Preservation of eccentric torque of the knee extensors and flexors in patients with COPD.

PURPOSE

The purpose of this study was to compare the concentric and eccentric torque of the knee extensors (KEs) and flexors (KFs) in persons with chronic obstructive pulmonary disease (COPD) with matched controls. Muscle volume and intramuscular fat infiltration of the thigh muscles were also compared between groups.

METHODS

Twenty persons with moderate to severe COPD and 20 control participants, matched for age, sex, and body mass index, participated in the study. Concentric and eccentric isokinetic torque of the KEs and KFs were measured on a KinCom dynamometer. Muscle volume of the quadriceps, hamstrings, and adductors and intramuscular fat infiltration were estimated from T1-weighted magnetic resonance imaging. Muscle volume of the quadriceps and hamstrings was used to normalize torque measurements of the KEs and KFs, respectively.

RESULTS

Absolute concentric and eccentric torque was lower in the COPD group than in controls. However, normalized eccentric torque was higher in persons with COPD (P < .05). Persons with COPD demonstrated lower muscle volume of all thigh muscle groups (P < .01) and greater intramuscular fat infiltration (P < .002) than controls.

CONCLUSIONS

Although absolute torque of the KEs and KFs are lower in persons with COPD than in controls, normalized eccentric torque is actually higher in persons with COPD. A further examination of factors that contribute to the enhancement of eccentric torque in persons with COPD is warranted.