Correction: Effects and mechanisms of supramaximal high-intensity interval training on extrapulmonary manifestations in people with and without chronic obstructive pulmonary disease (COPD-HIIT): study protocol for a multi-centre, randomized controlled trial - Johan Jakobsson; Chris Burtin; Mattias Hedlund; Carl-Johan Boraxbekk; Jonas Westman; Nina Karalija; Per Stål; Thomas Sandström; David Ruttens; Harry R. Gosker; Jana De Brandt; André Nyberg (Trials)