Striking similarities in systemic factors contributing to decreased exercise capacity in patients with severe chronic heart failure or COPD.
OBJECTIVE
Chronic heart failure (CHF) and COPD are both characterized by muscular impairment. To assess whether the severity and functional consequences of muscular impairment are disease specific, we compared skeletal muscle function, body composition, and daily activity level relative to exercise capacity between these two disorders.


METHODS
Twenty-five patients with CHF and 25 patients with COPD, and 36 healthy gender- and age-matched control subjects underwent measurement of fat-free mass (FFM) [by bioelectrical impedance analysis] as an index of muscle mass. Quadriceps and biceps functions were tested by isokinetic methods, and daily activity level was assessed by the Physical Activity Scale for Elderly (PASE) questionnaire. Peak oxygen consumption (O(2)peak) was measured by incremental cycle ergometry.


RESULTS
PASE results were similar in patients with CHF and in patients with COPD, each group scoring lower than control subjects. FFM was also lower in patients than control subjects and correlated closely with quadriceps and biceps strength in all three subgroups, R values ranging from 0.63 to 0.78, with identical slopes. FFM also correlated significantly with O(2)peak (p < 0.05), but slopes were less steep in patients than in control subjects. The type and severity of muscle dysfunction were similar in each group of patients. There were no significant correlations between indexes of cardiopulmonary function and muscle function or exercise performance in patients with CHF or in patients with COPD. In both control subjects and patients, FFM was the most significant determinant of O(2)peak.


CONCLUSIONS
Muscle dysfunction is not limited to the lower limbs, but generalized and comparable between patients with CHF and patients with COPD with similar exercise capacity. FFM is a strong predictor of peripheral muscle strength, to a lesser extent of O(2)peak, and not at all of peripheral muscle endurance.
Department of Pulmonology, University of Maastricht, the Netherlands. H.Gosker@pul.unimaas.nl
Harry R
HR
Gosker
Nicole H M K
NH
Lencer
Frits M E
FM
Franssen
Ger J
GJ
van der Vusse
Emiel F M
EF
Wouters
Annemie M W J
AM
Schols
D000203:Activities of Daily Living; D001823:Body Composition; D017097:Electric Impedance; D005080:Exercise Test; D017079:Exercise Tolerance; D005121:Extremities; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology; D010101:Oxygen Consumption; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*