The relationship of electronically monitored physical activity to blood pressure, heart rate, and the circadian blood pressure profile

We studied how closely changes in electronically monitored physical activit y are reflected in changes in blood pressure and heart rate in a group of u ntreated hypertensive subjects. Thirty-nine hypertensive patients (office b lood pressure > 140/90 mm Hg) of mean age 57 +/- 10 years (mean +/- SD) wor e an ambulatory blood pressure monitor and a wrist actigraph simultaneously . Both average and peak activity for 5 min before each valid blood pressure reading were determined, as was average activity for awake and sleep perio ds, determined by patient kept diaries. For the overall group, awake and 24 -h activities were inversely correlated to age (n = 39, r = -0.42; P = 0.01 and n = 39, r = -0.38; P = 0.01, respectively). No correlation was found b etween group awake activity and group-average blood pressure or heart rate. For individual patients, there was marked variation in the degree of corre lation between awake activity measures (both peak and average) and blood pr essure and heart rate. The strongest positive correlation was between activ ity levels and the heart rate-pressure product. Nondipper profile hypertens ives had higher sleep activity than dipper hypertensives (44 +/- 28 units/m in v 25 +/- 20 units/min, df = 37, t = 2.12; P = 0.04), but awake activity levels were similar. The higher sleep activity remained after adjustment fo r age. These findings indicate that the relationship between actigraphic activity and hemodynamic parameters is highly variable and that the rate-pressure pr oduct is the strongest correlate of short-term activity. Furthermore, hyper tensives with the nondipper profile have higher sleep activity than dipper hypertensives. These findings stress the need for further study into the ro le of day-to-day activity in determining ambulatory blood pressure and hear t rate variability. Am J Hypertens 2000; 13:262-267 (C) 2000 American Journ al of Hypertension, Ltd.