Interval training versus continuous training in patients with chronic obstructive pulmonary disease

Optimal intensity and type of lower limb aerobic training for patients with chronic obstructive pulmonary disease: a systematic review and network meta-analysis of RCTs

BACKGROUND

Lower limb aerobic exercise is the core component of pulmonary rehabilitation for chronic obstructive pulmonary disease (COPD) patients. The optimal intensity and type (e.g., interval or continuous) of exercise training remains to be determined.

OBJECTIVES

We aimed to evaluate the optimal intensities and types of lower limb aerobic exercise in patients with COPD.

DESIGN

Systematic review and network meta-analysis of randomized controlled trials.

DATA SOURCES AND METHODS

The PubMed, Web of Science, Embase, and the Cochrane Central Register of Controlled Trials were searched for relevant data. The interventions were classified according to their intensity and type as high-intensity interval training (HIIT), high-intensity continuous training (HICT), moderate-intensity continuous training (MICT), and low-intensity continuous training (LICT). We assessed exercise capacity using peak work rate (Wpeak) and the 6-min walking test (6-MWT). Lung function was evaluated by measuring peak minute ventilation (VE) and the percentage of predicted FEV1 (FEV1pred%). Dyspnea was assessed using the Modified Medical Research Council (mMRC) scale. Quality of life was measured with the Chronic Respiratory Questionnaire (CRQ).

RESULTS

Fifteen studies were identified (979 subjects). HIIT showed the greatest improvement in Wpeak, 6-MWT, VE, and mMRC compared to usual care (MD 18.48 (95% CI 12.35, 24.60), 67.73 (34.89, 100.57), 6.26 (2.81, 9.72), and -0.53 (-0.89, -0.17), respectively) and showed the improvement in CRQ (MD 10.80 (95% CI 1.65, 19.95)). MICT showed improvement in Wpeak and 6-MWT (MD 18.28 (95% CI 11.20, 25.22), 61.92 (28.34, 95.51)) similar to HICT (MD 16.08 (95% CI 8.19, 23.84), 64.64 (28.70, 100.57)) and showed the highest improvement in CRQ compared to usual care (MD 10.83 (95% CI 1.68, 19.98)). LICT significantly improved Wpeak compared to usual care (MD 13.47 (95% CI 4.77, 22.13)). The quality of evidence for outcomes varied from very low to moderate.

CONCLUSION

HIIT and MICT might be optimal training approaches for patients with COPD. LICT exhibited limited clinical efficacy. While HICT was as effective as MICT, it caused more dyspnea.

TRIAL REGISTRATION

This systematic review and network meta-analysis was prospectively registered with PROSPERO (No. CRD 42024520134).

High-intensity interval training versus moderate-intensity continuous training on patient quality of life in cardiovascular disease: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on the quality of life (QOL) and mental health (MH) of patients with cardiovascular disease (CVDs). Web of Science, Medline, Embase, Cochrane (CENTRAL), CINAHL, China National Knowledge Infrastructure, Wanfang, and China Science and Technology Journal databases were searched from their date of establishment to July, 2023. A total of 5798 articles were screened, of which 25 were included according to the eligibility criteria. The weighted mean difference (WMD) and standardized mean difference (SMD) were used to analyze data from the same and different indicator categories, respectively. The fixed-effects model (FE) or random-effects model (RE) combined data based on the between-study heterogeneity. There were no statistically significant differences regarding QOL, physical component summary (PCS), mental component summary (MCS), and MH, including depression and anxiety levels, between the HIIT and MICT groups [SMD = 0.21, 95% confidence interval (CI)  - 0.18-0.61, Z = 1.06, P = 0.290; SMD = 0.10, 95% CI  - 0.03-0.23, Z = 1.52, P = 0.128; SMD = 0.07, 95% CI  - 0.05-0.20, Z = 1.13, P = 0.25; SMD = - 0.08, 95% CI  - 0.40-0.25, Z = - 0.46, P = 0.646; WMD = 0.14. 95% CI  - 0.56-0.84, Z = 0.39, P = 0.694, respectively]. HIIT significantly improved PCS in the coronary artery disease (CAD) population subgroup relative to MICT. HIIT was also significantly superior to MICT for physical role, vitality, and social function. We conclude that HIIT and MICT have similar effects on QOL and MH in patients with CVD, while HIIT is favorable for improving patients' self-perceived physiological functioning based on their status and social adjustment, and this effect is more significant in patients with CAD.

High-intensity interval training improves the outcomes of patients with chronic obstructive pulmonary disease: A meta-analysis of randomized controlled trials

BACKGROUND

Pulmonary exercise is an important part in the treatment of chronic obstructive pulmonary disease (COPD). We aimed to evaluate the effects and safety of high-intensity interval training (HIIT) in patients with COPD, to provide insights to the COPD treatment and care.

METHODS

Two investigators searched PubMed, Medline, Embase, web of Science, Cochrane library, China National Knowledge Infrastructure (CNKI), Wanfang, and Weipu databases up to Sept 15, 2022 for randomized controlled trials (RCTs) on the effects and safety of HIIT for COPD patients. RevMan5.3 software was used for statistical analysis.

RESULTS

A total of 20 RCTs involving 962 COPD patients were finally included. 514 patients underwent HIIT interventions. Meta-analysis showed that HIIT increased the peak oxygen consumption (SMD = 0.30, 95%CI:0.14-0.46), peak minute ventilation (SMD = 0.26, 95%CI: 0.05-0.47), peak work rate (SMD = 0.34, 95%CI: 0.17-0.51), 6-min walking distance (SMD = 0.39, 95%CI: 0.23-0.55) in COPD patients (all P < 0.05). HIIT improved the quality of life (SMD = 0.30, 95%CI: 0.06-0.54) and reduced the dyspnea (SMD = -0.27, 95%CI: -0.51∼-0.03) in COPD patients (all P < 0.05). There were no significant differences in the forced expiratory volume in 1 s/forced vital capacity (SMD = 0.28, 95%CI: -0.01-0.56) and St. George's Respiratory Questionnaire score (SMD = -0.35, 95%CI: -0.73-0.03) between HIIT and control group (all P > 0.05). There was no publication bias analyzed by the Egger test and funnel plots (all P > 0.05).

CONCLUSIONS

HIIT may be beneficial to improve the pulmonary function, exercise capacity and quality of life of patients with COPD, which is worthy of clinical promotion for COPD treatment and care.

Effect of High-Intensity Interval Training on Functional Movement in Older Adults: A Systematic Review and Meta-analysis

BACKGROUND

Preserving physiological functional capacity (PFC), the ability to perform the activities of daily life, and the ease with which they can be performed, in older adults, defined for this study as ≥ 50 years of age, is an important consideration for maintaining health and independence through the ageing process. Physical activity, and exercise training in particular, has been positively associated with improvement in PFC. In addition to improving aerobic and anaerobic capacity, promoting and preserving functional movement as a component of PFC is an important goal of physical activity, especially for older adults. High-intensity interval training (HIIT), an exercise protocol where repeated bouts of increased intensity are interspersed with active or passive recovery periods, has often been studied as an alternative to traditional moderate-intensity continuous training (MICT) exercise, where a continuous intensity is maintained throughout the exercise session. A large body of research has determined that both types of exercise programme are effective in improving measures of aerobic and anaerobic fitness in older adults. However, the effect of the two exercise modalities on functional movement has most often been a secondary outcome, with a range of observational techniques applied for measurement.

OBJECTIVES

The primary objective of this research is to systematically review and meta-analyse published studies of HIIT interventions that measured functional movement in older adults to conclude if HIIT is effective for improving functional movement. A secondary objective is to determine if there are significant differences between HIIT and MICT effect on functional movement.

METHODS

A search strategy of terms locating studies of HIIT interventions, functional movement outcome measures, and older adult population samples was executed on seven digital databases. Randomized and pair-matched trials of > 2 weeks were considered for inclusion. Studies of participants with neurological impairment or studies using combined exercise modality were rejected. Standardized mean difference for functional movement outcome measures was calculated. A meta-analysis of the included studies and subgroups was performed along with study quality (risk of bias and publication bias) evaluation.

RESULTS

A total of 18 studies were included in random effects model pooled analysis. Subgroup analysis of HIIT versus MICT on functional movement showed a trivial effect in favour of HIIT (ES 0.13, 95% CI [-0.06, 0.33] p = 0.18) and did not achieve statistical significance. However, HIIT showed a medium, statistically significant favourable effect on functional movement versus non-intervention control (ES = 0.60 95% CI [0.24, 0.95] p = 0.001). Further subgroups analysis using singular and multiple functional movement outcome measures showed similar results.

CONCLUSION

This meta-analysis indicates that HIIT interventions in older adults may be effective at promoting improvements in functional movement, though it is unclear whether HIIT is superior to MICT.

A Systematic Review and Meta-Analysis of the Effectiveness of High-Intensity Interval Training in People with Cardiovascular Disease at Improving Depression and Anxiety

Background

To assess the effects of high-intensity interval training (HIIT) on depression and anxiety symptom in people with cardiovascular diseases (CVDs) compared with usual care (UC) and traditional aerobic continuous training (CT).

Methods

Randomized controlled trials (RCTs) that investigated the effectiveness of HIIT on depression and/or anxiety outcomes before and after treatment in people with CVDs were included. A systematic search of database containing PubMed, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, SPORTSDiscus, and CINAHL (EBSCOhost) was performed up to December 2021. The analyses of study characteristics, heterogeneity, and forest plot in analyses analogous were conducted via the pooled standardized mean difference (SMD) in random- or fixed-effect models as the measure of effectiveness.

Results

Twelve independent studies (515 participants) were included. One study was rated as low quality, and four studies were evaluated as high quality. The other studies were rated as moderate quality. Visual interpretation of funnel plots and Egger test indicated no evidence of publication bias. There was a statistically significant reduction in the severity of depression (12 studies, SMD = -0.42 [Random], 95% CI, -0.69 to -0.16, p=0.002, I ² = 52%) rather than that of anxiety symptoms (8 studies, SMD = -0.14 [Fixed], 95% CI, -0.35 to 0.06, p=0.18, I ² = 0%) following HIIT compared with UC and CT control groups. Subgroup analysis revealed that high-intensity treadmill training significantly improved (p=0.01) the depression symptom instead of training with a cycle ergometer (p=0.07) and strength training (p=0.40).

Conclusions

High-intensity interval treadmill training can significantly improve symptoms of depression rather than anxiety in cardiovascular patients compared to usual care and conventional aerobic continuous training.

Effects of High-Intensity Interval Training on Pulmonary Function and Exercise Capacity in Individuals with Chronic Obstructive Pulmonary Disease: A Meta-Analysis and Systematic Review

INTRODUCTION

This study aimed to examine the effectiveness of high-intensity interval training (HIIT) on pulmonary function and exercise capacity in individuals with chronic obstructive pulmonary disease (COPD).

METHODS

Ten databases (PubMed, the Cochrane Library, Web of Science, EMBASE, MEDLINE, CINAHL, CNKI, Wanfang, Weipu, and CBM) were searched for relevant articles published from inception to 30 June 2020. Studies were included if they were randomized controlled trials (RCTs) comparing a HIIT group with usual care or other training groups. Quality was assessed using the Physiotherapy Evidence Database (PEDro) scale, and the overall quality of evidence was assessed using the GRADE approach. The primary outcomes were peak VO2 and FEV1% predicted, and the secondary outcomes were FEV1/FVC, peak VE, peak WR, 6MWD, dyspnea, health-related quality of life, and adverse event.

RESULTS

Twelve articles (689 patients) were included. HIIT was shown to have a positive effect on exercise capacity (peak WR, 6MWD), pulmonary function (FEV1% pred, peak VE), dyspnea, and quality of life. However, sensitivity analyses for dyspnea were unstable, and the result changed from positive to negative after removing one study (SMD = - 0.13, 95% CI [- 0.44, 0.17], P = 0.40).

CONCLUSIONS

HIIT could improve pulmonary function, exercise capacity, and quality of life but may not decrease dyspnea in patients with COPD. It can be recommended as a safe and effective exercise modality in rehabilitation programs. Given that the overall results were based on a limited number of studies with significant heterogeneity and some of the results were based on low GRADE rating evidence, more high-quality, larger sample size, multicenter, and long-term follow-up RCTs are needed to confirm the clinical efficacy of HIIT in patients with COPD.

PROSPERO REGISTRATION

CRD42020165897.

Effect of interval compared to continuous exercise training on physiological responses in patients with chronic respiratory diseases: A systematic review and meta-analysis

Current evidence suggests that interval exercise training (IET) and continuous exercise training (CET) produce comparable benefits in exercise capacity, cardiorespiratory fitness and symptoms in patients with chronic obstructive pulmonary disease (COPD). However, the effects of these modalities have only been reviewed in patients with COPD. This meta-analysis compares the effectiveness of IET versus CET on exercise capacity, cardiorespiratory fitness and exertional symptoms in patients with chronic respiratory diseases (CRDs). Methods: PubMed, CINHAL, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL) and Nursing and Allied health were searched for randomised controlled trials from inception to September 2020. Eligible studies included the comparison between IET and CET, reporting measures of exercise capacity, cardiorespiratory fitness and symptoms in individuals with CRDs. Results: Thirteen randomised control trials (530 patients with CRDs) with fair to good quality on the PEDro scale were included. Eleven studies involved n = 446 patients with COPD, one involved n = 24 patients with cystic fibrosis (CF) and one n = 60 lung transplantation (LT) candidates. IET resulted in greater improvements in peak work rate (WR_peak) (2.40 W, 95% CI: 0.83 to 3.97 W; p = 0.003) and lower exercise-induced dyspnoea (−0.47, 95% CI: −0.86 to 0.09; p = 0.02) compared to CET; however, these improvements did not exceed the minimal important difference for these outcomes. No significant differences in peak values for oxygen uptake (VO_2peak), heart rate (HR_peak), minute ventilation (VE_peak), lactate threshold (LAT) and leg discomfort were found between the interventions. Conclusions: IET is superior to CET in improving exercise capacity and exercise-induced dyspnoea sensations in patients with CRDs; however, the extent of the clinical benefit is not considered clinically meaningful.

Comparison of High-Intensity Interval Training to Moderate-Intensity Continuous Training in Older Adults: A Systematic Review

High-intensity interval training (HIIT) is emerging as a safe and effective means to combat chronic diseases. The objective of this work was to perform a systematic review of the effect of HIIT interventions in an aging population. Three electronic databases were searched for randomized trials comparing the effect of HIIT and moderate-intensity continuous training in older adults. After a thorough screening process, 15 articles were identified as meeting the inclusion criteria. All studies expressed a comparable or superior effect of HIIT in cardiorespiratory fitness measures. No studies reported a lessened effect of HIIT in comparison with moderate-intensity continuous training. This systematic review demonstrates that HIIT is a useful exercise regimen, which can be used in older adults to increase cardiorespiratory fitness. More research is needed to determine the effects of HIIT in an aging, predominately female population.

High-Intensity Interval Training Is Effective at Increasing Exercise Endurance Capacity and Is Well Tolerated by Adults with Cystic Fibrosis

BACKGROUND

To optimize outcomes in people with cystic fibrosis (CF), guidelines recommend 30 to 60 min of moderate-intensity aerobic exercise on most days. Accumulating this volume of exercise contributes importantly to the substantial treatment burden associated with CF. Therefore, the main aim of this study was to investigate the effects of low-volume high-intensity interval training (HIIT) on exercise capacity in people with CF.

METHODS

This randomized controlled trial included people with CF aged ≥15 years, who were allocated to either eight weeks of thrice-weekly 10-min sessions of HIIT (experimental group) or eight weeks of weekly contact (control group). Before and after the intervention period, participants completed measurements of time to symptom limitation (T_lim) during a constant work rate cycle ergometry test (primary outcome), and maximal work rate (W_max) during a ramp-based cycle ergometry test and health-related quality of life (HRQoL).

RESULTS

Fourteen participants (median (IQR) age 31 (28, 35) years, forced expiratory volume in 1 second (FEV₁) 61 (45, 80) % predicted) were included (seven in each group). Compared to the control group, participants in the experimental group demonstrated a greater magnitude of change in T_lim, W_max (p = 0.017 for both) and in the physical function domain of HRQoL (p = 0.03). No other between-group differences were demonstrated. Mild post-exercise muscle soreness was reported on a single occasion by four participants. Overall, participants attended 93% of all HIIT sessions.

DISCUSSION

Eight weeks of low-volume (i.e., 30-min/week) HIIT produced gains in exercise capacity and self-reported physical function and was well tolerated by people with CF.

Interval Versus Continuous Aerobic Exercise Training in Overweight and Obese Patients With Chronic Obstructive Pulmonary Disease: A RANDOMIZED CONTROLLED STUDY

PURPOSE

The aim of this study was to compare the efficacy of the supervised pulmonary rehabilitation programs consisting of either an interval or continuous aerobic exercise program, with a home-based exercise program in patients with chronic obstructive pulmonary disease (COPD) who were overweight or obese.

METHODS

In this randomized controlled study, 72 overweight and obese patients diagnosed as having COPD were randomly assigned to 3 groups. Group 1 received an interval-type (IT) aerobic exercise program, group 2 received a continuous-type (CT) aerobic exercise program (both groups performed home exercises as well) and group 3 was only given a home-based exercise (HE) program. For the evaluation of patients, anthropometric measures, cardiopulmonary exercise testing (CPX), 6-min walk test (6MWT), modified-Borg dyspnea and leg fatigue scores, St George's Respiratory Questionnaire, and Hospital Anxiety and Depression Scale were used.

RESULTS

Both IT and CT groups showed significant improvement on CPX parameters, 6MWT distances, mental health, and health-related quality of life (HRQoL) compared with the HE group in overweight and obese patients with COPD (P < .001). Moreover, the IT group demonstrated a significant decrease in the modified-Borg dyspnea and leg fatigue during the CPX compared with both CT and HE groups (P < .001). Furthermore, the Borg dyspnea and leg fatigue during training were lower in the IT group than in the CT group (P < .05).

CONCLUSIONS

An interval or continuous aerobic exercise program added onto a home-based exercise program improved exercise capacity and HRQoL, and reduced anxiety and depression levels in overweight and obese patients with COPD.

Greater exercise tolerance in COPD during acute interval, compared to equivalent constant-load, cycle exercise: physiological mechanisms

KEY POINTS

Exercise intolerance is common in chronic obstructive pulmonary disease (COPD) patients. In patients with COPD, we compared an interval exercise (IE) protocol (alternating 30 s at 100% peak work rate (WR_peak ) with 30 s at 50% WR_peak ) with moderate-intensity constant-load exercise (CLE) at 75% WR_peak , which yielded the same work rate. Exercise endurance time and total work output were almost twice as high for IE than CLE. At exercise isotime (when work completed was the same between IE and CLE), IE was associated with less dynamic hyperinflation, lower blood lactate concentration, and greater respiratory and locomotor muscle oxygenation, but there were no differences in ventilation or cardiac output. However, at the limit of tolerance for each modality, dynamic hyperinflation was not different between IE and CLE, while blood lactate remained lower and muscle oxygenation higher with IE. Taken together, these findings suggest that dynamic hyperinflation and not muscle-based factors dictate the limits of tolerance in these COPD patients.

ABSTRACT

The relative importance of ventilatory, circulatory and peripheral muscle factors in determining tolerance to exercise in patients with chronic obstructive pulmonary disease (COPD) is not known. In 12 COPD patients (forced expiratory volume in one second: 58 ± 17%pred.) we measured ventilation, cardiac output, dynamic hyperinflation, local muscle oxygenation, blood lactate and time to exhaustion during (a) interval exercise (IE) consisting of 30 s at 100% peak work rate alternating with 30 s at 50%, and (b) constant-load exercise (CLE) at 75% peak work rate, designed to produce the same average work rate. Exercise time was substantially longer during IE than CLE (19.5 ± 4.8 versus 11.4 ± 2.1 min, p = 0.0001). Total work output was therefore greater during IE than CLE (81.3 ± 27.7 versus 48.9 ± 23.8 kJ, p = 0.0001). Dynamic hyperinflation (assessed by changes from baseline in inspiratory capacity, ΔIC) was less during IE than CLE at CLE exhaustion time (isotime, p = 0.009), but was similar at exhaustion (ΔIC_CLE : -0.38 ± 0.10 versus ΔIC_IE : -0.33 ± 0.12 l, p = 0.102). In contrast, at isotime, minute ventilation, cardiac output and systemic oxygen delivery did not differ between protocols (P > 0.05). At exhaustion in both protocols, the vastus lateralis and intercostal muscle oxygen saturation were higher in IE than CLE (p = 0.014 and p = 0.0002, respectively) and blood lactate concentrations were lower (4.9 ± 2.4 mmol l^-1 versus 6.4 ± 2.2 mmol l^-1 , p = 0.039). These results suggest that (1) exercise tolerance with COPD is limited by dynamic hyperinflation; and (2) cyclically lower (50%) effort intervals in IE help to preserve muscle oxygenation and reduce metabolic acidosis compared with CLE at the same average work rate; but these factors do not appear to determine time to exhaustion.

Effects of high intensity interval training on exercise capacity in people with chronic pulmonary conditions: a narrative review

BACKGROUND

Exercise training is important in the management of adults with chronic pulmonary conditions. However, achieving high intensity exercise may be challenging for this clinical population. There has been clinical interest in applying interval-based training as a strategy to optimise the load that can be tolerated during exercise training. Evidence for such an approach is limited in most chronic pulmonary populations.

MAIN BODY

In this narrative review, we provide an appraisal of studies investigating whole-body high intensity interval training (HIIT) in adults with chronic obstructive pulmonary disease (COPD). This is the first review to also include studies investigating HIIT in people with conditions other than COPD. Studies undertaken in adults with a chronic pulmonary condition were reviewed when participants were randomised to receive; (i) HIIT or no exercise or, (ii) HIIT or moderate intensity continuous exercise. Data were extracted on peak rate of oxygen uptake (VO2peak; 'cardiorespiratory fitness') and maximal work rate (Wmax; 'exercise capacity').In people with COPD, two studies demonstrated between-group differences favouring HIIT compared with no exercise. There appears to be no advantage for HIIT compared to continuous exercise on these outcomes. In people with cystic fibrosis (CF), no studies have compared HIIT to no exercise and the two studies that compared HIIT to continuous exercise reported similar benefits. In people prior to resection for non-small cell lung cancer, one study demonstrated a between-group difference in favour of HIIT compared with no exercise on VO2peak. In people with asthma, one study demonstrated a between-group difference in favour of HIIT compared with no exercise on VO2peak and one that compared HIIT to continuous exercise reported similar benefits. No studies were identified non-CF bronchiectasis or interstitial lung diseases.

CONCLUSIONS

High intensity interval training increases cardiorespiratory fitness and exercise capacity when compared with no exercise and produces a similar magnitude of change as continuous exercise in people with COPD. There is a paucity of studies exploring the effects of HIIT in other chronic pulmonary conditions.

Intensity of physical exercise and its effect on functional capacity in COPD: systematic review and meta-analysis

Objective:

To evaluate the effects of high-intensity interval training (HIIT), in comparison with those of continuous exercise, on functional capacity and cardiovascular variables in patients with COPD, through a systematic review and meta-analysis of randomized controlled trials.

Methods:

We searched PubMed, the Physiotherapy Evidence Database, the Cochrane Central Register of Controlled Trials, and EMBASE, as well as performing hand searches, for articles published up through January of 2017. We included studies comparing exercise regimens of different intensities, in terms of their effects on functional capacity and cardiovascular variables in patients with COPD.

Results:

Of the 78 articles identified, 6 were included in the systematic review and meta-analysis. Maximal oxygen consumption (VO_2max) did not differ significantly between HIIT and control interventions. That was true for relative VO_2max (0.03 mL/kg/min; 95% CI: −3.05 to 3.10) and absolute VO_2max (0.03 L/min, 95% CI: −0.02 to 0.08).

Conclusions:

The effects of HIIT appear to be comparable to those of continuous exercise in relation to functional and cardiovascular responses. However, our findings should be interpreted with caution because the studies evaluated present a high risk of bias, which could have a direct influence on the results.

Comparing the impact of different exercise interventions on fatigue in individuals with COPD: A systematic review and meta-analysis

To systematically review randomized controlled trials that compared the effectiveness of different types of exercise on the symptom of fatigue in individuals with chronic obstructive pulmonary disease (COPD). MEDLINE, EMBASE, EMcare, PsychINFO, and Cochrane library were searched from inception to October 2018. Studies were included if individuals with COPD were randomized into two or more physical exercise interventions that reported fatigue. Of the 395 full-texts reviewed, 17 studies were included. Fifteen studies reported the impact of exercise on health-related quality of life with fatigue as a subdomain. Reduction in fatigue was observed following endurance, resistance, or a combination of both exercises. There was no significant difference between continuous and interval training (n = 3 studies, pooled standardized mean difference (SMD) = -0.17, 95% CI = -0.47, 0.12, p = 0.25) or between endurance and resistance training (n = 3 studies, SMD = -0.35, 95% CI = -0.72, 0.01, p = 0.07) on fatigue in people with COPD. Fatigue reduction is not usually a primary outcome of exercise interventions, but it is frequently a secondary domain. The type of exercise did not influence the impact of exercise on fatigue, which was reduced in endurance, resistance, or a combination of both exercises, enabling clinicians to personalize training to match targeted outcomes.

Effects of high intensity interval training on exercise capacity in people with cystic fibrosis: study protocol for a randomised controlled trial

BACKGROUND

In people with cystic fibrosis (CF), higher exercise capacity is associated with better health-related quality of life (HRQoL), reduced risk of hospitalisation for a respiratory infection and survival. Therefore, optimisation of exercise capacity is an important treatment goal. The Australian and New Zealand clinical practice guidelines recommend that people with CF complete 30 to 60 min of moderate intensity aerobic exercise on most days of the week. This recommendation can be difficult to achieve by people with CF because of time constraints, and intolerable breathlessness and muscle fatigue during continuous exercise. In contrast, a low-volume, high intensity interval training (HIIT) program may be a more achievable and efficient training method to improve exercise capacity in people with CF.

METHODS

A randomised controlled trial will be undertaken. Forty people with CF (aged ≥15 years) will be randomly allocated, on a 1:1 ratio, to either the experimental or control group. Regardless of their group allocation, all participants will be asked to continue with their usual daily treatment for the study duration. Those in the experimental group will complete 8 weeks of thrice weekly HIIT on a cycle ergometer. Those in the control group will receive weekly contact with the investigators. The primary outcome of this study is exercise capacity. Secondary outcomes are HRQoL, exercise self-efficacy, feelings of anxiety, depression and enjoyment. These outcomes will be recorded at baseline (i.e. prior to randomisation) and following the 8-week intervention period. The study will also report other outcomes of the HIIT program (cardiovascular responses, symptom response, post-exercise muscle soreness and tolerance) and behaviour change techniques such as reinforcement, feedback and goal setting, used during the HIIT program.

DISCUSSION

This study will determine the effects of 8-weeks of supervised, low-volume HIIT, completed on a cycle ergometer on measures of exercise capacity, HRQoL, exercise self-efficacy, feelings of anxiety, depression and enjoyment. If effective, this type of training could be an attractive alternative to traditional continuous training because it may be more achievable and time efficient.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry (ANZCTR):12617001271392 (04/09/2017).

Short-Term (<8 wk) High-Intensity Interval Training in Diseased Cohorts

BACKGROUND AND AIM

Exercise training regimes can lead to improvements in measures of cardiorespiratory fitness (CRF), improved general health, and reduced morbidity and overall mortality risk. High-intensity interval training (HIIT) offers a time-efficient approach to improve CRF in healthy individuals, but the relative benefits of HIIT compared with traditional training methods are unknown in across different disease cohorts.

METHODS

This systematic review and meta-analysis compares CRF gains in randomized controlled trials of short-term (<8 wk) HIIT versus either no exercise control (CON) or moderate continuous training (MCT) within diseased cohorts. Literature searches of the following databases were performed: MEDLINE, EMBASE, CINAHL, AMED, and PubMed (all from inception to December 1, 2017), with further searches of Clinicaltrials.gov and citations via Google Scholar. Primary outcomes were effect on CRF variables: V˙O2peak and anaerobic threshold.

RESULTS

Thirty-nine studies met the inclusion criteria. HIIT resulted in a clinically significant increase in V˙O2peak compared with CON (mean difference [MD] = 3.32 mL·kg·min, 95% confidence interval [CI] = 2.56-2.08). Overall HIIT provided added benefit to V˙O2peak over MCT (MD = 0.79 mL·kg·min, 95% CI = 0.20-1.39). The benefit of HIIT was most marked in patients with cardiovascular disease when compared with MCT (V˙O2peak: MD = 1.66 mL·kg·min, 95% CI = 0.60-2.73; anaerobic threshold: MD = 1.61 mL·kg·min, 95% CI = 0.33-2.90).

CONCLUSIONS

HIIT elicits improvements in objective measures of CRF within 8 wk in diseased cohorts compared with no intervention. When compared with MCT, HIIT imparts statistically significant additional improvements in measures of CRF, with clinically important additional improvements in V˙O2peak in cardiovascular patients. Comparative efficacy of HIIT versus MCT combined with an often reduced time commitment may warrant HIIT's promotion as a viable clinical exercise intervention.

Influence of Disease Severity and Exercise Limitation on Exercise Training Intensity and Load and Health Benefits From Pulmonary Rehabilitation in Patients With COPD: AN EXPLORATORY STUDY

PURPOSE

Some patients with chronic obstructive pulmonary disease (COPD) fail to achieve health benefits with pulmonary rehabilitation (PR). Exercise intensity and load represent stimulus for adaptation but it is unclear whether inappropriate exercise intensity and/or load are affected by severity of COPD, which may affect health benefits. The purpose was to determine whether COPD severity and/or the severity of pulmonary limitation to exercise (PLE) impacted exercising intensity or load and whether resultant intensity/load affected health outcomes derived from PR.

METHODS

Patients with COPD (n = 58, age = 67 ± 7 y, forced expiratory volume in the first second of expiration [FEV1] % predicted = 52 ± 21%) were recruited upon referral to PR. Primary health outcomes evaluated were 6-min walk distance and St George's Respiratory Questionnaire. Patients were stratified for disease severity using Global Initiative for Obstructive Lung Disease (GOLD) staging and PLE severity by change in inspiratory capacity during exercise. Exercise intensity and load were calculated from daily exercise records.

RESULTS

Participants achieved comparable training duration and load regardless of GOLD severity. Patients with more severe PLE achieved greater training duration (more severe: 546 ± 143 min., less severe: 451 ± 109 min., P = .036), and relative training load (more severe: 2200.8 ± 595.3 kcal, less severe: 1648.3 ± 597.8 kcal, P = .007). Greater overall training load was associated with greater improvements in 6-min walk distance (r = 0.24, P = .035). No significant relationships were observed between PLE, GOLD severity, training parameters, and St George's Respiratory Questionnaire response.

CONCLUSIONS

Improvements in exercise tolerance can be explained by achieving greater training loads, demonstrating the importance of appropriate training load to maximize health outcomes in PR.

Supported self-management for patients with moderate to severe chronic obstructive pulmonary disease (COPD): an evidence synthesis and economic analysis

BACKGROUND

Self-management (SM) support for patients with chronic obstructive pulmonary disease (COPD) is variable in its coverage, content, method and timing of delivery. There is insufficient evidence for which SM interventions are the most effective and cost-effective.

OBJECTIVES

To undertake (1) a systematic review of the evidence for the effectiveness of SM interventions commencing within 6 weeks of hospital discharge for an exacerbation for COPD (review 1); (2) a systematic review of the qualitative evidence about patient satisfaction, acceptance and barriers to SM interventions (review 2); (3) a systematic review of the cost-effectiveness of SM support interventions within 6 weeks of hospital discharge for an exacerbation of COPD (review 3); (4) a cost-effectiveness analysis and economic model of post-exacerbation SM support compared with usual care (UC) (economic model); and (5) a wider systematic review of the evidence of the effectiveness of SM support, including interventions (such as pulmonary rehabilitation) in which there are significant components of SM, to identify which components are the most important in reducing exacerbations, hospital admissions/readmissions and improving quality of life (review 4).

METHODS

The following electronic databases were searched from inception to May 2012: MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Science Citation Index [Institute of Scientific Information (ISI)]. Subject-specific databases were also searched: PEDro physiotherapy evidence database, PsycINFO and the Cochrane Airways Group Register of Trials. Ongoing studies were sourced through the metaRegister of Current Controlled Trials, International Standard Randomised Controlled Trial Number database, World Health Organization International Clinical Trials Registry Platform Portal and ClinicalTrials.gov. Specialist abstract and conference proceedings were sourced through ISI's Conference Proceedings Citation Index and British Library's Electronic Table of Contents (Zetoc). Hand-searching through European Respiratory Society, the American Thoracic Society and British Thoracic Society conference proceedings from 2010 to 2012 was also undertaken, and selected websites were also examined. Title, abstracts and full texts of potentially relevant studies were scanned by two independent reviewers. Primary studies were included if ≈90% of the population had COPD, the majority were of at least moderate severity and reported on any intervention that included a SM component or package. Accepted study designs and outcomes differed between the reviews. Risk of bias for randomised controlled trials (RCTs) was assessed using the Cochrane tool. Random-effects meta-analysis was used to combine studies where appropriate. A Markov model, taking a 30-year time horizon, compared a SM intervention immediately following a hospital admission for an acute exacerbation with UC. Incremental costs and quality-adjusted life-years were calculated, with sensitivity analyses.

RESULTS

From 13,355 abstracts, 10 RCTs were included for review 1, one study each for reviews 2 and 3, and 174 RCTs for review 4. Available studies were heterogeneous and many were of poor quality. Meta-analysis identified no evidence of benefit of post-discharge SM support on admissions [hazard ratio (HR) 0.78, 95% confidence interval (CI) 0.52 to 1.17], mortality (HR 1.07, 95% CI 0.74 to 1.54) and most other health outcomes. A modest improvement in health-related quality of life (HRQoL) was identified but this was possibly biased due to high loss to follow-up. The economic model was speculative due to uncertainty in impact on readmissions. Compared with UC, post-discharge SM support (delivered within 6 weeks of discharge) was more costly and resulted in better outcomes (£683 cost difference and 0.0831 QALY gain). Studies assessing the effect of individual components were few but only exercise significantly improved HRQoL (3-month St George's Respiratory Questionnaire 4.87, 95% CI 3.96 to 5.79). Multicomponent interventions produced an improved HRQoL compared with UC (mean difference 6.50, 95% CI 3.62 to 9.39, at 3 months). Results were consistent with a potential reduction in admissions. Interventions with more enhanced care from health-care professionals improved HRQoL and reduced admissions at 1-year follow-up. Interventions that included supervised or unsupervised structured exercise resulted in significant and clinically important improvements in HRQoL up to 6 months.

LIMITATIONS

This review was based on a comprehensive search strategy that should have identified most of the relevant studies. The main limitations result from the heterogeneity of studies available and widespread problems with their design and reporting.

CONCLUSIONS

There was little evidence of benefit of providing SM support to patients shortly after discharge from hospital, although effects observed were consistent with possible improvement in HRQoL and reduction in hospital admissions. It was not easy to tease out the most effective components of SM support packages, although interventions containing exercise seemed the most effective. Future work should include qualitative studies to explore barriers and facilitators to SM post exacerbation and novel approaches to affect behaviour change, tailored to the individual and their circumstances. Any new trials should be properly designed and conducted, with special attention to reducing loss to follow-up. Individual participant data meta-analysis may help to identify the most effective components of SM interventions.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42011001588.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Interval Versus Continuous Training With Identical Workload: Physiological and Aerobic Capacity Adaptations

The interval model training has been more recommended to promote aerobic adaptations due to recovery period that enables the execution of elevated intensity and as consequence, higher workload in relation to continuous training. However, the physiological and aerobic capacity adaptations in interval training with identical workload to continuous are still uncertain. The purpose was to characterize the effects of chronic and acute biomarkers adaptations and aerobic capacity in interval and continuous protocols with equivalent load. Fifty Wistar rats were divided in three groups: Continuous training (GTC), interval training (GTI) and control (CG). The running training lasted 8 weeks (wk) and was based at Anaerobic Threshold (AT) velocity. GTI showed glycogen super-compensation (mg/100 mg) 48 h after training session in relation to CG and GTC (GTI red gastrocnemius (RG)=1.41±0.16; GTI white gastrocnemius (WG)=1.78±0.20; GTI soleus (S)=0.26±0.01; GTI liver (L)=2.72±0.36; GTC RG=0.42±0.17; GTC WG=0.54±0.22; GTC S=0.100±0.01; GTC L=1.12±0.24; CG RG=0.32±0.05; CG WG=0.65±0.17; CG S=0.14±0.01; CG L=2.28±0.33). The volume performed by GTI was higher than GTC. The aerobic capacity reduced 11 % after experimental period in GTC when compared to GTI, but this change was insignificant (19.6±5.4 m/min; 17.7±2.5 m/min, effect size = 0.59). Free fatty acids and glucose concentration did not show statistical differences among the groups. Corticosterone concentration increased in acute condition for GTI and GTC. Testosterone concentration reduced 71 % in GTC immediately after the exercise in comparison to CG. The GTI allowed positive adaptations when compared to GTC in relation to: glycogen super-compensation, training volume performed and anabolic condition. However, the GTI not improved the aerobic performance.

Principles of rehabilitation and reactivation: interstitial lung disease, sarcoidosis and rheumatoid disease with respiratory involvement

The interstitial lung diseases (ILDs) are characterised by dyspnoea on exertion, exercise-induced hypoxaemia, reduced skeletal muscle function and exercise intolerance. Evidence from nine randomised controlled trials shows that pulmonary rehabilitation improves exercise capacity, dyspnoea and quality of life in ILD, with moderately large effect sizes from 0.59 to 0.68. Participants with idiopathic pulmonary fibrosis, the most common and most progressive of the ILDs, achieve benefits in exercise capacity and quality of life that are of equal magnitude to those seen in other ILDs, with effect sizes from 0.59 to 0.75. Whole body exercise training is a core component of pulmonary rehabilitation for ILD. The standard exercise prescription used for other chronic lung diseases is effective in ILD, including 8 weeks of training with at least two supervised sessions per week and at least 30 min of aerobic training per session. However, the unique presentation and underlying pathophysiology of ILD may require modifications of the exercise prescription for individual patients. Those with connective tissue disease may present with joint pain and stiffness that require modification of the standard exercise prescription, including reduction in weight-bearing exercise. Some patients with severe disease may present with distressing dyspnoea that limits the intensity or progression of training. Because exercise-induced hypoxaemia is common in ILD and more severe than seen in other chronic lung diseases, pulmonary rehabilitation should be provided in a setting where supplemental oxygen therapy is available. Pulmonary rehabilitation programs offer the opportunity to address other critical aspects of ILD care, including management of comorbidities, symptoms and mood.

Contractile fatigue of the quadriceps muscle predicts improvement in exercise performance after pulmonary rehabilitation

RATIONALE

We hypothesized that among patients with chronic obstructive pulmonary disease, those who develop quadriceps contractile fatigue (QCF) after exhaustive submaximal cycle exercise would have a greater response to exercise training than those who do not develop QCF (NQCF).

METHODS

Patients (N = 132) had measurement of QCF at baseline. Six-minute walk distance (6 MWD), maximal incremental cycle exercise testing, and quality of life measured by the Chronic Respiratory Questionnaire were obtained before and after pulmonary rehabilitation (PR).

RESULTS

Eighty of the 132 patients (60.6%) developed QCF following constant workload exhaustive cycle exercise. Patients who developed QCF had a significantly greater improvement in 6 MWD following PR (45.3 ± 45.2 m) than those who did not (27.5 ± 45.7 m; P= .032). When baseline differences between patients who developed QCF and NQCF were accounted for, the difference in 6 MWD remained significant. Patients who developed QCF were not more likely to identify leg fatigue as the factor limiting exercise (56.2% of QCF group stated that leg fatigue was the limiting factor compared with 47.9% in the NQCF group; P= .46). When baseline differences were accounted for, the symptom causing exercise termination was not a predictor of the response to PR.

CONCLUSION

Patients who were capable of developing QCF had a significantly greater improvement in 6 MWD after PR compared to NQCF. Symptoms causing exercise termination could not be used to predict the development of contractile fatigue or the response to PR.

Exercise training in pulmonary rehabilitation

Exercise training remains a cornerstone of pulmonary rehabilitation (PR) in patients with chronic respiratory disease. The choice of type of exercise training depends on the physiologic requirements and goals of the individual patient as well as the available equipment at the PR center. Current evidence suggests that, at ground walking exercise training, Nordic walking exercise training, resistance training, water-based exercise training, tai chi, and nonlinear periodized exercise are all feasible and effective in (subgroups) of patients with chronic obstructive pulmonary disease. In turn, these exercise training modalities can be considered as part of a comprehensive, interdisciplinary PR program.

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.

Reporting of exercise attendance rates for people with chronic obstructive pulmonary disease: a systematic review

While recommendations for the duration, frequency, mode and intensity of exercise programmes for people with chronic obstructive pulmonary disease (COPD) are specified in consensus statements, criteria for exercise session attendance are less clear. The review questions were: (i) how commonly are a priori criteria and attendance rates reported for people with COPD participating in exercise programmes and (ii) what is the strength of association between attendance and improvements in functional exercise capacity. Database searches identified primary studies of people with COPD participating in exercise or pulmonary rehabilitation programmes of at least 2 weeks duration. Primary outcomes were a priori criteria for attendance, reports of attendance at supervised exercise sessions and mean improvements in functional exercise assessments. Data extraction processes were confirmed prospectively (>80% agreement). Variants of exercise attendance data were described. Linear associations between attendance and improvements in exercise outcomes were explored (Pearson r, P < 0.05). Of the 234 included studies, 86 (37%) reported attendance and 29 (12%) provided a priori criteria for attendance. In the small sample of studies which reported attendance and functional exercise data before and after the intervention, there was little to no relationship between improvements in functional exercise capacity and training volume (prescribed r = -0.03, P = 0.88; attended r = -0.24, P = 0.18). Reporting of exercise programme attendance rates is low and of variable quality for people with COPD. Consistent and explicit reporting of exercise attendance in people with COPD will enable calculation of dose-response relationships and determine the value of a priori exercise attendance criteria.

Interval versus continuous training in lung transplant candidates: a randomized trial

BACKGROUND

Interval (IT) and continuous training (CT) represent well-established exercise modalities in patients with moderate to severe chronic obstructive pulmonary disease (COPD). However, their effects and feasibility in patients with end-stage COPD remain unclear.

METHODS

Sixty patients (53 ± 6 years, 53% women) being evaluated for lung transplantation where randomly assigned either to IT (n = 30, cycling at 100% peak work rate for 30 seconds alternating with 30 seconds of rest) or CT (n = 30, cycling at 60% of peak work rate) during a 3-week inpatient rehabilitation program. Both exercise protocols yielded an equivalent amount of total work. Patients had a mean forced expiratory volume at 1 second (FEV(1)) of 25% ± 8% of predicted value.

RESULTS

Patients in both groups achieved similar clinically relevant improvements in 6-minute walking distance of 35 ± 29 meters for IT and 36 ± 43 meters for CT, with a between-group difference of 0.3 meters (95% confidence interval, -18.2 to 18.8). Changes in lung function parameters were not significant. Perceived intensity of dyspnea was significantly (p < 0.05) lower in IT (Borg 6.2 ± 1.8) compared with CT (Borg 7.1 ± 1.7). Patients required a median of 5 unintended breaks (interquartile range, 2-28) during IT exercise and 29 (interquartile range, 6-68) during CT (p < 0.001).

CONCLUSIONS

IT is associated with a lower intensity of dyspnea during exercise and fewer unintended breaks but achieves similar improvements in exercise capacity compared with CT in pre-lung transplant COPD patients.

Effect of exercise training in patients with chronic obstructive pulmonary disease compared with healthy elderly subjects

PURPOSE

Exercise training in patients with chronic obstructive pulmonary disease (COPD) can be challenging because whole-body exercise often elicits disabling symptoms of dyspnea before the exercising muscles reach their critical limits. The extent that this factor limits training has not been totally defined. The purpose of this study was to compare the response to training of patients with moderate to severe COPD with that achieved by healthy elderly subjects who were exercising using an identical program.

METHODS

Eight healthy subjects and 20 patients with COPD (forced expiratory volume in 1 second 42 ± 13% predicted) exercised 3 times a week for 8 weeks. Outcome measures included 6-minute walk distance, maximal exercise capacity (Wmax) during an incremental cycle ergometer test, and submaximal constant workload (60%-70% of subject Wmax) exercise time.

RESULTS

Six-minute walk distance and Wmax increased after training to a significantly greater extent in the healthy controls compared with the patients with COPD; 65 ± 24 versus 32 ± 50 m, P = .03; and 25.1±13.9 versus 11.5±13.1 watts, P = .025, respectively. However, these differences disappeared when data were expressed as percent improvement, 12.1 ± 5.3% versus 10.0 ± 15.8%, and 25.6 ± 13.5% versus 23.1 ± 33.3%. Improvement in submaximal constant workload exercise time after training was similar in healthy controls 21.6 ± 6.1 versus patients with COPD 18.8 ± 11.2 minutes.

CONCLUSIONS

Patients with COPD can show similar relative improvements in exercise capacity compared with healthy elderly subjects. The difference in absolute values reflects, at least in part, the greater baseline exercise capacity.

Optimal intensity and type of leg exercise training for people with chronic obstructive pulmonary disease

BACKGROUND

Intensity of exercise is considered a key determinant of training response, however, no systematic review has investigated the effects of different levels of training intensity on exercise capacity, functional exercise capacity and health-related quality of life (HRQoL) in people with chronic obstructive pulmonary disease (COPD). As type of training (continuous or interval) may also affect training response, the effects of the type of training in COPD also require investigation.

OBJECTIVES

To determine the effects of training intensity (higher versus lower) or type (continuous versus interval training) on primary outcomes in exercise capacity and secondary outcomes in symptoms and HRQoL for people with COPD.

SEARCH METHODS

We searched for studies in any language from the Cochrane Airways Group Specialised Register, CENTRAL, MEDLINE, EMBASE, CINAHL, AMED, PsycINFO and PubMed. Searches were current as of June 2011.

SELECTION CRITERIA

We included randomised controlled trials comparing higher training intensity to lower training intensity or comparing continuous training to interval training in people with COPD. We excluded studies that compared exercise training with no exercise training.

DATA COLLECTION AND ANALYSIS

We pooled results of comparable groups of studies and calculated the treatment effect and 95% confidence intervals (CI) using a random-effects model. We made two separate comparisons of effects between: 1) higher and lower training intensity; 2) continuous and interval training. We contacted authors of missing data.

MAIN RESULTS

We analysed three included studies (231 participants) for comparisons between higher and lower-intensity training and eight included studies (367 participants) for comparisons between continuous and interval training. Primary outcomes were outcomes at peak exercise (peak work rate, peak oxygen consumption, peak minute ventilation and lactate threshold), at isowork or isotime, endurance time on a constant work rate test and functional exercise capacity (six-minute walk distance). When comparing higher versus lower-intensity training, the pooled primary outcomes were endurance time and six-minute walk distance. There were no significant differences in endurance time improvement (mean difference (MD) 1.07 minutes; 95% CI -1.53 to 3.67) and six-minute walk distance improvement (MD 2.8 metres; 95% CI -10.1 to 15.6) following higher or lower-intensity training. However, heterogeneity of the endurance time results between studies was significant. When comparing continuous and interval training, there were no significant differences in any of the primary outcomes, except for oxygen consumption at isotime (MD 0.08; 95% CI 0.01 to 0.16) but the treatment effect was not considered clinically important. According to the GRADE system, studies were of low to moderate quality.

AUTHORS' CONCLUSIONS

Comparisons between the higher and lower training intensity were limited due to the small number of included studies and participants. Consequently, there are insufficient data to draw any conclusions on exercise capacity, symptoms and HRQoL for this comparison. For comparisons between continuous and interval training, both appear to be equally effective in improving exercise capacity, symptoms and HRQoL.

Structural and functional changes of peripheral muscles in chronic obstructive pulmonary disease patients

PURPOSE OF REVIEW

The purpose of this review is to identify new advances in our understanding of skeletal muscle dysfunction in patients with chronic obstructive pulmonary disease (COPD).

RECENT FINDINGS

Recent studies have confirmed the relevance of muscle dysfunction as an independent prognosis factor in COPD. Animal studies have shed light on the molecular mechanisms governing skeletal muscle hypertrophy/atrophy. Recent evidence in patients with COPD highlighted the contribution of protein breakdown and mitochondrial dysfunction as pathogenic mechanisms leading to muscle dysfunction in these patients.

SUMMARY

COPD is a debilitating disease impacting negatively on health status and the functional capacity of patients. COPD goes beyond the lungs and incurs significant systemic effects among which muscle dysfunction/wasting is one of the most important. Muscle dysfunction is a prominent contributor to exercise limitation, healthcare utilization and an independent predictor of morbidity and mortality. Gaining more insight into the molecular mechanisms leading to muscle dysfunction/wasting is key for the development of new and tailored therapeutic strategies to tackle skeletal muscle dysfunction/wasting in COPD patients.