Published in:
Open Access 01-12-2014 | Original research article
Association between peripheral muscle strength, exercise performance, and physical activity in daily life in patients with Chronic Obstructive Pulmonary Disease
Published in: Multidisciplinary Respiratory Medicine | Issue 1/2014
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Background
Resistance training of peripheral muscles has been recommended in order to increase muscle strength in patients with Chronic Obstructive Pulmonary Disease (COPD). However, whether peripheral muscle strength is associated with exercise performance (EP) and physical activity in daily life (PADL) in these patients needs to be investigated.
The aim of this study is to evaluate whether strength of the quadriceps muscle (QS) is associated with EP and daily PADL in patients with COPD.
Methods
We studied patients with COPD (GOLD A-D) and measured maximal isometric strength of the left QS. PADL was measured for 7 days with a SenseWear-Pro® accelerometer. EP was quantified by the 6-minute walk distance (6MWD), the number of stands in the Sit-to-Stand Test (STST), and the handgrip-strength. Univariate and multivariate analyses were used to examine possible associations between QS, PADL and EP.
Results
In 27 patients with COPD with a mean (SD) FEV1 of 37.6 (17.6)% predicted, QS was associated with 6MWD, STST, and handgrip-strength but not with PADL. Multiple linear regression analyses showed that QS was independently associated with the 6MWD (β = 0.42, 95% CI 0.09 to 0.84, p = 0.019), STST (β = 0.50, 95% CI 0.11 to 0.86, p = 0.014) and with handgrip-strength (β = 0.45, 95% CI 0.05 to 0.84, p = 0.038).
Conclusions
Peripheral muscle strength may be associated with exercise performance but not with physical activity in daily life. This may be due to the fact that EP tests evaluate patients’ true abilities while PADL accelerometers may not.