In this study the investigators will test the following hypothesis: A high-leucine essential amino acid mixture (dose of 7.0 g EAA + 15 g carbohydrates) will stimulate protein anabolism to a greater extent than a standard balanced mixture of total (essential and non-essential) amino acids (dose of 6.7 g total AA + 15 g carbohydrates) in COPD patients. The principal endpoints will be the extent of stimulation of protein synthesis rate and the reduction in endogenous protein breakdown. The current project will provide information that will enable us to better understand the underlying metabolic mechanisms that regulate protein metabolism in patients with COPD.