1 Department of Respiratory Medicine, Royal Brompton Hospital, London, UK; National Heart and Lung Institute, Imperial College London, London SW3 6LY, UK; MRC Unit for Lifelong Health and Ageing, University College London, London, UK. Electronic address: [email protected].
2 MRC Unit for Lifelong Health and Ageing, University College London, London, UK.
3 National Heart and Lung Institute, Imperial College London, London SW3 6LY, UK.
4 School of Sport, Exercise, and Health Sciences, Loughborough University, Loughborough, UK; Social Research Institute, University College London, London, UK.