Background: The aim of the study was to assess the effect of physical activity on 24-hr ambulatory blood pressure (ABPM) and office blood pressure (BP) in 572 male subjects with borderline to mild hypertension from the HARVEST study.
Methods: Subjects were 18 to 45 years old with diastolic BP of 90-99 mmHg and/or systolic BP of 140-159 mmHg. They never took any anti-hypertensive therapy. All subjects underwent physical examination, office BP measurement and two 24-hr ambulatory BP monitorings performed three months apart. Subjects were classified as non exercisers, group 1 (n=331), mild exercisers, group 2 (n=192) and heavy exercisers, group 3 (n=49). During the three months of follow-up subjects maintained the same physical activity habits. There was no difference in smoking and alcohol consumption between the 3 groups. As the groups differed significantly in age and body mass index data were adjusted for these confounders.
Results: At baseline office and ambulatory systolic BP were similar in the 3 groups, while diastolic BP was proportional to the level of physical activity although the difference was significant only between the group of non-exercisers and mild exercisers. Heart rate (HR) was always inversely related to the intensity of exercise. After three months follow-up office systolic BP was similar among the three groups and diastolic BP slightly decreased in the exercisers (group 1 vs group 3 p=0.02, group 2 vs group 3 p=0.04). At ABPM the group of heavy exercisers showed a significant decrease in daytime systolic BP (135.4plus minus0.6 vs 134plus minus0.8 vs 132.2plus minus1.6 mmHg; group 1 vs group 3 p<0.05) and the difference between systolic ambulatory BP at the 3rd month and at baseline, showed an additional significant decrease according to exercise intensity (24-hr systolic BP group 1 vs group 3 p=0.001, group 2 vs group 3 p=0.004; daytime systolic BP group 1 vs group 3 p=0.0009, group 2 vs group 3 p=0.004; night-time systolic BP group 1 vs group 3 p=0.02, group 2 vs group 3 p=0.02). No changes in ambulatory diastolic BP were observed.
Conclusions: In conclusion, physical activity has a positive effect in lowering BP attenuating the risk of hypertension in young subjects with borderline hypertension. The anti-hypertensive effect of physical activity persisted after three months and the group of exercisers had an additional reduction in systolic BP detected by ABPM. To obtain accurate information on chronic levels of arterial pressure over time 24-hr ambulatory BP should be preferred to traditional casual readings.