Quadriceps muscle endurance in patients with chronic obstructive pulmonary disease

The purpose of this study was to compare quadriceps muscle strength (maximal voluntary contraction, MVC), endurance (T(LIM)), and dynamic work capacity (W(LIM)) in 89 patients (57 men and 32 women) with chronic obstructive pulmonary disease (COPD) to 31 healthy controls (20 men and 11 women). Compared with the healthy subjects, COPD patients demonstrated statistically significant (P < 0.05) lower values for MVC, T(LIM) and W(LIM). The MVC was 20-30% lower, whereas T(LIM) and W(LIM) were 70-80% lower in the patients. Stepwise multiple regression analysis revealed that pulmonary function variables contributed only partially to the explanation of variance in MVC, T(LIM), and W(LIM). Our results indicate that in patients with COPD, quadriceps muscle endurance and dynamic work capacity are impaired to a greater extent than is quadriceps muscle strength. For rehabilitation purposes, the findings may lead to more specific exercise programs, further enhancing rehabilitation outcomes in terms of functional abilities and social participation.