Jornal Brasileiro de Pneumologia (Aug 2015)

Analysis of three different equations for predicting quadriceps femoris muscle strength in patients with COPD

  • Aline Gonçalves Nellessen,
  • Leila Donária,
  • Nidia Aparecida Hernandes,
  • Fabio Pitta

DOI
https://doi.org/10.1590/S1806-37132015000004515
Journal volume & issue
Vol. 41, no. 4
pp. 305 – 312

Abstract

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AbstractObjective: To compare equations for predicting peak quadriceps femoris (QF) muscle force; to determine the agreement among the equations in identifying QF muscle weakness in COPD patients; and to assess the differences in characteristics among the groups of patients classified as having or not having QF muscle weakness by each equation.Methods: Fifty-six COPD patients underwent assessment of peak QF muscle force by dynamometry (maximal voluntary isometric contraction of knee extension). Predicted values were calculated with three equations: an age-height-weight-gender equation (Eq-AHWG); an age-weight-gender equation (Eq-AWG); and an age-fat-free mass-gender equation (Eq-AFFMG).Results: Comparison of the percentage of predicted values obtained with the three equations showed that the Eq-AHWG gave higher values than did the Eq-AWG and Eq-AFFMG, with no difference between the last two. The Eq-AHWG showed moderate agreement with the Eq-AWG and Eq-AFFMG, whereas the last two also showed moderate, albeit lower, agreement with each other. In the sample as a whole, QF muscle weakness ( 0.05). Age, fat-free mass, and body mass index are characteristics that differentiate between patients with and without QF muscle weakness.Conclusions: The three equations were statistically equivalent in classifying COPD patients as having or not having QF muscle weakness. However, the Eq-AHWG gave higher peak force values than did the Eq-AWG and the Eq-AFFMG, as well as showing greater agreement with the other equations.

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