Foy CG, Wickley KL, Adair N, Lang W, Miller ME, Rejeski WJ, Woodard CM, Berry MJ. The Reconditioning Exercise and Chronic Obstructive Pulmonary Disease Trial II (REACT II): rationale and study design for a clinical trial of physical activity among individuals with chronic obstructive pulmonary disease. Contemp Clin Trials. 2006 Apr; 27(2):135-46.