Walking may be related to less vascular stiffness in the Activity Counseling Trial (ACT)

Background The ACT was a clinical trial of various patient education and counseling interventions to increase physical activity in sedentary primary care populations. It provided the opportunity to measure the effect of increasing physical activity on aortic pulse wave velocity (APWV), a measure of vascular stiffness, in a relatively healthy middle-aged population. The effects of the interventions, as well as the impact of walking and correlates such as older age and maximal oxygen uptake (V˙o2max), on APWV were assessed. Methods The participants in this study were a subset of the 874 persons recruited for the ACT. Information about self-reported physical activity and disease status was collected at baseline (464 persons), 6- month (528 persons), and 24-month (555 persons) intervals. Physiological measures included APWV, systolic blood pressure, and other correlates. Results In multivariate analyses, the various treatment arms did not have a significant effect on APWV. However, walking in hours per day was associated with slower APWV times or less stiffness (P = .03). This was significant for women and consistent but not significant for men. In addition, age, clinic site, race, systolic blood pressure, and V˙o2max were independently associated with APWV. Conclusions Increased walking frequency over a 24-month period was predictive of reduced vascular stiffness in ACT. The more significant result for walking frequency in women than in men might be caused by the presence of a low V˙o2max or physical activity threshold for an effect of walking on APWV, which most women achieved but most men had surpassed at the start of the study. Although needing confirmation because this was a secondary analysis, modest physical activity may have a beneficial effect on large vessel structure.