Coordinated increase in skeletal muscle fiber area and expression of IGF-I with resistance exercise in elderly post-operative patients

The effects of neuromuscular electrical stimulation on hospitalised adults: systematic review and meta-analysis of randomised controlled trials

INTRODUCTION

Neuromuscular electrical stimulation (NMES) is a treatment to prevent or reverse acquired disability in hospitalised adults. We conducted a systematic review and meta-analysis of its effectiveness.

METHOD

We searched MEDLINE, EMBASE, Cumulative Index to Nursing & Allied Health (CINAHL) and the Cochrane library. Inclusion criteria: randomised controlled trials of hospitalised adult patients comparing NMES to control or usual care. The primary outcome was muscle strength. Secondary outcomes were muscle size, function, hospital length of stay, molecular and cellular biomarkers, and adverse effects. We assessed risk of bias using the Cochrane risk-of-bias tool. We used Review Manager (RevMan) software for data extraction, critical appraisal and synthesis. We assessed certainty using the Grading of Recommendations Assessment, Development and Evaluation tool.

RESULTS

A total of 42 papers were included involving 1,452 participants. Most studies had unclear or high risk of bias. NMES had a small effect on muscle strength (moderate certainty) (standardised mean difference (SMD) = 0.33; P < 0.00001), a moderate effect on muscle size (moderate certainty) (SMD = 0.66; P < 0.005), a small effect on walking performance (moderate certainty) (SMD = 0.48; P < 0.0001) and a small effect on functional mobility (low certainty) (SMD = 0.31; P < 0.05). There was a small and non-significant effect on health-related quality of life (very low certainty) (SMD = 0.35; P > 0.05). In total, 9% of participants reported undesirable experiences. The effects of NMES on length of hospital stay, and molecular and cellular biomarkers were unclear.

CONCLUSIONS

NMES is a promising intervention component that might help to reduce or prevent hospital-acquired disability.

A scoping review of the contralateral effects of unilateral peripheral stimulation on neuromuscular function

It is known that resistance exercise using one limb can affect motor function of both the exercised limb and the unexercised contralateral limb, a phenomenon termed cross-education. It has been suggested that cross-education has clinical implications, e.g. in rehabilitation for orthopaedic conditions or post-stroke paresis. Much of the research on the contralateral effect of unilateral intervention on motor output is based on voluntary exercise. This scoping review aimed to map the characteristics of current literature on the cross-education caused by three most frequently utilised peripheral neuromuscular stimulation modalities in this context: electrical stimulation, mechanical vibration and percutaneous needling, that may direct future research and translate to clinical practice. A systematic search of relevant databases (Ebsco, ProQuest, PubMed, Scopus, Web of Science) through to the end of 2020 was conducted following the PRISMA Extension for Scoping Review. Empirical studies on human participants that applied a unilateral peripheral neuromuscular stimulation and assessed neuromuscular function of the stimulated and/or the unstimulated side were selected. By reading the full text, the demographic characteristics, context, design, methods and major findings of the studies were synthesised. The results found that 83 studies were eligible for the review, with the majority (53) utilised electrical stimulation whilst those applied vibration (18) or needling (12) were emerging. Although the contralateral effects appeared to be robust, only 31 studies claimed to be in the context of cross-education, and 25 investigated on clinical patients. The underlying mechanism for the contralateral effects induced by unilateral peripheral stimulation remains unclear. The findings suggest a need to enhance the awareness of cross-education caused by peripheral stimulation, to help improve the translation of theoretical concepts to clinical practice, and aid in developing well-designed clinical trials to determine the efficacy of cross-education therapies.

Aerobic and strength training exercise programme for cognitive impairment in people with mild to moderate dementia: the DAPA RCT

BACKGROUND

Approximately 670,000 people in the UK have dementia. Previous literature suggests that physical exercise could slow dementia symptom progression.

OBJECTIVES

To estimate the clinical effectiveness and cost-effectiveness of a bespoke exercise programme, in addition to usual care, on the cognitive impairment (primary outcome), function and health-related quality of life (HRQoL) of people with mild to moderate dementia (MMD) and carer burden and HRQoL.

DESIGN

Intervention development, systematic review, multicentred, randomised controlled trial (RCT) with a parallel economic evaluation and qualitative study.

SETTING

15 English regions.

PARTICIPANTS

People with MMD living in the community.

INTERVENTION

A 4-month moderate- to high-intensity, structured exercise programme designed specifically for people with MMD, with support to continue unsupervised physical activity thereafter. Exercises were individually prescribed and progressed, and participants were supervised in groups. The comparator was usual practice.

MAIN OUTCOME MEASURES

The primary outcome was the Alzheimer's Disease Assessment Scale - Cognitive Subscale (ADAS-Cog). The secondary outcomes were function [as measured using the Bristol Activities of Daily Living Scale (BADLS)], generic HRQoL [as measured using the EuroQol-5 Dimensions, three-level version (EQ-5D-3L)], dementia-related QoL [as measured using the Quality of Life in Alzheimer's Disease (QoL-AD) scale], behavioural symptoms [as measured using the Neuropsychiatric Inventory (NPI)], falls and fractures, physical fitness (as measured using the 6-minute walk test) and muscle strength. Carer outcomes were HRQoL (Quality of Life in Alzheimer's Disease) (as measured using the EQ-5D-3L) and carer burden (as measured using the Zarit Burden Interview). The economic evaluation was expressed in terms of incremental cost per quality-adjusted life-year (QALY) gained from a NHS and Personal Social Services perspective. We measured health and social care use with the Client Services Receipt Inventory. Participants were followed up for 12 months.

RESULTS

Between February 2013 and June 2015, 494 participants were randomised with an intentional unequal allocation ratio: 165 to usual care and 329 to the intervention. The mean age of participants was 77 years [standard deviation (SD) 7.9 years], 39% (193/494) were female and the mean baseline ADAS-Cog score was 21.5 (SD 9.0). Participants in the intervention arm achieved high compliance rates, with 65% (214/329) attending between 75% and 100% of sessions. Outcome data were obtained for 85% (418/494) of participants at 12 months, at which point a small, statistically significant negative treatment effect was found in the primary outcome, ADAS-Cog (patient reported), with a mean difference of -1.4 [95% confidence interval (CI) -2.62 to -0.17]. There were no treatment effects for any of the other secondary outcome measures for participants or carers: for the BADLS there was a mean difference of -0.6 (95% CI -2.05 to 0.78), for the EQ-5D-3L a mean difference of -0.002 (95% CI -0.04 to 0.04), for the QoL-AD scale a mean difference of 0.7 (95% CI -0.21 to 1.65) and for the NPI a mean difference of -2.1 (95% CI -4.83 to 0.65). Four serious adverse events were reported. The exercise intervention was dominated in health economic terms.

LIMITATIONS

In the absence of definitive guidance and rationale, we used a mixed exercise programme. Neither intervention providers nor participants could be masked to treatment allocation.

CONCLUSIONS

This is a large well-conducted RCT, with good compliance to exercise and research procedures. A structured exercise programme did not produce any clinically meaningful benefit in function or HRQoL in people with dementia or on carer burden.

FUTURE WORK

Future work should concentrate on approaches other than exercise to influence cognitive impairment in dementia.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN32612072.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full programme and will be published in full in Health Technology Assessment Vol. 22, No. 28. See the NIHR Journals Library website for further project information. Additional funding was provided by the Oxford NIHR Biomedical Research Centre and the Oxford NIHR Collaboration for Leadership in Applied Health Research and Care.

Role of androgen receptor on cyclic mechanical stretch-regulated proliferation of C2C12 myoblasts and its upstream signals: IGF-1-mediated PI3K/Akt and MAPKs pathways

OBJECTS

To detect the effects of androgen receptor (AR) on cyclic mechanical stretch-modulated proliferation of C2C12 myoblasts and its pathways: roles of IGF-1, PI3K and MAPK.

METHODS

C2C12 were randomly divided into five groups: un-stretched control, six or 8 h of fifteen percent stretch, and six or 8 h of twenty percent stretch. Cyclic mechanical stretch of C2C12 were completed using a computer-controlled FlexCell Strain Unit. Cell proliferation and IGF-1 concentration in medium were detected by CCK8 and ELISA, respectively. Expressions of AR and IGF-1R, and expressions and activities of PI3K, p38 and ERK1/2 in stretched C2C12 cells were determined by Western blot.

RESULTS

①The proliferation of C2C12 cells, IGF-1 concentration in medium, expressions of AR and IGF-1R, and activities of PI3K, p38 and ERK1/2 were increased by 6 h of fifteen percent stretch, while decreased by twenty percent stretch for six or 8 h ②The fifteen percent stretch-increased proliferation of C2C12 cells was reversed by AR inhibitor, Flutamide. ③The increases of AR expression, activities of PI3K, p38 and ERK1/2 resulted from fifteen percent stretch were attenuated by IGF-1 neutralizing antibody, while twenty percent stretch-induced decreases of the above indicators were enhanced by recombinant IGF-1. ④Specific inhibitors of p38, ERK1/2 and PI3K all decreased the expression of AR in fifteen percent and twenty percent of stretched C2C12 cells.

CONCLUSIONS

Cyclic mechanical stretch modulated the proliferation of C2C12 cells, which may be attributed to the alterations of AR via IGF-1-PI3K/Akt and IGF-1-MAPK (p38, ERK1/2) pathways in C2C12 cells.

A hypothesis for a possible synergy between ghrelin and exercise in patients with cachexia: Biochemical and physiological bases

This article reviews the biochemical and physiological observations underpinning the synergism between ghrelin and ghrelin agonists with exercise, especially progressive resistance training that has been shown to increase muscle mass. The synergy of ghrelin agonists and physical exercise could be beneficial in conditions where muscle wasting is present, such as that found in patients with advanced cancer. The principal mechanism that controls muscle anabolism following the activation of the ghrelin receptor in the central nervous system involves the release of growth hormone/insulin-like growth factor-1 (GH/IGF-1). GH/IGF-1 axis has a dual pathway of action on muscle growth: (a) a direct action on muscle, bone and fat tissue and (b) an indirect action via the production of both muscle-restricted mIGF-1 and anti-cachectic cytokines. Progressive resistance training is a potent inducer of the secretion the muscle-restricted IGF-1 (mIGF-1) that enhances protein synthesis, increases lean body mass and eventually leads to the improvement of muscle strength. Thus, the combination of ghrelin administration with progressive resistance training may serve to circumvent ghrelin resistance and further reduce muscle wasting, which are commonly associated with cachexia.

Development of an exercise intervention to improve cognition in people with mild to moderate dementia: Dementia And Physical Activity (DAPA) Trial, registration ISRCTN32612072

More than 800000 people in the UK have dementia, and it is a government priority to improve dementia care. Drug treatment options are relatively limited. The Dementia And Physical Activity (DAPA) study is a randomised trial which targets cognition in people with dementia, using an exercise programme. There is evidence to suggest that both aerobic and resistance exercise may be useful in improving cognition. Hence the intervention comprises a supervised part of twice-weekly exercise classes of one hour duration for 4 months, including aerobic exercise at moderate intensity on static bicycles, and resistance (weight training) exercise using weight vests, weight belts and dumbbells. Thereafter participants progress to unsupervised, independent exercise. Aids to behaviour modification have been incorporated into the intervention. The DAPA intervention has been designed to maximise likelihood of effectiveness and cost-effectiveness, and for delivery in the UK National Health Service.

Effectiveness of land-based physiotherapy exercise following hospital discharge following hip arthroplasty for osteoarthritis: an updated systematic review

BACKGROUND

Existing review required updating.

OBJECTIVE

To evaluate the effectiveness of physiotherapy exercise after discharge from hospital on function, walking, range of motion, quality of life and muscle strength, for patients following elective primary total hip arthroplasty for osteoarthritis.

DESIGN

Systematic review from January 2007 to November 2013.

DATA SOURCES

AMED, CINAHL, EMBASE, MEDLINE, Kingsfund Database, and PEDro. Cochrane CENTRAL, BioMed Central (BMC), The Department of Health National Research Register and Clinical Trials.gov register. Searches were overseen by a librarian. Authors were contacted for missing information. No language restrictions were applied.

ELIGIBILITY CRITERIA

Trials comparing physiotherapy exercise vs usual/standard care, or comparing two types of relevant exercise physiotherapy, following discharge from hospital after elective primary total hip replacement for osteoarthritis were reviewed.

OUTCOMES

Functional activities of daily living, walking, quality of life, muscle strength and joint range of motion.

STUDY APPRAISAL

Quality and risk of bias for studies were evaluated. Data were extracted and meta-analyses considered.

RESULTS

11 trials are included in the review. Trial quality was mixed. Newly included studies were assessed as having lower risk of bias than previous studies. Narrative review indicates that physiotherapy exercise after discharge following total hip replacement may potentially benefit patients in terms of function, walking and muscle strengthening.

LIMITATIONS

The overall quality and quantity of trials, and their diversity, prevented meta-analyses.

CONCLUSIONS

Disappointingly, insufficient evidence still prevents the effectiveness of physiotherapy exercise following discharge to be determined for this patient group. High quality, adequately powered, trials with long term follow up are required.

Progressive resistance training before and after total hip and knee arthroplasty: a systematic review

OBJECTIVE

To investigate the effect of progressive resistance training (PRT) on muscle strength and functional capacity before and/or after total hip arthroplasty (THA) and total knee arthroplasty (TKA). The effects of THA and TKA upon quality of life and the rate of adverse events were also investigated.

DATA SOURCES

Literature from nine databases.

REVIEW METHODS

Studies were included if 1) the effect of a PRT intervention was compared with no intervention or another type of intervention; 2) the outcomes included muscle strength and/or functional capacity; 3) all participants were scheduled for or had just undergone THA or TKA; 4) they were randomized, controlled trials (RCT); and 5) only full-length papers in English were studied. Data on patient characteristics, training regime, controls, and outcome measures were extracted.

RESULTS

Four RCT studies on PRT and THA including 136 patients and three RCT studies on PRT and TKA including 284 patients were identified and rated according to the PEDro scale. The general methodological quality of the studies was low. No adverse events were reported in any of the studies. Weak evidence of a beneficial effect of PRT before and/or after THA on muscle strength and functional capacity was found. No effect of PRT before TKA on muscle strength and functional capacity was found. The results of postoperative PRT were too heterogeneous to allow conclusions.

CONCLUSION

PRT is safe and feasible before and/or after THA. PRT is safe, but the methodological quality of existing evidence permits no conclusion on the effectiveness of PRT before and/or after TKA.

Exercise as an intervention to improve metabolic outcomes after intrauterine growth restriction

Individuals born after intrauterine growth restriction (IUGR) are at an increased risk of developing diabetes in their adult life. IUGR impairs β-cell function and reduces β-cell mass, thereby diminishing insulin secretion. IUGR also induces insulin resistance, with impaired insulin signaling in muscle in adult humans who were small for gestational age (SGA) and in rodent models of IUGR. There is epidemiological evidence in humans that exercise in adults can reduce the risk of metabolic disease following IUGR. However, it is not clear whether adult IUGR individuals benefit to the same extent from exercise as do normal-birth-weight individuals, as our rat studies suggest less of a benefit in those born IUGR. Importantly, however, there is some evidence from studies in rats that exercise in early life might be able to reverse or reprogram the long-term metabolic effects of IUGR. Studies are needed to address gaps in current knowledge, including determining the mechanisms involved in the reprogramming effects of early exercise in rats, whether exercise early in life or in adulthood has similar beneficial metabolic effects in larger animal models in which insulin resistance develops after IUGR. Human studies are also needed to determine whether exercise training improves insulin secretion and insulin sensitivity to the same extent in IUGR adults as in control populations. Such investigations will have implications for customizing the recommended level and timing of exercise to improve metabolic health after IUGR.

Characterization and regulation of mechanical loading-induced compensatory muscle hypertrophy

In mammalian systems, skeletal muscle exists in a dynamic state that monitors and regulates the physiological investment in muscle size to meet the current level of functional demand. This review attempts to consolidate current knowledge concerning development of the compensatory hypertrophy that occurs in response to a sustained increase in the mechanical loading of skeletal muscle. Topics covered include: defining and measuring compensatory hypertrophy, experimental models, loading stimulus parameters, acute responses to increased loading, hyperplasia, myofiber-type adaptations, the involvement of satellite cells, mRNA translational control, mechanotransduction, and endocrinology. The authors conclude with their impressions of current knowledge gaps in the field that are ripe for future study.

Ageing is associated with diminished muscle re-growth and myogenic precursor cell expansion early after immobility-induced atrophy in human skeletal muscle

Recovery of skeletal muscle mass from immobilisation-induced atrophy is faster in young than older individuals, yet the cellular mechanisms remain unknown. We examined the cellular and molecular regulation of muscle recovery in young and older human subjects subsequent to 2 weeks of immobility-induced muscle atrophy. Retraining consisted of 4 weeks of supervised resistive exercise in 9 older (OM: mean age) 67.3, range 61-74 yrs) and 11 young (YM: mean age 24.4, range 21-30 yrs) males. Measures of myofibre area (MFA), Pax7-positive satellite cells (SCs) associated with type I and type II muscle fibres, as well as gene expression analysis of key growth and transcription factors associated with local skeletal muscle milieu, were performed after 2 weeks immobility (Imm) and following 3 days (+3d) and 4 weeks (+4wks) of retraining. OM demonstrated no detectable gains in MFA (vastus lateralis muscle) and no increases in number of Pax7-positive SCs following 4wks retraining, whereas YM increased their MFA (P < 0.05), number of Pax7-positive cells, and had more Pax7-positive cells per type II fibre than OM at +3d and +4wks (P < 0.05). No age-related differences were observed in mRNA expression of IGF-1Ea, MGF, MyoD1 and HGF with retraining, whereas myostatin expression levels were more down-regulated in YM compared to OM at +3d (P < 0.05). In conclusion, the diminished muscle re-growth after immobilisation in elderly humans was associated with a lesser response in satellite cell proliferation in combination with an age-specific regulation of myostatin. In contrast, expression of local growth factors did not seem to explain the age-related difference in muscle mass recovery.

Activation of Toll-like receptor 3 amplifies mesenchymal stem cell trophic factors and enhances therapeutic potency

Clinical trials of bone marrow mesenchymal stem cell (MSC) therapy have thus far demonstrated moderate and inconsistent benefits, indicating an urgent need to improve therapeutic efficacy. Although administration of sufficient cells is necessary to achieve maximal therapeutic benefits, documented MSC clinical trials have largely relied on injections of ∼1 × 10(6) cells/kg, which appears too low to elicit a robust therapeutic response according to published preclinical studies. However, repeated cell passaging necessary for large-scale expansion of MSC causes cellular senescence and reduces stem cell potency. Using the RNA mimetic polyinosinic-polycytidylic acid [poly(I:C)] to engage MSC Toll-like receptor 3 (TLR3), we found that poly(I:C), signaling through multiple mitogen-activated protein kinase pathways, induced therapeutically relevant trophic factors such as interleukin-6-type cytokines, stromal-derived factor 1, hepatocyte growth factor, and vascular endothelial growth factor while slightly inhibiting the proliferation and migration potentials of MSC. At the suboptimal injection dose of 1 × 10(6) cells/kg, poly(I:C)-treated MSC, but not untreated MSC, effectively stimulated regeneration of the failing hamster heart 1 mo after cell administration. The regenerating heart exhibited increased CD34(+)/Ki67(+) and CD34(+)/GATA4(+) progenitor cells in the presence of decreased inflammatory cells and cytokines. Cardiac functional improvement was associated with a ∼50% reduction in fibrosis, a ∼40% reduction in apoptosis, and a ∼55% increase in angiogenesis, culminating in prominent cardiomyogenesis evidenced by abundant distribution of small myocytes and a ∼90% increase in wall thickening. These functional, histological, and molecular characterizations thus establish the utility of TLR3 engagement for enabling the low-dose MSC therapy that may be translated to more efficacious clinical applications.

Skeletal muscle hypertrophy and muscle myostatin reduction after resistive training in stroke survivors

BACKGROUND AND PURPOSE

Stroke survivors experience disproportionate muscle atrophy and other detrimental tissue composition changes on the paretic side. The purpose was to determine whether myostatin levels are higher in paretic vs nonparetic muscle and the effects of resistive training (RT) on paretic and nonparetic mid-thigh muscle composition and myostatin mRNA expression in stroke survivors.

METHODS

Fifteen stroke survivors (50-76 years) underwent bilateral multi-slice thigh CT scanning from the knee to the hip, bilateral vastus lateralis skeletal muscle tissue biopsies, a total body scan by dual-energy X-ray absorptiometry, and 1-repetition maximum strength test before and after a 12-week, (3 times/week) RT intervention.

RESULTS

Total body fat mass and fat-free mass did not change. Bilateral leg press and leg extension 1-repetition maximum strength increased 31% to 56% with RT (P<0.001). Paretic and nonparetic muscle area of the mid-thigh increased 13% (P<0.01) and 9% (P<0.05), respectively, after RT. Muscle attenuation of the mid-thigh increased 15% and 8% (both P<0.01) in the paretic and nonparetic thigh, respectively, representing reduced intramuscular fat. Muscle volume increased 14% (P<0.001) in the paretic thigh and 16% (P<0.05) in the nonparetic thigh after RT. Myostatin mRNA expression levels were 40% higher in the paretic than nonparetic muscle (P=0.001) at baseline and decreased 49% in the paretic muscle (P<0.005) and 27% in the nonparetic muscle (P=0.06) after RT.

CONCLUSIONS

Progressive RT stimulates significant muscle hypertrophy and intramuscular fat reductions in disabled stroke survivors. The increased myostatin mRNA in the paretic thigh and reduction with RT imply an important regulatory role for myostatin after stroke.

Activation of host tissue trophic factors through JAK-STAT3 signaling: a mechanism of mesenchymal stem cell-mediated cardiac repair

We recently demonstrated a cardiac therapeutic regimen based on injection of bone marrow mesenchymal stem cells (MSCs) into the skeletal muscle. Although the injected MSCs were trapped in the local musculature, the extracardiac cell delivery approach repaired the failing hamster heart. This finding uncovers a tissue repair mechanism mediated by trophic factors derived from the injected MSCs and local musculature that can be explored for minimally invasive stem cell therapy. However, the trophic factors involved in cardiac repair and their actions remain largely undefined. We demonstrate here a role of MSC-derived IL-6-type cytokines in cardiac repair through engagement of the skeletal muscle JAK-STAT3 axis. The MSC IL-6-type cytokines activated JAK-STAT3 signaling in cultured C2C12 skeletal myocytes and caused increased expression of the STAT3 target genes hepatocyte growth factor (HGF) and VEGF, which was inhibited by glycoprotein 130 (gp130) blockade. These in vitro findings were corroborated by in vivo studies, showing that the MSC-injected hamstrings exhibited activated JAK-STAT3 signaling and increased growth factor/cytokine production. Elevated host tissue growth factor levels were also detected in quadriceps, liver, and brain, suggesting a possible global trophic effect. Paracrine actions of these host tissue-derived factors activated the endogenous cardiac repair mechanisms in the diseased heart mediated by Akt, ERK, and JAK-STAT3. Administration of the cell-permeable JAK-STAT inhibitor WP1066 abrogated MSC-mediated host tissue growth factor expression and functional improvement. The study illustrates that the host tissue trophic factor network can be activated by MSC-mediated JAK-STAT3 signaling for tissue repair.