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Quadriceps and ankle dorsiflexor strength in chronic obstructive pulmonary disease
John M Seymour1, Katie Ward, Abrar Raffique
1King's College London School of Medicine, London, United Kingdom. john.seymour@fph-tr.nhs.uk
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 (RF(CSA)) 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 RF(CSA) 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.
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