Background Early rehabilitation in an intensive care unit (ICU) can shorten the ICU stay and reduce the associated risks and costs. However, mobilization has been shown to be slower and less successful in patients receiving blood purification therapy or extracorporeal membrane oxygenation (ECMO), and the ideal duration of rehabilitation has not been determined. To examine this, the time required for rehabilitation in patients receiving ECMO and blood purification therapy in the ICU was examined. Materials and methods This was a post-hoc analysis of the IPAM study (Investigating Physical Activity of Mechanical Ventilation Patients in the ICU). The IPAM study with data from hospitalization between September 2022 and March 2023 is a multicenter observational prospective cohort study. Inclusion criteria were subjects who were supported by mechanical ventilation in the ICU for ≥48 hours. The exclusion criteria were age <
18 years, loss of walking independence at least two weeks before admission, neurological complications or lack of communication skills due to preexisting mental conditions, terminal stage, and ongoing coronavirus infection. These cases were divided into an ECMO/blood purification group, in which ECMO and blood purification were performed upon admission to the ICU, and a group that did not receive these interventions. The primary endpoint was the daily duration of rehabilitation activity. The secondary endpoints were the daily durations of preparation and rehabilitation activity and the total ICU stay. Results Following case selection, 121 cases were analyzed, 28 in the ECMO/blood purification group and 93 in the control group. Total daily rehabilitation time and ICU stay were significantly longer in the ECMO/blood purification group. Among all cases, eight (1%) adverse events occurred during the 959 rehabilitation interventions. No adverse events such as death, cardiopulmonary resuscitation, falls, or intubation-related problems occurred. Kaplan-Meier curve analysis revealed that sitting (p = 0.042), standing (p = 0.001), and walking (p = 0.001) were significantly delayed in the ECMO/blood purification group. Conclusion Patients receiving ECMO/blood purification in the ICU require more rehabilitation activity each day, including longer preparation time.