Exercise confers cardioprotection through improved vascular function. Exercise confers cardioprotection through improved vascular function. Obstructive sleep apnoea is characterised by oxyhaemoglobin desaturations and sympathetic activation, which result in cardiovascular morbidity and mortality. The thin arrows imply that exercise may not confer cardioprotection in the presence of disturbed sleep. NO: nitric oxide bioavailability. Devon A. Dobrosielski et al. Eur Respir Rev 2017;26:160110 ©2017 by European Respiratory Society