EFFECT OF LIFESTYLE PHYSICAL ACTIVITY ON ARTERIAL COMPLIANCE

Abstract

Background: Regular exercise has been shown to slow progression of age-associated loss of arterial compliance, reducing cardiovascular risk. Lifestyle physical activity (LPA) may be a feasible preventive strategy in sedentary individuals. This randomized, parallel, single-blind study examined the effects of LPA on indices of arterial compliance in sedentary African-American women aged 18 to 45 years with prehypertension or untreated stage 1 hypertension. Methods: Women randomized to LPA (n=12) underwent an 8-week individualized, home-based program for 10 minutes, 3x/day, 5days/week, targeting 50%-60% of heart rate reserve. Women in the control group (n=10) continued their usual activities. Radial artery waveforms were obtained by tonometry (HDI CR-2000) at baseline and 8 weeks. Indices of diastolic contours (C1 and C2) were calculated by the HDI device. Raw waveforms were digitized and a generalized transfer function was utilized to calculate central pressures and aortic Augmentation index (AIx). Results: Adherence to LPA was high by all measures (65%-98%). Mean age was 39+/-6, BMI 36.5+/-7.8. 71% worked full-time, 13% part-time. As previously reported, LPA reduced systolic BP significantly (135+/-7 to 129+/-11, -6.4 mm Hg, p=0.36), with a smaller reduction in diastolic BP (91+/-5 to 87+/-10, -3.4 mm, p=NS), but these responses did not differ from controls (135+/-11 to 131+/-5, 92+/-4 to 94+/-9). Diastolic compliance indices (C1 and C2) did not change over the 8-week period in either group. AIx showed a trend toward a greater decrease with LPA (152.4 to 148.7, -3.77, versus 144.7 to 144.0, -0.7), but this did not reach statistical significance. Conclusion: LPA may be easier to implement than other exercise strategies. Systolic BP decreased with LPA, and this analysis showed a trend toward reduction in AIx, an index of arterial compliance. A significant reduction in AIx over 8-weeks period might not have been a realistic expectation, but this suggests the possibility that LPA sustained for a longer period might have a favorable impact on arterial structure. These findings may be clinically important given the especially strong correlation between hypertension and target organ damage in African-Americans.