For this study a resistance bout will be performed in order to promote the robust response of protein synthesis. Type II muscle fibers often exhibit more atrophy than type I fibers in COPD subjects therefore specifically targeting them in an exercise protocol could have more beneficial outcome for these individuals.

In this study, the following hypothesis will be tested: A bout of resistance exercise will affect the acute and 24h response in whole-body protein and amino acid metabolism and cognitive function as compared to baseline values in COPD patients and healthy subjects. To do this, subjects will complete a baseline visit in which they receive stable amino acid tracers. The next day they will complete a one-time resistance exercise with an immediate measurement of the amino acid tracers, and return 24 hours after exercise to repeat amino acid tracer measurements. This project will provide important clinical information on the whole body protein and amino acid metabolic response to acute resistance exercise in elderly subjects with COPD, as well as, the exercise induced changes in physical and cognitive function, and absolute muscular strength capacity in this population. In this way, this study will provide preliminary data for the development of standardized, repeatable resistance exercise protocols that will stop the process of ongoing muscle loss and improve metabolism and function in COPD subjects.

Inclusion criteria COPD subjects:

• Ability to walk, sit down and stand up independently
• Age 45 years or older
• Ability to lie in supine or elevated position for 4 hours
• Diagnosis of moderate to very severe chronic airflow limitation and compliant to the following criteria: FEV1 < 70% of reference FEV1
• Clinically stable condition and not suffering from a respiratory tract infection or exacerbation of their disease (defined as a combination of increased cough, sputum purulence, shortness of breath, systemic symptoms such as fever, and a decrease in FEV1 > 10% compared with values when clinically stable in the preceding year) at least 4 weeks prior to the first test day
• Shortness of breath on exertion
• Willingness and ability to comply with the protocol

Inclusion criteria healthy subjects:

• Healthy male or female according to the investigator's or appointed staff's judgment
• Ability to walk, sit down and stand up independently
• Age 45 years or older
• Ability to lay in supine or elevated position for 4 hours
• No diagnosis of COPD
• Willingness and ability to comply with the protocol

Exclusion Criteria all subjects:

• Any condition that may interfere with the definition 'healthy subject' according to the investigator's judgment (healthy subjects only)
• Established diagnosis of malignancy
• History of untreated metabolic diseases including hepatic or renal disorder
• Presence of acute illness or metabolically unstable chronic illness
• Presence of fever within the last 3 days
• Body mass index >40 kg/m2 (healthy subjects only)
• Any other condition according to the PI or nurse that was found during the screening visit, that would interfere with the study or safety of the patient
• Use of protein or amino acid containing nutritional supplements within 5 days of first study day
• Previous injury that could interfere with participation in resistance exercise protocol
• Use of short course of oral corticosteroids within 4 weeks preceding first study day
• Failure to give informed consent or Investigator's uncertainty about the willingness or ability of the subject to comply with the protocol requirements
• (Possible) pregnancy
• Already enrolled in another clinical trial and that clinical trial interferes with participating in this study