QUADRICEPS AND ANKLE DORSIFLEXOR STRENGTH IN CHRONIC OBSTRUCTIVE PULMONARY DISEASE

Introduction: Quadriceps strength and size are commonly reduced in chronic obstructive pulmonary disease (COPD). We wished to assess volitional and nonvolitional ankle dorsiflexor strength in COPD. Methods: Quadriceps and ankle dorsiflexor strength were measured by maximum voluntary contraction (MVC) and by twitch responses to supramaximal femoral and fibular nerve stimulation. Cross-sectional areas of the tibialis anterior (TA(CSA)) and rectus femoris muscles (RFCSA) were measured by ultrasound. Results: Eighteen elderly subjects and 20 COPD patients [mean(SD) %predictedFEV(1) 50(20)%] participated. No significant difference in fat-free mass index, ankle dorsiflexor strength, or TA(CSA) were observed in the presence of reduced quadriceps strength and size in COPD [mean MVC difference: -10.9 kg (95% confidence interval {CI}: -17.1 kg to -4.8 kg, P < 0.01; mean RFCSA difference -119 mm 2, 95% CI: -180 mm(2) to -58 mm(2), P < 0.01)]. Conclusions: Ankle dorsiflexor strength is less attenuated than quadriceps strength in COPD patients with moderate airflow obstruction. Direct quadriceps assessment may be more relevant than measurement of lower limb fat-free mass. Muscle Nerve 46: 548-554, 2012