Interrupting Prolonged Sitting With Different Walking Intensities And Durations: Effects On Resting Blood Pressure

Abstract

BACKGROUND: Greater time spent in sedentary behaviour is associated with an increased risk of cardiovascular disease, type-2 diabetes, and mortality. Regularly interrupting prolonged sitting with 2-min light-intensity and 2-min moderate-intensity walking every 20 minutes without matching for energy expenditure has been shown to reduce resting blood pressure. However, little is known whether interrupting prolonged sitting with 3-min light-intensity walking and 1.5-min brisk walking every 30 min when the energy expenditure of these trials is matched provides similar benefits on resting blood pressure. PURPOSES: To compare the effects of 1.5-min moderate-intensity walking every 30 minutes and 3-min light-intensity walking every 30 minutes on resting blood pressure in young men with central obesity when the energy expenditure of these trials is matched. METHODS: Sixteen East-Asian men with central obesity (mean age: 22.3 ± 4.2 years; body mass index: 29.9 ± 1.7 kg·m-2; waist circumference: 100.3 ± 5.9 cm) completed three, 7-h laboratory-based conditions in a randomised order: 1) prolonged sitting (SIT), 2) 3-min (at 20 - 39% of VO2 reserve) and 3) 1.5-min (at 40 - 59% of VO2 reserve). Each trial was separated by a 6-day washout period. Resting blood pressure was measured hourly using automated sphygmomanometer in a seated position (mean of two recordings, ≥ 15-min post-activity). Generalised Estimating Equations were used to examine differences among the three conditions. RESULTS: Resting systolic blood pressure (SBP) reduced in the 3-min condition (mean ± SEM; 119 ± 2 mmHg) but not in 1.5-min condition (120 ± 2 mmHg) when compared with SIT condition (123 ± 3 mmHg, P = 0.028). Resting diastolic blood pressure (DBP) reduced in both 3-min (75 ± 2 mmHg) and 1.5-min (75 ± 2 mmHg) conditions compared with SIT condition (76 ± 2 mmHg, P = 0.024 and P = 0.001, respectively). CONCLUSIONS: Interrupting prolonged sitting with 3-min of light-intensity walking every 30 minutes is more effective on reducing resting blood pressure when compared to the trial with 1.5-min of moderate-intensity walking every 30 minutes in young East-Asian men with central obesity.