For the most severe cases of obesity, recourse to bariatric surgery is the ultimate solution. Although highly beneficial to individual health, this massive loss of body mass could also have negative effects on metabolism and neuromuscular function. Unfortunately, these effects have been relatively little studied in the scientific literature, and are poorly taken into account in patient follow-up when bariatric surgery has been recommended. One of the adverse effects of bariatric surgery is the release into the bloodstream of Persistent Organic Pollutants (POPs) which, are not only persistent, but also bioaccumulative, toxic and mobile. The major problem is that these circulating POPs are linked to a number of adverse side effects, including reproductive disorders, neurobehavioral alterations, metabolic disorders, gut microbiota alterations inflammatory changes and physiological alterations. POP neurotoxicity could also affect psychomotor abilities and neuromuscular function. In addition, the mechanical unloading (i.e., reduced mechanical stress on muscles) induced by loss of body mass, an effect targeted by bariatric surgery and largely beneficial to the health of individuals, could also alter neuromuscular function and potentially alter muscle architecture and contractile properties. Unfortunately, no data are currently available in the scientific literature to confirm or refute these hypotheses. Physical activity-based intervention strategies may be usefull to counteract the effects of mechanical unloading and the release of POPs as suggested in scientific literature. However it is also possible to question which exercise modality should be preferred. Our hypothesis is that eccentric muscle strengthening would better preserve muscle mass and neuromuscular function while limiting the risks associated with POPs release, compared with an aerobic and a control group.

Inclusion Criteria:

• Adult patient (18-55 years)
• Patient scheduled for bariatric surgery
• Patient practicing a leisure-time physical activity < 8 hours of moderate intensity per week or < 4 hours of high intensity per week
• Presence of effective contraception (hormonal or mechanical)

Exclusion Criteria:

• Patient already involved in another experimental study
• Pregnant (urine pregnancy test) or breast-feeding women
• Patient in a particular situation deemed incompatible with the study by the investigator
• Patients from outside the Alpes-Maritimes and Var departments
• Patient having received antibiotic treatment during the 3 months preceding the first stool collection
• Presence of a contraindication to adapted physical activity
• Presence of a contraindication to neurostimulation