A COMPARISON OF 24-H AVERAGE BLOOD PRESSURES AND BLOOD-PRESSURE LOAD FOLLOWING EXERCISE

Although the use of 24-h ambulatory blood pressure monitoring has been recommended in the study of blood pressure and exercise, consistent r esults have not been found for average 24-h systolic or diastolic bloo d pressures. Systolic load and diastolic load (the percentage of press ures >140/90 mm Hg during daytime hours and >120/80 mm Hg during sleep ) have recently been identified as an important variable, but has had limited use with exercise. The purpose of this study was to compare th e average systolic and diastolic pressures to systolic and diastolic l oads from 24-h data recorded after a 50-min treadmill walk at 50% VO(2 )max to data from a nonexercise control day. Subjects were 36 normoten sive (116.9 +/- 10.7/77.0 +/- 8.9 mm Hg) and 25 hypertensive (141.0 +/ - 13.7/96.6 +/- 9.0 mm Hg) adults. No significant differences were fou nd for systolic and diastolic pressures or loads between the control a nd exercise days for normotensives. Even though no significant changes were found for any of the average systolic and diastolic pressures be tween the control and exercise days for the hypertensives, significant reductions were found in systolic load for 24-h (-25.7%), day (6 AM t o 10 PM, -23.1%), work (6 AM to 5 FM, -22.9%), and leisure (5 PM to 10 PM, -26.7%) periods; and in diastolic load for the work (-22.5%) peri od. Thus, the measurement of systolic and diastolic load may be more s ensitive than average systolic and diastolic blood pressures for the d etection of 24-h ambulatory blood pressure changes with exercise in bo rderline hypertension. (C) 1997 American Journal of Hypertension, Ltd.