 - that involving a large muscle mass during exercise e.g., two-limb low load, high-repetition resistance training compared to involving a small muscle mass during training e.g., single limb low load, high-repetition resistance training would lead to larger restraints on the cardiorespiratory system in patients with severe to very severe COPD. Conversely, single limb interventions should produce less dyspnea and more muscle deoxygenation and fatigue than two-limb simultaneous exercise while healthy controls will be able to perform both legsarms exercise without a central constraint, and no negative consequences on muscle fatigue or exercise stimulus. 