The Effect of STIOLTO™ RESPIMAT® on Fatigue in Chronic Obstructive Pulmonary Disease

Patients with chronic obstructive pulmonary disease (COPD) have reduced exercise tolerance. One mechanism for this is thought to be due to dynamic hyperinflation during exercise (an increase in the end-expiratory lung volume) that contributes to the sensation of breathlessness. Whether this also contributes to inhibiting motor recruitment, and reduces the available power output (termed performance fatigue; PF), is not well understood. Preliminary data suggests that many COPD patients, unlike healthy subjects, stop exercise with a 'skeletal muscle power reserve' i.e. the ability to acutely increase muscle power output. This suggests that they are limited in the exercise task by mechanisms other than acute intramuscular limitations to power production (termed muscle fatigue; MF). Exercise tolerance is increased by treatment with the fixed-dose combination bronchodilator, STIOLTO™ RESPIMAT®. We hypothesize that increased exercise tolerance with STIOLTO™ RESPIMAT® (reduced performance fatigue; PF) will be mediated by a combination of: 1) reduced inhibition of muscle activation (termed activation fatigue; AF) allowing patients to drive their leg muscles harder, and thus; 2) increased muscle fatigue (MF).