Muscle strength and exercise kinetics in COPD patients with a normal fat-free mass index are comparable to control subjects.
OBJECTIVE
This study was designed to investigate the extent of clinical muscle dysfunction in stable patients with COPD who were attending an out-patient pulmonary clinic compared with that of age-matched control subjects without COPD.


METHODS
Respiratory muscle and hand grip strength, steady-state O(2) kinetics, and body composition were measured in 32 patients with COPD (19 women) [mean (+/- SD) FEV(1), 38 +/- 11% predicted] and 36 age-matched control subjects (13 women).


RESULTS
Measurements of handgrip force (mean, 97 +/- 32% vs 106 +/- 26% predicted, respectively), maximal expiratory pressure (mean, 57 +/- 33% vs 61 +/- 22% predicted, respectively), steady-state O(2) kinetics (mean tau, 72 +/- 34 s vs 78 +/- 37 s, respectively) and steady-state CO(2) kinetics (mean tau, 77 +/- 38 s vs 65 +/- 32 s, respectively) at submaximal exercise were similar in patients and control subjects. All the subjects, except for one female COPD patient, had a normal fat-free mass index (FFMI), although on average the FFMI was lower in male patients (19.8 +/- 2.8) than in male control subjects (23.0 +/- 2.8; p < 0.01).


CONCLUSIONS
In patients with COPD who were attending a regular outpatient pulmonary clinic, there was no evidence of reduced upper extremity and expiratory muscle strength or prolonged O(2) and CO(2) kinetics during isowork submaximal cardiopulmonary exercise compared to healthy, age-matched control subjects. Also, a normal body composition was found in nearly all COPD patients. This argues against the existence of a clinically significant systemic myopathy in most stable patients with severe COPD and normal FFMI.
Heijdra
Yvonne F
YF
Pulmonary Department, University Medical Center St. Radboud, Nijmegen, the Netherlands.
Pinto-Plata
Victor
V
Frants
Regina
R
Rassulo
John
J
Kenney
Lawrence
L
Celli
Bartolome R
BR
D000368:Aged; D015992:Body Mass Index; D016022:Case-Control Studies; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009135:Muscular Diseases / Q000150:complications; D009752:Nutritional Status; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology*; D012132:Respiratory Muscles / Q000503:physiopathology*; D013147:Spirometry