Normal daily posture and physical activity explained 74% of the variance in cardiac output and 56% in heart rate, but only 32% in systolic and 28% in diastolic blood pressure.
Observational (n=34)
What are the relationships between body posture, physical activity, and systemic haemodynamics during everyday life?
Normal daily posture and activity are major determinants of heart rate and cardiac output variation, but only moderate determinants of blood pressure.
OBJECTIVE: To determine the relationships between body posture and physical activity and systemic haemodynamics during everyday life. METHODS: Continuous measurements were performed in 34 subjects (16 hypertensive, 12 male), aged 49 +/- 13 (mean +/- standard deviation) years. Blood pressure (BP) was measured in the brachial artery. Physical activity and posture were measured with four accelerometers. Beat-to-beat values of systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) were computed from the pressure waveforms. Multiple correlation coefficients (R) between activity and haemodynamic variables were computed and responses to physical activity were estimated with random regression models. RESULTS: The overall percentages of variance in SBP, DBP, HR, SV, CO and SVR explained by activity (R2) were 32, 28, 56, 44, 74, and 45%, respectively. The SBP and HR increased linearly with increasing levels of activity (19 mmHg and 30 beats/min when activity increased 90 percentiles). Other variables showed parabolic relationships. The initial decrease in SV and CO (14 ml and 0.5 l/min) and increase in DBP and SVR (9 mmHg and 2 mmHg min/l) with increasing levels of activity coincided with changes in posture (lying-sitting-standing). The subsequent SV and CO increase (23 ml and 3.7 l/min) and DBP and SVR decrease (8 mmHg and 8 mmHg min/l) coincided with changes in activity (standing-moving generally-walking). CONCLUSIONS: Our findings show that normal daily posture and activity are only moderate determinants of BP, but main determinants of HR and CO variation.
Cavelaars et al. (Tue,) reported a observational. Physical activity and body posture was evaluated on Relationships between body posture and physical activity and systemic haemodynamics. Normal daily posture and physical activity explained 74% of the variance in cardiac output and 56% in heart rate, but only 32% in systolic and 28% in diastolic blood pressure.