Abstract
Bariatric surgery is currently the most effective treatment to reduce excess body weight and obesity related comorbidities. A pre-operative low calorie diet is standard medical practice to induce weight loss and shrink liver size for improved patient safety during surgery, yet not all patients undergoing bariatric surgery respond similarly. In fact, there is large inter-patient variability in surgical outcomes and up to 70% of patients have blunted improvements in cardiometabolic health post-operatively. It has been well established that aerobic exercise can decrease inflammation as well as increase insulin sensitivity, cardiometabolic health, and fitness in obese adults. Therefore, combining pre-operative exercise with standard medical care for 30 days prior to bariatric surgery could elicit greater improvements in surgical outcomes as well as cardiometabolic health and overall well-being at the time of and 30 days after surgery than standard care (SC) alone. The focus of Aim 1 was to examine if increasing cardiorespiratory fitness and insulin sensitivity as well as decreasing inflammation by adding aerobic exercise to SC (EX+SC) improved surgical outcomes and metabolic health 30 days after surgery compared to SC alone in patients receiving bariatric surgery. Despite both treatments improving insulin sensitivity and adiposopathy, a measure of adipose tissue endocrine function, comparably over the study, we found that EX+SC had a shorter length of hospital stay and increased metabolic flexibility post-intervention compared to SC. The pre-operative increase in aerobic fitness was associated with a decrease in operating time and length of hospital stay in bariatric patients. We also showed for the first time that the pre-operative rise in aerobic fitness was linked to preservation of lean mass pre- to post-intervention which was secondarily linked to decreased fat mass and increased post-prandial carbohydrate utilization 30 days post-operation. The objective of Aim 2 was to determine if improving cardiometabolic risk factors prior to bariatric surgery by combining EX with SC compared to SC alone related to surgical outcomes and improved cardiometabolic health 30 days after surgery. Pre-operative SC and EX+SC elicited similar improvements in cardiometabolic disease risk factors throughout the study. However, pre-operative increases in aerobic fitness and lean mass were associated with a decrease in C-reactive protein, a measure of low grade systemic inflammation, 30 days post-operation. In Aim 3, we evaluated the interaction of quality of life, dietary intake, and physical activity as it relates to surgical outcomes and cardiometabolic health responsiveness in bariatric patients receiving pre-operative SC or EX+SC. Patients decreased nutrient intake pre- and post-operatively. Pre-operative SC and EX+SC as well as bariatric surgery was effective at increasing quality of life. Improving pre-operative perceived physical functioning was associated with decreased length of hospital stay. Further, greater adherence to the pre-operative low calorie diet was linked to greater perceived general health 30 days after surgery. Taken together, our findings suggest that EX+SC may be a more effective pre-operatively therapy to reduce length of hospital stay than SC alone. Further, increasing lean mass and aerobic fitness prior to bariatric surgery is important for post-operative responsiveness as these outcomes related to decreased fat mass and systemic inflammation 30 days after surgery.
