Acute Care Medical

The purpose of this multi-site prospective study is to assess validity of a new step test called Functional-Incremental Stepping-in-place- Test (F-IST) compared to gold-standard cardiopulmonary exercise testing (CPET) and to physical function and health perception, respectively. The investigators will also assess test-retest reliability of the F-IST. The investigators hypothesize that the F-IST will have high validity and test-retest reliability to be used in field testing environments such as the ICU.