There is substantial evidence that establishes the benefits of being physically active on prevention of cardiovascular diseases and diabetes (Arnett et al., 2019; Fretts et al., 2012; Fretts et al., 2009; Sattelmair et al., 2011; Zheng et al., 2009; Wahid et al., n.d.; Lee et al., 2012; Kyu et al., 2016), and the 2019 American College of Cardiology (ACC) and American Heart Association (AHA) guidelines highlight physical activity as a key component of prevention efforts (Arnett et al., 2019). The guideline recommends 150 min per week of moderate-intensity (or 75 min of vigorous-intensity) aerobic physical activity, such as brisk walking, for adults to reduce risk of atherosclerotic cardiovascular diseases (ASCVD) (Arnett et al., 2019). This is consistent with AHA's Life's Essential 8 recommendations for lowering risks of coronary heart disease (CHD) (Lloyd-Jones et al., 2022).

CHD is the progressive narrowing of the arteries that supply blood and oxygen to the heart due buildup of cholesterol deposits in the arterial wall (CDC Coronary Artery Disease, n.d.). CHD events, such as angina or myocardial infarction, can occur when blood flow to the heart becomes significantly occluded (CDC Coronary Artery Disease, n.d.; Coronary Heart Disease, n.d.). In this study, we assessed the impact of physical activity on the risk of CHD among American Indians, who historically have been disproportionately affected by heart diseases and underrepresented in past cardiovascular disease studies, compared to other ethnicities (Breathett et al., 2020a; Disparities, n.d.; Heart Disease and American Indians, n.d.). In fact, heart disease was the leading cause of death in American Indian men (18.9%) and second leading cause of death in American Indian women (17.1%) of all ages in 2018 (From the CDC-Leading Causes of Death-Males All Races and Origins, 2018; From CDC-Leading Causes of Death-Females All Races and Origins, 2018). In addition, prevalence of physical inactivity, obesity, diabetes, and other lifestyle-based risk factors in American Indians may be higher compared to the general population (Fretts et al., 2012; Zhao, 2022). Combined Behavioral Risk Factor Surveillance System (BRFSS) data from 2017 to 2020 estimated physical inactivity outside of work to be 29.1% in American Indian adults compared to 23.0% in non-Hispanic White adults (Adult Physical Inactivity, n.d.). Therefore, due to the differences in population characteristics, it is unclear if the findings in other studies can be easily generalized to the American Indian communities.

Our study results will describe the effects of ambulatory activity on CHD prevention among the American Indian participants of the Strong Heart Family Study (SHFS). Specifically, our objective is to evaluate the association between average daily step counts and incidence of CHD in the SHFS cohort.