BackgroundEnhanced mobility in the Intensive Care Unit (ICU) could minimize the negative effects of critical illness, such as declines in cognitive, muscular, respiratory, and functional capacity. We aim to compare the functional status at ICU discharge of patients who underwent a progressive mobilization protocol versus patients who received conventional physiotherapy. We also examine the level of physical activity in the ICU, the degree of pulmonary and muscle function, and the length of stay to analyze correlations between these variables.MethodsThis is a protocol for a randomized controlled trial with blind evaluation. Ninety-six ICU patients will be recruited from a single center and randomly assigned to a control group or an intervention group. To determine the level of protocol activity the patient will receive, the patients’ ability to participate actively and their muscle strength will be considered. The protocol consists of five phases, ranging from passive therapies to walking and climbing stairs. The primary outcome will be the functional status at ICU discharge, measured with the Barthel Index and the ICU Mobility Scale (IMS). Measured secondary outcomes will include the level of physical activity, maximal inspiratory and expiratory pressures, forced expiratory volume in 1 second, maximum voluntary ventilation, handgrip strength, surface electromyography of the lower limb muscles, and results of the Timed Up and Go and 2-Minute Walk tests. Evaluations will be made within 2 days of ICU discharge except for the level of activity, which will be evaluated daily. Physiological variables and activity level will be analyzed by chi-square and t tests, according to the intention-to-treat paradigm.DiscussionMobility and exercise in the ICU should be undertaken with intensity, quantity, duration, and frequency adjusted according to the patients’ status. The results of this study may contribute to new knowledge of early mobility in the ICU, activity level, and varying benefits in critical patients, directing new approaches to physiotherapeutic interventions in these patients.Trial registrationRecruitment will begin in February 2017, and the expected completion date is August 2018. Patients are already being recruited.ClinicalTrials.gov, ID: NCT02889146. Registered on 3 March 2016.Electronic supplementary materialThe online version of this article (10.1186/s13063-018-2641-4) contains supplementary material, which is available to authorized users.