The CST is a 10-minute sub-maximal standardized multistage test and like the 3MST has minimal space and equipment requirements. The CST was originally designed for workplace screening and is now widely used for exercise prescription in the UK cardiac population (20). In healthy individuals one study reported a ceiling effect and a positive relationship between predicted VO2max using the CST and measured VO2max (21) however a subsequent study questioned this prediction validity (22). The CST has been found to be highly reproducible in patients with chronic obstructive lung disease (COPD) and reliable in patients with Bronchiectasis, but too challenging for both groups (23,24).