Impacts of Reducing Sitting Time or Increasing Sit-to-Stand Transitions on Blood Pressure and Glucose Regulation in Postmenopausal Women: Three-Arm Randomized Controlled Trial

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BACKGROUND: Public health and clinical guidelines identify the importance of sedentary behaviors for cardiovascular diseases, particularly among postmenopausal women. The goal of this trial was to compare the behavioral and physiological impacts of 2 distinct approaches to changing sedentary behaviors. METHODS: Overweight or obese sedentary postmenopausal women (N=407) were randomly assigned to 1 of 3 study conditions for 3 months: (1) healthy living (control), (2) reduce sitting time (sit less), and (3) increase sit-to-stand transitions (STSTs; sit-to-stand). Each study arm received 7 individual health coach sessions across 12 weeks. At baseline and 3 months, participants had fasting blood drawn, had blood pressure measured, and wore thigh (activPAL) and hip (ActiGraph) accelerometers for 7 days. Linear mixed models evaluated each intervention arm compared with the control (healthy living) arm. RESULTS: A total of 388 women (95%) completed the 3-month trial. The sit less arm reduced total sitting time by 58 minutes per day more than the healthy living arm (95% CI, –82.9 to –33.6; P <0.001) but did not change STSTs (–1 STST/day [95% CI, –9.4 to 6.5]; P =0.72). Conversely, the sit-to-stand arm significantly increased STST by 26 STST per day more than the healthy living arm (95% CI, 17.71 to 33.64; P <0.001) but did not differ in change to sitting time (–10 min/day [95% CI, –34.6 to 14.9]; P =0.44). The sit-to-stand arm had significant decreases in diastolic blood pressure compared with the healthy living arm (–2.24 mm Hg [95% CI, –4.08 to –0.40]; P =0.02) and similar decreases in systolic blood pressure compared with the healthy living arm (–3.33 mm Hg [95% CI, –6.32 to –0.33]; P =0.03), although it did not reach the a priori significance threshold of P <0.025. There were no significant intervention effects on blood pressure for the sit less arm and no intervention effects for the glucoregulatory outcomes for either arm. CONCLUSIONS: This trial demonstrated the feasibility of changing sedentary behaviors as well as the distinct nature of sitting time and STST. Increasing STST improved blood pressure in overweight and obese postmenopausal women within 3 months. Focusing on increasing STST may be an achievable behavioral target to reduce cardiovascular disease risk in postmenopausal women. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03473145.

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