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Pre-bariatric surgery aerobic exercise decreases hospital stay

Tue, 10/20/2020 - 17:13
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Undertaking aerobic exercise prior to bariatric surgery in addition to standard medical care decreased the length of hospital stay in patients receiving bariatric surgery, compared to standard medical care alone, according to the outcomes of a small pilot trial by researchers from University of Virginia, Charlottesville, VA. The outcomes were featured in the paper, ‘Pre-operative aerobic exercise on metabolic health and surgical outcomes in patients receiving bariatric surgery: A pilot trial’, published in PLOS One.

The authors noted that there is a large variability to bariatric surgery outcomes and it is known that decreased inflammation, elevated insulin sensitivity and greater fitness at the time of surgery is associated with improved surgical outcomes. Current standard medical care (SC), prior to surgery, includes 2-4 weeks of low-calorie diets (LCD), typically consisting of meal replacement shakes for breakfast and lunch along with sensible snacks and a lean protein, high fibre dinner. These pre-operative LCD can reduce liver size prior to surgery and are associated with lower surgical complication rates and improved surgical outcomes. Additionally, previous studies have shown that pre-operative exercise induces greater weight loss and quality of life, compared to SC.

The authors previously carried out two studies that found LCD+exercise increased aerobic fitness, maintained post-prandial carbohydrate (CHO) utilisation and improved glucose tolerance, compared with LCD alone. Following these findings, they established the current pilot trial to examine if combining exercise to SC (EX+SC) improved metabolic health and surgical outcomes compared to SC alone in patients receiving bariatric surgery. They hypothesised that pre-operative EX+SC would increase cardiorespiratory fitness and insulin sensitivity, and decrease adipose-derived inflammation compared to SC. They also anticipated that these changes in metabolic health would correlate with improved bariatric surgery outcomes.

In total, 14 bariatric patients (age: 42.3±2.5y, BMI: 45.1±2.5 kg/m2) were match-paired to pre-operative SC (n=7) or EX+SC (n=7; walking 30min/day, 5day/week, at 65–85% heart rate peak) for 30 days. A 120min mixed meal tolerance test was performed pre- and post-intervention (~2 days prior to surgery) to assess insulin sensitivity (Matsuda Index) and metabolic flexibility (indirect calorimetry). Aerobic fitness (VO2peak), body composition (BodPod) and adipokines (adiponectin, leptin) were also measured. Omental adipose tissue was collected during surgery to quantify gene expression of adiponectin and leptin, and operating time and length of hospital stay were recorded. ANOVA and Cohen’s d effect size (ES) was used to test group differences.


The researchers report that there were no intra- or post-surgical complications and no participants were readmitted to the hospital within 30 days of surgery. Three participants (SC n=2, EX+SC n=1) visited the emergency department within 30 days of surgery.

They found that SC tended to increase percent body fat (p=0.06) after the intervention compared to EX+SC. Although SC and EX+SC tended to raise insulin sensitivity (p=0.11), EX+SC enhanced metabolic flexibility (p=0.01, ES = 1.55), reduced total adiponectin (p=0.01, ES = 1.54) with no change in high-molecular-weight adiponectin and decreased the length of hospital stay (p=0.05), compared to SC.

In addition, EX+SC increased VO2peak 2.9% compared to a 5.9% decrease with SC (p=0.24, ES=0.91), although not statistically significant. This increased fitness correlated to shorter operating time (r=-0.57, p=0.03) and length of stay (r=-0.58, p=0.03). Less omental total adiponectin (r=0.52, p=0.09) and leptin expression (r=0.58, p=0.05) correlated with shorter operating time, and low leptin expression was linked to shorter length of stay (r=0.70, p=0.01), and low leptin expression was linked to shorter length of stay (r=0.70, p=0.01).

“The reduction in length of hospital stay with EX+SC may be mediated by fitness-related adaptations including the reduction in adipose tissue derived hormones, preservation of lean mass, and enhanced metabolic flexibility,” they concluded. “This study highlights the potential benefit of adding aerobic exercise to SC for improving metabolic health in the bariatric patient.”

To access this paper, please click here