The distensibility of the arterial wall progressively decreases with age, and the aging of the arterial wall may be responsible for the decrease of central arterial compliance and the consequent rise of systolic blood pressure (SBP) in the elderly. We hypothesized that an increase in daily physical activity (DPA) might have a favorable effect on systemic arterial compliance (SAC : an index of central arterial compliance) and lower SBP in the elderly. We therefore investigated relationships among DPA, SAC and SBP cross-sectionally in 92 middle-aged and elderly individuals (30 males, 62 fe- males ; aged 64 ± 8 years, mean ± SD). DPA was estimated by using an accelerometer as expended calories. SAC was calculated from the finger pulse pressure waveform recorded by using a Portapres and the stroke volume obtained from the same pressure waveform based on the volume-clamp method. Preliminarily in 37 subjects (17 male, 20 females ; aged 25-97 years), we confirmed a significant negative correlation between the simultaneously measured SAC and aortic pulse wave velocity (r=-0.68, p<0.0001). Correlation analysis and path analysis applied to the hypothetical model demonstrated that SBP was directly affected by both DPA and the SAC which decreased with age, and that DPA had an increasing effect on SAC, i. e. DPA might have a suppressive effect on the rise of SBP not only directly but also indirectly through SAC. These results suggest that an increased level of daily physical activity could improve the age-dependent decrease of central arterial compliance and the rise of systolic blood pressure in middle-aged and elderly humans.