aaAmong the overall pattern of functional impairment in patients with chronic obstructive pulmonary disease (COPD), limitation of peak exercise capacity is an essential feature, which can be accurately determined by incremental cycle ergometry [1]. The impaired exercise capacity in COPD patients has long been ascribed to an impaired ventilatory capacity due to disturbed pulmonary mechanics, respiratory muscle dysfunctioning, impaired gas exchange and cardiovascular dysfunctioning. Recent publications have drawn attention to peripheral muscle weakness and an altered muscle energy metabolism as contributing factors to impaired exercise capacity [2,3]. Muscle strength and metabolism are closely related to body composition [4]. It could be hypothesized that the association between peripheral muscle weakness and alterations in muscle metabolism with exercise impairment is partly related to depletion of muscle mass.Muscle mass is the largest constituent of the body cell mass (BCM), the energy-exchanging part of the body. The BCM and the extracellular fluids and solids of the body represent the fat-free mass (FFM). Direct measurement of muscle mass, for instance by magnetic resonance imaging, requires expensive, sophisticated instrumentation, that is not readily accessible [5]. Dilution methods are the next most accurate methods in the hierarchy of body composition methods [5] that can be applied to estimate muscle mass, by the assessment of FFM. The additional value of measurement of FFM instead of body weight in the functional characterization of patients with COPD was demonstrated in an earlier study which showed that FFM correlated stronger with the 12 min walking distance than body weight [6]. In addition, in this previous study it was found that normal weight patients with a selective loss of FFM expressed a lower walking distance than underweight patients with a relative preservation of FFM [6].In a recent study it was shown, however, that measurement of FFM may mask the loss of BCM in some COPD patients [7]. From this study it was hypothesized that subtle changes in the BCM can be estimated by the extracellular water (ECW)/intracellular water (ICW) ratio, and it was found that an increased ECW/ICW ratio may occur particularly in patients with severe FFM depletion [7]. Peak exercise response in relation to tissue depletion in patients with chronic obstructive pulmonary disease. E.M. Baarends, A.M.W.J. Schols, R. Mostert, E.F.M. Wouters. ERS Journals Ltd 1997.ABSTRACT: In several studies a correlation between body weight and peak exercise capacity has been found in patients with chronic obstructive pulmonary disease (COPD). In the present study a thorough analysis of the relationship between body composition and peak exercise performance was executed in 62 patients with clinically stable COPD. This was based on the hypothesis that particularly muscle mass, as the largest constituent of both fat-free mass (FFM) and body cell mass, is related to exercise capacity.Body composition was assessed using deuterium and b...

Resting energy expenditure (REE) is often elevated in patients with chronic obstructive pulmonary disease (COPD), but no data are available regarding total energy expenditure in free living conditions. We compared total daily energy expenditure (TDE) in eight COPD patients (FEV1 36 +/- 13%) admitted to a pulmonary rehabilitation center and eight independently living healthy subjects, matched for sex, age, and body mass index (BMI). TDE was measured over a 2-wk interval using doubly labeled water in combination with measurement of REE and body composition. The COPD patients had a significantly higher TDE than the healthy subjects (2,499 +/- 320 kcal/d and 2,107 +/- 88 kcal/d, respectively, p < 0.01). The nonresting component of TDE (TDE-REE: physical activity and diet-induced thermogenesis [DIT]) was significantly higher in the COPD patients than in the healthy subjects, resulting in a ratio between TDE and REE of 1.7 +/- 0.2 and 1.4 +/- 0.1, respectively (p < 0.01). The results indicate that COPD patients exhibit an increased TDE in comparison with healthy subjects. The difference could by attributed to an increase in the nonresting component of TDE, since REE was comparable between the groups.

Interval versus continuous training in patients with severe COPD: a randomized clinical trial. R. Coppoolse, A.M.W.J. Schols, E.M. Baarends, R. Mostert, M.A. Akkermans, P.P. Janssen, E.F.M. Wouters. #ERS Journals Ltd 1999. ABSTRACT: Limited information is available regarding the physiological responses to different types of exercise training in patients with severe chronic obstructive pulmonary disease (COPD). The aim of this study was two fold: firstly, to investigate the physiological response to training at 60% of achieved peak load in patients with severe COPD; and secondly to study the effects of interval (I) versus continuous (C) training in these patients.Twenty-one patients with COPD (mean SD forced expiratory volume in one second: 37 15% of predicted, normoxaemic at rest) were evaluated at baseline and after 8 weeks' training. Patients were randomly allocated to either I or C training. The training was performed on a cycle ergometer, 5 days a week, 30 min daily. The total work load was the same for both training programmes.C training resulted in a significant increase in oxygen consumption (V 'O 2 ) (17%, p<0.05) and a decrease in minute ventilation (V 'E)/V 'O 2 (p<0.01) and V 'E/carbon dioxide production (V 'CO 2 ) (p<0.05) at peak exercise capacity, while no changes in these measures were observed after interval training. During submaximal exercise a significant decrease was observed in lactic acid production, being most pronounced in the C-trained group (-31%, p<0.01 versus -20%, p<0.05). Only in the I-trained group did a significant increase in peak work load (17%, p<0.05) and a decrease in leg pain (p<0.05) occur. Training did not result in a significant improvement in lung function, but maximal inspiratory mouth pressure increased in both groups by 10% (C: p<0.05) and 23% (I: p<0.01).The present study shows a different physiological response pattern to interval or continuous training in chronic obstruction pulmonary disease, which might be a reflection of specific training effects in either oxidative or glycolytic muscle metabolic pathways. Further work is required to determine the role of the different exercise programmes and the particular category of patients for whom this might be beneficial. Eur Respir J 1999; 14: 258±263. Pulmonary rehabilitation has become a cornerstone in an integrated management of patients with chronic obstructive pulmonary disease (COPD) [1]. Dyspnoea and an impaired exercise tolerance are prominent complaints in these patients and exercise training is therefore an essential component of a pulmonary rehabilitation programme [1]. Although several studies have shown beneficial effects of exercise training on exercise tolerance in COPD, the question persists as to whether these increases are principally due to improved psychological benefits of pulmonary rehabilitation or to improved physiological ability to perform exercise.The physiological response to exercise depends on four training principles [2]. 1) A specific exercise overload must be applied to enhance physiologi...

Mechanical efficiency and exercise capacity of the upper and lower limbs are not homogeneously affected in COPD, with a relative preservation of the upper limbs. This may have implications for screening of exercise tolerance and prescription of training interventions in patients with COPD. Future studies need to elucidate the mechanism behind this observation.

Abstractmultifactorially determined. After considering factors such as an impaired ventilatory capacity, Background -It has recently been reported that total daily energy expenditure respiratory muscle dysfunction, impaired gas exchange and cardiovascular problems, 1 recent (TDE) is increased in patients with chronic obstructive pulmonary disease (COPD) studies have focused on peripheral muscle weakness and impaired muscle metabolism as and it was hypothesised that these patients may have a decreased mechanical effi-factors that contribute to the decreased exercise capacity in patients with COPD. 2 3 Muscle ciency during activities. The purpose of the present study was to measure the strength and muscle metabolism are closely related to body composition. 4 In patients with mechanical efficiency of submaximal leg exercise, and to characterise patients with COPD a disturbed body composition is frequently present 5 owing to loss of body weight a potentially low efficiency in terms of body composition, resting energy expenditure, as well as to a selective depletion of fat free mass (FFM). In particular, loss of FFM negatively lung function, and symptom limited exercise performance.influences the exercise capacity in patients with COPD 6 7 independently of lung function imMethods -Metabolic and ventilatory variables were measured breath by breath dur-pairment.The reason for the observed disturbances in ing submaximal cycle ergometry exercise performed at 50% of symptom limited body composition is not completely understood, but loss of body weight implies a achieved maximal load in 33 clinically stable patients with COPD (23 men) with negative energy balance. We have recently shown that total daily energy expenditure is forced expiratory volume in one second (FEV 1 ) of 40 (12)% predicted. Net mech-increased in patients with COPD compared with healthy subjects. 8 Furthermore, it was anical efficiency was calculated adjusting for resting energy expenditure (REE).demonstrated that, in particular, the non-resting component (predominantly the energy exResults -Median mechanical efficiency was 15.5% and ranged from 8.5% to 22.7%. penditure for activity) contributes to the increased total daily energy expenditure Patients with an extremely low mechanical efficiency (<17%, n=21) demonstrated an (TDE). In a subsequent study it was shown that the variation in TDE in patients with increased V O 2 /V E compared with those with a normal efficiency (median differ-COPD was not strongly related to resting energy expenditure (REE) but was mainly a reence 4.7 ml/l, p=0.005) during submaximal exercise. There was no difference flection of the energy expenditure for activities. 9Based on the results of these two studies it was between the groups differentiated by mechanical efficiency in blood gas tensions hypothesised that patients with COPD could have a reduced mechanical efficiency during at rest, airflow obstruction, respiratory muscle strength, hyperinflation at rest, exercise.To test this hypothesis we measured the resting energy ...