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PloS One 2024Neuromuscular electrical stimulation (NMES) can improve physical function in different populations. NMES-related outcomes may be influenced by muscle length (i.e., joint...
Effect of muscle length on maximum evoked torque, discomfort, contraction fatigue, and strength adaptations during electrical stimulation in adult populations: A systematic review.
Neuromuscular electrical stimulation (NMES) can improve physical function in different populations. NMES-related outcomes may be influenced by muscle length (i.e., joint angle), a modulator of the force generation capacity of muscle fibers. Nevertheless, to date, there is no comprehensive synthesis of the available scientific evidence regarding the optimal joint angle for maximizing the effectiveness of NMES. We performed a systematic review to investigate the effect of muscle length on NMES-induced torque, discomfort, contraction fatigue, and strength training adaptations in healthy and clinical adult populations (PROSPERO: CRD42022332965). We conducted searches across seven electronic databases: PUBMED, Web of Science, EMBASE, PEDro, BIREME, SCIELO, and Cochrane, over the period from June 2022 to October 2023, without restricting the publication year. We included cross-sectional and longitudinal studies that used NMES as an intervention or assessment tool for comparing muscle lengths in adult populations. We excluded studies on vocalization, respiratory, or pelvic floor muscles. Data extraction was performed via a standardized form to gather information on participants, interventions, and outcomes. Risk of bias was assessed using the Revised Cochrane risk-of-bias tool for cross-over trials and the Physiotherapy Evidence Database scale. Out of the 1185 articles retrieved through our search strategy, we included 36 studies in our analysis, that included 448 healthy young participants (age: 19-40 years) in order to investigate maximum evoked torque (n = 268), contraction fatigability (n = 87), discomfort (n = 82), and muscle strengthening (n = 22), as well as six participants with spinal cord injuries, and 15 healthy older participants. Meta-analyses were possible for comparing maximal evoked torque according to quadriceps muscle length through knee joint angle. At optimal muscle length 50° - 70° of knee flexion, where 0° is full extension), there was greater evoked torque during nerve stimulation compared to very short (0 - 30°) (p<0.001, CI 95%: -2.03, -1.15 for muscle belly stimulation, and -3.54, -1.16 for femoral nerve stimulation), short (31° - 49°) (p = 0.007, CI 95%: -1.58, -0.25), and long (71° - 90°) (p<0.001, CI 95%: 0.29, 1.02) muscle lengths. At long muscle lengths, NMES evoked greater torque than very short (p<0.001, CI 95%: -2.50, -0.67) and short (p = 0.04, CI 95%: -2.22, -0.06) lengths. The shortest quadriceps length generated the highest perceived discomfort for a given current amplitude. The amount of contraction fatigability was greater when muscle length allowed greater torque generation in the pre-fatigue condition. Strength gains were greater for a protocol at the optimal muscle length than for short muscle length. The quality of evidence was very high for most comparisons for evoked torque. However, further studies are necessary to achieve certainty for the other outcomes. Optimal muscle length should be considered the primary choice during NMES interventions, as it promotes higher levels of force production and may facilitate the preservation/gain in muscle force and mass, with reduced discomfort. However, a longer than optimal muscle length may also be used, due to possible muscle lengthening at high evoked tension. Thorough understanding of these physiological principles is imperative for the appropriate prescription of NMES for healthy and clinical populations.
Topics: Humans; Torque; Adult; Muscle Fatigue; Muscle, Skeletal; Muscle Contraction; Electric Stimulation; Muscle Strength; Adaptation, Physiological; Electric Stimulation Therapy
PubMed: 38857245
DOI: 10.1371/journal.pone.0304205 -
Cureus Apr 2024Rhabdomyolysis, a medical condition caused by the destruction of striated muscle fibers, can have many etiologies, with the most common one being traumatic etiologies,... (Review)
Review
Rhabdomyolysis, a medical condition caused by the destruction of striated muscle fibers, can have many etiologies, with the most common one being traumatic etiologies, that is, crushing injuries, heavy exertion, and being trapped under rubbles, and so forth. Rhabdomyolysis causes many complications, including acute kidney injury and different electrolyte imbalances, which later can cause cardiac dysrhythmia and even death as a result. This systematic review and meta-analysis investigate the incidence of imbalances of four important electrolytes among patients diagnosed with traumatic rhabdomyolysis. PubMed, Scopus, Web of Science, and Embase databases were searched for any article related to traumatic rhabdomyolysis using keywords related to the topic of our study, excluding case studies and case series. Relevant data were extracted from the included articles, and finally, a meta-analysis was performed on them to calculate the pooled incidence of each electrolyte imbalance. Collectively, 32 articles were included in our study (through the database and citation checking). The following were the pooled incidence of each electrolyte imbalance: hyperkalemia, 31% (95%CI 22%-41%); hypokalemia, 10% (95%CI 4%-17%); hypernatremia, 3% (95%CI 0%-8%); hyponatremia, 23% (95%CI 7%-44%); hypercalcemia, 0% (95%CI 0%-1%); hypocalcemia, 57% (95%CI: 22%-88%); hyperphosphatemia, 33% (95%CI 11%-59%); hypophosphatemia, 4% (95%CI 0%-16%). According to the meta-analyses, the rate of hyperkalemia, hyponatremia, hypocalcemia, and hyperphosphatemia is higher than their counterpart in patients diagnosed with traumatic rhabdomyolysis.
PubMed: 38817473
DOI: 10.7759/cureus.59333 -
Journal of Orthopaedic Translation May 2024The neuromuscular junction (NMJ) is a specialized chemical synapse that converts neural impulses into muscle action. Age-associated NMJ degeneration, which involves... (Review)
Review
The neuromuscular junction (NMJ) is a specialized chemical synapse that converts neural impulses into muscle action. Age-associated NMJ degeneration, which involves nerve terminal and postsynaptic decline, denervation, and loss of motor units, significantly contributes to muscle weakness and dysfunction. Although physical training has been shown to make substantial modifications in NMJ of both young and aged animals, the results are often influenced by methodological variables in existing studies. Moreover, there is still lack of strong consensus on the specific effects of exercise on improving the morphology and function of the ageing NMJ. Consequently, the purpose of this study was to conduct a systematic review to elucidate the effects of exercise training on NMJ compartments in the elderly. We conducted a systematic review using PubMed, Embase, and Web of Science databases, employing relevant keywords. Two independent reviewers selected studies that detailed NMJ changes during exercise in ageing, written in English, and available in full text. In total, 20 papers were included. We examined the altered adaptation of the NMJ to exercise, focusing on presynaptic and postsynaptic structures and myofibers in older animals or humans. Our findings indicated that aged NMJs exhibited different adaptive responses to physical exercise compared to younger counterparts. Endurance training, compared with resistance and voluntary exercise regimens, was found to have a more pronounced effect on NMJ structural remodeling, particularly in fast twitch muscle fibers. Physical exercise was observed to promote the formation and maintenance of acetylcholine receptor (AChR) clusters by increasing the recombinant docking protein 7 (Dok7) expression and stabilizing Agrin and lipoprotein receptor-related protein 4 (LRP4). These insights suggest that research on exercise-related therapies could potentially attenuate the progression of neuromuscular degeneration. Translational potential of this article: This systematic review provides a detailed overview of the effects of different types of physical exercise on improving NMJ in the elderly, providing scientific support for the timely intervention of muscle degeneration in the elderly by physical exercise, and providing help for the development of new therapeutic interventions in the future.
PubMed: 38817243
DOI: 10.1016/j.jot.2024.03.007 -
Frontiers in Bioengineering and... 2024Diabetic neuropathy affects nearly half of all diabetics and poses a significant threat to public health. Recent preclinical studies suggest that mesenchymal stem cells...
Diabetic neuropathy affects nearly half of all diabetics and poses a significant threat to public health. Recent preclinical studies suggest that mesenchymal stem cells (MSCs) may represent a promising solution for the treatment of diabetic neuropathy. However, an objective assessment of the preclinical effectiveness of MSCs is still pending. We conducted a comprehensive search of PubMed, Web of Science, Embase, and Cochrane library to identify preclinical studies that investigate the effects of MSCs on diabetic neuropathy up until 15 September 2023. Outcome indicators consisted of motor and sensory nerve conduction velocities, intra-epidermal nerve fiber density, sciatic nerve blood flow, capillary-to-muscle fiber ratio, neurotrophic factors, angiogenic factors and inflammatory cytokines. The literature review and meta-analysis were conducted independently by two researchers. 23 studies that met the inclusion criteria were included in this system review for qualitative and quantitative analysis. Pooled analyses indicated that MSCs exhibited an evident benefit in diabetic neuropathy in terms of motor (SMD = 2.16, 95% CI: 1.71-2.61) and sensory nerve conduction velocities (SMD = 2.93, 95% CI: 1.78-4.07), intra-epidermal nerve fiber density (SMD = 3.17, 95% CI: 2.28-4.07), sciatic nerve blood flow (SMD = 2.02, 95% CI: 1.37-2.66), and capillary-to-muscle fiber ratio (SMD = 2.28, 95% CI: 1.55 to 3.01, < 0.00001). Furthermore, after MSC therapy, the expressions of neurotrophic and angiogenic factors increased significantly in most studies, while the levels of inflammatory cytokines were significantly reduced. The relevance of this review relies on the fact that summarizes an extensive body of work entailing substantial preclinical evidence that supports the efficacy of MSCs in mitigating diabetic neuropathy. While MSCs emerge as a promising potential treatment for diabetic neuropathy, further research is essential to elucidate the underlying mechanisms and the best administration strategy for MSCs.
PubMed: 38770273
DOI: 10.3389/fbioe.2024.1349050 -
Sports Medicine (Auckland, N.Z.) May 2024There are a myriad of exercise variations in which upper body (UB) and lower body (LB) exercises have been intermittently used. However, it is still unclear how training...
BACKGROUND
There are a myriad of exercise variations in which upper body (UB) and lower body (LB) exercises have been intermittently used. However, it is still unclear how training of one body region (e.g. LB) affects adaptations in distant body areas (e.g. UB), and how different UB and LB exercise configurations could help facilitate physiological adaptations of either region; both referred to in this review as vertical strength transfer.
OBJECTIVE
We aimed to investigate the existence of the vertical strength transfer phenomenon as a response to various UB and LB exercise configurations and to identify potential mechanisms underpinning its occurrence.
METHODS
A systematic search using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) for Scoping Reviews protocol was conducted in February 2024 using four databases (Web of Science, MEDLINE, Scopus and CINAHL) to identify peer-reviewed articles that investigated the vertical strength transfer phenomenon.
RESULTS
Of the 5242 identified articles, 24 studies met the inclusion criteria. Findings suggest that the addition of UB strength training to LB endurance exercise may help preserve power-generating capacity for the leg muscle fibres. Furthermore, systemic endocrine responses to high-volume resistance exercise may beneficially modulate adaptations in precedingly or subsequently trained muscles from a different body region, augmenting their strength gains. Last, strength training for LB could result in improved strength of untrained UB, likely due to the increased central neural drive.
CONCLUSIONS
Vertical strength transfer existence is enabled by neurophysiological mechanisms. Future research should involve athletic populations, examining the potential of vertical strength transfer to facilitate athletic performance and preserve strength in injured extremities.
PubMed: 38743172
DOI: 10.1007/s40279-024-02039-8 -
Journal of Cachexia, Sarcopenia and... Jun 2024Proliferating cancer cells shift their metabolism towards glycolysis, even in the presence of oxygen, to especially generate glycolytic intermediates as substrates for...
BACKGROUND
Proliferating cancer cells shift their metabolism towards glycolysis, even in the presence of oxygen, to especially generate glycolytic intermediates as substrates for anabolic reactions. We hypothesize that a similar metabolic remodelling occurs during skeletal muscle hypertrophy.
METHODS
We used mass spectrometry in hypertrophying C2C12 myotubes in vitro and plantaris mouse muscle in vivo and assessed metabolomic changes and the incorporation of the [U-C]glucose tracer. We performed enzyme inhibition of the key serine synthesis pathway enzyme phosphoglycerate dehydrogenase (Phgdh) for further mechanistic analysis and conducted a systematic review to align any changes in metabolomics during muscle growth with published findings. Finally, the UK Biobank was used to link the findings to population level.
RESULTS
The metabolomics analysis in myotubes revealed insulin-like growth factor-1 (IGF-1)-induced altered metabolite concentrations in anabolic pathways such as pentose phosphate (ribose-5-phosphate/ribulose-5-phosphate: +40%; P = 0.01) and serine synthesis pathway (serine: -36.8%; P = 0.009). Like the hypertrophy stimulation with IGF-1 in myotubes in vitro, the concentration of the dipeptide l-carnosine was decreased by 26.6% (P = 0.001) during skeletal muscle growth in vivo. However, phosphorylated sugar (glucose-6-phosphate, fructose-6-phosphate or glucose-1-phosphate) decreased by 32.2% (P = 0.004) in the overloaded muscle in vivo while increasing in the IGF-1-stimulated myotubes in vitro. The systematic review revealed that 10 metabolites linked to muscle hypertrophy were directly associated with glycolysis and its interconnected anabolic pathways. We demonstrated that labelled carbon from [U-C]glucose is increasingly incorporated by ~13% (P = 0.001) into the non-essential amino acids in hypertrophying myotubes, which is accompanied by an increased depletion of media serine (P = 0.006). The inhibition of Phgdh suppressed muscle protein synthesis in growing myotubes by 58.1% (P < 0.001), highlighting the importance of the serine synthesis pathway for maintaining muscle size. Utilizing data from the UK Biobank (n = 450 243), we then discerned genetic variations linked to the serine synthesis pathway (PHGDH and PSPH) and to its downstream enzyme (SHMT1), revealing their association with appendicular lean mass in humans (P < 5.0e-8).
CONCLUSIONS
Understanding the mechanisms that regulate skeletal muscle mass will help in developing effective treatments for muscle weakness. Our results provide evidence for the metabolic rewiring of glycolytic intermediates into anabolic pathways during muscle growth, such as in serine synthesis.
Topics: Glucose; Muscle, Skeletal; Animals; Mice; Humans; Hypertrophy; Muscle Fibers, Skeletal; Insulin-Like Growth Factor I; Metabolomics
PubMed: 38742477
DOI: 10.1002/jcsm.13468 -
Heart Failure Reviews Jul 2024Exercise offers many physical and health benefits to people with heart failure (CHF), but aerobic training (AT) predominates published literature. Resistance training... (Review)
Review
Exercise offers many physical and health benefits to people with heart failure (CHF), but aerobic training (AT) predominates published literature. Resistance training (RT) provides additional and complementary health benefits to AT in people with CHF; we aimed to elucidate specific health benefits accrued, the mechanism of effect and safety of RT. We conducted a systematic search for RT randomised, controlled trials in people with CHF, up until August 30, 2023. RT offers several benefits including improved physical function (peak VO and 6MWD), quality of life, cardiac systolic and diastolic function, endothelial blood vessel function, muscle strength, anti-inflammatory muscle markers, appetite and serious event rates. RT is beneficial and improves peak VO and 6MWD, partly restores normal muscle fibre profile and decreases inflammation. In turn this leads to a reduced risk or impact of sarcopenia/cachexia via effect on appetite. The positive impact on quality of life and performance of activities of daily living is related to improved function, which in turn improves prognosis. RT appears to be safe with only one serious event reported and no deaths. Nevertheless, few events reported to date limit robust analysis. RT appears to be safe and offers health benefits to people with CHF. RT modifies the adverse muscle phenotype profile present in people with CHF and it appears safe. Starting slowly with RT and increasing load to 80% of 1 repetition maximum (RM) appears to offer optimal benefit.
Topics: Humans; Heart Failure; Resistance Training; Quality of Life; Muscle Strength; Exercise Tolerance
PubMed: 38619757
DOI: 10.1007/s10741-024-10402-0 -
Sports Medicine - Open Apr 2024Previous studies reported differences in genotype frequency of the ACTN3 R577X polymorphisms (rs1815739; RR, RX and XX) in athletes and non-athletic populations. This...
BACKGROUND
Previous studies reported differences in genotype frequency of the ACTN3 R577X polymorphisms (rs1815739; RR, RX and XX) in athletes and non-athletic populations. This systematic review with meta-analysis assessed ACTN3 R577X genotype frequencies in power versus endurance athletes and non-athletes.
METHODS
Five electronic databases (PubMed, Web of Science, Scopus, Science Direct, SPORTDiscus) were searched for research articles published until December 31st, 2022. Studies were included if they reported the frequency of the ACTN3 R577X genotypes in power athletes (e.g., weightlifters) and if they included a comparison with endurance athletes (e.g., long-distance runners) or non-athletic controls. A meta-analysis was then performed using either fixed or random-effects models. Pooled odds ratios (OR) were determined. Heterogeneity was detected using I and Cochran's Q tests. Publication bias and sensitivity analysis tests were computed.
RESULTS
After screening 476 initial registrations, 25 studies were included in the final analysis (13 different countries; 14,541 participants). In power athletes, the RX genotype was predominant over the two other genotypes: RR versus RX (OR 0.70; 95% CI 0.57-0.85, p = 0.0005), RR versus XX (OR 4.26; 95% CI 3.19-5.69, p < 0.00001), RX versus XX (OR 6.58; 95% CI 5.66-7.67, p < 0.00001). The R allele was higher than the X allele (OR 2.87; 95% CI 2.35-3.50, p < 0.00001) in power athletes. Additionally, the frequency of the RR genotype was higher in power athletes than in non-athletes (OR 1.48; 95% CI 1.25-1.75, p < 0.00001). The RX genotype was similar in both groups (OR 0.84; 95% CI 0.71-1.00, p = 0.06). The XX genotype was lower in power athletes than in controls (OR 0.73; 95% CI 0.64-0.84, p < 0.00001). Furthermore, the R allele frequency was higher in power athletes than in controls (OR 1.28; 95% CI 1.19-1.38, p < 0.00001). Conversely, a higher frequency of X allele was observed in the control group compared to power athletes (OR 0.78; 95% CI 0.73-0.84, p < 0.00001). On the other hand, the frequency of the RR genotype was higher in power athletes than in endurance athletes (OR 1.27; 95% CI 1.09-1.49, p = 0.003). The frequency of the RX genotype was similar in both groups (OR 1.07; 95% CI 0.93-1.24, p = 0.36). In contrast, the frequency of the XX genotype was lower in power athletes than in endurance athletes (OR 0.63; 95% CI 0.52-0.76, p < 0.00001). In addition, the R allele was higher in power athletes than in endurance athletes (OR 1.32; 95% CI 1.11-1.57, p = 0.002). However, the X allele was higher in endurance athletes compared to power athletes (OR 0.76; 95% CI 0.64-0.90, p = 0.002). Finally, the genotypic and allelic frequency of ACTN3 genes were similar in male and female power athletes.
CONCLUSIONS
The pattern of the frequencies of the ACTN3 R577X genotypes in power athletes was RX > RR > XX. However, the RR genotype and R allele were overrepresented in power athletes compared to non-athletes and endurance athletes. These data suggest that the RR genotype and R allele, which is associated with a normal expression of α-actinin-3 in fast-twitch muscle fibers, may offer some benefit in improving performance development in muscle strength and power.
PubMed: 38609671
DOI: 10.1186/s40798-024-00711-x -
Nursing Open Mar 2024To describe home-based care and practices recommended for mothers after caesarean section (CS), existing in the literature.
AIM
To describe home-based care and practices recommended for mothers after caesarean section (CS), existing in the literature.
DESIGN
Systematic review.
METHODS
This integrative literature review was conducted by using Google Scholar, PubMed and Hinari databases from its inception to June 2021. The search included research articles, protocols and guidelines that describe home care practice after CS and assessed for their quality. Synthesis of recommendations from the included literature was classified based on the type of study design, and the review was guided by methodology registered in Prospero (ID CRD42021276905).
RESULTS
A total of 681 literatures were found, and 12 met the criteria. Recommended home care components were divided into four major categories; wound care practice (wound cleaning, drying and bandage change); nutrition (high-protein diet, vitamin C, fibre and balanced diet); exercise (pelvic floor muscle, walking and breathing exercise) and hygiene (bathing and wearing clean clothes). There was limited literature addressing the components of perineal care and home environment. Varying recommendations were found regarding wound cleaning and dressing in the studies done in low- and high-income countries.
Topics: Female; Humans; Pregnancy; Cesarean Section; Home Care Services
PubMed: 38532272
DOI: 10.1002/nop2.2145 -
Frontiers in Nutrition 2024Studies have shown that sphingomyelin (SM) and its metabolites play signaling roles in the regulation of human health. Endogenous SM is involved in metabolic syndrome...
BACKGROUND
Studies have shown that sphingomyelin (SM) and its metabolites play signaling roles in the regulation of human health. Endogenous SM is involved in metabolic syndrome (MetS), while dietary SM supplementation may maintain lipid metabolism and prevent or alleviate MetS. Therefore, we hypothesized that dietary SM supplementation is beneficial for human health.
AIMS
In order to examine the impacts of dietary SM on metabolic indexes in adults without MetS, we performed a meta-analysis to test our hypothesis.
METHODS
A comprehensive search was performed to retrieve randomized controlled trials that were conducted between 2003 and 2023 to examine the effects of dietary SM supplementation on metabolic parameters in the Cochrane Library, PubMed, Web of Science, Embase, and ClinicalTrials.gov databases. RevMan 5.4 and Stata 14.0 software were used for meta-analysis, a sensitivity analysis, the risk of bias, and the overall quality of the resulted evidence.
RESULTS
Eventually, 10 articles were included in this meta-analysis. Dietary SM supplementation did not affect the endline blood SM level. When compared to the control, SM supplementation reduced the blood total cholesterol level [MD: -12.97, 95% CI: (-14.57, -11.38), < 0.00001], low-density lipoprotein cholesterol level [MD: -6.62, 95% CI: (-10.74, -2.49), = 0.002], and diastolic blood pressure [MD: -3.31; 95% CI (-4.03, -2.58), < 0.00001] in adults without MetS. The supplementation also increased high-density lipoprotein level [MD:1.41, 95% CI: (0.94, 1.88), < 0.00001] and muscle fiber conduction velocity [MD: 95% 1.21 CI (0.53, 1.88), = 0.0005]. The intake of SM had no effect on the blood phospholipids and lyso-phosphatidylcholine, but slightly decreased phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol concentrations. Dietary SM supplementation reduced insulin level [MD: -0.63; 95% CI (-0.96, -0.31), = 0.0001] and HOMA-IR [MD: -0.23; 95% CI (-0.31, -0.16), < 0.00001] without affecting blood levels of glucose and inflammatory cytokines.
CONCLUSION
Overall, dietary SM supplementation had a protective effect on blood lipid profiles and insulin level, but had limited impacts on other metabolic parameters in adults without MetS. More clinical trials and basic research are required.
SYSTEMATIC REVIEW REGISTRATION
PROSPERO, identifier CRD42023438460.
PubMed: 38463938
DOI: 10.3389/fnut.2024.1363077