For outcome measures specific to COPD pasients, final analyses will be performed on data from the COPD population only. For other outcome measures, final analyses will be performed on data merged from COPD patients and healthy subjects. An important rationale behind implementing healthy control subjects is to increase the statistical power of outcome measures unrelated to COPD epidemiology, which are of general relevance to physiological adaptation to strength training. In a related set of analyses, we will perform between-groups comparisons, including multivariate analyses. We will also compare the efficacy of high- and low-resistance strength training in COPD patients and healthy control subjects. The two training modalities are expected to result in similar muscular adaptations.