The strength of the respiratory muscles can be evaluated from static measurements (maximal inspiratory and expiratory pressures, MIP and MEP) or inferred from dynamic maneuvers (maximal voluntary ventilation, MVV). Although these data could be suitable for a number of clinical and research applications, no previous studies have provided reference values for such tests using a healthy, randomly selected sample of the adult Brazilian population. With this main purpose, we prospectively evaluated 100 non-smoking subjects (50 males and 50 females), 20 to 80 years old, selected from more than 8,000 individuals. Gender-specific linear prediction equations for MIP, MEP and MVV were developed by multiple regression analysis: age and, secondarily, anthropometric measurements explained up to 56% of the variability of the dependent variables. The most cited previous studies using either Caucasian or non-Caucasian samples systematically underestimated the observed values of MIP (P<0.05). Interestingly, the self-reported level of regular physical activity and maximum aerobic power correlates strongly with both respiratory and peripheral muscular strength (knee extensor peak torque) (P<0.01). Our results, therefore, provide a new frame of reference to evaluate the normalcy of some useful indexes of respiratory muscle strength in Brazilian males and females aged 20 to 80.
This document reviews 1) the measurement properties of commonly used exercise tests in patients with chronic respiratory diseases and 2) published studies on their utilty and/or evaluation obtained from MEDLINE and Cochrane Library searches between 1990 and March 2015.Exercise tests are reliable and consistently responsive to rehabilitative and pharmacological interventions. Thresholds for clinically important changes in performance are available for several tests. In pulmonary arterial hypertension, the 6-min walk test (6MWT), peak oxygen uptake and ventilation/carbon dioxide output indices appear to be the variables most responsive to vasodilators. While bronchodilators do not always show clinically relevant effects in chronic obstructive pulmonary disease, high-intensity constant work-rate (endurance) tests (CWRET) are considerably more responsive than incremental exercise tests and 6MWTs. High-intensity CWRETs need to be standardised to reduce interindividual variability. Additional physiological information and responsiveness can be obtained from isotime measurements, particularly of inspiratory capacity and dyspnoea. Less evidence is available for the endurance shuttle walk test. Although the incremental shuttle walk test and 6MWT are reliable and less expensive than cardiopulmonary exercise testing, two repetitions are needed at baseline. All exercise tests are safe when recommended precautions are followed, with evidence suggesting that no test is safer than others. @ERSpublications A review of exercise testing to evaluate interventions aimed to improve exercise tolerance in respiratory patients
Supervised exercise training might be associated with beneficial effects on disease control and quality of life in asthmatic children. These data suggest an adjunct role of physical conditioning on clinical management of patients with more advanced disease.
Background: Passive training of specific locomotor muscle groups by means of neuromuscular electrical stimulation (NMES) might be better tolerated than whole body exercise in patients with severe chronic obstructive pulmonary disease (COPD). It was hypothesised that this novel strategy would be particularly effective in improving functional impairment and the consequent disability which characterises patients with end stage COPD. Methods: Fifteen patients with advanced COPD (nine men) were randomly assigned to either a home based 6 week quadriceps femoris NMES training programme (group 1, n=9, FEV 1 =38.0 (9.6)% of predicted) or a 6 week control period before receiving NMES (group 2, n=6, FEV 1 =39.5 (13.3)% of predicted). Knee extensor strength and endurance, whole body exercise capacity, and health related quality of life (Chronic Respiratory Disease Questionnaire, CRDQ) were assessed. Results: All patients were able to complete the NMES training programme successfully, even in the presence of exacerbations (n=4). Training was associated with significant improvements in muscle function, maximal and endurance exercise tolerance, and the dyspnoea domain of the CRDQ (p<0.05). Improvements in muscle performance and exercise capacity after NMES correlated well with a reduction in perception of leg effort corrected for exercise intensity (p<0.01). Conclusions: For severely disabled COPD patients with incapacitating dyspnoea, short term electrical stimulation of selected lower limb muscles involved in ambulation can improve muscle strength and endurance, whole body exercise tolerance, and breathlessness during activities of daily living.
Static lung volume (LV) measurements have a number of clinical and research applications; however, no previous studies have provided reference values for such tests using a healthy sample of the adult Brazilian population. With this as our main purpose, we prospectively evaluated 100 non-smoking subjects (50 males and 50 females), 20 to 80 years old, randomly selected from more than 8,000 individuals. Gender-specific linear prediction equations were developed by multiple regression analysis with total lung capacity (TLC), functional residual capacity (FRC), residual volume (RV), RV/TLC ratio and inspiratory capacity (IC) as dependent variables, and with age, height, weight, lean body mass and indexes of physical fitness as independent ones. Simpler demographic and anthropometric variables were as useful as more complex measurements in predicting LV values, independent of gender and age (R 2 values ranging from 0.49 to 0.78, P<0.001). Interestingly, prediction equations from North American and European studies overestimated the LV at low volumes and underestimated them at high volumes (P<0.05). Our results, therefore, provide a more appropriate frame of reference to evaluate the normalcy of static lung volume values in Brazilian males and females aged 20 to 80 years.
All of the most widely-cited studies for the prediction of maximum exercise responses have utilized either volunteers or referred subjects. Therefore, selection bias, with overestimation of the reference values, is a likely consequence.In order to establish a set of predictive equations for the gas exchange, ventilatory and cardiovascular responses to maximum ramp-incremental cycle ergometry, this study prospectively evaluated 120 sedentary individuals (60 males, 60 females, aged 20±80), randomly-selected from >8,000 subjects. Regular physical activity pattern by questionnaire, body composition by anthropometry and dual energy X-ray absorptiometry (n=75) and knee strength by isokinetic dynamometry were also assessed.Previously reported equations typically overestimated the subjects' peak oxygen uptake (p<0.05). Prediction linear equations for the main variables of clinical interest were established by backward stepwise regression analysis including: sex, age, knee extensor peak torque, bone-free lean leg mass, total and lean body mass, height, and physical activity scores. Reference intervals (95% confidence limits) were calculated: some of these values differed markedly from those formerly recommended.The results therefore might provide a more appropriate frame of reference for interpretation of the responses to symptom-limited ramp incremental cycle ergometry in sedentary subjects; i.e. those usually referred tor clinical cardiopulmonary exercise tests.
Background: Respiratory muscle unloading during exercise could improve locomotor muscle oxygenation by increasing oxygen delivery (higher cardiac output and/or arterial oxygen content) in patients with chronic obstructive pulmonary disease (COPD). Methods: Sixteen non-hypoxaemic men (forced expiratory volume in 1 s 42.2 (13.9)% predicted) undertook, on different days, two constant work rate (70-80% peak) exercise tests receiving proportional assisted ventilation (PAV) or sham ventilation. Relative changes (D%) in deoxyhaemoglobin (HHb), oxyhaemoglobin (O 2 Hb), tissue oxygenation index (TOI) and total haemoglobin (Hb tot ) in the vastus lateralis muscle were measured by nearinfrared spectroscopy. In order to estimate oxygen delivery (DO 2 est, l/min), cardiac output and oxygen saturation (SpO 2 ) were continuously monitored by impedance cardiography and pulse oximetry, respectively. Results: Exercise tolerance (Tlim) and oxygen uptake were increased with PAV compared with sham ventilation. In contrast, end-exercise blood lactate/Tlim and leg effort/Tlim ratios were lower with PAV (p,0.05). There were no between-treatment differences in cardiac output and SpO 2 either at submaximal exercise or at Tlim (ie, DO 2 est remained unchanged with PAV; p.0.05). Leg muscle oxygenation, however, was significantly enhanced with PAV as the exercise-related decrease in D(O 2 Hb)% was lessened and TOI was improved; moreover, D(Hb tot )%, an index of local blood volume, was increased compared with sham ventilation (p,0.01). Conclusions: Respiratory muscle unloading during highintensity exercise can improve peripheral muscle oxygenation despite unaltered systemic DO 2 in patients with advanced COPD. These findings might indicate that a fraction of the available cardiac output had been redirected from ventilatory to appendicular muscles as a consequence of respiratory muscle unloading.
A 6-min step test (6MST) may constitute a practical method for routinely assessing effort tolerance and exercise-related oxyhaemoglobin desaturation (ERD) in the primary care of patients with interstitial lung disease.In total, 31 patients (19 males) with idiopathic pulmonary fibrosis (n525) and chronic hypersensitivity pneumonia were submitted, on different days, to two 6MSTs. Physiological responses were compared with those found on maximal and submaximal cycle ergometer tests at the same oxygen uptake (V9O 2 ). Chronic breathlessness was also determined, as measured by the baseline dyspnoea index (BDI).Responses to 6MST were highly reproducible: 1.3¡2.0 steps?min -1 , ¡5 beats?min -1 (cardiac frequency), ¡50 mL?min -1 (V9O 2 ), ¡7 L?min -1 (minute ventilation) and ¡2% (arterial oxygen saturation measured by pulse oximetry (Sp,O 2 )). The number of steps climbed in 6 min was correlated to peak V9O 2 and the BDI. There were significant associations among the tests in relation to presence (change in Sp,O 2 between rest and exercise o4%) and severity (Sp,O 2 ,88%) of ERD. Four patients, however, presented ERD only in response to 6MST. Resting diffusing capacity of the lung for carbon monoxide and alveolar-arterial oxygen tension difference were the independent predictors of the number of steps climbed. A single-stage, self-paced 6-min step test provided reliable and reproducible estimates of exercise capacity and exercise-related oxyhaemoglobin desaturation in interstitial lung disease patients.
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