1. Human Bio-Energetics Research Centre, Crickhowell, Powys, United Kingdom
2. Anaesthesia and Critical Care Research Unit and
3. Critical Care Research Area, National Institute for Health Research Respiratory Biomedical Research Unit, University Hospital Southampton National Health Service Foundation Trust, Southampton, United Kingdom; and
4. Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom