Electrical stimulation and peripheral muscle function in COPD: A systematic review

20 years of neuromuscular electrical stimulation in COPD

Although a lung disease, COPD is also associated with extrapulmonary manifestations including, among others, limb muscle dysfunction. Limb muscle dysfunction is a key systemic consequence of COPD that impacts patients' physical activity, exercise tolerance, quality of life and survival. Deconditioning is the main mechanism underlying the development of limb muscle dysfunction in COPD, which can be partially improved with exercise. However, some patients may not be able to tolerate exercise because of incapacitating breathlessness or unwillingness to undertake whole-body exercise. Alternative training modalities that do not give rise to dyspnoea, such as neuromuscular electrical stimulation (NMES), are urged. Over the past 20 years, NMES in COPD has presented conflicting conclusions in meta-analysis. In this review, we try to understand the reason for this result by analysing possible biases and factors that brought conflicting conclusions. We discuss the population (the intervention group, but also the control group), the outcome measures, the frequency of stimulation, the rehabilitation protocol (i.e. NMES alone versus standard care/rehabilitation or NMES plus conventional exercise training versus conventional exercise training alone or NMES versus sham treatment) and the trial design. The main reason for this discrepancy is the lack of dedicated guidelines for NMES. Further research is urged to determine the optimal parameters for an NMES programme. Despite this, NMES appears to be an effective means of enhancing quadriceps strength and exercise capacity in COPD with the potential to break the vicious circle induced by the disease and COPD patients' lifestyle.

Electrical Stimulation and Muscle Strength Gains in Healthy Adults: A Systematic Review

ABSTRACT

Mukherjee, S, Fok, JR, and van Mechelen, W. Electrical stimulation and muscle strength gains in healthy adults: A systematic review. J Strength Cond Res 37(4): 938-950, 2023-Electrical muscle stimulation (EMS) is a popular method for strength gains among athletes and fitness enthusiasts. This review investigated the literature from 2008 to 2020 on EMS application protocols, strength adaptations, neural adaptations, and its use as an independent and combined training tool for strength gain in healthy adults. The investigation was modeled after the 2020 PRISMA guidelines. The eligibility criteria included studies that assessed the effect of EMS, either alone or in combination with voluntary resistance training (VRT) in healthy adult populations, involving a control group performing either usual or sham training, with at least 1 performance outcome measure assessed during experimental randomized controlled trials (RCTs), cluster RCT, randomized crossover trials, or nonrandomized studies. Ten studies met the eligibility criteria with a total of 174 subjects. Eight studies investigated the effect of EMS on lower limb muscles and 2 on elbow flexors. Five studies used concurrent VRT. Studies were heterogenous in methods, subject characteristics, intervention, and EMS protocols. All 10 studies reported significant strength gains as an outcome of EMS treatment, but there were no improvements in strength-related functional outcome measures. The optimal threshold for treatment duration, EMS intensity, pulse, and frequency could not be determined due to methodological differences and EMS application protocol inconsistency between studies. Protocol variations also existed between the studies that combined EMS with VRT. Standardized protocols are needed for electrode placement location, motor point identification, positioning of the body part being investigated, impulse type, intensity, and duration of stimulus.

Self-directed home-based neuromuscular electrical stimulation (NMES) in patients with advanced cancer and poor performance status: a feasibility study

PURPOSE

Concurrent neuromuscular electrical stimulation (NMES) involving sub-tetanic low frequency and tetanic high frequency which targets aerobic and muscular fitness is a potential alternative to conventional exercise in cancer rehabilitation. However, its safety and feasibility in patients with advanced cancer are unknown. The aim of this feasibility study was to determine safety and feasibility and evaluate changes in functional and health-related quality of life (HR-QoL) outcomes in individuals with advanced cancer and poor performance status after concurrent NMES. These results should help inform the design of future studies.

METHODS

Participants with advanced cancer and poor performance status (Eastern Cooperative Oncology Group scale ≥ 2) (n = 18) were recruited. The intervention included a novel NMES intervention implemented over a 4-week period. Functional exercise capacity, lower limb muscle endurance and HR-QoL were measured by 6-min walk test (6MWT), 30-s sit-to-stand (30STS) and European Organization for Research and Treatment quality of life questionnaire core-30 (EORTC QLQ C30) pre and post-intervention. Participants unable to complete the 6-min walk test completed the timed up and go test. Participant experience and the impact of the intervention on daily life were investigated through semi-structured interviews.

RESULTS

Ten of 18 participants completed the intervention. No adverse events were reported. Seven of 8 participants improved 6MWT performance (2 of 2 improved timed up and go), 8 of 10 participants improved 30STS and 8 of 10 participants improved Global quality of life. Perceived benefits included improved mobility and muscle strength.

CONCLUSIONS

Neuromuscular electrical stimulation appears safe and feasible in advanced cancer and may improve physical and HR-QoL outcomes. Future prospective trials are warranted to confirm these findings prior to clinical implementation in an advanced cancer setting.

Design considerations for the development of neuromuscular electrical stimulation (NMES) exercise in cancer rehabilitation

Aim: The aim of this narrative review is to explore design considerations for effective neuromuscular electrical stimulation exercise prescription in cancer rehabilitation, with simultaneous consideration for fundamental principles of exercise training and the current state of the art in neuromuscular electrical stimulation technologies and application methodologies.Method: Narrative review.Results: First, we consider the key neuromuscular electrical stimulation exercise design considerations, with a focus on training objectives and individual training requirements and constraints for individuals with cancer. Here, we contend that concurrent, low and high frequency neuromuscular electrical stimulation exercise, individually prescribed and progressed may be optimal for enhancing physical function. Second, we review the appropriate literature to identify the most appropriate stimulation parameters (pulse frequency, intensity, duration and duty cycle) to deliver effective neuromuscular electrical stimulation in cancer rehabilitation.Conclusions: We propose an informed and innovative neuromuscular electrical stimulation exercise intervention design and provide practical information for clinicians and practitioners who may work with and implement neuromuscular electrical stimulation exercise in cancer.Implications for rehabilitationNeuromuscular electrical stimulation is an emerging technology in cancer rehabilitation to help provide an aerobic and muscle strengthening exercise stimulus.Neuromuscular electrical stimulation may help improve aerobic exercise capacity, muscle strength and augment quality of life.Current prescription in cancer lacks adherence to the fundamental principles of exercise training, which may negatively affect adherence.

The Impact of Upper Limb Training with Breathing Maneuver in Lung Function, Functional Capacity, Dyspnea Scale, and Quality of Life in Patient with Stable Chronic Obstructive of Lung Disease

BACKGROUND

Exercise tolerance is one of the main impacts of COPD. COPD patients often experience dyspnea and fatigue after doing daily activities using their limb parts, even in simple thing such as lifting or grooming. Nowadays, many pulmonologists concerned in pulmonary rehabilitation to modify some limb training with breathing manoeuvre to get positive impact in stable COPD patient.

AIM

The purpose of this study is to examine the impact of this modified upper limb training in lung function, functional capacity, dyspnea scale, and quality of life in patients with stable COPD.

METHOD

This was a quasi-experimental study held in 2017 on 22 stable COPD patients (based on GOLD 2018 criteria). Patients were given modified upper limb training with breathing manoeuvre that leads and monitored by a physiotherapist and physician in 10-20 minutes twice a week for 8 weeks. Before and after completed all sessions of training, we measured pulmonary functions test include FEV1 and FVC, functional capacity by 6 MWT, dyspnea scale by mMRC, and quality of life by CAT assessment. Statistical analysis was performed by Wilcoxon and paired t-test.

RESULTS

There was an improvement of lung function, both FEV1 (40.7 ± 13.8 to 47.3 ± 14.2; p-value 0.001) and FVC (50.7 ± 14.1 to 54.1 ± 14.7; p-value: 0.207) after training. There was a significant change of functional capacity in 6 MWT mean (277.3 ± 80.8 to 319.1 ± 78.3; p-value: 0.001). There was an improved quality of life after training, measured by decreasing in CAT score (23.9 ± 5.5 to 18.3 ± 5.2; p-value: 0.000). There was no significant change in the mMRC scale (p-value: 0.429).

CONCLUSION

There was an improvement of lung function, functional capacity, and quality of life in stable COPD after upper limb training with breathing manoeuvre in stable COPD patients.

Hypoglossal-facial 'side'-to-side Neurorrhaphy Combined with Electrical Myostimulation for Facial Palsy in Rats

Introduction This study investigated the effect of combining hypoglossal-facial nerve “side”-to-side neurorrhaphy and electrical myostimulation in a rat model of facial palsy.

Methods Rats with facial nerve crush injury were subjected to control condition, monotherapy of either neurorrhaphy or electrical myostimulation, or bitherapy of the two treatments. After 1, 3, and 6 months, rats were performed the facial symmetry evaluation, electrophysiological examination and the retrograde labeling of motor neurons.

Results As early as 3 months after injury, face symmetry significantly improved in rats of the bitherapy group. At 3 or 6 months after injury, either the parameters of electrophysiological examination or the number of labeled motor neurons were significantly increased in the bitherapy group than in any other group.

Discussion The combination of neurorrhaphy and electrical myostimulation effectively promoted the functional recovery after facial nerve crush injury.

The efficacy and prescription of neuromuscular electrical stimulation (NMES) in adult cancer survivors: a systematic review and meta-analysis

PURPOSE

This study aims to (1) summarise and critically evaluate the effects of neuromuscular electrical stimulation (NMES) on indices of health and quality of life (QoL) in adult cancer survivors, (2) assess the safety of NMES as a rehabilitation method in this population, and (3) identify commonly used NMES treatment parameters and describe treatment progression.

METHODS

A systematic search of four electronic databases targeted studies evaluating the effects of NMES on physical function, aerobic fitness, muscle strength, body composition, and health-related quality of life (HR-QoL) in adult cancer survivors, published through March 2018. Two reviewers independently reviewed and appraised the risk of bias of each study.

RESULTS

Nine studies were included. Meta-analyses found that the overall pooled effect favoured NMES for improving muscle strength, but the standardised mean difference was not significant (0.36; 95% CI - 0.25, 0.96). Further meta-analyses indicated that NMES significantly improved HR-QoL (0.36; 95% CI 0.10, 0.62), with notable gains identified under the subcategories QoL Function (0.87; 95% CI 0.32, 1.42). Current NMES prescription is not standardised and NMES is prescribed to target secondary complications of treatment. Risk of bias was high for most studies.

CONCLUSIONS

NMES use in adult cancer survivors is an emerging field and current literature is limited by studies of poor quality and a lack of adequately powered RCTs. Existing evidence suggests that NMES is safe and may be more effective than usual care for improving HR-QoL. Prescription and progression should be tailored for the individual based on functional deficits.

Technical development of transcutaneous electrical nerve inhibition using medium-frequency alternating current

Background

Innovative technical approaches to controlling undesired sensory and motor activity, such as hyperalgesia or spasticity, may contribute to rehabilitation techniques for improving neural plasticity in patients with neurologic disorders. To date, transcutaneous electrical stimulation has used low frequency pulsed currents for sensory inhibition and muscle activation. Yet, few studies have attempted to achieve motor nerve inhibition using transcutaneous electrical stimulation. This study aimed to develop a technique for transcutaneous electrical nerve inhibition (TENI) using medium-frequency alternating current (MFAC) to suppress both sensory and motor nerve activity in humans.

Methods

Surface electrodes were affixed to the skin of eight young adults to stimulate the median nerve. Stimulation intensity was increased up to 50% and 100% of the pain threshold. To identify changes in sensory perception by transcutaneous MFAC (tMFAC) stimulation, we examined tactile and pressure pain thresholds in the index and middle fingers before and after stimulation at 10 kHz. To demonstrate the effect of tMFAC stimulation on motor inhibition, stimulation was applied while participants produced flexion forces with the index and middle fingers at target forces (50% and 90% of MVC, maximum voluntary contraction).

Results

tMFAC stimulation intensity significantly increased tactile and pressure pain thresholds, indicating decreased sensory perception. During the force production task, tMFAC stimulation with the maximum intensity immediately reduced finger forces by ~ 40%. Finger forces recovered immediately after stimulation cessation. The effect on motor inhibition was greater with the higher target force (90% MVC) than with the lower target (50% MVC). Also, higher tMFAC stimulation intensity provided a greater inhibition effect on both sensory and motor nerve activity.

Conclusion

We found that tMFAC stimulation immediately inhibits sensory and motor activity. This pre-clinical study demonstrates a novel technique for TENI using MFAC stimulation and showed that it can effectively inhibit both sensory perception and motor activity. The proposed technique can be combined with existing rehabilitation devices (e.g., a robotic exoskeleton) to inhibit undesired sensorimotor activities and to accelerate recovery after neurologic injury.

Neuromuscular electrostimulation for adults with chronic obstructive pulmonary disease

BACKGROUND

In people with chronic obstructive pulmonary disease (COPD), the use of neuromuscular electrostimulation (NMES) either alone, or together with conventional exercise training, might improve the condition of the peripheral muscles, increase exercise capacity and functional performance, reduce symptoms and improve health-related quality of life (HRQoL).

OBJECTIVES

To determine the effects of NMES, applied in isolation or concurrently with conventional exercise training to one or more peripheral muscles, on peripheral muscle force and endurance, muscle size, exercise capacity, functional performance, symptoms, HRQoL and adverse events in people with COPD.

SEARCH METHODS

We searched the Cochrane Airways Group Specialised Register, the Physiotherapy Evidence Database, clinical trial registries and conference abstracts on 14 March 2018.

SELECTION CRITERIA

Randomised controlled trials that recruited adults with COPD if they had compared outcomes between a group that received NMES and a group that received usual care or compared outcomes between a group that received NMES plus conventional exercise training and a group that participated in conventional exercise training alone.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias using the Cochrane 'Risk of bias' tool. We expressed continuous data as either the standardised mean difference (SMD) or mean difference (MD) with the corresponding 95% confidence interval (CI). We assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

Nineteen studies met the inclusion criteria of which 16 contributed data on 267 participants with COPD (mean age 56 to 76 years and 67% were men). Of these 16 studies, seven explored the effect of NMES versus usual care and nine explored the effect of NMES plus conventional exercise training versus conventional exercise training alone. Six studies utilised sham stimulation in the control group. When applied in isolation, NMES produced an increase in peripheral muscle force (SMD 0.34, 95% CI 0.02 to 0.65; low-quality evidence) and quadriceps endurance (SMD 1.36, 95% CI 0.59 to 2.12; low-quality evidence) but the effect on thigh muscle size was unclear (MD 0.25, 95% CI -0.11 to 0.61; low-quality evidence). There were increases in six-minute walk distance (6MWD) (MD 39.26 m, 95% CI 16.31 to 62.22; low-quality evidence) and time to symptom limitation exercising at a submaximal intensity (MD 3.62 minutes, 95% CI 2.33 to 4.91). There was a reduction in the severity of leg fatigue on completion of an exercise test (MD -1.12 units, 95% CI -1.81 to -0.43). The increase in peak rate of oxygen uptake (VO_2peak) was of borderline significance (MD 0.10 L/minute, 95% CI 0.00 to 0.19).For NMES with conventional exercise training, there was an uncertain effect on peripheral muscle force (SMD 0.47, 95% CI -0.10 to 1.04; very low-quality evidence) and there were insufficient studies to undertake a meta-analysis on the effect on quadriceps endurance or thigh muscle size. However, there was an increase in 6MWD in favour of NMES combined with conventional exercise training (MD 25.87 m, 95% CI 1.06 to 50.69; very low-quality evidence). In people admitted to either in an intensive care unit or a respiratory high dependency centre, NMES combined with conventional exercise reduced the time taken for participants to first sit out of bed by 4.98 days (95% CI -8.55 to -1.41; very low-quality evidence), although the statistical heterogeneity for this analysis was high (I² = 60%). For both types of studies (i.e. NMES versus usual care and NMES with conventional exercise training versus conventional exercise training alone), there was no risk difference for mortality or minor adverse events in participants who received NMES.

AUTHORS' CONCLUSIONS

NMES, when applied in isolation, increased quadriceps force and endurance, 6MWD and time to symptom limitation exercising at a submaximal intensity, and reduced the severity of leg fatigue on completion of exercise testing. It may increase VO_2peak, but the true effect on this outcome measure could be trivial. However, the quality of evidence was low or very low due to risk of bias within the studies, imprecision of the estimates, small number of studies and inconsistency between the studies. Although there were no additional gains in quadriceps force with NMES plus conventional exercise training, there was evidence of an increase in 6MWD. Further, in people who were the most debilitated, the addition of NMES may have accelerated the achievement of a functional milestone, that is, the first time someone sits out of bed.

Effectiveness of neuromuscular electrical stimulation for the rehabilitation of moderate-to-severe COPD: a meta-analysis

PURPOSE

Patients with COPD often experience skeletal muscle dysfunction. For those who are unable or unwilling to undertake physical training, neuromuscular electrical stimulation (NMES) may provide an alternative method of rehabilitation. The purpose of this meta-analysis was to investigate the controversial topic of whether this therapy is effective in patients with moderate-to-severe COPD.

PATIENTS AND METHODS

We pooled data from nine trials published between January 9, 2002 and January 4, 2016 across PubMed, Embase, Cochrane Central Register of Controlled Trials, Google Scholar, and relevant websites for randomized controlled trials. In these trials, patients with moderate-to-severe COPD were randomly allocated to receive NMES. Primary outcomes were quadricep strength and exercise capacity. The secondary outcome was health-related quality of life.

RESULTS

We extracted data from 276 patients. NMES contributed to statistically improved quadricep strength (standardized mean difference 1.12, 95% confidence interval [CI] 0.64-1.59, I²=54%; P<0.00001) and exercise capacity, including longer exercise distance (weighted mean difference 51.53, 95% CI 20.13-82.93, I²=90%; P=0.001), and longer exercise endurance (standardized mean difference 1.11, 95% CI 0.14-2.08, I²=85%; P=0.02). There was no significant difference in St George's Respiratory Questionnaire scores (weighted mean difference -0.07, 95% CI -2.44 to 2.30, I²=56%; P=0.95).

CONCLUSION

NMES appears an effectual means of enhancing quadricep strength and exercise capacity in moderate-to-severe COPD patients. Further research is demanded to clarify its effect on other outcomes and determine the optimal parameters for an NMES program.

Neuromuscular electrical stimulation for muscle weakness in adults with advanced disease

BACKGROUND

This review is an update of a previously published review in the Cochrane Database of Systematic Reviews Issue 1, 2013 on Neuromuscular electrical stimulation for muscle weakness in adults with advanced disease.Patients with advanced progressive disease often experience muscle weakness, which can impact adversely on their ability to be independent and their quality of life. In those patients who are unable or unwilling to undertake whole-body exercise, neuromuscular electrical stimulation (NMES) may be an alternative treatment to enhance lower limb muscle strength. Programmes of NMES appear to be acceptable to patients and have led to improvements in muscle function, exercise capacity, and quality of life. However, estimates regarding the effectiveness of NMES based on individual studies lack power and precision.

OBJECTIVES

Primary objective: to evaluate the effectiveness of NMES on quadriceps muscle strength in adults with advanced disease. Secondary objectives: to examine the safety and acceptability of NMES, and its effect on peripheral muscle function (strength or endurance), muscle mass, exercise capacity, breathlessness, and health-related quality of life.

SEARCH METHODS

We identified studies from searches of the Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Database of Systematic Reviews (CDSR), and Database of Abstracts of Reviews of Effects (DARE) (the Cochrane Library), MEDLINE (OVID), Embase (OVID), CINAHL (EBSCO), and PsycINFO (OVID) databases to January 2016; citation searches, conference proceedings, and previous systematic reviews.

SELECTION CRITERIA

We included randomised controlled trials in adults with advanced chronic respiratory disease, chronic heart failure, cancer, or HIV/AIDS comparing a programme of NMES as a sole or adjunct intervention to no treatment, placebo NMES, or an active control. We imposed no language restriction.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data on study design, participants, interventions, and outcomes. We assessed risk of bias using the Cochrane 'Risk of bias' tool. We calculated mean differences (MD) or standardised mean differences (SMD) between intervention and control groups for outcomes with sufficient data; for other outcomes we described findings from individual studies. We assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

Eighteen studies (20 reports) involving a total of 933 participants with COPD, chronic respiratory disease, chronic heart failure, and/or thoracic cancer met the inclusion criteria for this update, an additional seven studies since the previous version of this review. All but one study that compared NMES to resistance training compared a programme of NMES to no treatment or placebo NMES. Most studies were conducted in a single centre and had a risk of bias arising from a lack of participant or assessor blinding and small study size. The quality of the evidence using GRADE comparing NMES to control was low for quadriceps muscle strength, moderate for occurrence of adverse events, and very low to low for all other secondary outcomes. We downgraded the quality of evidence ratings predominantly due to inconsistency among study findings and imprecision regarding estimates of effect. The included studies reported no serious adverse events and a low incidence of muscle soreness following NMES.NMES led to a statistically significant improvement in quadriceps muscle strength as compared to the control (12 studies; 781 participants; SMD 0.53, 95% confidence interval (CI) 0.19 to 0.87), equating to a difference of approximately 1.1 kg. An increase in muscle mass was also observed following NMES, though the observable effect appeared dependent on the assessment modality used (eight studies, 314 participants). Across tests of exercise performance, mean differences compared to control were statistically significant for the 6-minute walk test (seven studies; 317 participants; 35 m, 95% CI 14 to 56), but not for the incremental shuttle walk test (three studies; 434 participants; 9 m, 95% CI -35 to 52), endurance shuttle walk test (four studies; 452 participants; 64 m, 95% CI -18 to 146), or for cardiopulmonary exercise testing with cycle ergometry (six studies; 141 participants; 45 mL/minute, 95% CI -7 to 97). Limited data were available for other secondary outcomes, and we could not determine the most beneficial type of NMES programme.

AUTHORS' CONCLUSIONS

The overall conclusions have not changed from the last publication of this review, although we have included more data, new analyses, and an assessment of the quality of the evidence using the GRADE approach. NMES may be an effective treatment for muscle weakness in adults with advanced progressive disease, and could be considered as an exercise treatment for use within rehabilitation programmes. Further research is very likely to have an important impact on our confidence in the estimate of effect and may change the estimate. We recommend further research to understand the role of NMES as a component of, and in relation to, existing rehabilitation approaches. For example, studies may consider examining NMES as an adjuvant treatment to enhance the strengthening effect of programmes, or support patients with muscle weakness who have difficulty engaging with existing services.

Neuromuscular electrical stimulation improves clinical and physiological function in COPD patients

BACKGROUND

Neuromuscular electrical stimulation (NMES) improves muscle performance and exercise tolerance in chronic obstructive pulmonary disease (COPD) patients. In contrast, no study has assessed the effect of NMES on dynamic hyperinflation (DH) in COPD. This study investigated the effect of short-term, high-frequency NMES on DH in patients with COPD.

METHODS

Twenty patients were randomly allocated to either a NMES applied bilaterally to the quadriceps muscles (n = 11: 8 weeks, 5 days/week, twice/day, 45 min/session) or a control group (n = 09). All patients received respiratory physical therapy and stretching exercises. Free fat mass, pulmonary function, time to exercise tolerance (Tlim), 6-min walk test distance (6-MWTD), tumor necrosis factor (TNF-α) and β-endorphin levels, Borg dyspnea and leg score (BDS and BLS) and quality of life by the St. George's Respiratory Questionnaire score (SGRQ) were examined before and after the intervention.

RESULTS

Compared with the control group, NMES increased FEV1 and FEV1/FVC, 6-MWD and Tlim (P < 0.01) and reduced BDS and SGRQ (P < 0.01). Additionally, changes in the Tlim were positively correlated with respiratory improvements in FEV1 (rho = 0.48, P < 0.01). Also, NMES reduced TNF-α and increased β-endorphin levels, compared with the control group (P < 0.001).

CONCLUSION

In summary, 8 weeks of NMES promotes reduction of the perceived sensation of dyspnea during exercise in patients with COPD. This finding is accompanied by improvements in FEV1, exercise tolerance and quality of life, and DH. Interestingly, these findings may be associated with enhanced vasodilatory function and a reduction in inflammatory responses.

CLINICAL TRIAL REGISTRATION

NCT01695421.

Effects of neuromuscular electrical stimulation combined with exercises versus an exercise program on the pain and the function in patients with knee osteoarthritis: a randomized controlled trial

Objectives. To investigate the effect of 8 weeks of NMES + Ex (neuromuscular electrical stimulation combined with exercises) on pain and functional improvement in patients with knee osteoarthritis (OA) compared to exercise (Ex) alone. Design. Randomized controlled trial. Setting. A specialty outpatient clinic. Participants. Patients (N = 100; women = 86, men = 14; age range, 50–75 years) with knee OA. Interventions. Participants were randomly assigned to NMES + Ex or Ex group. Outcome Measures. Numerical Rating Scale 0 to 10 (NRS) and the Timed Up and Go (TUG) test were the primary outcomes. The secondary outcomes used were the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Results. Following the interventions, a statistically significant improvement in both groups was observed in all outcomes assessed. For the comparison between the groups, no statistically significant difference was found between the NMES + Ex and the Ex groups in NRS (P = 0.52), TUG test (P = 0.12), and aspects of WOMAC: pain (P = 0.26), function (P = 0.23), and stiffness (P = 0.63). Conclusion. The addition of NMES to exercise did not improve the outcomes assessed in knee OA patients. This study was registered at the Australian Clinical Trials Registry (ACTRN012607000357459).

Neuromuscular electrical stimulation for preventing skeletal-muscle weakness and wasting in critically ill patients: a systematic review

BACKGROUND

Neuromuscular electrical stimulation (NMES) therapy may be useful in early musculoskeletal rehabilitation during acute critical illness. The objective of this systematic review was to evaluate the effectiveness of NMES for preventing skeletal-muscle weakness and wasting in critically ill patients, in comparison with usual care.

METHODS

We searched PubMed, CENTRAL, CINAHL, Web of Science, and PEDro to identify randomized controlled trials exploring the effect of NMES in critically ill patients, which had a well-defined NMES protocol, provided outcomes related to skeletal-muscle strength and/or mass, and for which full text was available. Two independent reviewers extracted data on muscle-related outcomes (strength and mass), and participant and intervention characteristics, and assessed the methodological quality of the studies. Owing to the lack of means and standard deviations (SDs) in some studies, as well as the lack of baseline measurements in two studies, it was impossible to conduct a full meta-analysis. When means and SDs were provided, the effect sizes of individual outcomes were calculated, and otherwise, a qualitative analysis was performed.

RESULTS

The search yielded 8 eligible studies involving 172 patients. The methodological quality of the studies was moderate to high. Five studies reported an increase in strength or better preservation of strength with NMES, with one study having a large effect size. Two studies found better preservation of muscle mass with NMES, with small to moderate effect sizes, while no significant benefits were found in two other studies.

CONCLUSIONS

NMES added to usual care proved to be more effective than usual care alone for preventing skeletal-muscle weakness in critically ill patients. However, there is inconclusive evidence for its benefit in prevention of muscle wasting.

Neuromuscular electrical stimulation for muscle weakness in adults with advanced disease

BACKGROUND

Patients with progressive diseases often experience muscle weakness, which impacts adversely on levels of independence and quality of life. In those who are unable or unwilling to undertake traditional forms of exercise, neuromuscular electrical stimulation (NMES) may provide an alternative method of enhancing leg muscle strength. Programmes appear to be well tolerated and have led to improvements in muscle function, exercise capacity and quality of life. However, estimates regarding the effectiveness of NMES from individual studies lack power and precision.

PRIMARY OBJECTIVE

to evaluate the effectiveness of NMES for improving muscle strength in adults with advanced disease.

SECONDARY OBJECTIVE

to examine the acceptability and safety of NMES, and changes in muscle function (strength or endurance), muscle mass, exercise capacity, breathlessness and health-related quality of life.

SEARCH METHODS

Studies were identified from searches of The Cochrane Library, MEDLINE, EMBASE, CINAHL and PsycINFO databases to July 2012, citation searches, conference proceedings and previous systematic reviews.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in adults with advanced chronic obstructive pulmonary disease (COPD), chronic heart failure, cancer or human immunodeficiency virus/acquired immunodeficency syndrome (HIV/AIDS) comparing a programme of NMES as a sole or adjunct intervention to no treatment, placebo NMES or an active control. We imposed no language restriction.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data on study design, participants, interventions and outcomes. We assessed risk of bias using the Cochrane Collaboration's tool. We calculated mean differences (MD) or standardised mean differences (SMD) between intervention and control groups for outcomes with sufficient data; for other outcomes we described findings from individual studies.

MAIN RESULTS

Eleven studies involving a total of 218 participants met the inclusion criteria across COPD, chronic heart failure and thoracic cancer. NMES significantly improved quadriceps strength by a SMD of 0.9 (95% confidence interval (CI) 0.33 to 1.46), equating to approximately 25 Newton metres (Nm) (95% CI 9 to 41). Mean differences across various walking tests, favouring NMES, were 40 m (95% CI -4 to 84) for the six-minute walk test, 69 m (95% CI 19 to 119) for the incremental shuttle walk test and 160 m (95% CI 34 to 287) for the endurance shuttle walk test. Limited evidence was available for the assessment of other secondary outcomes.

AUTHORS' CONCLUSIONS

NMES appears an effective means of improving muscle weakness in adults with progressive diseases such as COPD, chronic heart failure and cancer. Further research is required to clarify its place in clinical practice, by determining the optimal parameters for a NMES programme, the patients most likely to benefit, and its impact on morbidity and service use.

Muscle function in COPD: a complex interplay

The skeletal muscles play an essential role in life, providing the mechanical basis for respiration and movement. Skeletal muscle dysfunction is prevalent in all stages of chronic obstructive pulmonary disease (COPD), and significantly influences symptoms, functional capacity, health related quality of life, health resource usage and even mortality. Furthermore, in contrast to the lungs, the skeletal muscles are potentially remedial with existing therapy, namely exercise-training. This review summarizes clinical and laboratory observations of the respiratory and peripheral skeletal muscles (in particular the diaphragm and quadriceps), and current understanding of the underlying etiological processes. As further progress is made in the elucidation of the molecular mechanisms of skeletal muscle dysfunction, new pharmacological therapies are likely to emerge to treat this important extra-pulmonary manifestation of COPD.

Improving muscle mass and function in cachexia: non-drug approaches

PURPOSE OF REVIEW

Therapeutic exercise may help maintain or slow down the rate of decline in muscle mass and physical function that occurs with cachexia. This review considers recent evidence in relation to patients with cachexia as regards the rationale for the use of exercise, the challenges in its clinical application and future developments.

RECENT FINDINGS

Exercise may attenuate the effects of cachexia by modulating muscle metabolism, insulin sensitivity and levels of inflammation. Studies targeting cachectic patients have demonstrated that even in advanced disease peripheral muscle has the capacity to respond to exercise training. Nonetheless, there are challenges in implementing the use of exercise, particularly once cachexia is established in which tolerance to even low levels of exercise is poor. Strategies to make exercise a more accessible therapy are required and could include offering exercise earlier on in the course of the disease, at lower intensities and in various forms, including more novel approaches.

SUMMARY

The use of therapeutic exercise has a sound rationale, even in patients with advanced disease and cachexia. Because of practical issues with its application, further study is required to examine if benefits achieved in small studies can be translated to a wider clinical population.

Repetitive magnetic stimulation of the phrenic nerves for diaphragm conditioning: a normative study of feasibility and optimal settings

Electrical stimulation can enhance muscle function. We applied repetitive cervical magnetic phrenic stimulation (rCMS) to induce diaphragm contractions in 7 healthy subjects (800 ms trains; transdiaphragmatic pressure (Pdi) measurements; tolerance ratings). Each rCMS train produced a sustained diaphragm contraction. Sixty-five percent of the maximal available output at 15 Hz proved the best compromise between Pdi and discomfort with nonfatiguing contractions. rCMS appears feasible and should be investigated for diaphragm conditioning in appropriate clinical populations.

Strategy for respiratory exercise pattern associated with upper limb movements in COPD patients

INTRODUCTION

Upper limb exercises are frequently used in respiratory physiotherapy, with UL elevation and controlled inspiratory timing. However, the use of expiration during upper limb elevation appears to be a strategy that could minimize the action of accessory muscles in patients with chronic obstructive pulmonary disease. In this context, little is known about the synchrony of upper limb (UL) movements associated with breathing. The aim of this study was to investigate the respiratory pattern of chronic obstructive pulmonary disease patients during different UL exercises associated with respiratory exercises.

METHODS

Fifteen chronic obstructive pulmonary disease patients participated in this study. Respiratory pattern analysis by inductance plethysmography was performed during four types of upper limb exercises, two shoulder flexion-extension (one associated with inspiratory time during the concentric phase and the other associated with expiratory time) and two shoulder abduction-adduction (same timing as above). Statistical analysis was performed by the Kolmogorov-Smirnov test and ANOVA with Tukey tests (p< 0.05).

RESULTS

The thoracoabdominal coordination measurements increased in the two exercises using both inspiration during shoulder flexion (PhRIB: 172%; PhREB: 131%; PhRTB: 142% and PhAng: 238%) as well as in shoulder horizontal abduction (PhRIB: 145%; PhREB: 109%; PhRTB: 130% and PhAng: 229%), differing from the exercises with expiration at the time of shoulder flexion and horizontal abduction.

CONCLUSION

The exercises performed with inverted respiratory time produced less asynchrony and can be used as important strategies during physical exercise programs in these patients.

Neuromuscular electrical stimulation improves exercise tolerance in chronic obstructive pulmonary disease patients with better preserved fat-free mass

BACKGROUND

High-frequency neuromuscular electrical stimulation increases exercise tolerance in patients with advanced chronic obstructive pulmonary disease (COPD patients). However, it is conceivable that its benefits are more prominent in patients with better-preserved peripheral muscle function and structure.

OBJECTIVE

To investigate the effects of high-frequency neuromuscular electrical stimulation in COPD patients with better-preserved peripheral muscle function.

DESIGN

Prospective and cross-over study.

METHODS

Thirty COPD patients were randomly assigned to either home-based, high-frequency neuromuscular electrical stimulation or sham stimulation for six weeks. The training intensity was adjusted according to each subject's tolerance. Fat-free mass, isometric strength, six-minute walking distance and time to exercise intolerance (Tlim) were assessed.

RESULTS

Thirteen (46.4%) patients responded to high-frequency neuromuscular electrical stimulation; that is, they had a post/pre Δ Tlim >10% after stimulation (unimproved after sham stimulation). Responders had a higher baseline fat-free mass and six-minute walking distance than their seventeen (53.6%) non-responding counterparts. Responders trained at higher stimulation intensities; their mean amplitude of stimulation during training was significantly related to their fat-free mass (r = 0.65; p<0.01). Logistic regression revealed that fat-free mass was the single independent predictor of Tlim improvement (odds ratio [95% CI] = 1.15 [1.04-1.26]; p<0.05).

CONCLUSIONS

We conclude that high-frequency neuromuscular electrical stimulation improved the exercise capacity of COPD patients with better-preserved fat-free mass because they tolerated higher training stimulus levels. These data suggest that early training with high-frequency neuromuscular electrical stimulation before tissue wasting begins might enhance exercise tolerance in patients with less advanced COPD.

Oxygen uptake, ventilation, and symptoms during low-frequency versus high-frequency NMES in COPD: a pilot study

Transcutaneous neuromuscular electrical stimulation (NMES) involves the application of an electrical current through electrodes placed on the skin over the targeted muscles. During high-frequency NMES (HF-NMES), oxygen uptake, minute ventilation, and the degree of symptom perception (dyspnea and fatigue) have been shown to be acceptable in chronic obstructive pulmonary disease (COPD). Currently, oxygen uptake and ventilation load have never been assessed during low-frequency NMES (LF-NMES) of the lower-limb muscles. The purpose of this study was to compare prospectively oxygen uptake, ventilation, and symptom perception during a single session of LF-NMES versus a single session of HF-NMES of quadriceps muscles in patients with COPD. In 17 COPD patients (mean FEV(1) = 45% predicted, mean body mass index = 26.2 kg/m(2)), peak exercise capacity, functional exercise capacity, and the Medical Research Council dyspnea grade were evaluated. In addition, oxygen uptake, minute ventilation, heart rate, and Borg symptom scores were assessed during one session of LF-NMES (15 Hz) and one session of HF-NMES (75 Hz) and compared with peak values. Mean oxygen uptake (LF-NMES: 327 ml/min vs. HF-NMES: 315 ml/min), minute ventilation (LF-NMES: 14 L vs. HF-NMES: 15 L), and heart rate (LF-NMES: 86 BPM vs. HF-NMES: 83 BPM) were similar during both NMES frequencies. Patients used a relatively low proportion of their peak aerobic capacity during both NMES sessions (LF-NMES: 34% vs. HF-NMES: 33%; P = 0.397). In addition, symptom Borg scores for dyspnea and leg fatigue were also comparable. Oxygen uptake, ventilation, and symptoms of dyspnea and fatigue were comparable and tolerable during LF-NMES and HF-NMES in patients with COPD. Therefore, LF-NMES and HF-NMES may both be suitable rehabilitative modalities to be used in severely dyspneic patients with lower-limb muscle dysfunction.

Muscle training with repetitive magnetic stimulation of the quadriceps in severe COPD patients

BACKGROUND

Previous studies have used electrical neuromuscular stimulation as a physical training method in patients with severe COPD. We introduce the use of the more tolerable magnetic stimulation for the same purpose, investigating the effectiveness of an eight-week protocol.

METHODS

Eighteen patients with severe COPD were randomly assigned to a magnetic stimulation training protocol, n=10, FEV(1)=30% (SD: 7) or to parallel clinical monitoring, control group, n=8, FEV(1)=35% (SD: 8). During eight weeks, patients were stimulated for 15min on each quadriceps femoris, three times per week. Quadriceps muscle strength and endurance measurements, quality-of-life questionnaires (SF36, SGRQ) and a six-minute walking test were all carried out before and after the training period in the stimulated and control subjects.

RESULTS

All patients completed the training with increasing intensity of stimulation, displaying a significant improvement in voluntary quadriceps strength (17.5% of the baseline value) and exercise capacity, with a mean increase of 23m in the six-minute walking test. The questionnaire scores showed greater increases in quality-of-life scores in the trained subjects compared to the controls, particularly in the physical function areas: mean increments in SF36 in "physical function": +26, "role limitations due to physical problems": +40 and "vitality": +17.5, while +13, -4 and +1, respectively in controls. Saint George's "Activity" score improved by 19.6 points, for 11.5 in controls.

CONCLUSIONS

In COPD patients who are limited due to dyspnoea, magnetic neuromuscular stimulation of the quadriceps constitutes a feasible training method for the lower limbs, with positive effects on the muscle function, effort capacity and perception areas.