Abstract MP45: Effects of an mHealth Adaptive Intervention on Vascular Health and Cardiorespiratory Fitness
Introduction: Behavioral economics-based interventions for increasing steps/day may improve cardiorespiratory fitness (CRF; Peak O2 uptake - VO2peak), central/aortic blood pressure, and vascular stiffness. The purpose of this study was to examine the effects of adaptive (Ad) physical activity (PA) goals (daily step goals based on prior 10-day window and a percentile algorithm) vs. static (St) PA goals (10,000 steps/day) combined with either immediate (Im) financial micro-incentives or delayed (De) incentives (Groups: Ad+Im; Ad+De; St+Im; St+De) on VO2peak, blood pressure and vascular stiffness. We hypothesized that participants randomized to adaptive goals with immediate reinforcement (Ad+Im) would have greater improvements in cardiovascular health measures than participants assigned to static goals and/or delayed reinforcement conditions (active controls).
Methods: Inactive adults (Age = 41.8 ± 6.7yrs; BMI = 34.5 ± 6 kg/m2) were randomized to an adaptive/static goal intervention with either immediate micro-incentives or delayed incentives in a 4-month factorial RCT to improve steps/day. Additionally, all four groups received daily text-message prompts-to-action and Fitbit ZipTM activity monitors. Pre and post VO2peak (n=81) were estimated using a modified, sub-maximal Balke treadmill protocol while central blood pressures, augmentation index (Aix@75) (n=70) and carotid-femoral pulse wave velocity (cf-PWV) (n=64) were assessed with the Sphygmocor XCELTM device. Between- and within-group differences were examined using linear mixed models, adjusted for sex, age, race/ethnicity, and smoking history. Alpha was set at 0.05, and data are presented as estimated marginal means ± standard errors (SE).
Results: All groups improved from pre to post, but we found no significant between-group differences in the degree of improvement. Across all groups, we found the following: VO2peak and all vascular markers improved significantly pre to post intervention (p<0.05). VO2peak improved by ~5% (pre = 24.9 ± 0.65 vs. post = 26.3 ± 0.66 ml/kg/min). Central systolic blood pressures (cSBP) decreased (cSBP pre = 117.5 ± 2.1 vs. post = 113.1 ± 2.2 mmHg). Cf-PWV (pre = 7.5 ± 0.18 vs. post = 7.3 ± 0.18 m/sec) and AIX@75 (pre =14.1 ± 2.2 vs. post = 11.4 ± 2.2) decreased.
Conclusion: Cardiorespiratory fitness and markers of vascular health improved when participants were simply provided a Fitbit and prompted daily to be more physically active, regardless of incentive or goal-setting approach. Implications for designing behavioral interventions for cardiovascular risk reduction will be discussed.
Author Disclosures: C.L. Jarrett: None. W.J. Tucker: None. J.C. Hurley: None. M. Todd: None. N. Bhuiyan: None. J.A. Fernandez: None. M.A. Adams: None. S.S. Angadi: None.
- © 2016 by American Heart Association, Inc.