The relationship between ambulatory blood pressure and physical activity in young and older shiftworkers. A quantitative assessment of physical activity using a microcomputer with acceleration sensor

Abstract

We studied the relationship between physical activity and ambulatory blood pressure (BP) in young and older shiftworkers by simultaneous recordings of activity, blood pressure and pulse rate (PR). Activity was assessed using Activetracer, a self-contained microcomputer with an acceleration sensor, attached to a waist belt. Ambulatory BP was monitored every 30 minutes for 48 hours with a TM2421. Three types of hemodynamic responses were noted in relation to the physical activity. The balance type, in which both BP and PR increase with physical activity, was observed in 5 of 10 young cases (50%) but only in 1 of 7 older cases (14.3%). The BP response type, in which the BP increases with no change in the PR, was observed in 6 of the 7 older (86%) but only in 3 cases in the young group (30%). The PR response type, in which only the PR increase correlated with activity, was observed in 2 cases in the young group (20%) and none in the older group. The difference in systolic BP between periods of activity and rest in the older shiftworker was significantly larger than that in the young group (15.9 +/- 6.4 vs. 5.9 +/- 6.6 mmHg, p < .01), although no significant difference was observed in diastolic BP. In contrast, the increase in pulse rate after movement was significantly higher in the young group (4.4 +/- 4.0 vs. 9.0 +/- 4.8 bpm, p < .05). Thus, the fluctuation of the systolic BP was more dependent on physical activity in the older group, whereas PR variations correlated with the physical activity in the young group.