The physiological basis of rehabilitation in chronic heart and lung disease

Development of a complex exercise rehabilitation intervention for people with pulmonary hypertension: the supervised pulmonary hypertension exercise rehabilitation (SPHERe) trial

BACKGROUND

People with pulmonary hypertension (PH) are not routinely referred for exercise rehabilitation despite the potential for reducing breathlessness and improving quality of life. We describe the development of a supervised pulmonary hypertension exercise rehabilitation (SPHERe) programme for people with PH.

METHODS

Development was completed in three phases: (1) systematic review, (2) stakeholder engagement with consensus from patients and experts and (3) prepilot intervention acceptability testing. We completed systematic reviews to identify international cardiopulmonary rehabilitation guidance and trials of exercise-based interventions for people with PH. Evidence from systematic reviews and stakeholder consensus shaped the SPHERe intervention, including addition of individual behavioural support sessions to promote exercise adherence. The draft SPHERe intervention was ratified through discussions with multidisciplinary professionals and people living with PH. We acceptability tested the centre-based intervention with eight participants in a prepilot development phase which identified a number of condition-specific issues relating to safety and fear avoidance of activity. Comprehensive intervention practitioner training manuals were produced to ensure standardised delivery. Participant workbooks were developed and piloted. Trial recruitment began in January 2020 but was subsequently suspended in March 2020 further to COVID-19 pandemic 'lockdowns'. In response to the pandemic, we undertook further development work to redesign the intervention to be suitable for exclusively home-based online delivery. Recruitment to the revised protocol began in June 2021.

DISCUSSION

The final SPHERe intervention incorporated weekly home-based online group exercise and behavioural support 'coaching' sessions supervised by trained practitioners, with a personalised home exercise plan and the optional loan of a stationary exercise bike. The intervention was fully manualised with clear pathways for assessment and individualised exercise prescription. The clinical and cost-effectiveness of the SPHERe online rehabilitation intervention is currently being tested in a UK multicentre randomised controlled trial.

TRIAL REGISTRATION NUMBER

ISCRTN10608766.

Exercise-based rehabilitation programmes for pulmonary hypertension

BACKGROUND

Individuals with pulmonary hypertension (PH) have reduced exercise capacity and quality of life. Despite initial concerns that exercise training may worsen symptoms in this group, several studies have reported improvements in functional capacity and well-being following exercise-based rehabilitation.

OBJECTIVES

To evaluate the benefits and harms of exercise-based rehabilitation for people with PH compared with usual care or no exercise-based rehabilitation.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 28 June 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in people with PH comparing supervised exercise-based rehabilitation programmes with usual care or no exercise-based rehabilitation.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were 1. exercise capacity, 2. serious adverse events during the intervention period and 3. health-related quality of life (HRQoL). Our secondary outcomes were 4. cardiopulmonary haemodynamics, 5. Functional Class, 6. clinical worsening during follow-up, 7. mortality and 8. changes in B-type natriuretic peptide. We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included eight new studies in the current review, which now includes 14 RCTs. We extracted data from 11 studies. The studies had low- to moderate-certainty evidence with evidence downgraded due to inconsistencies in the data and performance bias. The total number of participants in meta-analyses comparing exercise-based rehabilitation to control groups was 462. The mean age of the participants in the 14 RCTs ranged from 35 to 68 years. Most participants were women and classified as Group I pulmonary arterial hypertension (PAH). Study durations ranged from 3 to 25 weeks. Exercise-based programmes included both inpatient- and outpatient-based rehabilitation that incorporated both upper and lower limb exercise. The mean six-minute walk distance following exercise-based rehabilitation was 48.52 metres higher than control (95% confidence interval (CI) 33.42 to 63.62; I² = 72%; 11 studies, 418 participants; low-certainty evidence), the mean peak oxygen uptake was 2.07 mL/kg/min higher than control (95% CI 1.57 to 2.57; I² = 67%; 7 studies, 314 participants; low-certainty evidence) and the mean peak power was 9.69 W higher than control (95% CI 5.52 to 13.85; I² = 71%; 5 studies, 226 participants; low-certainty evidence). Three studies reported five serious adverse events; however, exercise-based rehabilitation was not associated with an increased risk of serious adverse event (risk difference 0, 95% CI -0.03 to 0.03; I² = 0%; 11 studies, 439 participants; moderate-certainty evidence). The mean change in HRQoL for the 36-item Short Form (SF-36) Physical Component Score was 3.98 points higher (95% CI 1.89 to 6.07; I² = 38%; 5 studies, 187 participants; moderate-certainty evidence) and for the SF-36 Mental Component Score was 3.60 points higher (95% CI 1.21 to 5.98 points; I² = 0%; 5 RCTs, 186 participants; moderate-certainty evidence). There were similar effects in the subgroup analyses for participants with Group 1 PH versus studies of groups with mixed PH. Two studies reported mean reduction in mean pulmonary arterial pressure following exercise-based rehabilitation (mean reduction: 9.29 mmHg, 95% CI -12.96 to -5.61; I² = 0%; 2 studies, 133 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

In people with PH, supervised exercise-based rehabilitation may result in a large increase in exercise capacity. Changes in exercise capacity remain heterogeneous and cannot be explained by subgroup analysis. It is likely that exercise-based rehabilitation increases HRQoL and is probably not associated with an increased risk of a serious adverse events. Exercise training may result in a large reduction in mean pulmonary arterial pressure. Overall, we assessed the certainty of the evidence to be low for exercise capacity and mean pulmonary arterial pressure, and moderate for HRQoL and adverse events. Future RCTs are needed to inform the application of exercise-based rehabilitation across the spectrum of people with PH, including those with chronic thromboembolic PH, PH with left-sided heart disease and those with more severe disease.

Physiological underpinnings of exertional dyspnoea in mild fibrosing interstitial lung disease

The functional disturbances driving "out-of-proportion" dyspnoea in patients with fibrosing interstitial lung disease (f-ILD) showing only mild restrictive abnormalities remain poorly understood. Eighteen patients (10 with idiopathic pulmonary fibrosis) showing preserved spirometry and mildly reduced total lung capacity (≥70% predicted) and 18 controls underwent an incremental cardiopulmonary exercise test with measurements of operating lung volumes and Borg dyspnoea scores. Patients' lower exercise tolerance was associated with higher ventilation (V̇_E)/carbon dioxide (V̇CO₂) compared with controls (V̇_E/V̇CO₂ nadir=35 ± 3 versus 29 ± 2; p < 0.001). Patients showed higher tidal volume/inspiratory capacity and lower inspiratory reserve volume at a given exercise intensity, reporting higher dyspnoea scores as a function of both work rate and V̇_E. Steeper dyspnoea-work rate slopes were associated with lower lung diffusing capacity, higher V̇_E/V̇CO₂, and lower peak O₂ uptake (p < 0.05). Heightened ventilatory demands in the setting of progressively lower capacity for tidal volume expansion on exertion largely explain higher-than-expected dyspnoea in f-ILD patients with largely preserved dynamic and "static" lung volumes at rest.

Relationship of arterial tonometry and exercise in patients with chronic heart failure: a systematic review with meta-analysis and trial sequential analysis

Background

Arterial stiffness is a common characteristic in patients with chronic heart failure (CHF), and arterial tonometric technologies related to arterial stiffness are novel and effective methods and have an important value in the diagnosis and prognosis of CHF. In terms of ameliorating arterial stiffness in patients with CHF, exercise training is considered an adjuvant treatment and also an effective means in the diagnosis and judgment of prognosis. However, there are huge controversies and inconsistencies in these aspects. The objective of this meta-analysis was to systematically test the connection of arterial tonometry and exercise in patients with CHF.

Methods

Databases, including MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, were accessed from inception to 7 March 2022. The meta-analysis was then conducted, and trial sequential analysis (TSA) was performed jointly to further verify our tests and reach more convincing conclusions by using RevMan version 5.4 software, STATA version 16.0 software, and TSA version 0.9.5.10 Beta software.

Results

Eighteen articles were included, with a total of 876 participants satisfying the inclusion criteria. The pooling revealed that flow-mediated dilation (FMD) was lower in basal condition [standardized mean difference (SMD): − 2.28%, 95% confidence interval (CI) − 3.47 to − 1.08, P < 0.001] and improved significantly after exercise (SMD: 5.96%, 95% CI 2.81 to 9.05, P < 0.001) in patients with heart failure with reduced ejection fraction (HFrEF) compared with healthy participants. The high-intensity training exercise was more beneficial (SMD: 2.88%, 95% CI 1.78 to 3.97, P < 0.001) than the moderate-intensity training exercise to improve FMD in patients with CHF. For augmentation index (AIx), our study indicated no significant differences (SMD: 0.50%, 95% CI − 0.05 to 1.05, P = 0.074) in patients with heart failure with preserved ejection fraction (HFpEF) compared with healthy participants. However, other outcomes of our study were not identified after further verification using TSA, and more high-quality studies are needed to reach definitive conclusions in the future.

Conclusions

This review shows that FMD is lower in basal condition and improves significantly after exercise in patients with HFrEF compared with healthy population; high-intensity training exercise is more beneficial than moderate-intensity training exercise to improve FMD in patients with CHF; besides, there are no significant differences in AIx in patients with HFpEF compared with the healthy population. More high-quality studies on this topic are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02792-6.

Does branched-chain amino acid supplementation improve pulmonary rehabilitation effect in COPD?

BACKGROUND

Muscle wasting is frequent in chronic obstructive lung disease (COPD) and associated with low branched-chain amino acids (BCAA). We hypothesized that BCAA supplementation could potentiate the effect of a pulmonary rehabilitation program (PRP) by inducing muscular change.

MATERIALS AND METHODS

Sixty COPD patients (GOLD 2-3) were involved in an ambulatory 4-week PRP either with BCAA oral daily supplementation or placebo daily supplementation in a randomized double-blind design. Maximal exercise test including quadriceps oxygenation measurements, functional exercise test, muscle strength, lung function tests, body composition, dyspnea and quality of life were assessed before and after PRP.

RESULTS

Fifty-four patients (64.9 ± 8.3 years) completed the protocol. In both groups, maximal exercise capacity, functional and muscle performances, quality of life and dyspnea were improved after 4-week PRP (p ≤ 0.01). Changes in muscle oxygenation during the maximal exercise and recovery period were not modified after 4-week PRP in BCAA group. Contrarily, in the placebo group the muscle oxygenation kinetic of recovery was slowed down after PRP.

CONCLUSION

This study demonstrated that a 4-week PRP with BCAA supplementation is not more beneficial than PRP alone for patients. A longer duration of supplementation or a more precise targeting of patients would need to be investigated to validate an effect on muscle recovery and to demonstrate other beneficial effects.

Oxygen Extraction Based on Inspiratory and Expiratory Gas Analysis Identifies Ventilatory Inefficiency in Chronic Obstructive Pulmonary Disease

Aims: In contrast to cardiovascular disease, low rather than high ventilatory inefficiency, evaluated by the minute ventilation-carbon dioxide output (V'_E-V'_CO2)-slope, has been recognized as being related to greater disease severity in chronic obstructive pulmonary disease (COPD). To better care for patients with cardiopulmonary disease, understanding the physiological correlation between ventilatory inefficiency and exercise limitation is necessary, but remains inadequate. Given that oxygen uptake (V'_O2) evaluated by cardiopulmonary exercise testing (CPET) depends on both the ventilatory capability and oxygen extraction, i.e., the difference between inspiratory and expiratory oxygen concentration (ΔFO₂), the aim of this study was to investigate the correlations between V'_E-V'_CO2-slope and the ΔFO₂ during exercise and their physiological implications in patients with COPD.

Methods: A total of 156 COPD patients (mean age, 70.9 ± 7.2 years) with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages I–IV and 16 controls underwent CPET with blood gas analysis.

Results: With the progression of COPD, mechanical ventilatory constraints together with a slower respiratory frequency led to exertional respiratory acidosis. In GOLD IV cases, (1) decrease in the dependence of reduced peak V'_O2 on V'_E led to an increase in its dependence on peak ΔFO₂ during exercise; and (2) the ΔFO₂-V'_CO2-slope became steeper, correlating with the severity of exertional respiratory acidosis (r = 0.6359, p < 0.0001). No significant differences in peak exercise ΔFO₂ or V'_E-V'_CO2-slope were observed among the various GOLD stages. In all subjects, including controls, peak exercise ΔFO₂ had the strongest correlation with the V'_E-V'_CO2-slope (r = −0.8835, p < 0.0001) and correlated well with body mass index (r = 0.3871, p < 0.0001), although it did not correlate with the heart rate-V'_CO2-relationship and V'_E.

Conclusions: Ventilatory efficiency related to CO₂ clearance might depend on exertional oxygen extraction in the body. Measuring ΔFO₂ might be a key component for identifying ventilatory inefficiency and oxygen availability. Increasing ΔFO₂ would help to improve ventilatory inefficiency and exercise tolerance separately from cardiac and ventilatory capability in COPD patients.

Oxygen supplementation during exercise improves leg muscle fatigue in chronic fibrotic interstitial lung disease

BACKGROUND

Exercise-induced hypoxaemia is a hallmark of chronic fibrotic interstitial lung disease (f-ILD). It remains unclear whether patients' severe hypoxaemia may exaggerate locomotor muscle fatigue and, if so, to what extent oxygen (O₂) supplementation can ameliorate these abnormalities.

METHODS

Fifteen patients (12 males, 9 with idiopathic pulmonary fibrosis) performed a constant-load (60% peak work rate) cycle test to symptom limitation (Tlim) while breathing medical air. Fifteen age-matched and sex-matched controls cycled up to patients' Tlim. Patients repeated the exercise test on supplemental O₂ (42%±7%) for the same duration. Near-infrared spectroscopy assessed vastus lateralis oxyhaemoglobin concentration ((HbO₂)). Pre-exercise to postexercise variation in twitch force (∆Tw) induced by femoral nerve magnetic stimulation quantified muscle fatigue.

RESULTS

Patients showed severe hypoxaemia (lowest O₂ saturation by pulse oximetry=80.0%±7.6%) which was associated with a blunted increase in muscle (HbO₂₎ during exercise vs controls (+1.3±0.3 µmol vs +4.4±0.4 µmol, respectively; p<0.001). Despite exercising at work rates ∼ one-third lower than controls (42±13 W vs 66±13 W), ∆Tw was greater in patients (∆Tw/external work performed by the leg muscles=-0.59±0.21 %/kJ vs -0.25±0.19 %/kJ; p<0.001). Reversal of exertional hypoxaemia with supplemental O₂ was associated with a significant increase in muscle (HbO₂₎, leading to a reduced decrease in ∆Tw in patients (-0.33±0.19 %/kJ; p<0.001 vs air). Supplemental O₂ significantly improved leg discomfort (p=0.005).

CONCLUSION

O₂ supplementation during exercise improves leg muscle oxygenation and fatigue in f-ILD. Lessening peripheral muscle fatigue to enhance exercise tolerance is a neglected therapeutic target that deserves clinical attention in this patient population.

Effects of Exercise Alone or in Combination with High-Protein Diet on Muscle Function, Aerobic Capacity, and Physical Function in Middle-Aged Obese Adults: A Randomized Controlled Trial

BACKGROUND

Obesity accelerates and exacerbates the age-related changes on muscle function and exercise capacity. In addition, the middle-aged population is often overlooked when talking about the prevention of sarcopenia. This study investigated the effects of exercise alone or in combination with a high-protein diet on muscle function and physical fitness in middle-aged obese adults.

MATERIALS AND METHODS

Sixty-nine middle-aged (50-64 years old) obese adults were randomly assigned to one of the following groups: control group (C; n=23), exercise group (E; n=23) or exercise plus high-protein group (EP; n=23). Individuals within the E and EP groups received 12 weeks of exercise training; whereas, the individuals in the EP group also received a high-protein diet intervention (1.6g/kg/day). Individuals within the C group were asked to maintain their lifestyle for 12 weeks. Participants were evaluated before and after the intervention. Outcome measures included maximal exercise capacity, muscle function and functional physical performance. Analysis of covariance was used to determine the effects of the intervention.

RESULTS

After the intervention, the E and EP groups had greater maximal work rate, peak oxygen consumption, and muscle power during muscle contractions at 180°/sec than that in the C group (P<0.05). The EP group, but not the E group, showed significant improvement in the sit-to-stand test and climbing stairs test than the C group after the intervention (P<0.05). Within group comparisons showed that the anaerobic threshold only increased in the EP group (+12% from pre-test).

CONCLUSIONS

For middle-aged obese adults, exercise with a high-protein diet not only improved muscle power and exercise capacity but also enhanced their functional physical performance.

Effects of bi-level positive airway pressure on ventilatory and perceptual responses to exercise in comorbid heart failure-COPD

This study tested the hypothesis that, by increasing the volume available for tidal expansion (inspiratory capacity, IC), bi-level positive airway pressure (BiPAP™) would lead to greater beneficial effects on dyspnea and exercise intolerance in comorbid heart failure (HF)-chronic obstructive pulmonary disease (COPD) than HF alone. Ten patients with HF and 9 with HF-COPD (ejection fraction = 30 ± 6% and 35 ± 7%; FEV₁ = 83 ± 12% and 65 ± 15% predicted, respectively) performed a discontinuous exercise protocol under sham ventilation or BiPAP™. Time to intolerance increased with BiPAP™ only in HF-COPD (p < 0.05). BiPAP™ led to higher tidal volume and lower duty cycle with longer expiratory time (p < 0.05). Of note, BiPAP™ improved IC (by ∼0.5 l) across exercise intensities only in HF-COPD. These beneficial consequences were associated with lower dyspnea scores at higher levels of ventilation (p < 0.05). By improving the qualitative" (breathing pattern and operational lung volumes) and sensory (dyspnea) features of exertional ventilation, BiPAP™ might allow higher exercise intensities to be sustained for longer during cardiopulmonary rehabilitation in HF-COPD.

Exercise intolerance in comorbid COPD and heart failure: the role of impaired aerobic function

Impaired aerobic function is a potential mechanism of exercise intolerance in patients with combined cardiorespiratory disease. We investigated the pathophysiological and sensory consequences of a low change in oxygen uptake (ΔV'_O2 )/change in work rate (ΔWR) relationship during incremental exercise in patients with coexisting chronic obstructive pulmonary disease (COPD) and systolic heart failure (HF).After clinical stabilisation, 51 COPD-HF patients performed an incremental cardiopulmonary exercise test to symptom limitation. Cardiac output was non-invasively measured (impedance cardiography) in a subset of patients (n=18).27 patients presented with ΔV'_O2 /ΔWR below the lower limit of normal. Despite similar forced expiratory volume in 1 s and ejection fraction, the low ΔV'_O2 /ΔWR group showed higher end-diastolic volume, lower inspiratory capacity and lower transfer factor compared to their counterparts (p<0.05). Peak WR and peak V'_O2 were ∼15% and ∼30% lower, respectively, in the former group: those findings were associated with greater symptom burden in daily life and at a given exercise intensity (leg discomfort and dyspnoea). The low ΔV'_O2 /ΔWR group presented with other evidences of impaired aerobic function (sluggish V'_O2 kinetics, earlier anaerobic threshold) and cardiocirculatory performance (lower oxygen pulse, lower stroke volume and cardiac output) (p<0.05). Despite similar exertional hypoxaemia, they showed worse ventilatory inefficiency and higher operating lung volumes, which led to greater mechanical inspiratory constraints (p<0.05).Impaired aerobic function due to negative cardiopulmonary-muscular interactions is an important determinant of exercise intolerance in patients with COPD-HF. Treatment strategies to improve oxygen delivery to and/or utilisation by the peripheral muscles might prove particularly beneficial to these patients.

Utility of ultrasound assessment of diaphragmatic function before and after pulmonary rehabilitation in COPD patients

Background

Pulmonary rehabilitation (PR) may improve respiratory symptoms and skeletal muscle strength in patients with COPD. We aimed to evaluate changes in ultrasound (US) measurements of diaphragmatic mobility and thickness after PR in COPD patients and to test its correlation with PR outcomes.

Methods

Twenty-five COPD patients were enrolled and underwent a diaphragm US assessment before and after a 12-week PR program.

Results

We found a correlation between the intraindividual percentage of change in the diaphragmatic length of zone of apposition at functional residual capacity (ΔLzapp%) and the change in 6-minute walking distance (6MWD) after PR (rho=0.49, P=0.02). ΔLzapp% was significantly higher in patients with improved 6MWD and COPD Assessment Test (CAT) score (mean rank=12.03±2.57 vs 6.88±4.37; P=0.02). A ΔLzapp% of ≥10% was able to discriminate among patients with improved 6MWD, with a sensitivity of 83% and a specificity of 74%. The area under the receiver operating characteristic curve for ΔLzapp% was 0.83. A cutoff value of ≥9% of ΔLzapp% had a positive predictive value in discriminating a reduction in ≥2 points of CAT score after PR, with a sensitivity and a specificity of 80% and 62%, respectively.

Conclusion

Diaphragm US assessment represents a useful prognostic marker of PR outcomes in COPD patients.

Serial changes in exercise capacity, quality of life and cardiopulmonary responses after pulmonary rehabilitation in patients with chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVES

Patients with chronic obstructive pulmonary disease (COPD) often have poor health-related quality of life (HRQL), exercise capacity and cardiopulmonary function. Pulmonary rehabilitation (PR) is beneficial to improve exercise capacity and HRQL. However, series changes of these parameters remain unclear.

METHODS

Forty-three subjects participated in a 3-months PR program. Subjects were evaluated at baseline and at 8, 16, and 24 sessions after PR.

RESULTS

After 8 sessions, there were significant improvements in the SGRQ-symptom domain, exertional dyspnea, and oxygen pulse (all p < 0.05). Maximal VO₂, SGRQ-activity and SGRQ-impact domains, and respiratory muscle strength were significantly improved after 16 and 24 sessions (all p < 0.05).

CONCLUSIONS

Eight sessions of exercise training lead to improvement of symptoms and exertional dyspnea. 16 to 24 sessions result in further improvement. We suggest patients receive 16 to 24 sessions of PR.

Osteopathic manual therapy in heart failure patients: A randomized clinical trial

BACKGROUND

Heart Failure (HF) patients usually present with increased arterial resistance and reduced blood pressure (BP) leading to an impaired functional capacity. Osteopathic Manual Therapy (OMT) focused on myofascial release techniques (MRT) and in the balancing of diaphragmatic tensions, has been shown to improve blood flow in individuals using the resistive index (RI). However, its effects in HF patients have not been examined.

PURPOSE

To evaluate the acute response of selected osteopathic techniques on RI, heart rate (HR), and BP in patients with HF.

METHODS

Randomized-controlled clinical trial of HF patients assigned to MRT (six different techniques with three aimed at the pelvis, two at the thorax, and one at the neck for 15 min) or Control group (subjects in supine position for 15 min without intervention). The RI of the femoral, brachial and carotid arteries was measured via doppler ultrasound while HR and BP were measured via sphygmomanometry before and after a single MRT or control intervention.

RESULTS

Twenty-two HF patients equally distributed (50% male, mean age 53 years; range 32-69 years) (ejection fraction = 35.6%, VO_2peak: 12.9 mL/kg^-1 min^-1) were evaluated. We found no intra or inter group differences in RI of the carotid (Δ_MRT: 0.07% vs Δ _Control:11.8%), brachial (Δ_MRT:0.17% vs Δ_Control: 2.9%), or femoral arteries (Δ_MRT:1.65% vs Δ_Control: 0.97%) (P > 0.05) and no difference in HR or BP (Δ_MRT:0.6% vs Δ_Control: 3%), (P > 0.05).

CONCLUSION

A single MRT session did not significantly change the RI, HR, or BP of HF patients.

Rehabilitation of Patients with Coexisting COPD and Heart Failure

Chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF) frequently coexist, significantly reducing the patient's quality of life (QoL) and increasing morbidity, disability and mortality. For both diseases, a multidisciplinary disease-management approach offers the best outcomes and reduces hospital readmissions. In both conditions, muscle dysfunction may dramatically influence symptoms, exercise tolerance/performance, health status and healthcare costs. The present review describes muscular abnormalities and mechanisms underlying these alterations. This review also discusses studies on training programs for patients with COPD, CHF and, where available, combined COPD-CHF diagnosis. Dyspnea, peripheral muscles and activities of daily living (ADL) represent a potential starting point for improving patients' functioning level and quality of life in COPD and CHF. A synergy of the combined diagnostic, pharmacological and rehabilitation treatment interventions is also essential. Integration between exercise training, drug therapy and nutritional care could be a valid, synergic and tailored approach for patients presenting with both diseases, and may have a positive impact on the exercise performance.

The degree of arm elevation impacts the endurance and cardiopulmonary adaptations of COPD patients performing upper-limb exercise: a cross-over study

BACKGROUND

In Chronic Obstructive Pulmonary Disease (COPD), upper limb exercise is widely recommended. However, how the degree of shoulder flexion may influence the exercise response is unknown.

AIM

We compared metabolic, ventilatory and symptomatic responses during constant-load supported and unsupported exercise performed at 80° and 120° arm elevation.

DESIGN

Randomized cross-over study.

SETTING

Pulmonary Pathophysiology Service in an Italian Respiratory Rehabilitative Division, in-patients were enrolled.

METHODS

Twelve patients with moderate-to-severe COPD (FEV1 51%, BMI 26.7 ± 6.3 Kg/m2) performed 4 symptom-limited constant-load tests at 70% of their individual maximal workload: 2 supported and 2 unsupported, respectively at 80° and 120° of glenohumeral joint flexion, executed in a random order.

RESULTS

Time to exhaustion (Tlim), evaluated by Kaplan-Maier curve, was shorter at 120° than 80° arm elevation in both supported (360 vs.. 486 seconds, p=0.031) and unsupported exercise (210 vs.. 375 seconds, p=0.005). No difference in dynamic hyperinflation was found between 80° and 120° elevation, even at the peak of exercise and at iso-ventilation. When normalized to Tlim, 120° arm elevation had a significantly higher metabolic cost, heart rate, minute ventilation and dyspnea/fatigue symptoms compared to 80° elevation, both in unsupported and supported conditions.

CONCLUSIONS

A larger shoulder flexion shortens per se exercise endurance due to the increased metabolic, ventilatory and cardiac response, without worsening dynamic hyperinflation.

CLINICAL REHABILITATION IMPACT

Arm position should be considered when prescribing individual exercise training and may be adjusted to modulate the workload.

Measured Physical Activity and 30-Day Rehospitalization in Heart Failure Patients

BACKGROUND

Patients hospitalized with decompensated heart failure are at high risk for readmission within 30 days of discharge. Since physical inactivity is associated with increased health care utilization in other diseases, it may predict rehospitalization in heart failure.

METHODS

In a single-center, prospective study, physical activity was measured following hospital discharge using an accelerometer on the wrist. We then related this activity to the 30-day all-cause rehospitalization rate in heart failure. Each minute of activity was dichotomized into higher or lower intensity, based on a threshold of 3000 vector magnitude units. Counts above this threshold corresponded to a higher level of physical activity. Logistic regression and Kaplan-Meier survival analyses were used to relate the activity group to 30-day readmissions.

RESULTS

Ninety-five patients admitted to a heart failure unit were screened; 61 met inclusion criteria and provided consent. Fifty patients were evaluated. Forty-six percent were male, mean age was 71 ± 15 years, and 46% had left ventricular ejection fraction <40%. Thirty-day all-cause hospitalizations occurred in 13 of these 50 patients (26%). Sixty-six percent and 34% were dichotomized into the higher and lower physical activity groups, respectively, over the first week; the latter were more likely to be readmitted within 30 days, with an OR = 5.0 (95% CI, 1.3-19.1), P = .02.

CONCLUSION

Physical inactivity is related to 30-day all-cause readmissions for heart failure. Further studies are necessary to assess causality and to determine whether treatments directed at increasing physical activity could reduce readmission rate.

Dysfunctional breathing is more frequent in chronic obstructive pulmonary disease than in asthma and in health

Involuntary adaptations of breathing patterns to counter breathlessness may lead to dysfunctional breathing in obstructive lung diseases. However, no studies examining dysfunctional breathing in Chronic Obstructive Pulmonary Disease (COPD) have been reported. Patients with verified COPD (n=34), asthma (n=37) and a healthy control group (n=41) were recruited. All participants completed the Nijmegen questionnaire for dysfunctional breathing as well as measures of disease activity. Comparisons between groups employed analysis of variance with post-hoc Bonferroni analyses and Pearson correlation for associations. Patients with COPD had significantly higher Nijmegen questionnaire scores than asthmatics (COPD: 23.4±10.6 versus 17.3±10.6, p=0.016) and healthy individuals (14.3±9.6, p=0.002). Significantly more patients with COPD had severe dysfunctional breathing with Nijmegen scores >23 (47%; 16/34) compared to asthma (27%; 10/37) and healthy controls (17%; 7/41) respectively (p=0.019). Dysfunctional breathing was detected in ∼50% of patients with COPD, more so than in asthma or health. Strategies to reduce abnormal breathing behaviours may have important benefits for treatment of breathlessness in COPD.

Exercise performance and differences in physiological response to pulmonary rehabilitation in severe chronic obstructive pulmonary disease with hyperinflation

Objective:

Pulmonary rehabilitation (PR) improves exercise capacity in most but not all COPD patients. The factors associated with treatment success and the role of chest wall mechanics remain unclear. We investigated the impact of PR on exercise performance in COPD with severe hyperinflation.

Methods:

We evaluated 22 COPD patients (age, 66 ± 7 years; FEV₁ = 37.1 ± 11.8% of predicted) who underwent eight weeks of aerobic exercise and strength training. Before and after PR, each patient also performed a six-minute walk test and an incremental cycle ergometer test. During the latter, we measured chest wall volumes (total and compartmental, by optoelectronic plethysmography) and determined maximal workloads.

Results:

We observed significant differences between the pre- and post-PR means for six-minute walk distance (305 ± 78 vs. 330 ± 96 m, p < 0.001) and maximal workload (33 ± 21 vs. 39 ± 20 W; p = 0.02). At equivalent workload settings, PR led to lower oxygen consumption, carbon dioxide production (VCO₂), and minute ventilation. The inspiratory (operating) rib cage volume decreased significantly after PR. There were 6 patients in whom PR did not increase the maximal workload. After PR, those patients showed no significant decrease in VCO₂ during exercise, had higher end-expiratory chest wall volumes with a more rapid shallow breathing pattern, and continued to experience symptomatic leg fatigue.

Conclusions:

In severe COPD, PR appears to improve oxygen consumption and reduce VCO₂, with a commensurate decrease in respiratory drive, changes reflected in the operating chest wall volumes. Patients with severe post-exercise hyperinflation and leg fatigue might be unable to improve their maximal performance despite completing a PR program.

Exercise-based rehabilitation programmes for pulmonary hypertension

BACKGROUND

Individuals with pulmonary hypertension (PH) have reduced exercise capacity and quality of life. Despite initial concerns that exercise training may worsen symptoms in this group, several studies have reported improvements in functional capacity and well-being following exercise-based rehabilitation in PH.

OBJECTIVES

To assess the efficacy and safety of exercise-based rehabilitation for people with PH. Primary outcomes were exercise capacity, adverse events during the intervention period and health-related quality of life (HRQoL). Secondary outcomes included cardiopulmonary haemodynamics, functional class, clinical worsening during follow-up, mortality and changes in B-type natriuretic peptide.

SEARCH METHODS

We searched the Cochrane Airways Specialised Register of Trials up to August 2016, which is based on regular searches of CINAHL, AMED, Embase, PubMed, MEDLINE, PsycINFO and registries of clinical trials. In addition we searched CENTRAL and the PEDro database up to August 2016 and handsearched relevant journals.

SELECTION CRITERIA

All randomised controlled trials (RCTs) focusing on exercise-based rehabilitation programmes for PH.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data independently. For binary outcomes, we calculated odds ratios and their 95% confidence interval (CI), on an intention-to-treat basis. For continuous data, we estimated the mean difference (MD) between groups and its 95% CI. We employed a random-effects model for analyses. We assessed risk of bias for included studies and created 'Summary of findings' tables using GRADE.

MAIN RESULTS

We included six RCTs and were able to extract data from five studies. The majority of participants were Group I pulmonary artery hypertension (PAH). Study duration ranged from three to 15 weeks. Exercise programmes included both inpatient- and outpatient-based rehabilitation that incorporated both upper and lower limb exercise. The mean six-minute walk distance following exercise training was 60.12 metres higher than control (30.17 to 90.07 metres, n = 165, 5 RCTs, low-quality evidence; minimal important difference was 30 metres), the mean peak oxygen uptake was 2.4 ml/kg/minute higher (1.4 to 3.4 ml/kg/min, n = 145, 4 RCTs, low-quality evidence) and the mean peak power in the intervention groups was 16.4 W higher (10.9 to 22.0 higher, n = 145, 4 RCTs, low-quality evidence). The mean change in HRQoL for the SF-36 physical component score was 4.63 points higher (0.80 to 8.47 points, n = 33, 2 RCTs, low-quality evidence) and for the SF-36 mental component score was 4.17 points higher (0.01 to 8.34 points; n = 33; 2 RCTs, low-quality evidence). One study reported a single adverse event, where a participant stopped exercise training due to lightheadedness.

AUTHORS' CONCLUSIONS

In people with PH, exercise-based rehabilitation results in clinically relevant improvements in exercise capacity. Exercise training was not associated with any serious adverse events. Whilst most studies reported improvements in HRQoL, these may not be clinically important. Overall, we assessed the quality of the evidence to be low. The small number of studies and lack of information on participant selection makes it difficult to generalise these results across the spectrum of people with PH.

High-Intensity Training Improves Global and Segmental Strains in Severe Congestive Heart Failure

BACKGROUND

High-intensity training (HIT) is superior to moderate aerobic training (MAT) for improving quality of life in congestive heart failure (CHF) patients. Speckle-tracking echocardiography (STE) has recently been suggested for estimation of left ventricle global and regional function. We evaluated the utility of STE for characterizing differences in cardiac function following MAT or HIT in a CHF rat model.

METHODS AND RESULTS

After baseline physiologic assessment, CHF was induced by means of coronary artery ligation in Sprague-Dawley rats. Repeated measurements confirmed the presence of CHF (ejection fraction 52 ± 10%, global circumferential strain (GCS) 10.5 ± 4, and maximal oxygen uptake (V˙O_2max) 71 ± 11 mL⋅min^-1⋅kg^-1; P < .001 vs baseline for all). Subsequently, rats were divided into training protocols: sedentary (SED), MAT, or HIT. After the training period, rats underwent the same measurements and were killed. Training intensity improved V˙O_2max (73 ± 13 mL⋅min^-1⋅kg^-1 in MAT [P < .01 vs baseline] and 82 ± 6 mL⋅min^-1⋅kg^-1 in HIT [P < .05 vs baseline or SED] and ejection fraction (50 ± 21% in MAT [P < .001 vs baseline] and 66 ± 7% in HIT [P > .05 vs baseline]). In addition, strains of specific segments adjacent to the infarct zone regained basal values (P > .05 vs baseline), whereas global cardiac functional parameters as assessed with the use of 2-dimensional echocardiography did not improve.

CONCLUSIONS

High-intensity exercise training improved function in myocardial segments remote from the scar, which resulted in compensatory cardiac remodeling. This effect is prominent, yet it could be detected only with the use of STE.

Skeletal muscle power and fatigue at the tolerable limit of ramp-incremental exercise in COPD

Muscle fatigue (a reduced power for a given activation) is common following exercise in chronic obstructive pulmonary disease (COPD). Whether muscle fatigue, and reduced maximal voluntary locomotor power, are sufficient to limit whole body exercise in COPD is unknown. We hypothesized in COPD: 1) exercise is terminated with a locomotor muscle power reserve; 2) reduction in maximal locomotor power is related to ventilatory limitation; and 3) muscle fatigue at intolerance is less than age-matched controls. We used a rapid switch from hyperbolic to isokinetic cycling to measure the decline in peak isokinetic power at the limit of incremental exercise ("performance fatigue") in 13 COPD patients (FEV₁ 49 ± 17%pred) and 12 controls. By establishing the baseline relationship between muscle activity and isokinetic power, we apportioned performance fatigue into the reduction in muscle activation and muscle fatigue. Peak isokinetic power at intolerance was ~130% of peak incremental power in controls (274 ± 73 vs. 212 ± 84 W, P < 0.05), but ~260% in COPD patients (187 ± 141 vs. 72 ± 34 W, P < 0.05), greater than controls (P < 0.05). Muscle fatigue as a fraction of baseline peak isokinetic power was not different in COPD patients vs. controls (0.11 ± 0.20 vs. 0.19 ± 0.11). Baseline to intolerance, the median frequency of maximal isokinetic muscle activity, was unchanged in COPD patients but reduced in controls (+4.3 ± 11.6 vs. -5.5 ± 7.6%, P < 0.05). Performance fatigue as a fraction of peak incremental power was greater in COPD vs. controls and related to resting (FEV₁/FVC) and peak exercise (V̇_E/maximal voluntary ventilation) pulmonary function (r² = 0.47 and 0.55, P < 0.05). COPD patients are more fatigable than controls, but this fatigue is insufficient to constrain locomotor power and define exercise intolerance.

Manual evaluation of the diaphragm muscle

The respiratory diaphragm is the most important muscle for breathing. It contributes to various processes such as expectoration, vomiting, swallowing, urination, and defecation. It facilitates the venous and lymphatic return and helps viscera located above and below the diaphragm to work properly. Its activity is fundamental in the maintenance of posture and body position changes. It can affect the pain perception and emotional state. Many authors reported on diaphragmatic training by using special instruments, whereas only a few studies focused on manual therapy approaches. To the knowledge of the authors, the existing scientific literature does not exhaustively examines the manual evaluation of the diaphragm in its different portions. A complete evaluation of the diaphragm is mandatory for several professional subjects, such as physiotherapists, osteopaths, and chiropractors not only to elaborate a treatment strategy but also to obtain information on the validity of the training performed on the patient. This article aims to describe a strategy of manual evaluation of the diaphragm, with particular attention to anatomical fundamentals, in order to stimulate further research on this less explored field.

Heart Failure Impairs Muscle Blood Flow and Endurance Exercise Tolerance in COPD

Heart failure, a prevalent and disabling co-morbidity of COPD, may impair cardiac output and muscle blood flow thereby contributing to exercise intolerance. To investigate the role of impaired central and peripheral hemodynamics in limiting exercise tolerance in COPD-heart failure overlap, cycle ergometer exercise tests at 20% and 80% peak work rate were performed by overlap (FEV1 = 56.9 ± 15.9% predicted, ejection fraction = 32.5 ± 6.9%; N = 16), FEV1-matched COPD (N = 16), ejection fraction-matched heart failure patients (N = 15) and controls (N = 12). Differences (Δ) in cardiac output (impedance cardiography) and vastus lateralis blood flow (indocyanine green) and deoxygenation (near-infrared spectroscopy) between work rates were expressed relative to concurrent changes in muscle metabolic demands (ΔO2 uptake). Overlap patients had approximately 30% lower endurance exercise tolerance than COPD and heart failure (p < 0.05). ΔBlood flow was closely proportional to Δcardiac output in all groups (r = 0.89-0.98; p < 0.01). Overlap showed the largest impairments in Δcardiac output/ΔO2 uptake and Δblood flow/ΔO2 uptake (p < 0.05). Systemic arterial oxygenation, however, was preserved in overlap compared to COPD. Blunted limb perfusion was related to greater muscle deoxygenation and lactate concentration in overlap (r = 0.78 and r = 0.73, respectively; p < 0.05). ΔBlood flow/ΔO2 uptake was related to time to exercise intolerance only in overlap and heart failure (p < 0.01). In conclusion, COPD and heart failure add to decrease exercising cardiac output and skeletal muscle perfusion to a greater extent than that expected by heart failure alone. Treatment strategies that increase muscle O2 delivery and/or decrease O2 demand may be particularly helpful to improve exercise tolerance in COPD patients presenting heart failure as co-morbidity.

Effective Bronchoscopic Lung Volume Reduction Accelerates Exercise Oxygen Uptake Kinetics in Emphysema

BACKGROUND

The impact of bronchoscopic lung volume reduction (BLVR) on physiologic responses to exercise in patients with advanced emphysema remains incompletely understood. We hypothesized that effective BLVR (e-BLVR), defined as a reduction in residual volume > 350 mL, would improve cardiovascular responses to exercise and accelerate oxygen uptake (Vo₂) kinetics.

METHODS

Thirty-one patients (FEV1, 36% ± 9% predicted; residual volume, 219% ± 57% predicted) underwent a constant intensity exercise test at 70% peak work rate to the limit of tolerance before and after treatment bronchoscopy (n = 24) or sham bronchoscopy (n = 7). Physiologic responses in patients who had e-BLVR (n = 16) were compared with control subjects (ineffective BLVR or sham bronchoscopy; n = 15).

RESULTS

e-BLVR reduced residual volume (-1.1 ± 0.5 L, P = .001), improved lung diffusing capacity by 12% ± 13% (P = .001), and increased exercise tolerance by 181 ± 214 s (P = .004). Vo₂ kinetics were accelerated in the e-BLVR group but remained unchanged in control subjects (Δ mean response time, -20% ± 29% vs 1% ± 25%, P = .04). Acceleration of Vo₂ kinetics was associated with reductions in heart rate and oxygen pulse response half-times by 8% (84 ± 14 to 76 ± 15 s, P = .04) and 20% (49 ± 16 to 34 ± 16 s, P = .01), respectively. There were also increases in heart rate and oxygen pulse amplitudes during the cardiodynamic phase post e-BLVR. Faster Vo₂ kinetics in the e-BLVR group were significantly correlated with reductions in residual volume (r = 0.66, P = .005) and improvements in inspiratory reserve volume (r = 0.56, P = .024) and exercise tolerance (r = 0.63, P = .008).

CONCLUSIONS

Lung deflation induced by e-BLVR accelerated exercise Vo₂ kinetics in patients with emphysema. This beneficial effect appears to be related mechanistically to an enhanced cardiovascular response to exercise, which may contribute to improved functional capacity.

Early chronic obstructive pulmonary disease: definition, assessment, and prevention

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. COPD, however, is a heterogeneous collection of diseases with differing causes, pathogenic mechanisms, and physiological effects. Therefore a comprehensive approach to COPD prevention will need to address the complexity of COPD. Advances in the understanding of the natural history of COPD and the development of strategies to assess COPD in its early stages make prevention a reasonable, if ambitious, goal.

Non invasive ventilation as an additional tool for exercise training

Recently, there has been increasing interest in the use of non invasive ventilation (NIV) to increase exercise capacity. In individuals with COPD, NIV during exercise reduces dyspnoea and increases exercise tolerance. Different modalities of mechanical ventilation have been used non-invasively as a tool to increase exercise tolerance in COPD, heart failure and lung and thoracic restrictive diseases. Inspiratory support provides symptomatic benefit by unloading the ventilatory muscles, whereas Continuous Positive Airway Pressure (CPAP) counterbalances the intrinsic positive end-expiratory pressure in COPD patients. Severe stable COPD patients undergoing home nocturnal NIV and daytime exercise training showed some benefits. Furthermore, it has been reported that in chronic hypercapnic COPD under long-term ventilatory support, NIV can also be administered during walking. Despite these results, the role of NIV as a routine component of pulmonary rehabilitation is still to be defined.

Effect of induced leg muscle fatigue on exertional dyspnea in healthy subjects

The genesis of dyspnea is complex. It appears to be related to central respiratory drive although prevailing leg fatigue could independently potentiate dyspnea. We hypothesized that experimentally induced leg fatigue generates more intense exertional dyspnea for a given level of ventilatory drive. Following familiarization, 19 healthy subjects (32.2 ± 7.6 yr; 11 men) performed a 5-min treadmill test (speed: ∼4 km/h; grade: ∼25%) on two separate days randomized between control (C) and experimentally induced leg fatigue (E) achieved by repeated knee extension against 40% body weight until task failure. Oxygen uptake (V̇o2, l/min), carbon dioxide output (V̇co2, l/min), ventilation (V̇e, l/min), and respiratory rate (fR) were measured breath by breath. Heart rate (HR) and perceived dyspnea intensity (0–10 numerical scale) were recorded continuously. Data were averaged over 30-s intervals. Exertional dyspnea during E was statistically significantly higher (E vs. C: 4.2 ± 0.2 vs. 3.4 ± 0.2, P < 0.001) and accompanied by a significant increase in V̇e (E vs. C: 61.7 ± 3.7 vs. 55.3 ± 2.8, P = 0.005) and fR (E vs. C: 26.7 ± 1.0 vs. 24.2 ± 1.3, P = 0.036). Dyspnea following E remained significantly higher after allowing for the V̇e confound (ANCOVA, P = 0.003). V̇o2, V̇co2, and HR were not significantly different between two conditions. However, the slopes for dyspnea vs. V̇o2 and dyspnea vs. V̇e were similar between E and C, which suggested that gain in dyspnea per unit change in V̇o2 or V̇e was not altered by leg fatigue. These findings support the hypothesis that the intensity of exertional dyspnea is exacerbated by peripheral afferent information from fatigued leg muscles.

Instantaneous quantification of skeletal muscle activation, power production, and fatigue during cycle ergometry

A rapid switch from hyperbolic to isokinetic cycling allows the velocity-specific decline in maximal power to be measured, i.e., fatigue. We reasoned that, should the baseline relationship between isokinetic power (Piso) and electromyography (EMG) be reproducible, then contributions to fatigue may be isolated from 1) the decline in muscle activation (muscle activation fatigue); and 2) the decline in Piso at a given activation (muscle fatigue). We hypothesized that the EMG-Piso relationship is linear, velocity dependent, and reliable for instantaneous fatigue assessment at intolerance during and following whole body exercise. Healthy participants (n = 13) completed short (5 s) variable-effort isokinetic bouts at 50, 70, and 100 rpm to characterize baseline EMG-Piso. Repeated ramp incremental exercise tests were terminated with maximal isokinetic cycling (5 s) at 70 rpm. Individual baseline EMG-Piso relationships were linear (r(2) = 0.95 ± 0.04) and velocity dependent (analysis of covariance). Piso at intolerance (two legs, 335 ± 88 W) was ∼45% less than baseline [630 ± 156 W, confidence interval of the difference (CIDifference) 211, 380 W, P < 0.05]. Following intolerance, Piso recovered rapidly (F = 44.1; P < 0.05; η(2) = 0.79): power was reduced (P < 0.05) vs. baseline only at 0-min (CIDifference 80, 201 W) and 1-min recovery (CIDifference 13, 80 W). Activation fatigue and muscle fatigue (one leg) were 97 ± 55 and 60 ± 50 W, respectively. Mean bias ± limits of agreement for reproducibility were as follows: baseline Piso 1 ± 30 W; Piso at 0-min recovery 3 ± 35 W; and EMG at Piso 3 ± 14%. EMG power is linear, velocity dependent, and reproducible. Deviation from this relationship at the limit of tolerance can quantify the "activation" and "muscle" related components of fatigue during cycling.

Activity restriction in mild COPD: a challenging clinical problem

Dyspnea, exercise intolerance, and activity restriction are already apparent in mild chronic obstructive pulmonary disease (COPD). However, patients may not seek medical help until their symptoms become troublesome and persistent and significant respiratory impairment is already present; as a consequence, further sustained physical inactivity may contribute to disease progression. Ventilatory and gas exchange impairment, cardiac dysfunction, and skeletal muscle dysfunction are present to a variable degree in patients with mild COPD, and collectively may contribute to exercise intolerance. As such, there is increasing interest in evaluating exercise tolerance and physical activity in symptomatic patients with COPD who have mild airway obstruction, as defined by spirometry. Simple questionnaires, eg, the modified British Medical Research Council dyspnea scale and the COPD Assessment Test, or exercise tests, eg, the 6-minute or incremental and endurance exercise tests can be used to assess exercise performance and functional status. Pedometers and accelerometers are used to evaluate physical activity, and endurance tests (cycle or treadmill) using constant work rate protocols are used to assess the effects of interventions such as pulmonary rehabilitation. In addition, alternative outcome measurements, such as tests of small airway dysfunction and laboratory-based exercise tests, are used to measure the extent of physiological impairment in individuals with persistent dyspnea. This review describes the mechanisms of exercise limitation in patients with mild COPD and the interventions that can potentially improve exercise tolerance. Also discussed are the benefits of pulmonary rehabilitation and the potential role of pharmacologic treatment in symptomatic patients with mild COPD.

Skeletal muscle abnormalities and exercise intolerance in older patients with heart failure and preserved ejection fraction

Heart failure (HF) with preserved ejection fraction (HFPEF) is the most common form of HF in older persons. The primary chronic symptom in HFPEF is severe exercise intolerance, and its pathophysiology is poorly understood. To determine whether skeletal muscle abnormalities contribute to their severely reduced peak exercise O2 consumption (Vo2), we examined 22 older HFPEF patients (70 ± 7 yr) compared with 43 age-matched healthy control (HC) subjects using needle biopsy of the vastus lateralis muscle and cardiopulmonary exercise testing to assess muscle fiber type distribution and capillarity and peak Vo2. In HFPEF versus HC patients, peak Vo2 (14.7 ± 2.1 vs. 22.9 ± 6.6 ml·kg(-1)·min(-1), P < 0.001) and 6-min walk distance (454 ± 72 vs. 573 ± 71 m, P < 0.001) were reduced. In HFPEF versus HC patients, the percentage of type I fibers (39.0 ± 11.4% vs. 53.7 ± 12.4%, P < 0.001), type I-to-type II fiber ratio (0.72 ± 0.39 vs. 1.36 ± 0.85, P = 0.001), and capillary-to-fiber ratio (1.35 ± 0.32 vs. 2.53 ± 1.37, P = 0.006) were reduced, whereas the percentage of type II fibers was greater (61 ± 11.4% vs. 46.3 ± 12.4%, P < 0.001). In univariate analyses, the percentage of type I fibers (r = 0.39, P = 0.003), type I-to-type II fiber ratio (r = 0.33, P = 0.02), and capillary-to-fiber ratio (r = 0.59, P < 0.0001) were positively related to peak Vo2. In multivariate analyses, type I fibers and the capillary-to-fiber ratio remained significantly related to peak Vo2. We conclude that older HFPEF patients have significant abnormalities in skeletal muscle, characterized by a shift in muscle fiber type distribution with reduced type I oxidative muscle fibers and a reduced capillary-to-fiber ratio, and these may contribute to their severe exercise intolerance. This suggests potential new therapeutic targets in this difficult to treat disorder.

Chronic obstructive pulmonary disease: clinical integrative physiology

Peripheral airway dysfunction, inhomogeneous ventilation distribution, gas trapping, and impaired pulmonary gas exchange are variably present in all stages of chronic obstructive pulmonary disease (COPD). This article provides a cogent physiologic explanation for the relentless progression of activity-related dyspnea and exercise intolerance that all too commonly characterizes COPD. The spectrum of physiologic derangements that exist in smokers with mild airway obstruction and a history compatible with COPD is examined. Also explored are the perceptual and physiologic consequences of progressive erosion of the resting inspiratory capacity. Finally, emerging information on the role of cardiocirculatory impairment in contributing to exercise intolerance in patients with varying degrees of airway obstruction is reviewed.