 3-min constant rate shuttle walking test. This test consists in one bout of three minutes of walking at the initial walking speed of 4.0 kmh. Thirty minutes after this first bout of walking, a second test will be performed at a walking speed of either 6.0 or 2.5 kmh. The second walking speed will be determined by the ability to carry through the test at 4.0 kmh. If a patient cannot complete the first test, then the second speed will be stepped down to 2.5 kmh. If a patient is able to carry though the first test, then the second walking speed will be raised to 6.0 kmh. Patients will be asked to perform two tests at two different speeds in order to determine, amongst the 3 different walking speeds, the highest speed that can be sustained for the entire 3 minutes. In doing so, our objective is to induce a level of dyspnea that is sufficiently high to be amenable to therapy. These walking speeds are selected based on our previous work19 showing that these were sufficiently demanding to induce measurable levels of dyspnea and that most moderate to severe patients with COPD are able to complete the test for the desired duration. Patients will be directed to follow the audio signal for the entire 3 minutes of the test or until they became symptom limited. They will be instructed to walk around the two cones set-up in the hospital hallway pacing their walk in a way not to wait at the cones for the following audio signal. 