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Objective: To test the hypothesis that Physical Activity (PA) improves cardiovascular disease (CVD)-related lipids beyond that associated with weight loss in adolescents with severe obesity, post-metabolic bariatric surgery (MBS). Methods: We used objective StepWatch™ PA data from 108 participants of the Teen Longitudinal Assessment of Bariatric Surgery (Teen-LABS) study from baseline to 3 years post-MBS. Primary outcomes included absolute change in low density lipoprotein (LDL-C) and non-high density lipoprotein (non-HDL-C) from baseline. We adjusted for baseline measurement, visit, surgical procedure, and percent change in iliac waist circumference (IWC) or body mass index (BMI) from baseline in linear regression models using generalized estimating equations. PROC TRAJ in SAS generated optimal activity trajectories based on individual step count. Results: Despite low step counts and slow cadence, differences by activity trajectory were found. Greater absolute decreases in LDL-C and non-HDL-C (−15 mg/dL [95% CI: (−28, −2)], p =0.026 and −15 mg/dL [95% CI: (−28, −1)], p = 0.035), respectively, were associated with more activity (MA). MA was associated with greater resolution of triglycerides, LDL-C and non-HDL-C dyslipidemia and with greater weight loss 3 years post-MBS. Conclusion: More activity in adolescents was associated with improvements in CVD-related lipid measures and weight loss, post-MBS.

Background/Objectives: We hypothesized that physical activity (PA) improves insulin sensitivity in adolescents with severe obesity beyond that attributable to metabolic bariatric surgery (MBS). Subjects/Methods: StepWatch™ monitors objectively measured PA in 88 participants in the Teen Longitudinal Assessment of Bariatric Surgery (Teen-LABS) study. Primary outcomes included absolute change in fasting insulin, HOMA-IR, and fasting glucose from pre-surgery (baseline) to 6, 12, 24, and 36 months post-MBS. SAS PROC TRAJ generated activity trajectories based on probability and individual participant step count trajectories. Linear regression models were used, adjusted for baseline value, visit, surgical procedure, sex, and percent change in BMI. Additional models adjusted for percent change in iliac waist circumference (IWC) or percent body fat (BF), measured by bio-impedance. Results: Two activity trajectories were identified: more active (MA, n=13) and less active (LA, n=75). MA baseline mean daily step count was >6 000, increasing to > 9 000 at 2 years. LA mean daily step count remained at approximately 4 000. Few participants recorded moderate step activity (cadence >80 steps/minute). Still, fasting insulin and HOMA-IR differed in association with activity trajectory. MA was associated with a greater absolute decrease in fasting insulin (−7.8μU/ml [95% CI: (−11.8, −3.7)], p =<0.001) and a greater decrease in HOMA- IR (−1.9 [95% CI: (−3.0, −0.7)], p = 0.001), when adjusted for percent change in BMI. The significant independent effect of MA remained when adjusted for percent change in IWC or percent BF. Clinically, 100% of MA trajectory participants normalized fasting insulin, HOMA-IR and fasting glucose by 6 months and normalization remained throughout the 36 month follow up. In contrast, 76.3% and 65.8% of LA trajectory participants normalized fasting insulin and HOMA-IR, respectively, by 12 months with 28.6% of both remaining normalized at 36 months. Conclusion: PA is independently associated with improved insulin sensitivity beyond that attributable to MBS in adolescents with severe obesity.

Introduction: Severe obesity is increasing in adolescents and is strongly associated with CVD risk. Weight loss surgery (WLS) effectively treats severe obesity and improves CVD-related lipid measures. Independent of weight loss (WL), physical activity (PA) also improves lipid-related CVD measures and is key to WL maintenance. Longitudinal PA behaviors post-WLS and the impact on CVD-related lipid measures in adolescents is unclear, in part because PA data are largely self-reported. Hypothesis: We assessed the hypothesis that PA improves plasma lipids beyond that associated with active WL in adolescents, post-WLS. Methods: We used objective StepWatch TM PA data from 108 participants of the Teen-LABS bariatric surgery study from baseline to 3 years post-WLS. Inclusion criteria included 1) at least 3 days (1 weekend day and 2 weekdays) of recorded StepWatch TM data, including 6 hours or more of continuously recorded data per day, 2) at least 10 steps per hour, 3) data at baseline and one or more postoperative time points (6 months, 1 year, 2 years and/or 3 years), and 4) matched laboratory and anthropometric data. Participants on lipid lowering therapy were excluded. The primary outcome of interest was absolute change in plasma lipids (TC, TG, HDL-C, LDL-C, and non-HDL-C), holding sex, race, time, % change in iliac waist circumference and procedure constant in a linear regression model with generalized estimating equations assuming an exchangeable working correlation structure. PROC TRAJ in SAS was used to determine the optimal number of group activity trajectories based on step counts at all visits. Results: Two activity groups were identified from PROC TRAJ : less and more active. When considering all mean daily step count data, the overall mean was 4241 (95% CI: 3970, 4513), the more active trajectory mean was 8494 (95% CI: 7596, 9392), and the less active trajectory mean was 3722 (95% CI: 3530, 3915), all well below the recommended 12,000 steps for age. Yet statistically and clinically significant differences by activity trajectory emerged. Greater absolute decreases in LDL-C and non-HDL-C (-15 mg/dL [95% CI: (-28, -2)], p =0.026 and -15 mg/ld. [95% CI: (-28, -1)], p = 0.035), respectively, were associated with activity, holding stated co-variables constant. Activity was also associated with greater percentages of TG, LDL-C and non-HDL-C values being within acceptable ranges, by 2011 NIHLB Integrated Criteria, at 2 years, (TG, 83% vs 70%; LDL-C, 100% vs 83%; non-HDL-C, 83% vs 70%). Conclusion: In conclusion, greater improvement in CVD-related lipid measures was associated with more activity 2 years post-WLS in adolescents, one year post-active WL. Of great interest, the predominant lipid measure influencing CVD risk post-WLS was not HDL-C, as reported in adults. Importantly, the PA-associated reductions of LDL-C, and non-HDL-C are more strongly associated with improved CVD risk than HDL-C increase.

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