Clinical and integrative exercise & cardio-respiratory physiology; Physiological/pathophysiological mechanisms of exertional breathlessness and activity-limitation in health & disease; Lifestyle & pharmacological interventions to improve exertional breathlessness & exercise performance in patient populations; Effects of obesity, aging and sex (or gender) on exercise physiological responses; Chemoreflex control of breathing; Acid-base balance; Exercise hyperpnea; Respiratory mechanical/muscular function; Diaphragmatic EMG