Introduction: In a recent randomized crossover trial, using a sit-stand desk to alternate postures resulted in small but statistically significant decreases in average blood pressure (BP) across a simulated workday.
Hypothesis: We tested the hypothesis that certain baseline characteristics are associated with a greater acute BP-lowering response to use of a sit-stand desk.
Methods: This secondary analysis used data from all subjects (n=25; 36% female; mean (SD) age 42 (12) years, screening baseline SBP 132 (9) mmHg and DBP 83 (8) mmHg, BMI 32 (5) kg/m2) completing a randomized crossover study with two simulated workday conditions: 1) continuous sitting (SIT) and 2) alternating sitting and standing every 30 minutes (SS). Oscillometric BP was measured hourly. Average time spent sitting and in moderate-to-vigorous intensity physical activity (MVPA) were reported using the Global Physical Activity Questionnaire. Linear regression models identified whether participant characteristics (morning BP per 10 mmHg; age > 50 years; sex (female); MVPA ≥ 150 mins/week; sedentary time ≥ 10 hours/day; BMI ≥ 30 kg/m2) were associated with a greater BP-lowering effect of using a sit-stand desk with a backward selection stepwise approach removing independent variables with P ≥ 0.2.
Results: Lower morning baseline SBP (β = 2.8 mmHg per 10 mmHg, P = 0.012) and higher MVPA (β = -4.4 mmHg, P = 0.025) were associated with a greater SBP-lowering effect; higher age (β = -3.8 mmHg, P = 0.170) and higher BMI (β = 4.2 mmHg, P = 0.067) were retained in the model but were not statistically significant. Higher MVPA (β = -3.0 mmHg, P = 0.040) and lower BMI (β = 4.1 mmHg, P = 0.002) were associated with a greater DBP-lowering effect; female sex (β = -1.7 mmHg, P = 0.172) was retained in the model but was not statistically significant (Figure 1).
Conclusions: In conclusion, physically active, non-obese adults with lower SBP experienced the most beneficial BP response to intermittent standing. Future studies should investigate the mechanisms explaining this acute BP response.