Physical Activity Following Surgery Induced Weight Loss

The primary objective of this study will be to determine the effects of physical activity in
patients during substantial surgery-induced weight loss. We propose to employ a randomized
controlled physical activity intervention trial in a group of patients undergoing bariatric
surgery for weight loss. The study will involve two sites with an active bariatric surgery
program, which have a strong track record of bariatric surgery research.

Recruitment goals are 160-200 gastric bypass patients who will undergo 6 months of moderate
physical activity compared to an educational control group not engaged structured exercise.
Subjects will be included if their BMI is less than 55 kg/m2 prior to surgery and they are
located relatively close to centers for intervention sessions. At baseline (3 months
following surgery) and 6 months later (9 months following surgery), subjects will have a CT
scan, IV glucose tolerance test (IVGTT) and muscle biopsy (~8 hour visit). They will be
scheduled for separate visits for a test of physical fitness (VO2max) and general body
composition (DXA scan)(~2 hour visit), and a 15-min sub-maximal exercise session.

1. Physical activity group: Subjects will be progressed to 4-5 days per week, 30-45 min
per session (120-180 min per week) of moderate intensity exercise.

2. Control (educational) group: Subjects will receive their usual care following surgery
that includes information on physical activity. They will also be asked to participate
in monthly health education sessions.

We will promote this study as one that will help determine whether physical activity may be
beneficial in addition to their weight loss.

Aim 1: Insulin resistance and metabolic risk factors. Approach: To address Aim 1, we will
determine 6-month changes in insulin sensitivity in subjects after 3-month initial weight
loss from bariatric surgery. As outlined above, we will employ a randomized controlled
physical activity intervention trial in which half of the subjects will be entered into a
physical activity group, while the other half will participate in monthly health education
sessions (control). By randomizing these groups three months after initial weight loss, both
groups should begin the intervention with similar baseline characteristics (e.g. insulin
sensitivity, body weight, physical fitness, etc.). We are not attempting to determine the
effect of the weight loss per se on insulin sensitivity. However, we realize that the amount
of weight loss could potentially have a major confounding influence on detecting changes in
insulin sensitivity between the two groups. Thus, we will examine the degree of weight loss
as a covariate in our analyses.

Aim 2: Intramyocellular lipids and body composition. Approach: We will examine pre to post
intervention, changes in intramyocellular lipid determined with percutaneous biopsies, as
well as abdominal and intermuscular adipose tissue determined by CT imaging.

Aim 3: Mitochondria content, function and fat oxidation. Approach: We will use three
complimentary measures to quantify changes in oxidative metabolism before and after the
randomized controlled trial described above. All three of these measures will make specific
contributions to this specific aim. Rates of resting post-absorptive fat oxidation will be
measured with indirect calorimetry. Since skeletal muscle accounts for the vast majority of
energy production during physical activity, sub-maximal exercise is a good model to assess
skeletal muscle fatty acid metabolism. We will employ whole body gas exchange indirect
calorimetry during moderate exercise designed to elicit high rates of fatty acid oxidation.
The non-invasive measures of systemic fat oxidation during both resting and exercise
conditions procedures take very little time and present relatively little burden on the
volunteers or technical staff, thus providing an efficient means to obtain significant
information concerning the capacity for fat oxidation in vivo. Muscle biopsy samples will
be obtained before and after the trial to measure changes in the oxidative capacity
(electron transport chain activity, in vitro fatty acid oxidation, muscle fiber type and
oxidative enzyme (succinate dehydrogenase) staining activity of muscle.

Inclusion Criteria:

- Men and women (21-60 years of age) good health, stable weight, and without any
contraindication to exercise.

Exclusion Criteria:

- Anemia (Hct<34%)

- Elevated liver enzyme (25% above normal),

- Proteinuria,

- Hypothyroidism (sTSH > 8)

- Hypertension (blood pressure > 150 mmHg systolic, or > 95 mmHg diastolic)

- Diabetes mellitus (fasting glucose ≥ 126 mg/dl)

- A history of myocardial infarction or peripheral vascular disease

- Liver disease

- Alcohol or drug abuse

- Malignancy or neuromuscular disease

- Subjects will be excluded if taking chronic medications known to adversely affect
glucose homeostasis (oral glucocorticoids, nicotinic acid)

- Females currently on hormone replacement therapy (HRT) can participate in the study
if they have been on HRT for at least 6 months and will continue to be on HRT during
the study.

- Disqualifying findings on physical examination include:

- Lower extremity thrombophlebitis

- Evidence of peripheral neuropathy, paresis or edema.

If the resting EKG prior to the exercise test shows any abnormalities, the test will not
be conducted. If any abnormalities develop during the test, the test will be stopped. On
both occasions, the participant will be referred to their PCP for further evaluation and
will only be allowed to continue the study with written clearance by his/her PCP or
cardiologist. American College of Sports Medicine (ACSM) criteria will be used to halt
maximal exercise testing should adverse cardiovascular responses develop. Only after a
cardiologist interprets the resting and exercise ECG of the participant and clears them
for exercise, will subjects be able to continue with the study