Pre-operative aerobic exercise on metabolic health and surgical outcomes in patients receiving bariatric surgery: A pilot trial

Abstract

Objective: Examine if adding aerobic exercise to standard medical care (EX+SC) prior to bariatric surgery improves metabolic health in relation to surgical outcomes.

Methods: Fourteen bariatric patients (age: 42.3±2.5y, BMI: 45.1±2.5 kg/m2) met inclusion criteria and were match-paired to pre-operative SC (n = 7) or EX+SC (n = 7; walking 30min/d, 5d/wk, 65-85% HRpeak) for 30d. A 120min mixed meal tolerance test was performed pre- and post-intervention (~2d 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.

Results: 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 HMW adiponectin and decreased the length of hospital stay (P = 0.05) compared to SC. Albeit not statistically significant, EX+SC increased VO2peak 2.9% compared to a 5.9% decrease with SC (P = 0.24, ES = 0.91). 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 (r = 0.58, P = 0.05) expression 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).

Conclusion: Adding pre-operative aerobic exercise to standard care may improve surgical outcomes through a fitness and adipose tissue derived mechanism.

Fig 1. CONSORT flow diagram.

Fig 2

The effect of SC (A-C) and EX+SC (D-F) on mixed meal tolerance test glucose, free fatty acid (FFA), and insulin curves. Data are means ± SEM. There was a trend for a time effect for 90 minute glucose (P = 0.08) and 120 minute FFA (P = 0.06). Conversions: Glucose, 1.00 mmol/L = 18.01 mg/dL; FFA 1.00 mEq/L = 1.00 mmol/L; Insulin, 1.00 μU/mL = 6.95 pmol/L.

Fig 3

The effect of SC (A) and EX+SC (B) on fasting and average post-prandial respiratory exchange ratio as well as metabolic flexibility (C). Data are means ± SEM. There is a trend (P = 0.08) for a time effect for average post-prandial RER. ^Denotes a significant (P = 0.01) group x time interaction. Metabolic flexibility was determined by subtracting fasting respiratory exchange ratio (RER) from the average of post-prandial (avg. PP) RER.

Fig 4. Correlations in metabolic outcomes following the intervention.

The change (Δ) in VO₂peak (L/min) to the Δ in the ratio of high molecular weight (HMW) to total adiponectin (A). The Δ in HMW adiponectin:leptin to the Δ in fasting respiratory exchange ratio (RER) (B) and Δ in average post-prandial (PP) RER (C). The Δ in peripheral insulin sensitivity to the Δ in PP RER (D). The Δ in VO₂peak (L/min) to operating time (E) and length of hospital stay (F).