The metabolic response during resistance training and neuromuscular electrical stimulation (NMES) in patients with COPD, a pilot study

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.

Combined Exercise Training and Nutritional Interventions or Pharmacological Treatments to Improve Exercise Capacity and Body Composition in Chronic Obstructive Pulmonary Disease: A Narrative Review

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disease that is associated with significant morbidity, mortality, and healthcare costs. The burden of respiratory symptoms and airflow limitation can translate to reduced physical activity, in turn contributing to poor exercise capacity, muscle dysfunction, and body composition abnormalities. These extrapulmonary features of the disease are targeted during pulmonary rehabilitation, which provides patients with tailored therapies to improve the physical and emotional status. Patients with COPD can be divided into metabolic phenotypes, including cachectic, sarcopenic, normal weight, obese, and sarcopenic with hidden obesity. To date, there have been many studies performed investigating the individual effects of exercise training programs as well as nutritional and pharmacological treatments to improve exercise capacity and body composition in patients with COPD. However, little research is available investigating the combined effect of exercise training with nutritional or pharmacological treatments on these outcomes. Therefore, this review focuses on exploring the potential additional beneficial effects of combinations of exercise training and nutritional or pharmacological treatments to target exercise capacity and body composition in patients with COPD with different metabolic phenotypes.

[The role of the physiotherapist in the assessment and management of dyspnea]

The role of the physiotherapist in the assessment and management of dyspnea. Dyspnea is the most common symptom in cardio-respiratory diseases. Recently improved comprehension of dyspnea mechanisms have underlined the need for three-faceted assessment. The three key aspects correspond to the "breathing, thinking, functioning" clinical model, which proposes a multidimensional - respiratory, emotional and functional - approach. Before initiating treatment, it is essential for several reasons to assess each specific case, determining the type of dyspnea affecting the patient, appraising the impact of shortness of breath, and estimating the effectiveness of the treatment applied. The physiotherapist has a major role to assume in the care of dyspneic patients, not only in assessment followed by treatment but also as a major collaborator in a multidisciplinary team, especially with regard to pulmonary rehabilitation. The aim of this review is to inventory the existing assessment tools and the possible physiotherapies for dyspnea, using a holistic approach designed to facilitate the choice of techniques and to improve quality of care by fully addressing the patient's needs.

Effects of Whole-Body Electromyostimulation Associated with Dynamic Exercise on Functional Capacity and Heart Rate Variability After Bariatric Surgery: a Randomized, Double-Blind, and Sham-Controlled Trial

PURPOSE

Bariatric surgery is the most effective treatment for morbid obesity. In association with dietary restrictions, the ability to exercise in the immediate post-surgical phase is limited. In this context, whole-body electromyostimulation (WB-EMS), strategy that stimulates various muscle groups, in conjunction with physical exercise, holds promise for improving functional capacity, and cardiac autonomic control, following surgery. The purpose of this study was to analyze whether a rehabilitation program consisting of WB-EMS with 30 exercise training sessions following bariatric surgery significantly improves functional capacity, body mass and heart rate variability (HRV).

METHODS

Randomized, double-blind, and sham-controlled trial. Twenty obesity patients were randomized into the WB-EMS (n = 10) and sham (n = 10) groups. On average, 7 days after surgery, individuals underwent a six-minute walk test (6MWT), HRV, and body composition analysis at rest. The next day, patients initiated an exercise training protocol, five times per week, over 6 weeks. Walking distance changes (post-pre = ΔWD) obtained by 6MWT and HRV indices were determined following the intervention.

RESULTS

Only WB-EMSG significantly increased WD and body mass index (BMI) after the intervention (p = 0.002) and ΔWD was significantly higher in this group when compared with sham (p = 0.04). Moreover, both groups demonstrated an improvement in key measures of HRV after the intervention.

CONCLUSION

An exercise training intervention initiated shortly after bariatric surgery improved functional capacity and cardiac autonomic tone. Improvements in functional capacity and BMI following exercise training were greater with the addition of WB-EMS but did not promote additional improvements in HRV beyond that realized with exercise training alone.

Respiratory, cardiac and metabolic responses during electrical muscle stimulation in quadriceps muscle versus comparable voluntary muscle contractions

Electrical Muscle Stimulation (EMS) and voluntary muscle contraction (VMC) are both acceptable rehabilitative modalities to preserve muscle strength loss. The study aimed to compare respiratory, metabolic, and cardiac parameters during quadriceps muscle contraction (QMC) using either EMS or VMC with comparable generated low intensity muscle force. Thirty healthy non-smoker males, age 20-58 years with normal BMI and low to moderate physical activity, underwent two 20-min sessions of comparable QMC using EMS vs VMC at the same day. The BIODEX III isokinetic dynamometer was used to assess maximum isometric force and the comparable force generated during each condition (EMS vs VMC), while the METAMAX 3B portable metabolic system was used to measure continuously the physiological parameters. Tolerable EMS was used (mean: 33 ± 1.5 mA, at 75 Hz). Each contraction lasted 10 sec followed by 20 sec rest. Paired t-tests were used for comparisons between sessions. A relatively low proportion of maximum isometric force (EMS: 8.5% vs VMC: 8.6%) and torque (EMS: 16 ± 1.3 vs VMC: 16 ± 1.1 Nm) were generated during each session. Mean minute ventilation (EMS: 10.8 L vs VMC: 9.8 L), tidal volume (EMS: 0.6 L vs VMC: 0.5 L), O₂ uptake (EMS: 0.31 L/min vs VMC: 0.26 L/min) and O₂ pulse (EMS: 3.9 ml/beat vs VMC: 3.6 ml/beat) were different between sessions (p ≤ .05); while heart rate (EMS: 72 beats/min vs VMC: 71 beats/min) was equal. Quadriceps muscle EMS induces higher respiratory and metabolic responses compared to equal magnitude VMC in healthy males.

An update on pulmonary rehabilitation techniques for patients with chronic obstructive pulmonary disease

Introduction: Pulmonary rehabilitation (PR) is one of the core components in the management of patients with chronic obstructive pulmonary disease (COPD). In order to achieve the maximal level of independence, autonomy, and functioning of the patient, targeted therapies and interventions based on the identification of physical, emotional and social traits need to be provided by a dedicated, interdisciplinary PR team.Areas covered: The review discusses cardiopulmonary exercise testing in the selection of different modes of training modalities. Neuromuscular electrical stimulation as well as gait assessment and training are discussed as well as add-on therapies as oxygen, noninvasive ventilator support or endoscopic lung volume reduction in selected patients. The potentials of pulsed inhaled nitric oxide in patients with underlying pulmonary hypertension is explored as well as nutritional support. The impact of sleep quality on outcomes of PR is reviewed.Expert opinion: Individualized, comprehensive intervention based on thorough assessment of physical, emotional, and social traits in COPD patients forms a continuous challenge for health-care professionals and PR organizations in order to dynamically implement and adapt these strategies based on dynamic, more optimal understanding of underlying pathophysiological mechanisms.

Impact of transcutaneous neuromuscular electrical stimulation or resistance exercise on skeletal muscle mRNA expression in COPD

Background: Voluntary resistance exercise (RE) training increases muscle mass and strength in patients with chronic obstructive pulmonary disease (COPD). Nonvolitional transcutaneous neuromuscular electrical stimulation (NMES) may be an alternative strategy for reducing ambulatory muscle weakness in patients unable to perform RE training, but little comparative data are available. This study, therefore, investigated changes in muscle mRNA abundance of a number of gene targets in response to a single bout of NMES compared with RE. Methods: Twenty-six patients with stable COPD (15 male; FEV₁, 43±18% predicted; age, 64±8 years; fat free mass index, 16.6±1.8 kg/m²) undertook 30 minutes of quadriceps NMES (50 Hz, current at the limit of tolerance) or 5×30 maximal voluntary isokinetic knee extensions. Vastus lateralis muscle biopsies were obtained at rest immediately before and 24 hours after intervention. Expression of 384 targeted mRNA transcripts was assessed by real time TaqMan PCR. Significant change in expression from baseline was determined using the ΔΔC_T method with a false discovery rate (FDR) of <5%. Results: NMES and RE altered mRNA abundance of 18 and 68 genes, respectively (FDR <5%), of which 14 genes were common to both interventions and of the same magnitude of fold change. Biological functions of upregulated genes included inflammation, hypertrophy, muscle protein turnover, and muscle growth, whilst downregulated genes included mitochondrial and cell signaling functions. Conclusions: Compared with NMES, RE had a broader impact on mRNA abundance and, therefore, appears to be the superior intervention for maximizing transcriptional responses in the quadriceps of patients with COPD. However, if voluntary RE is not feasible in a clinical setting, NMES by modifying expression of genes known to impact upon muscle mass and strength may have a positive influence on muscle function.

The feasibility of early pulmonary rehabilitation and activity after COPD exacerbations: external pilot randomised controlled trial, qualitative case study and exploratory economic evaluation

BACKGROUND

Chronic obstructive pulmonary disease (COPD) affects > 3 million people in the UK. Acute exacerbations of COPD (AECOPD) are the second most common reason for emergency hospital admission in the UK. Pulmonary rehabilitation is usual care for stable COPD but there is little evidence for early pulmonary rehabilitation (EPR) following AECOPD, either in hospital or immediately post discharge.

OBJECTIVE

To assess the feasibility of recruiting patients, collecting data and delivering EPR to patients with AECOPD to evaluate EPR compared with usual care.

DESIGN

Parallel-group, pilot 2 × 2 factorial randomised trial with nested qualitative research and an economic analysis.

SETTING

Two acute hospital NHS trusts. Recruitment was carried out from September 2015 to April 2016 and follow-up was completed in July 2016.

PARTICIPANTS

Eligible patients were those aged ≥ 35 years who were admitted with AECOPD, who were non-acidotic and who maintained their blood oxygen saturation level (SpO₂) within a prescribed range. Exclusions included the presence of comorbidities that affected the ability to undertake the interventions.

INTERVENTIONS

(1) Hospital EPR: muscle training delivered at the patient's hospital bed using a cycle ergometer and (2) home EPR: a pulmonary rehabilitation programme delivered in the patient's home. Both interventions were delivered by trained physiotherapists. Participants were allocated on a 1 : 1 : 1 : 1 ratio to (1) hospital EPR (n = 14), (2) home EPR (n = 15), (3) hospital EPR and home EPR (n = 14) and (4) control (n = 15). Outcome assessors were blind to treatment allocation; it was not possible to blind patients.

MAIN OUTCOME MEASURES

Feasibility of recruiting 76 participants in 7 months at two centres; intervention delivery; views on intervention/research acceptability; clinical outcomes including the 6-minute walk distance (6WMD); and costs. Semistructured interviews with participants (n = 27) and research health professionals (n = 11), optimisation assessments and an economic analysis were also undertaken.

RESULTS

Over 7 months 449 patients were screened, of whom most were not eligible for the trial or felt too ill/declined entry. In total, 58 participants (76%) of the target 76 participants were recruited to the trial. The primary clinical outcome (6MWD) was difficult to collect (hospital EPR, n = 5; home EPR, n = 6; hospital EPR and home EPR, n = 5; control, n = 5). Hospital EPR was difficult to deliver over 5 days because of patient discharge/staff availability, with 34.1% of the scheduled sessions delivered compared with 78.3% of the home EPR sessions. Serious adverse events were experienced by 26 participants (45%), none of which was related to the interventions. Interviewed participants generally found both interventions to be acceptable. Home EPR had a higher rate of acceptability, mainly because patients felt too unwell when in hospital to undergo hospital EPR. Physiotherapists generally found the interventions to be acceptable and valued them but found delivery difficult because of staffing issues. The health economic analysis results suggest that there would be value in conducting a larger trial to assess the cost-effectiveness of the hospital EPR and hospital EPR plus home EPR trial arms and collect more information to inform the hospital cost and quality-adjusted life-year parameters, which were shown to be key drivers of the model.

CONCLUSIONS

A full-scale randomised controlled trial using this protocol would not be feasible. Recruitment and delivery of the hospital EPR intervention was difficult. The data obtained can be used to design a full-scale trial of home EPR. Because of the small sample and large confidence intervals, this study should not be used to inform clinical practice.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN18634494.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 11. See the NIHR Journals Library website for further project information.

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.

Cardiorespiratory Responses to Short Bouts of Resistance Training Exercises in Individuals With Chronic Obstructive Pulmonary Disease: A COMPARISON OF EXERCISE INTENSITIES

PURPOSE

Resistance training is recommended in pulmonary rehabilitation for people with chronic obstructive pulmonary disease (COPD); however, the acute cardiorespiratory responses to different intensities of resistance training are not known. We compared acute cardiorespiratory responses with high-intensity versus low-intensity resistance exercises in persons with COPD and healthy, matched controls. This research may assist in developing training parameters in COPD.

METHODS

Participants (n = 10 per group) performed 1 set of 10 repetitions of leg extension and arm elevation at 2 intensities: 40% (low) and 80% (high) of 1-repetition maximum. Minute ventilation ((Equation is included in full-text article.)E), oxygen uptake ((Equation is included in full-text article.)O2), and heart rate (HR) data were collected continuously and expressed as absolute values and relative to values at (Equation is included in full-text article.)O2peak derived from a cardiopulmonary exercise test. Blood pressure, oxygen saturation, and rating of perceived exertion (RPE) were monitored before and after each set of exercises.

RESULTS

Individuals with COPD showed similar (Equation is included in full-text article.)E, (Equation is included in full-text article.)O2, and HR with high- versus low-intensity exercises. RPE was higher after high- vs low-intensity leg extension (4 ± 1.4 vs 2 ± 1, P < .005) and arm elevation (3 ± 2 vs 1 ± 1.4, P < .005). Compared with healthy participants, relative (Equation is included in full-text article.)O2, (Equation is included in full-text article.)E, and HR were higher in COPD (≅40% vs 20% of the (Equation is included in full-text article.)O2peak; ≅60% vs 20% of (Equation is included in full-text article.)Epeak; and ≅80% vs 20% of HRpeak; all Ps ≤ .004). Absolute responses and RPE were similar between groups, irrespective of intensity and exercise.

CONCLUSION

Immediate cardiorespiratory responses to an acute bout of resistance exercise appear to be independent of the exercise intensity in COPD. Although people with COPD are working closer to their (Equation is included in full-text article.)O2peak, their responses and RPE are comparable with healthy controls.

Relevance of nutritional support and early rehabilitation in hospitalized patients with COPD

Exacerbation of COPD is associated with a worsening of lung function and symptoms, and a serious loss in functional status and health related quality of life. It also represents the major cause for emergency hospitalization in COPD patients which places the patient at risk for developing further muscle weakness. Actually, loss of muscle function developed fast and continued to decrease over time during hospitalization and may be further compromised when disease deterioration would require the use of ventilator support. Exacerbations have long term consequences on physical performance, physical activity and health-related quality of life as recovery of skeletal muscle function is slow and incomplete and may even be compromised in case of re-exacerbation. Factors such as bed rest, reduced physical activity, hypoxia, inflammation, drug treatment and negative protein balance due to insufficient dietary intake and increased resting energy expenditure are all potential contributors to skeletal muscle weakness during exacerbation. Because low levels of physical activity and poor physical performance are predictor of hospital re-admission and are associated with lower survival in these patients, interventions to prevent the additional loss of muscle function during exacerbation or to hasten functional recovery have been recently explored. This review focuses on the knowledge regarding the potential benefit of early rehabilitation and nutritional supplementation as modifiable factors susceptible to ameliorate muscle weakness during exacerbation in hospitalized COPD patients.

Functional Electrical Stimulation-A New Therapeutic Approach to Enhance Exercise Intensity in Chronic Obstructive Pulmonary Disease Patients: A Randomized, Controlled Crossover Trial

OBJECTIVE

To evaluate the effect of quadriceps functional electrical stimulation (FES)-cycling on exertional oxygen uptake (V˙o₂) compared with placebo FES-cycling in patients with chronic obstructive pulmonary disease (COPD).

DESIGN

A randomized, single-blind, placebo-controlled crossover trial.

SETTING

Pulmonary rehabilitation department.

PARTICIPANTS

Consecutive patients (N=23) with COPD Global Initiative for Chronic Obstructive Lung Disease stage 2, 3, or 4 (mean forced expiratory volume during the first second, 1.4±0.4L [50.3% predicted]) who had recently begun a respiratory rehabilitation program.

INTERVENTION

Two consecutive 30-minute sessions were carried out at a constant load with active and placebo FES-cycling.

MAIN OUTCOME MEASURES

The primary outcome was mean V˙o₂ during the 30-minute exercise session. The secondary outcomes were respiratory gas exchange and hemodynamic parameters averaged over the 30-minute endurance session. Lactate values, dyspnea, and perceived muscle fatigue were evaluated at the end of the sessions.

RESULTS

FES-cycling increased the physiological response more than the placebo, with a greater V˙o₂ achieved of 36.6mL/min (95% confidence interval [CI], 8.9-64.3mL/min) (P=.01). There was also a greater increase in lactate after FES-cycling (+1.5mmol/L [95% CI, .05-2.9mmol/L]; P=.01). FES-cycling did not change dyspnea or muscle fatigue compared with the placebo condition.

CONCLUSIONS

FES-cycling effectively increased exercise intensity in patients with COPD. Further studies should evaluate longer-term FES-cycling rehabilitation programs.

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.

High oxygen extraction and slow recovery of muscle deoxygenation kinetics after neuromuscular electrical stimulation in COPD patients

PURPOSE

It was hypothesized that patients with chronic obstructive pulmonary disease (COPD) would exhibit a slow muscle deoxygenation (HHb) recovery time when compared with sedentary controls.

METHODS

Neuromuscular electrical stimulation (NMES 40 and 50 mA, 50 Hz, 400 µs) was employed to induce isometric contraction of the quadriceps. Microvascular oxygen extraction (µO2EF) and HHb were estimated by near-infrared spectroscopy (NIRS). Recovery kinetic was characterized by measuring the time constant Tau (HHb-τ). Torque and work were measured by isokinetic dynamometry in 13 non-hypoxaemic patients with moderate-to-severe COPD [SpO2 = 94.1 ± 1.6 %; FEV1 (% predict) 48.0 ± 9.6; GOLD II-III] and 13 age- and sex-matched sedentary controls.

RESULTS

There was no desaturation in either group during NMES. Torque and work were reduced in COPD versus control for 40 and 50 mA [torque (Nm) 50 mA = 28.9 ± 6.9 vs 46.1 ± 14.2; work (J) 50 mA = 437.2 ± 130.0 vs. 608.3 ± 136.8; P < 0.05 for all]. High µO2EF values were observed in the COPD group at both NMES intensities (corrected by muscle mass 50 mA = 6.18 ± 1.1 vs. 4.68 ± 1.0 %/kg; corrected by work 50 mA = 0.12 ± 0.05 vs. 0.07 ± 0.02 %/J; P < 0.05 for all). Absolute values of HHb-τ (50 mA = 31.11 ± 9.27 vs. 18.08 ± 10.70 s), corrected for muscle mass (50 mA 3.80 ± 1.28 vs. 2.05 ± 1.45 s/kg) and corrected for work (50 mA = 0.08 ± 0.04 vs. 0.03 ± 0.02 s/J) were reduced in COPD (P < 0.05 for all). The variables behaviour for 40 mA was similar to those of 50 mA.

CONCLUSIONS

COPD patients exhibited a slower muscle deoxygenation recovery time after NMES. The absence of desaturation, low torque and work, high µO2EF and high values for recovery time corrected by muscle mass and work suggest that intrinsic muscle dysfunction has an impact on muscle recovery capacity.

Metabolic load during strength training or NMES in individuals with COPD: results from the DICES trial

Background

Strength training and neuromuscular electrical stimulation (NMES) are effective training modalities for improving muscle function, exercise performance and health status in individuals with COPD. The aim of the present study was to analyze the metabolic load of these training modalities at baseline, half-way, and at the end of an eight-week interdisciplinary pulmonary rehabilitation program in a subgroup of individuals with COPD of the DICES trial.

Methods

Of 24 individuals with COPD (FEV₁: 34 ± 2% predicted, men: 58%, age: 66 (61–68) years), peak oxygen uptake (VO₂), peak minute ventilation (V_E), heart rate, oxygen saturation and symptom scores were assessed during HF-NMES (75 Hz), LF-NMES (15 Hz) and strength training at three moments during their pulmonary rehabilitation program.

Results

Intervention-related peak VO₂ did not change over time during HF-NMES, LF-NMES or strength training. Intervention-related peak V_E did not change over time during strength training or LF-NMES and increased slightly, but significantly over time during HF-NMES. Peak VO₂ and V_E were significantly higher during strength training compared to HF-NMES or LF-NMES. Oxygen saturation significantly decreased after the first measurements during HF-NMES and strength training group to baseline, while no significant changes in oxygen saturation were observed during the other measurements. Heart rate significantly increased compared to baseline in all groups at all moments and was significantly higher after strength training compared to HF-NMES or LF-NMES. Median end scores (points) for dyspnea, fatigue and muscle pain ranged from 1 to 3, from 0.5 to 2 and from 0 to 6 after HF-NMES, from 2 to 3, from 2 to 5 and from 0 to 9 after LF-NMES and from 2 to 5, from 1.5 to 4 and from 0 to 28 after strength training respectively.

Conclusions

To conclude, the metabolic load and symptom scores remain acceptable low over time with increasing training loads during HF-NMES, LF-NMES or strength training.

Trial registration

Trial registration:NTR2322

Ventilatory requirements of quadriceps resistance training in people with COPD and healthy controls

Background

It is proposed that resistance training (RT) does not activate the cardiopulmonary system to the same extent as whole-body exercise. This is important for patients with chronic obstructive pulmonary disease (COPD) who are ventilatory limited.

Objective

The aim was to assess the ventilatory response to an isokinetic quadriceps RT program in people with COPD and healthy controls.

Design

Observational.

Registration number

ISRCTN22764439.

Setting

Outpatient, university teaching hospital.

Participants and outcome measures

People with COPD (n=14) and healthy controls (n=11) underwent breath-by-breath analysis of their ventilation during an RT session (five sets of 30 maximal knee extensions at 180°/sec). Subjects performed a maximal cycle ergometry test (CET) at baseline. Peak ventilation (VE; L/min) and oxygen consumption (VO₂; mL/kg/min) were collected. The same system measured VO₂ and VE during the RT session. Parameters are presented as a percentage of the maximal CET. Isokinetic workload, symptom scores, heart rate (HR), and oxygen saturation were documented post-training.

Results

People with COPD worked at higher percentages of their maximal capacity than controls (mean range between sets 1–5 for VO₂ =49.1%–60.1% [COPD], 45.7%–51.43% [controls] and for VE =57.6%–72.2% [COPD], 49.8%–63.6% [controls]), although this was not statistically significant (P>0.1 in all cases). In absolute terms, the difference between groups was only significant for actual VO₂ on set 2 (P<0.05). Controls performed more isokinetic work than patients with COPD (P<0.05). Median Borg symptom scores after RT were the same in both groups (3 breathlessness, 13 exertion), no de-saturation occurred, and both groups were training at ≥65% of their maximum HR.

Conclusion

No statistically significant differences were found between people with COPD and healthy controls for VO₂ and VE achieved during training. The symptoms associated with training were within acceptable limits.

Tolerance and physiological correlates of neuromuscular electrical stimulation in COPD: a pilot study

Rationale

Neuromuscular electrical stimulation (NMES) of the lower limbs is an emerging training strategy in patients with COPD. The efficacy of this technique is related to the intensity of the stimulation that is applied during the training sessions. However, little is known about tolerance to stimulation current intensity and physiological factors that could determine it. Our goal was to find potential physiological predictors of the tolerance to increasing NMES stimulation intensity in patients with mild to severe COPD.

Methods

20 patients with COPD (FEV₁ = 54±14% pred.) completed 2 supervised NMES sessions followed by 5 self-directed sessions at home and one final supervised session. NMES was applied simultaneously to both quadriceps for 45 minutes, at a stimulation frequency of 50 Hz. Spirometry, body composition, muscle function and aerobic capacity were assessed at baseline. Cardiorespiratory responses, leg discomfort, muscle fatigue and markers of systemic inflammation were assessed during or after the last NMES session. Tolerance to NMES was quantified as the increase in current intensity from the initial to the final NMES session (ΔInt).

Results

Mean ΔInt was 12±10 mA. FEV₁, fat-free-mass, quadriceps strength, aerobic capacity and leg discomfort during the last NMES session positively correlated with ΔInt (r = 0.42 to 0.64, all p≤0.06) while post/pre NMES IL-6 ratio negatively correlated with ΔInt (r = −0.57, p = 0.001). FEV₁, leg discomfort during last NMES session and post/pre IL-6 ratio to NMES were independent factors of variance in ΔInt (r² = 0.72, p = 0.001).

Conclusion

Lower tolerance to NMES was associated with increasing airflow obstruction, low tolerance to leg discomfort during NMES and the magnitude of the IL-6 response after NMES.

Trial Registration

ClinicalTrials.gov NCT00809120

Efficacy of lower-limb muscle training modalities in severely dyspnoeic individuals with COPD and quadriceps muscle weakness: results from the DICES trial

RATIONALE

Strength training and neuromuscular electrical stimulation (NMES) improve lower-limb muscle function in dyspnoeic individuals with chronic obstructive pulmonary disease (COPD). However, high-frequency NMES (HF-NMES) and strength training have never been compared head-to-head; and effects of low-frequency NMES (LF-NMES) have never been studied in COPD. Therefore, the optimal training modality to improve lower-limb muscle function, exercise performance and other patient-related outcomes in individuals with severe COPD remains unknown.

OBJECTIVES

To study prospectively the efficacy of HF-NMES (75 Hz), LF-NMES (15 Hz) or strength training in severely dyspnoeic individuals with COPD with quadriceps muscle weakness at baseline.

METHODS

120 individuals with COPD (FEV1: 33±1% predicted, men: 52%, age: 64.8±0.8 years) were randomised to HF-NMES, LF-NMES or strength training as part of a comprehensive inpatient pulmonary rehabilitation programme. No treadmill walking or stationary cycling was provided.

MEASUREMENTS AND MAIN RESULTS

Groups were comparable at baseline. Quadriceps muscle strength increased after HF-NMES (+10.8 Newton-metre (Nm)) or strength training (+6.1 Nm; both p<0.01), but not after LF-NMES (+1.4 Nm; p=0.43). Quadriceps muscle endurance, exercise performance, lower-limb fat-free mass, exercise-induced symptoms of dyspnoea and fatigue improved significantly compared with baseline after HF-NMES, LF-NMES or strength training. The increase in quadriceps muscle strength and muscle endurance was greater after HF-NMES than after LF-NMES.

CONCLUSIONS

HF-NMES is equally effective as strength training in severely dyspnoeic individuals with COPD and muscle weakness in strengthening the quadriceps muscles and thus may be a good alternative in this particular group of patients. HF-NMES, LF-NMES and strength training were effective in improving exercise performance in severely dyspnoeic individuals with COPD and quadriceps weakness.

TRIAL REGISTRATION

NTR2322.

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.

Acute microcirculatory effects of medium frequency versus high frequency neuromuscular electrical stimulation in critically ill patients - a pilot study

BACKGROUND

Intensive care unit-acquired weakness (ICUAW) is a common complication, associated with significant morbidity. Neuromuscular electrical stimulation (NMES) has shown promise for prevention. NMES acutely affects skeletal muscle microcirculation; such effects could mediate the favorable outcomes. However, optimal current characteristics have not been defined. This study aimed to compare the effects on muscle microcirculation of a single NMES session using medium and high frequency currents.

METHODS

ICU patients with systemic inflammatory response syndrome (SIRS) or sepsis of three to five days duration and patients with ICUAW were studied. A single 30-minute NMES session was applied to the lower limbs bilaterally using current of increasing intensity. Patients were randomly assigned to either the HF (75 Hz, pulse 400 μs, cycle 5 seconds on - 21 seconds off) or the MF (45 Hz, pulse 400 μs, cycle 5 seconds on - 12 seconds off) protocol. Peripheral microcirculation was monitored at the thenar eminence using near-infrared spectroscopy (NIRS) to obtain tissue O2 saturation (StO2); a vascular occlusion test was applied before and after the session. Local microcirculation of the vastus lateralis was also monitored using NIRS.

RESULTS

Thirty-one patients were randomized. In the HF protocol (17 patients), peripheral microcirculatory parameters were: thenar O2 consumption rate (%/minute) from 8.6 ± 2.2 to 9.9 ± 5.1 (P = 0.08), endothelial reactivity (%/second) from 2.7 ± 1.4 to 3.2 ± 1.9 (P = 0.04), vascular reserve (seconds) from 160 ± 55 to 145 ± 49 (P = 0.03). In the MF protocol: thenar O2 consumption rate (%/minute) from 8.8 ± 3.8 to 9.9 ± 3.6 (P = 0.07), endothelial reactivity (%/second) from 2.5 ± 1.4 to 3.1 ± 1.7 (P = 0.03), vascular reserve (seconds) from 163 ± 37 to 144 ± 33 (P = 0.001). Both protocols showed a similar effect. In the vastus lateralis, average muscle O2 consumption rate was 61 ± 9%/minute during the HF protocol versus 69 ± 23%/minute during the MF protocol (P = 0.5). The minimum amplitude in StO2 was 5 ± 4 units with the HF protocol versus 7 ± 4 units with the MF protocol (P = 0.3). Post-exercise, StO2 increased by 6 ± 7 units with the HF protocol versus 5 ± 4 units with the MF protocol (P = 0.6). These changes correlated well with contraction strength.

CONCLUSIONS

A single NMES session affected local and systemic skeletal muscle microcirculation. Medium and high frequency currents were equally effective.

An official American Thoracic Society/European Respiratory Society statement: key concepts and advances in pulmonary rehabilitation

BACKGROUND

Pulmonary rehabilitation is recognized as a core component of the management of individuals with chronic respiratory disease. Since the 2006 American Thoracic Society (ATS)/European Respiratory Society (ERS) Statement on Pulmonary Rehabilitation, there has been considerable growth in our knowledge of its efficacy and scope.

PURPOSE

The purpose of this Statement is to update the 2006 document, including a new definition of pulmonary rehabilitation and highlighting key concepts and major advances in the field.

METHODS

A multidisciplinary committee of experts representing the ATS Pulmonary Rehabilitation Assembly and the ERS Scientific Group 01.02, "Rehabilitation and Chronic Care," determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant clinical and scientific expertise. The final content of this Statement was agreed on by all members.

RESULTS

An updated definition of pulmonary rehabilitation is proposed. New data are presented on the science and application of pulmonary rehabilitation, including its effectiveness in acutely ill individuals with chronic obstructive pulmonary disease, and in individuals with other chronic respiratory diseases. The important role of pulmonary rehabilitation in chronic disease management is highlighted. In addition, the role of health behavior change in optimizing and maintaining benefits is discussed.

CONCLUSIONS

The considerable growth in the science and application of pulmonary rehabilitation since 2006 adds further support for its efficacy in a wide range of individuals with chronic respiratory disease.

Metabolic and structural changes in lower-limb skeletal muscle following neuromuscular electrical stimulation: a systematic review

Background

Transcutaneous neuromuscular electrical stimulation (NMES) can be applied as a complementary intervention to regular exercise training programs. A distinction can be made between high-frequency (HF) NMES and low-frequency (LF) NMES. In order to increase understanding of the mechanisms of functional improvements following NMES, the purpose of this study was to systematically review changes in enzyme activity, muscle fiber type composition and muscle fiber size in human lower-limb skeletal muscles following only NMES.

Methods

Trials were collected up to march 2012 and were identified by searching the Medline/PubMed, EMBASE, Cochrane Central Register of Controlled Trials, CINAHL and The Physical Therapy Evidence Database (PEDro) databases and reference lists. 18 trials were reviewed in detail: 8 trials studied changes in enzyme activities, 7 trials studied changes in muscle fiber type composition and 14 trials studied changes in muscle fiber size following NMES.

Results

The methodological quality generally was poor, and the heterogeneity in study design, study population, NMES features and outcome parameters prohibited the use of meta-analysis. Most of the LF-NMES studies reported significant increases in oxidative enzyme activity, while the results concerning changes in muscle fiber composition and muscle size were conflicting. HF-NMES significantly increased muscle size in 50% of the studies.

Conclusion

NMES seems to be a training modality resulting in changes in oxidative enzyme activity, skeletal muscle fiber type and skeletal muscle fiber size. However, considering the small sample sizes, the variance in study populations, the non-randomized controlled study designs, the variance in primary outcomes, and the large heterogeneity in NMES protocols, it is difficult to draw definitive conclusions about the effects of stimulation frequencies on muscular changes.

The effects of neuromuscular electrical stimulation on cardiopulmonary function in healthy adults

Objective

To evaluate the effect of neuromuscular electrical stimulation (NMES) on cardiopulmonary function in healthy adults.

Method

Thirty-six healthy adults without a cardiac problem were enrolled. All patients were randomly assigned to either a control (17 subjects, mean age 29.41) or an electrical stimulation group (19 subjects, mean age 29.26). The electrical stimulation group received NMES on both sides of quadriceps muscle using a Walking Man II® in a sitting position for 30 minutes over 2 weeks. Maximum oxygen consumption (VO_2max), metabolic equivalent (MET), resting, maximal heart rate (RHR, MHR), resting, maximal blood pressure (RBP, MBP), and maximal rate pressure product (MRPP), exercise tolerance test (ETT) duration were determined using an exercise tolerance test and a 6 minute walk test (6MWT) before and after treatment.

Results

The electrical stimulation group showed a significant increase in VO_2max (p=0.03), 6MWT (p<0.01), MHR (p<0.04), MsBP (p<0.03), ETT duration (p<0.01) and a significant decrease in RsBP (p<0.02) as compared with the control group after two weeks. NMES induced changes improved only in RsBP (p<0.049) and ETT duration (p<0.01). The effects of NMES training were stronger in females.

Conclusion

We suggest that NMES is an additional therapeutic option for cardiopulmonary exercise in disabled patients with severe refractory heart failure or acute AMI.

Neuromuscular stimulation of quadriceps in patients hospitalised during an exacerbation of COPD: a comparison of low (35 Hz) and high (50 Hz) frequencies

BACKGROUND

Neuromuscular electrical stimulation (NMES) has shown to improve skeletal muscle strength and exercise capacity in stable patients with chronic obstructive pulmonary disease (COPD). Variations in NMES protocols are considerable. We aimed to compare changes in muscle strength after high-frequency and low-frequency NMES in patients admitted to hospital with an acute exacerbation of COPD.

METHODS

Patients were referred for inpatient (IP) rehabilitation during hospitalisation for an acute worsening of their COPD. They received 30-minute daily NMES to both quadriceps at a frequency of 35 or 50 Hz. NMES intensity was titrated to patients' tolerance. Isometric quadriceps muscle strength and endurance walking (ESWT) time were measured at baseline and on hospital discharge.

RESULTS

A total of 10 patients in each treatment group underwent NMES during hospitalisation (mean [SD] age 68.0 [±7.4] years, FEV1 0.99 L [±0.58], FEV1/FVC 47% [± 27%], MRC 5 [IQR ±1]). There were no significant differences in baseline characteristics between groups. Muscle strength (legs combined) increased in both groups regardless of the NMES frequency used (35 Hz--3.8 ± 4.9; 50 Hz--3.4 ± 5.5 kg). This was only significant within the 35 Hz group. The change in ESWT also showed a trend to increase in both groups (35 Hz--109 ± 92.7; 50 Hz--145.6 ± 94.7). There was no significant difference between groups for either outcome.

CONCLUSION

NMES is a feasible intervention to improve muscle strength in a cohort of patients admitted with an exacerbation of COPD. The response appears to be independent of the frequency used and both were well-tolerated.

Comparative effect of a 1 h session of electrical muscle stimulation and walking activity on energy expenditure and substrate oxidation in obese subjects

It has previously been shown that low-frequency neuromuscular electrical stimulation (NMES) techniques can induce increases in energy expenditure similar to those associated with exercise. This study investigated the metabolic and cardiovascular effects of a 1 h session of lower limb NMES and compared cardiovascular response with that observed during walking in nine obese subjects (three males) (age = 43.8 ± 3.0 years; body mass index (BMI) = 41.5 ± 1.8 kg/m(2)). The NMES protocol consisted of delivering a complex pulse pattern to the thigh muscles for 1 h. The walking test consisted of five 4-min bouts starting at 2 km/h with 1 km/h increments up to 6 km/h. In both tests, an open-circuit gas analyser was used to assess O(2) consumption ([Formula: see text]O(2)), CO(2) production ([Formula: see text]CO(2)), respiratory exchange ratio (RER), and heart rate (HR). Rates of fat oxidation (RFO) and carbohydrate oxidation (CHO) were estimated by indirect calorimetry. One hour of NMES significantly increased [Formula: see text]O(2), HR, RER, and mean energy expenditure compared with resting values, reaching 8.7 ± 1.3 mL·min(-2)·kg(-1) (47% of [Formula: see text]O(2peak)), 114.8 ± 7.5 bpm, 0.95, and 318.5 ± 64.3 kcal/h, respectively. CHO, but not RFO, increased during 1 h of NMES. With NMES, CHO was greater and RFO was less than at all walking speeds except 6 km/h. Lactate also increased more with NMES, to 3.5 ± 0.7 mmol versus a maximum of 1.5 ± 0.3 mmol with the walking protocol. These results suggest that NMES can be used in an obese population to induce an effective cardiovascular exercise response. In fact, the observed increase in energy expenditure induced by 1 h of NMES is clinically important and comparable with that recommended in weight management programs.

Effects of body mass index on task-related oxygen uptake and dyspnea during activities of daily life in COPD

BACKGROUND

Patients with COPD use a higher proportion of their peak aerobic capacity during the performance of domestic activities of daily life (ADLs) compared to healthy peers, accompanied by a higher degree of task-related symptoms. To date, the influence of body mass index (BMI) on the task-related metabolic demands remains unknown in patients with COPD. Therefore, the aim of our study was to determine the effects of BMI on metabolic load during the performance of 5 consecutive domestic ADLs in patients with COPD.

METHODOLOGY

Ninety-four COPD patients and 20 healhty peers performed 5 consecutive, self-paced domestic ADLs putting on socks, shoes and vest; folding 8 towels; putting away groceries; washing up 4 dishes, cups and saucers; and sweeping the floor for 4 min. Task-related oxygen uptake and ventilation were assessed using a mobile oxycon, while Borg scores were used to assess task-related dyspnea and fatigue.

PRINCIPAL FINDINGS

1. Relative task-related oxygen uptake after the performance of domestic ADLs was increased in patients with COPD compared to healthy elderly, whereas absolute oxygen uptake is similar between groups; 2. Relative oxygen uptake and oxygen uptake per kilogram fat-free mass were comparable between BMI groups; and 3. Borg symptom scores for dyspnea en fatigue were comparable between BMI groups.

CONCLUSION

Patients with COPD in different BMI groups perform self-paced domestic ADLs at the same relative metabolic load, accompanied by comparable Borg symptom scores for dyspnea and fatigue.

Neuromuscular electrical stimulation prevents muscle function deterioration in exacerbated COPD: a pilot study

PURPOSE

COPD is a condition with systemic effects of which peripheral muscle dysfunction is a prominent contributor to exercise limitation, health related quality of life (HRQoL) impairment, and is an independent predictor of morbidity and mortality. Pulmonary rehabilitation (PR) is a successful strategy to improve exercise tolerance and HRQoL through the improvement of muscle function in patients with stable COPD or early after severe exacerbations of COPD (SECOPD). However, muscle function further deteriorates during SECOPD before early PR programmes commence. We aimed to investigate the feasibility and efficacy of quadriceps neuromuscular electrical stimulation (NMES) applied during a SECOPD to prevent muscle function deterioration.

METHODS

We have conducted a pilot study in eleven COPD patients (FEV(1) 41.3 ± 5.6 % pred) admitted to hospital with a SECOPD. We randomly allocated one leg to receive NMES (once a day for 14 days) with the other leg as a control (non-stimulated leg). We measured the change in quadriceps maximal voluntary contraction (ΔQMVC) as the main outcome.

RESULTS

Mean quadriceps muscle strength decreased in control legs (ΔQMVC -2.9 ± 5.3 N, p = ns) but increased in the stimulated legs (ΔQMVC 19.2 ± 6.1 N, p < 0.01). The difference in ΔQMVC between groups was statistically significant (p < 0.05). The effect of NMES was directly related to the stimulation intensity (∑mA) applied throughout the 14 sessions (r = 0.76, p < 0.01). All patients tolerated NMES without any side effects.

CONCLUSIONS

NMES is a feasible and effective treatment to prevent quadriceps muscle strength derangement during severe exacerbations of COPD and may be used to compliment early post-exacerbation pulmonary rehabilitation.

Peripheral muscle dysfunction in COPD: lower limbs versus upper limbs

In patients with COPD, the degree of functional impairment appears to differ between the upper and lower limbs. Significant dyspnea and fatigue have been reported by these patients when performing tasks with unsupported upper limbs and two mechanisms have been proposed to explain this fact: neuromechanical dysfunction of respiratory muscles; and changes in lung volume during such activities. The neuromechanical dysfunction seen in COPD patients during this type of exercise is related to changes in the breathing pattern, as well as to the simultaneity of afferent and efferent muscle stimuli, resulting in respiratory muscle asynchrony. In addition, the increased ventilation during upper limb exercise in patients with COPD leads to dynamic hyperinflation at different workloads. During lower limb exercises, the strength and endurance of the quadriceps muscle is lower in COPD patients than in healthy subjects. This could by explained by abnormal muscle metabolism (decreased aerobic capacity), dependence on glycolytic metabolism, and rapid accumulation of lactate during exercise. In comparison with lower limb exercises, upper limb exercises result in higher metabolic and ventilatory demands, as well as in a more intense sensation of dyspnea and greater fatigue. Because there are differences between the upper and lower limb muscles in terms of the morphological and functional adaptations in COPD patients, specific protocols for strength training and endurance should be developed and tested for the corresponding muscle groups.

Recovery pattern of motor reflex after a single bout of neuromuscular electrical stimulation session

We aimed at determining the recovery pattern of neural properties of soleus muscle after a single bout of neuromuscular electrical stimulation (NMES) session. Thirteen subjects performed an NMES exercise (75 Hz, 40 contractions, 6.25 s per contraction). Maximal voluntary contraction (MVC), H-reflex at rest and during voluntary contraction fixed at 60% of MVC (respectively, H(max) and H(sup) ) and volitional (V) wave were measured before and during the recovery period following this exercise [i.e., immediately after, 2 h (H2), 2 days (D2) and 7 days (D7)]. MVC exhibited an immediate and a delayed declines at 2 days (respectively, -29.8±4.6%, P<0.001; -13.0±3.4%, P<0.05). Likewise, V/M(sup) was decreased immediately and 2 days after NMES session (respectively, -43.3±11.6%, P<0.05; 35.3±6.6%, P<0.05). The delayed decrements in MVC and V-wave occurred concomitantly with muscle soreness peak (P<0.001). It could be concluded that motor command alterations after an NMES resistance session contributed to the immediate and also to the delayed decreases in MVC without affecting resting and active H-reflex excitability. These results suggested that spinal circuitry function of larger motoneurons was inhibited by NMES (as indicated by the depressed V-wave responses) contrary to the smaller one (indicated by the unchanged H-reflex responses).

Task-related oxygen uptake and symptoms during activities of daily life in CHF patients and healthy subjects

Patients with chronic heart failure (CHF) have a significantly lower peak aerobic capacity compared to healthy subjects, and, may therefore experience more inconvenience during the performance of domestic activities of daily life (ADLs). To date, the extent to which task-related oxygen uptake, heart rate, ventilation and symptoms during the performance of ADLs in CHF patients is different than in healthy subjects remains uncertain. General demographics, pulmonary function, body composition and peak aerobic capacity were assessed in 23 CHF outpatients and 20 healthy peers. In addition, the metabolic requirement of five simple self-paced domestic ADLs was assessed using a mobile oxycon. Task-related oxygen uptake (ml/min) was similar or lower in CHF patients compared to healthy subjects. In contrast, patients with CHF performing ADLs consumed oxygen at a higher proportion of their peak aerobic capacity than healthy subjects (p < 0.05). For example, getting dressed resulted in a mean task-related oxygen uptake of 49% of peak aerobic capacity, while sweeping the floor resulted in a mean task-related oxygen uptake of 52% of peak aerobic capacity, accompanied by significantly higher Borg symptom scores for dyspnea and fatigue (p < 0.05). Patients with CHF experience use a higher proportion of their peak aerobic capacity, peak ventilation and peak heart rate during the performance of simple self-paced domestic ADL than their healthy peers. These findings represent a necessary step in improving our understanding of improving what troubles patients the most—not being able to do the things that they could when they were healthy.

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.

Randomized controlled pilot study of neuromuscular electrical stimulation of the quadriceps in patients with non-small cell lung cancer

Patients with lung cancer experience muscle wasting and weakness. Therapeutic exercise may be beneficial but is not always practical. An alternative approach may be neuromuscular electrical stimulation (NMES) of the quadriceps muscles, but this has not been formally examined in patients with cancer. Thus, we have undertaken this pilot study to assess feasibility and inform the design of future studies. Sixteen patients were randomized to receive usual care (control group) or usual care plus NMES for four weeks. NMES consisted of daily stimulation to both thighs for up to 30minutes (frequency 50Hz, "on" cycle 11%-25%). Adherence was assessed by a self-report diary and a semistructured evaluation form. Quadriceps muscle strength, exercise endurance, and free-living physical activity were assessed using a Cybex NORM dynamometer, an endurance shuttle walk test, and an ActivPAL accelerometer (mean daily step count), respectively. Changes in outcome from baseline were compared between groups by mean differences and their 95% confidence intervals using independent t-test (P=0.05). Median (range) adherence to the program was 80% (69%-100%). All patients found the NMES device easy to use. Changes in outcome favored the NMES group, with mean differences of 9.4 Nm (21%) in quadriceps muscle strength, 768 steps (15%) in free-living activity, and 138 m (8%) in exercise endurance, but none of the differences were statistically significant. In conclusion, NMES warrants further study in patients with lung cancer.

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.

Short-term systemic effect of electrical muscle stimulation in critically ill patients

BACKGROUND

Our study assessed the short-term effect of electrical muscle stimulation (EMS) of the lower extremities on the thenar muscle microcirculation of patients who are critically ill.

METHODS

Twenty-nine hospital ICU patients (19 men; mean [+/- SD] age, 58 +/- 19 years; mean acute physiology and chronic health evaluation score, 17 +/- 5; mean sequential organ failure assessment score, 9 +/- 3) underwent a 45-min session of EMS of the lower extremities. BP and heart rate were measured, and blood samples were retrieved. Tissue oxygen saturation (Sto(2)) was assessed with near infrared spectroscopy at the thenar muscle with a vascular occlusion before and after EMS. A control group of six patients who were critically ill (4 men; mean age, 50 +/- 19 years) also were included in the study.

RESULTS

The mean Sto(2) did not differ significantly before and after the EMS session (81 +/- 16% vs 83 +/- 16%, respectively). The oxygen consumption rate during vascular occlusion differed significantly before the beginning and at the end of the session (20 +/- 9%/min vs 22 +/- 9%/min, respectively; p < 0.05). The reperfusion rate differed significantly before the beginning and at the end of the session (299 +/- 177%/min vs 375 +/- 182%/min, respectively; p < 0.05). Heart rate increased significantly at the end of the session (94 +/- 16 beats/min vs 99 +/- 16 beats/min, respectively; p < 0.05) as did systolic BP (127 +/- 21 mm Hg vs 133 +/- 23 mm Hg; p < 0.05, respectively). The Sto(2) value did not differ between the two measurements in control patients.

CONCLUSION

The data suggest that EMS has a systemic effect on microcirculation. These results suggest that further studies are needed to explore the potential use of EMS as a preventive and rehabilitation tool in critically ill patients.

Effects of neuromuscular electrical stimulation of muscles of ambulation in patients with chronic heart failure or COPD: a systematic review of the English-language literature

INTRODUCTION

Despite optimal drug treatment, many patients with congestive heart failure (CHF) or COPD still experience disabling dyspnea, fatigue, and exercise intolerance. They also exhibit significant changes in body composition. Attempts to rehabilitate these patients are often futile because conventional exercise-training modalities are limited by the severity of exertional dyspnea. Therefore, there is substantial interest in new training modalities that do not evoke dyspnea, such as transcutaneous neuromuscular electrical stimulation (NMES).

MATERIALS AND METHODS

In this article, we systematically review the literature that addresses the effects of NMES applied to the muscles of ambulation. We focused on the effects of NMES on strength, exercise capacity, and disease-specific health status in patients with CHF or COPD. We also address the methodological quality of the reported studies as well as the safety of NMES. Manuscripts published prior to December 2007 were identified by searching the Medline/PubMed, Embase, Cochrane Controlled Trials Register, CINAHL, and Physiotherapy Evidence Database (PEDro) databases.

RESULTS

Fourteen trials were identified (nine trials that examined NMES in CHF patients, and five in COPD patients). PEDro scores for methodological quality of the trials were generally moderate to good. Many of the studies reported significant improvements in muscle strength, exercise capacity, and/or health status.

DISCUSSION

Nonetheless, the limited number of studies, the disparity in patient populations, and the variability in NMES methodology prohibit the use of metaanalysis. Yet, from the viewpoint of a systematic review, NMES looks promising as a means of rehabilitating patients with CHF and COPD. There is at least sufficient evidence to warrant more large prospective, randomized, controlled trials.