 This is a phase III multicenter, randomized, double-blind, placebo-controlled, combination and component, two-period, incomplete block design cross-over study using GSK573719GW642444. The primary objective is to evaluate lung function and exercise endurance time after 12 weeks of once-daily administration of GSK573719GW642444 Inhalation Powder 12525mcg and 62.525mcg, GSK573719 Inhalation Powder 125mcg and 62.5mcg, GW642444 Inhalation Powder 25 mcg and placebo delivered by a Novel dry powder inhaler Novel DPI Approximately 312 subjects with moderatesevere chronic obstructive pulmonary disease COPD will be randomised in order to achieve 208 subjects completing both treatment periods of 3 months.. There will be a total of 12 study clinic visits conducted on an outpatient basis. Subjects who meet the eligibility criteria at Screening Visit 1 will complete a 12 to 21 day run-in period followed by two 12-week treatment periods that are separated by a 14 day wash-out. Clinic visits will be conducted at Screening Visit 1, twice during the run-in period Visits 2 and 3, at randomization Visit 4 and three times during the first treatment period, on Treatment Day 2 Visit 5 and at 6 and 12 weeks Visits 6 and 7 respectively. During the washout period of 14 days there will be 2 clinic visits Visits 8 and 9. During the second treatment period there will be 3 clinic visits, on Treatment Day 2 Visit 10 and at 6 and 12 weeks Visits 11 and 12 respectively. A Safety Follow-Up assessment Visit 13 to record adverse events will be conducted by telephone 7 days after the end of the second treatment period or early withdrawal. Efficacy measurements will include pre and post dose FEV1, lung volume measurements and exercise endurance time measured using the endurance shuttle walking test ESWT. Safety and tolerability will be assessed by collection of adverse events AEs, vital signs, 12-lead electrocardiograms ECGs, clinical laboratory tests and incidence of COPD exacerbations. Dyspnea will be assessed using the Exercise Dyspnea Scale EDS, a patient-reported outcome. Blood samples will also be collected for potential pharmacogenetics analysis 