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Effects of Lifestyle Physical Activity on Vascular Function in Asymptomatic PAD
Quick Takes
- People with peripheral arterial disease (PAD) have lower exercise capacity and greater sedentarism than healthy peers, even if they are asymptomatic (no claudication).
- A 12-week home-based intervention that combined relatively modest-intensity walking and technology-aided modifications in sedentary behavior resulted in more physical activity in 16 older sedentary participants with asymptomatic PAD.
- Microvascular endothelial function improved though arterial compliance but ankle-brachial index (ABI) did not, indicating a need for further research that characterizes endothelial function with different frequency, intensity, and volume of physical activity and sedentary-behavior-reduction techniques.
Study Questions:
What are the effects of a 12-week intervention that combines increased daily physical activity with reduced sedentary behavior on endothelial vasodilatory function and arterial compliance in individuals with asymptomatic PAD?
Methods:
A total of 38 individuals with asymptomatic PAD (ABI of less than 0.9 by Doppler ultrasound) were randomized into either an attention control group or a physical activity/sedentary reduction intervention group. All participants received 12 weeks of twice-monthly health-recommendation videos related to PAD. In addition, each physical activity/sedentary reduction intervention group member participated in a 12-week home-based sedentary behavior-reduction program, took at least twice-daily 10-min walks, and received interactive wearable activity trackers, which included online self-monitoring software that provided individualized personal daily, weekly, and monthly summaries of time spent sitting, standing, and walking. Participants in both groups received pre- and post-intervention testing: noninvasive vascular function testing for peripheral arterial tone-reactive hyperemia index (PAT-RHI), an index of microvascular reactivity, and augmentation index (PAT-AIx), an index of arterial stiffness/compliance, as well as 6-minute walk tests (6MWT) for evaluation of walking capacity.
Results:
Baseline demographic characteristics of the two groups, including 6MWT, PAT-RHI, PAT-AIx and other physical activity and sedentary behavior metrics, were the same. The physical activity/sedentary reduction intervention group demonstrated significant post-intervention increases in mean standing and stepping hours per day, mean sit-to-stand transitions per day, total steps per day, and 6MWT distances, along with a significant decrease in mean non-sleep sit/lie hours per day. The attention control group experienced a modest but statistically significant decrease in stepping hours per day. For the physical activity/sedentary reduction intervention group, the post-intervention PAT-RHI increased significantly and was positively correlated with changes in mean step counts per day and mean stepping hours per day. The attention control group had no significant change in PAT-RHI. Neither group experienced a significant post-intervention change in PAT-AIx or ABI from baseline. However, within the physical activity/sedentary reduction intervention group, those individuals who achieved 2 or more 10-minute walks per day improved their PAT-AIx, though this value did not reach statistical significance. Participants in the physical activity/sedentary reduction intervention group increased their peak 1-min step rates and peak 10-min step rates, indicating an improvement in intensity of exercise (from low to low-moderate). The attention control group participants showed no significant changes in step rates.
Conclusions:
This study demonstrated that a 12-week interactive online, home-based intervention that combined relatively modest-intensity walking and technology-aided modifications in sedentary behavior resulted in more physical activity in older sedentary participants with asymptomatic PAD. These changes in physical activity patterns demonstrated improvements in microvascular endothelial function by improved PAT-RHI; there were no significant improvements in PAT-AIx or ABI. The findings indicate that the relationship among PAT-RHI, PAT-AIx, and ABI with a change in physical activity patterns is complex, and a 3-month intervention may be insufficient to see improved arterial compliance in asymptomatic PAD.
Perspective:
Less sitting and more physical activity is beneficial to cardiovascular health generally and for the middle- to older-aged individuals with asymptomatic PAD in this study specifically, a group that is more sedentary than healthy peers. More studies are needed to determine the minimum frequency, intensity, and/or volume of physical activity needed to achieve optimal benefits in asymptomatic PAD and inform clinical recommendations for patients with PAD.
Clinical Topics: Cardiovascular Care Team, Diabetes and Cardiometabolic Disease, Prevention, Vascular Medicine, Atherosclerotic Disease (CAD/PAD), Exercise
Keywords: Peripheral Arterial Disease, Exercise, Sedentary Behavior, Ankle Brachial Index, Walking, Arteries, Vascular Stiffness
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