Effect of Exercise and Surgical Weight Loss on Polyneuropathy

Inclusion Criteria: * Attending a bariatric surgery clinic * BMI \> 35 with one comorbid condition present or BMI \> 40 without comorbid conditions present * Willing and capable to sign the Institutional Review Board (IRB) approved consent form and cooperate with the medical procedures for the study duration * Willing to accept random treatment assignment to HIIT or routine exercise counseling Exclusion Criteria: * History of distal symmetric polyneuropathy (DSP) from causes other than diabetes and/or the metabolic syndrome as determined through medical history, family history, history of medications, occupational history, history of exposure to toxins, physical and neurological examinations; * Use of warfarin, heparin, or other anticoagulants, which would increase the risk of complications from skin biopsy * Contraindication to HIIT participation including a failed exercise stress test * Participation in an experimental medication trial within 3 months of starting the study * Undergoing therapy for malignant disease other than basal-cell or squamous-cell skin cancer * Medical or psychiatric reason for not being a surgical candidate * Requiring a walking assist device; * Currently smoking