Abstract
BackgroundLittle is known about limb muscle abnormalities in mild COPD. Inactivity and systemic inflammation could play a role in the development of limb muscle dysfunction in COPD. The objective of the present study was to characterize quadriceps function, enzymatic activities and morphometry, levels of plasma inflammatory markers and physical activity levels in daily life (PAdl) in patients with mild COPD (GOLD 1).MethodsMid-thigh muscle cross-sectional area (MTCSA), quadriceps strength, endurance, fiber-type distribution, capillarity, pro-angiogenesis factors (VEGF-A, angiopoietin I and II) and muscle oxidative capacity were assessed in 37 patients with mild COPD and 19 controls. Systemic inflammatory markers (CRP, IL-6, TNF-α, Fibrinogen, SP-D) and PAdl were assessed.ResultsMTCSA, quadriceps strength and endurance were not different between COPD and controls. Capillarity and muscle oxidative capacity were all preserved in mild COPD. Reduced pro-angiogenesis factor mRNA expression was seen in COPD. The level of moderately active intensity (>3 METs) was significantly lower in mild COPD and, in multiple regression analyses, the level of physical activity was a determinant of muscle oxidative capacity and capillarization. No between-group differences were found regarding muscle oxidative stress while circulating IL-6 levels were elevated in mild COPD.ConclusionsThe quadriceps muscle function was preserved in mild COPD although a reduced potential for angiogenesis was found. The reduced level of daily activities and evidence of systemic inflammation in these individuals suggest that these factors precede the development of overt limb muscle dysfunction in COPD.
Highlights
Chronic obstructive pulmonary disease (COPD) is often accompanied by important systemic consequences such as limb muscle dysfunction [1]
If reduced physical activity and systemic inflammation were mechanistically linked to the development of limb muscle dysfunction, one would expect them to precede the development of limb muscle dysfunction
We studied limb muscle function, enzymatic activities and morphometry in patients with mild COPD (GOLD 1) thinking that this would provide insights about the potential contribution of systemic inflammation, muscle oxidative stress and physical inactivity to the development of any muscle abnormalities
Summary
Chronic obstructive pulmonary disease (COPD) is often accompanied by important systemic consequences such as limb muscle dysfunction [1]. Studies reporting about limb muscle dysfunction in COPD mostly involve patients with advanced disease in whom inactivity, systemic inflammation and limb muscle dysfunction are well established making it impossible to know which one came first. In this investigation, we studied limb muscle function, enzymatic activities and morphometry in patients with mild COPD (GOLD 1) thinking that this would provide insights about the potential contribution of systemic inflammation, muscle oxidative stress and physical inactivity to the development of any muscle abnormalities. The objective of the present study was to characterize quadriceps function, enzymatic activities and morphometry, levels of plasma inflammatory markers and physical activity levels in daily life (PAdl) in patients with mild COPD (GOLD 1)
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