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Background: Reduced peripheral muscle strength is an important determinant of exercise intolerance in COPD, though little is known on the association between muscle endurance and exercise capacity. Objectives: To determine the association between quadriceps muscle function (strength and endurance) and exercise capacity in patients with COPD after stratification for sex and resting lung function (LF). Methods: Peak VO2 (mL/min), isokinetic quadriceps muscle strength (peak torque (QPT, Newton-meter (Nm)) and endurance (total work (QTW, Joules (J)) during 30 maximal isokinetic contractions on a Biodex) were measured in 3258 patients with COPD (60% men, age 64±9 yrs, FEV1 51±19%pred, transfer factor for carbon monoxide (TLCO) 53±17%pred, residual volume (RV) 163±52%pred) and stratified for sex, FEV1 (≥50%pred/ Results: After stratification for sex and resting LF, peak VO2 was significantly associated with QPT (Pearson’s r range: 0.439 to 0.597 for men; 0.462 to 0.744 for women, all p Conclusion: Using a large sample of patients with COPD, we showed good correlations between both quadriceps muscle strength and endurance and exercise performance in men and women, which appear to be independent of resting LF function parameters. |
