A high variability in functional tests and activities used during the pulmonary rehabilitation has been observed in post-intensive care unit (ICU) patients, and the best battery of tests to adopt has not been described yet. We tested in patients admitted in a post-ICU Step Down Unit the ability to perform the more frequent functional volitional tests. The relations of each single volitional test with general disability and dyspnea at discharge were also evaluated. Ten volitional tests including: bedside spirometry test (ST: FEV1%, FVC%), maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), Peak Expiratory Flow during Cough (PCEF), Quadriceps Muscle Strength (QMS), latissimus Dorsi and teres Major Strength (DMS), Brachial biceps Muscle Strength (BMS), effort tolerance measured by sit-to-stand test, Takahashi test and 6-Min Walking Test (6MWT), were evaluated in post-ICU patients at entry and discharge from in-hospital rehabilitation. General disability was assessed by Barthel Index, while dyspnea by Borg scale. At admission, >70% of subjects performed muscle strength test, while <25% performed respiratory and effort tolerance tests. At discharge, feasibility of spirometry, respiratory muscle strength and effort tolerance tests improved (all, p<0.001); 6MWT was the least feasible. At discharge, cardiorespiratory patients were more capable to perform tests compared to neurological ones. All outcome measures, with exception of FEV1%, and FVC%, were significantly related to the disability score. Peripheral muscle exercises showed the highest feasibility, spirometry and leg effort tolerance the lowest. Motor disability was explained mainly by the peripheral muscle strength. The study of non-volitional outcome measures and tests linked to a protocol-driven intervention should be performed in this specific population.