Step 1: The objective is to evaluate the effectiveness of the Observation of Virtual Actions on gait recovery in patients hospitalized in Physical and Rehabilitation Medicine (MPR) and presenting ICU-weakness, in particular following a COVID-19 infection. If the patient is included in the Virtual Reality group, they will be asked to observe once a day for 9 days for 5 minutes Virtual Motor Actions (avatar moving in a virtual environment) using a headset. Virtual Reality, followed by 5 minutes of relaxation performed using soothing music played through headphones. If the patient is included in the Relaxation group, they will be offered 10 minutes of relaxation performed using soothing music played in headphones once a day for 9 days. We will assess gait, motive power, balance, confidence in the future and patient autonomy before the start of the first session, the day after the last session and one month after inclusion. At the end of each session, we will ask the patient questions about fatigue (VAS) and the occurrence of side effects (open question) after wearing the Virtual Reality headset or headset. At the end of the 9 sessions, we will ask to patients in the Virtual Reality group to complete a questionnaire concerning the acceptance of the proposed device. We want to include 20 patients in the Virtual Reality group and 20 patients in the Relaxation group.

Step 2: The objective is to assess the acceptability (a priori) of the Virtual Reality tool created in ICU by the nursing staff and by the patients who are hospitalized there. It will be offered to caregivers of the ICU of the Rennes University Hospital and to patients hospitalized in these 2 services and presenting ICU- weakness, especially in the aftermath of COVID infection. We will be asked to complete an acceptability questionnaire (a priori) concerning the use of a Virtual Reality tool intended to improve walking in the ICU. The duration of filling in this questionnaire is estimated at 30 minutes. Caregivers will be invited to participate in an information meeting (4 will be carried out) at least 1 week before their possible participation (which they will be informed by internal mail, and which will be led by investigators). We believe that approximately 300 caregivers and 50 patients will participate in this acceptability survey.

Step 3: The objective is to evaluate the effectiveness of the Observation of Virtual Actions on gait recovery in patients hospitalized in ICU and with ICU-weakness. If the acceptability questionnaire is in favor of a good future acceptance of the tool designed and after possible adaptations of the Virtual Reality device based on the responses of caregivers and patients to the acceptability questionnaire proposed during the step 2, we will suggest to patients hospitalized in ICU with ICU-weakness to carry out a protocol similar to that carried out with Physical and Rehabilitation Medicine patients in step 1. If the patient is included in the Virtual Reality group, they will be asked to observe once a day for 9 days for 5 minutes Virtual Motor Actions (avatar moving in a virtual environment) using a Virtual Reality headset, followed by 5 minutes of relaxation performed using soothing music played through headphones. If the patient is included in the Relaxation group, they will be offered 10 minutes of relaxation performed using soothing music played in headphones once a day for 9 days. We will assess gait, motive power, balance, confidence in the future and patient autonomy before the start of the first session, the day after the last session and 1 month after inclusion. At the end of each session, we will ask the patient questions about fatigue (VAS) and the occurrence of side effects (open question) after wearing the Virtual Reality headset. At the end of the 9 sessions, we will suggest to patients in the Virtual Reality group that they complete a questionnaire concerning the acceptance of the proposed device. We want to include 20 patients in the Virtual Reality group and 20 patients in the Relaxation group.

Step 4: The objective is to assess the effectiveness of the realization of virtual actions compared to the observation of virtual actions on gait recovery in patients hospitalized in ICU or in Physical and Rehabilitation Medicine and presenting ICU-weakness. If the patient is included in the group Performing Virtual Actions, they will be asked to perform Virtual Actions of the lower limbs by controlling the legs of his avatar (virtual double) in order to move around in a virtual environment for 10 minutes per day, once a day for 9 days. If the patient is included in the Observation of Virtual Actions group, they will be asked to observe for 10 minutes once a day for 9 days Virtual Motor Actions (avatar moving in a virtual environment) using a Virtual Reality headset. We will assess gait, motive power, balance, confidence in the future and patient autonomy before the start of the first session, the day after the last session and 1 month after inclusion. At the end of each session, we will ask the patient questions about fatigue (VAS) and the occurrence of side effects (open question) after wearing the Virtual Reality headset. At the end of the 9 sessions, we will offer patients to fill out a questionnaire concerning the acceptance of the proposed device. We want to include 20 patients in the Virtual Actions group and 20 patients in the Virtual Actions Observation group.

Step 5: The objective is to evaluate the effectiveness of adding a sensation of walking using haptic stimuli during the Observation or Realization of Virtual Actions on the recovery of walking in patients hospitalized in ICU or in Physical and Rehabilitation Medicine and with ICU-weakness. Depending on the superiority or not of the Realization of Virtual Actions or the Observation of Virtual Actions, we will test the most effective condition of step 4 in combination with: either haptic stimulation (sensory feedback through vibrators positioned on the lower limbs to give a feeling of walking), either without haptic stimulation, once a day for 10 minutes for 9 days. We will assess gait, motive power, balance, confidence in the future and patient autonomy before the start of the first session, the day after the last session and 1 month after inclusion. At the end of each session, we will ask the patient questions about fatigue (VAS) and the occurrence of side effects (open question) in the aftermath of wearing a Virtual Reality headset. At the end of the 9 sessions, we will offer patients to fill out a questionnaire concerning the acceptance of the proposed device. We want to include 20 patients in the group with haptic stimulation and 20 patients in the group without haptic stimulation.