An isocapnic hyperpnea trial will be performed to assess respiratory muscle perfusion, dyspnea intensity and unpleasantness, respiratory muscle recruitment pattern, respiratory effort and neural respiratory drive without the work of locomotor muscle before and after IMT. Patients will be asked to maintain a targeted minute ventilation pattern equal to their breathing frequency, tidal volume and minute ventilation recorded at rest and during the final minute of constant load exercise test (at ~75% WRpeak). Experimenters will provide verbal guidance to patients to adjust the rate and depth of their breathing such that the target ventilation will be obtained and maintained constant within ±5%. Isocapnia will be maintained by having subjects inspire from a Douglas bag containing 5% CO2, 21% O2, balance N2 that will be connected to a two-way non-rebreathing valve (model 2700, Hans Rudolph) by a piece of tubing.