenia such as muscle mass and strength in humans is unclear. The aim of this systematic review and meta-analysis was to explore the impact of probiotic supplementation on muscle mass, total lean mass and muscle strength in human adults. A literature search of randomized controlled trials (RCTs) was conducted through PubMed, Scopus, Web of Science and Cochrane Library from inception until June 2022. Eligible RCTs compared the effect of probiotic supplementation versus placebo on muscle and total lean mass and global muscle strength (composite score of all muscle strength outcomes) in adults (>18 years). To evaluate the differences between groups, a meta-analysis was conducted using the random effects inverse-variance model by utilizing standardized mean differences. Twenty-four studies were included in the systematic review and meta-analysis exploring the effects of probiotics on muscle mass, total lean mass and global muscle strength. Our main analysis (k = 10) revealed that muscle mass was improved following probiotics compared with placebo (SMD: 0.42, 95% CI: 0.10-0.74, I = 57%, P = 0.009), although no changes were revealed in relation to total lean mass (k = 12; SMD: -0.03, 95% CI: -0.19 - 0.13, I = 0%, P = 0.69). Interestingly, a significant increase in global muscle strength was also observed among six RCTs (SMD: 0.69, 95% CI: 0.33-1.06, I = 64%, P = 0.0002). Probiotic supplementation enhances both muscle mass and global muscle strength; however, no beneficial effects were observed in total lean mass. Investigating the physiological mechanisms underpinning different ageing groups and elucidating appropriate probiotic strains for optimal gains in muscle mass and strength are warranted.
Topics: Adult; Humans; Sarcopenia; Randomized Controlled Trials as Topic; Probiotics; Muscle Strength; Muscles
PubMed: 36414567
DOI: 10.1002/jcsm.13132 -
Medicine Jul 2019Due to demographic changes the world's population is progressively ageing. The physiological decay of the elderly adult may lead to a reduction in the ability to balance...
BACKGROUND
Due to demographic changes the world's population is progressively ageing. The physiological decay of the elderly adult may lead to a reduction in the ability to balance and an increased risk of falls becoming an important issue among the elderly. In order to counteract the decay in the ability to balance, physical activity has been proven to be effective. The aim of this study is to systematically review the scientific literature in order to identify physical activity programs able to increase balance in the elderly.
METHODS
This review is based on the data from Medline-NLM, Pubmed, ScienceDirect, and SPORTDiscuss and includes randomized control trials that have analyzed balance and physical activity in healthy elderly over 65 years of age during the last decade. A final number of 8 manuscripts were included in the qualitative synthesis, which comprised 200 elderly with a mean age of 75.1 ± 4.4 years. The sample size of the studies varied from 9 to 61 and the intervention periods from 8 to 32 weeks.
RESULTS
Eight articles were considered eligible and included in the quantitative synthesis. The articles investigated the effects of resistance and aerobic exercise, balance training, T-bow© and wobble board training, aerobic step and stability ball training, adapted physical activity and Wii Fit training on balance outcomes. Balance measures of the studies showed improvements between 16% and 42% compared to baseline assessments.
CONCLUSIONS
Balance is a multifactorial quality that can be effectively increased by different exercise training means. It is fundamental to promote physical activity in the aging adult, being that a negative effect on balance performance has been seen in the no-intervention control groups.
Topics: Accidental Falls; Aged; Exercise; Exercise Therapy; Humans; Muscle Strength; Postural Balance
PubMed: 31277132
DOI: 10.1097/MD.0000000000016218 -
Journal of Strength and Conditioning... Jun 2022Kassiano, W, Nunes, JP, Costa, B, Ribeiro, AS, Schoenfeld, BJ, and Cyrino, ES. Does varying resistance exercises promote superior muscle hypertrophy and strength gains?...
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.
Topics: Exercise; Humans; Hypertrophy; Male; Muscle Strength; Muscle, Skeletal; Resistance Training
PubMed: 35438660
DOI: 10.1519/JSC.0000000000004258 -
Sports Medicine (Auckland, N.Z.) Jul 2013The aging process results in a number of functional (e.g., deficits in balance and strength/power performance), neural (e.g., loss of sensory/motor neurons), muscular... (Review)
Review
BACKGROUND
The aging process results in a number of functional (e.g., deficits in balance and strength/power performance), neural (e.g., loss of sensory/motor neurons), muscular (e.g., atrophy of type-II muscle fibers in particular), and bone-related (e.g., osteoporosis) deteriorations. Traditionally, balance and/or lower extremity resistance training were used to mitigate these age-related deficits. However, the effects of resistance training are limited and poorly translate into improvements in balance, functional tasks, activities of daily living, and fall rates. Thus, it is necessary to develop and design new intervention programs that are specifically tailored to counteract age-related weaknesses. Recent studies indicate that measures of trunk muscle strength (TMS) are associated with variables of static/dynamic balance, functional performance, and falls (i.e., occurrence, fear, rate, and/or risk of falls). Further, there is preliminary evidence in the literature that core strength training (CST) and Pilates exercise training (PET) have a positive influence on measures of strength, balance, functional performance, and falls in older adults.
OBJECTIVE
The objectives of this systematic literature review are: (a) to report potential associations between TMS/trunk muscle composition and balance, functional performance, and falls in old adults, and (b) to describe and discuss the effects of CST/PET on measures of TMS, balance, functional performance, and falls in seniors.
DATA SOURCES
A systematic approach was employed to capture all articles related to TMS/trunk muscle composition, balance, functional performance, and falls in seniors that were identified using the electronic databases PubMed and Web of Science (1972 to February 2013).
STUDY SELECTION
A systematic approach was used to evaluate the 582 articles identified for initial review. Cross-sectional (i.e., relationship) or longitudinal (i.e., intervention) studies were included if they investigated TMS and an outcome-related measure of balance, functional performance, and/or falls. In total, 20 studies met the inclusionary criteria for review.
STUDY APPRAISAL AND SYNTHESIS METHODS
Longitudinal studies were evaluated using the Physiotherapy Evidence Database (PEDro) scale. Effect sizes (ES) were calculated whenever possible. For ease of discussion, the 20 articles were separated into three groups [i.e., cross-sectional (n = 6), CST (n = 9), PET (n = 5)].
RESULTS
The cross-sectional studies reported small-to-medium correlations between TMS/trunk muscle composition and balance, functional performance, and falls in older adults. Further, CST and/or PET proved to be feasible exercise programs for seniors with high-adherence rates. Age-related deficits in measures of TMS, balance, functional performance, and falls can be mitigated by CST (mean strength gain = 30 %, mean effect size = 0.99; mean balance/functional performance gain = 23 %, mean ES = 0.88) and by PET (mean strength gain = 12 %, mean ES = 0.52; mean balance/functional performance gain = 18 %, mean ES = 0.71).
LIMITATIONS
Given that the mean PEDro quality score did not reach the predetermined cut-off of ≥6 for the intervention studies, there is a need for more high-quality studies to explicitly identify the relevance of CST and PET to the elderly population.
CONCLUSIONS
Core strength training and/or PET can be used as an adjunct or even alternative to traditional balance and/or resistance training programs for old adults. Further, CST and PET are easy to administer in a group setting or in individual fall preventive or rehabilitative intervention programs because little equipment and space is needed to perform such exercises.
Topics: Accidental Falls; Aged; Aged, 80 and over; Aging; Exercise Movement Techniques; Humans; Muscle Strength; Postural Balance; Resistance Training; Torso
PubMed: 23568373
DOI: 10.1007/s40279-013-0041-1 -
British Journal of Sports Medicine Dec 2022Critically appraise and summarise the measurement properties of knee muscle strength tests after anterior cruciate ligament (ACL) and/or meniscus injury using the... (Meta-Analysis)
Meta-Analysis Review
Measurement properties for muscle strength tests following anterior cruciate ligament and/or meniscus injury: What tests to use and where do we need to go? A systematic review with meta-analyses for the OPTIKNEE consensus.
OBJECTIVES
Critically appraise and summarise the measurement properties of knee muscle strength tests after anterior cruciate ligament (ACL) and/or meniscus injury using the COnsensus-based Standards for the selection of health Measurement INstruments Risk of Bias checklist.
DESIGN
Systematic review with meta-analyses. The modified Grading of Recommendations Assessment, Development and Evaluation-guided assessment of evidence quality.
DATA SOURCES
Medline, Embase, CINAHL and SPORTSDiscus searched from inception to 5 May 2022.
ELIGIBILITY CRITERIA FOR SELECTING STUDIES
Studies evaluating knee extensor or flexor strength test reliability, measurement error, validity, responsiveness or interpretability in individuals with ACL and/or meniscus injuries with a mean injury age of ≤30 years.
RESULTS
Thirty-six studies were included involving 31 different muscle strength tests (mode and equipment) in individuals following an ACL injury and/or an isolated meniscus injury. Strength tests were assessed for reliability (n=8), measurement error (n=7), construct validity (n=27) and criterion validity (n=7). Isokinetic concentric extensor and flexor strength tests were the best rated with sufficient intrarater reliability (very low evidence quality) and construct validity (moderate evidence quality). Isotonic extensor and flexor strength tests showed sufficient criterion validity, while isometric extensor strength tests had insufficient construct and criterion validity (high evidence quality).
CONCLUSION
Knee extensor and flexor strength tests of individuals with ACL and/or meniscus injury lack evidence supporting their measurement properties. There is an urgent need for high-quality studies on these measurement properties. Until then, isokinetic concentric strength tests are most recommended, with isotonic strength tests a good alternative.
Topics: Humans; Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Reconstruction; Reproducibility of Results; Consensus; Anterior Cruciate Ligament Injuries; Muscle Strength; Meniscus
PubMed: 36113973
DOI: 10.1136/bjsports-2022-105498 -
Sports Medicine (Auckland, N.Z.) Feb 2018Low-load resistance training (< 50% of one-repetition maximum [1RM]) associated with blood-flow restriction (BFR-RT) has been thought to promote increases in muscle... (Meta-Analysis)
Meta-Analysis Review
Magnitude of Muscle Strength and Mass Adaptations Between High-Load Resistance Training Versus Low-Load Resistance Training Associated with Blood-Flow Restriction: A Systematic Review and Meta-Analysis.
BACKGROUND
Low-load resistance training (< 50% of one-repetition maximum [1RM]) associated with blood-flow restriction (BFR-RT) has been thought to promote increases in muscle strength and mass. However, it remains unclear if the magnitude of these adaptations is similar to conventional high-load resistance training (> 65% 1RM; HL-RT).
OBJECTIVE
To compare the effects of HL- versus BFR-RT on muscle adaptations using a systematic review and meta-analysis procedure.
METHODS
Studies were identified via electronic databases based on the following inclusion criteria: (a) pre- and post-training assessment of muscular strength; (b) pre- and post-training assessment of muscle hypertrophy; (c) comparison of HL-RT vs. BFR-RT; (d) score ≥ 4 on PEDro scale; (e) means and standard deviations (or standard errors) are reported from absolute values or allow estimation from graphs. If this last criterion was not met, data were directly requested from the authors.
RESULTS
The main results showed higher increases in muscle strength for HL- as compared with BFR-RT, even when considering test specificity, absolute occlusion pressure, cuff width, and occlusion pressure prescription. Regarding the hypertrophic response, results revealed similar effects between HL- and BFR-RT, regardless of the absolute occlusion pressure, cuff width, and occlusion pressure prescription.
CONCLUSIONS
Based on the present data, maximum muscle strength may be optimized by specific training methods (i.e., HL-RT) while both HL- and BFR-RT seem equally effective in increasing muscle mass. Importantly, BFR-RT is a valid and effective approach for increasing muscle strength in a wide spectrum of ages and physical capacity, although it may seem particularly of interest for those individuals with physical limitations to engage in HL-RT.
Topics: Adaptation, Physiological; Humans; Muscle Strength; Muscle, Skeletal; Regional Blood Flow; Resistance Training; Weight-Bearing
PubMed: 29043659
DOI: 10.1007/s40279-017-0795-y -
Developmental Neurorehabilitation May 2023To review the effects of functional strength training (FST) on muscle strength and mobility in children with spastic cerebral palsy (CP). (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To review the effects of functional strength training (FST) on muscle strength and mobility in children with spastic cerebral palsy (CP).
METHODS
Eight databases were screened through March 2022 for studies assessing the impact of FST on strength, mobility, balance, and endurance in children with spastic CP. Study quality was assessed using the Downs and Black checklist and Cochrane Risk of Bias tools, followed by a meta-analysis.
RESULTS
Twelve intervention studies of moderate-to-high-level evidence were selected. The interventions included open and closed chain exercises using free weights or body weight, administered approximately thrice a week for 12 weeks. The FST was found to have a moderate-to-large, statistically significant, positive effect on muscle strength (quadriceps, hamstrings, and plantar flexors) and mobility (GMFM D and E), with only four studies showing maintenance of gains during follow-up assessment.
CONCLUSION
FST has a positive effect on muscle strength and mobility in children with spastic CP, but evidence of sustained effects following FST is limited.
Topics: Humans; Child; Resistance Training; Muscle Spasticity; Cerebral Palsy; Exercise; Muscle Strength
PubMed: 37254274
DOI: 10.1080/17518423.2023.2218905 -
Journal of Strength and Conditioning... Feb 2017Chiang, C-m, Ismaeel, A, Griffis, RB, and Weems, S. Effects of vitamin D supplementation on muscle strength in athletes: A systematic review. J Strength Cond Res 31(2):... (Review)
Review
Chiang, C-m, Ismaeel, A, Griffis, RB, and Weems, S. Effects of vitamin D supplementation on muscle strength in athletes: A systematic review. J Strength Cond Res 31(2): 566-574, 2017-The purpose of this systematic review of the literature was to investigate the effects of vitamin D supplementation on muscle strength in athletes. A computerized literature search of 3 databases (PubMed, MEDLINE, and Scopus) was performed. Included in the review were randomized controlled trials (RCTs), published in English, which measured serum vitamin D concentrations and muscle strength in healthy, athletic participants aged 18-45 years. Quality was assessed using the PEDro scale. Five RCTs and 1 controlled trial were identified, and quality assessment showed 5 trials were of "excellent quality" and 1 was of "good quality." Trials lasted from 4 weeks to 6 months and dosages ranged from 600 to 5,000 International Units (IU) per day. Vitamin D2 was found to be ineffective at impacting muscle strength in both studies wherein it was administered. In contrast, vitamin D3 was shown to have a positive impact on muscle strength. In 2 studies, strength outcome measures were significantly improved after supplementation (p ≤ 0.05). In the other 2 studies administering vitamin D3, there were trends for improved muscle strength. Specifically, improvements in strength ranged from 1.37 to 18.75%. Additional studies are needed to confirm these associations.
Topics: Adolescent; Adult; Athletes; Cholecalciferol; Controlled Clinical Trials as Topic; Dietary Supplements; Dose-Response Relationship, Drug; Ergocalciferols; Female; Humans; Male; Middle Aged; Muscle Strength; Outcome Assessment, Health Care; Vitamin D; Young Adult
PubMed: 27379960
DOI: 10.1519/JSC.0000000000001518