Inclusion Criteria:  women between 18 and 55 years old undergoing bariatric surgery (a "bypass gastric" or a "sleeve") not practicing a supervised physical activity having read and signed an informed consent prior to the start of the trial being affiliated to a social security system  Exclusion Criteria:  Women with a contraindication to physical activity any medical contraindication to the practice of stress tests. unable to go to the hospital regularly having a significant functional limitation that does not allow her to perform the 6-minute walk test with an intellectual disability and/or psychiatric illness does not speak and/or understand French pregnant woman under guardianship or curatorship participating in another clinical research