Physical activity, inflammation, coronary artery calcification and incident coronary heart disease in African Americans: Insights from the Jackson Heart Study

Abstract

Objective:

To examine associations between physical activity, inflammation, coronary artery calcification and incident coronary heart disease in African Americans.

Methods:

Among Jackson Heart Study participants without prevalent coronary heart disease at baseline (n=4295), we examined the relationships between physical activity and high-sensitivity CRP, the presence of coronary artery calcification (Agatston score≥100), and incident coronary heart disease. Based on the American Heart Association’s Life’s Simple 7 metrics, participants were classified as having poor, intermediate or ideal physical activity.

Results:

After adjusting for possible confounding factors, ideal physical activity was associated with lower high-sensitivity CRP levels (β: −0.15, 95%CI −0.15, −0.002) and a lower prevalence of coronary artery calcification (odds ratio: 0.70, 95%CI 0.51, 0.96) compared with poor physical activity. Over a median of 12.8 years follow up, there were 164 incident coronary heart disease events (3.3/1000 person-years). Ideal physical activity was associated with a lower rate of incident coronary heart disease compared with poor physical activity (hazard ratio 0.55, 95% CI 0.31, 0.98).

Conclusions:

In a large community-based African American cohort, ideal physical activity was associated with lower inflammation levels, a lower prevalence of coronary artery calcification, and a lower rate of incident coronary heart disease. These findings suggest that promotion of ideal physical activity may be an important way to reduce the risk of subclinical and future clinical coronary heart disease in African Americans.

Introduction

Many previous reports have suggested that physical activity (PA) is associated with reduced risk of coronary heart disease (CHD). However, relatively few studies have examined the relationship between PA and CHD in African Americans.¹ Manson and colleagues showed that walking and vigorous exercise were associated with similar risk reductions for CHD events and total cardiovascular (CV) events in white and African American women and that the results did not vary substantially according to race, age, or body-mass index in the Women’s Health Initiative Observational Study.² The number of participants in the study was large, but all of the participants were women. The Atherosclerosis Risk in Communities Study reported that there was a significant interaction between race and PA; however, there was no significant relationship between PA and risk of CHD in African Americans.³ To the contrary, another report using the ARIC Study population showed an inverse relationship between PA and cardiovascular events.⁴ However, this longitudinal study included smaller numbers of African Americans, and the baseline examination was conducted 30 years ago (between 1987 and 1989).⁴ The Jackson Heart Study (JHS) is the largest contemporary African American cohort, and PA assessment has been validated within this cohort.⁵

PA is inversely associated with subclinical atherosclerosis including coronary artery calcification (CAC),⁶ peripheral artery disease assessed by ankle brachial index,⁷ carotid artery stiffness,⁸ and carotid intima-media thickness,⁹ all of which have been associated with CHD.^10–12 Therefore, previous negative findings regarding PA and heart disease in African Americans are not consistent with prior work. Very few studies have been performed evaluating PA and subclinical atherosclerosis in African Americans.

Chronic inflammation has been reported to play a role in the pathogenesis of atherosclerosis.¹³ A recently published meta-analysis of exercise intervention trials showed exercise interventions reduced hs-CRP levels in adults irrespective of the presence of heart disease.¹⁴ The effects of PA on inflammation have not been investigated in a large cohort of African Americans.

Only 19.3% of African Americans get ideal PA, a significantly lower proportion than observed in non-Hispanic whites.¹⁵ Therefore, robust scientific data are needed to provide high quality recommendations specific to this population. Thus, the aim of this study is to investigate the relationships of PA and inflammation, coronary artery calcification, and incident CHD in a large cohort of African Americans, the JHS.

Methods

Study Participants

The JHS is a prospective community-based observational study designed to investigate risk factors for CV diseases in African Americans.¹⁶ Details of the JHS have been described elsewhere.¹⁷ Briefly, 5306 African American participants residing in the Jackson, Mississippi tri-county area (Hinds, Rankin, and Madison) were recruited for the baseline exam (Visit 1) between 2000 and 2004 and completed 2 subsequent follow-up visits (Visit 2: between 2005 and 2008, Visit 3: between 2009 and 2013). The JHS was approved by the Institutional Review Boards of Jackson State University, Tougaloo College, and the University of Mississippi Medical Center, Jackson, Mississippi. All study participants gave written informed consent. From the 5306 participants, we excluded those with past history of CHD at baseline (n=400), as well as those with missing information on the following (in hierarchical order): body mass index (BMI) (n=12), systolic blood pressure and blood pressure medication use (n=133), history of diabetes (n=49), total cholesterol and high density lipoprotein cholesterol (n=344), current smoking status (n=39), education level (n=15), and current alcohol drinking status (n=18) (Figure 1). In addition, those who did not undergo coronary CT (n=1876) were excluded from the CAC analysis, and those who had no longitudinal follow-up were excluded from the incident CHD study (Figure 1). The remaining participants were included in the final analysis (for CAC analysis n=2420, for incident CHD study n=4132) of the current study. The differences of baseline characteristics between included and excluded participants in this study are shown in the Supplementary Table 1. As expected, those excluded from this study were older and had higher prevalence of male gender, hypertension, diabetes, and current smoking. The differences of baseline characteristics between those included in the CAC analysis are shown in Supplementary Table 2. Participants included in the CAC analysis had higher prevalence of male gender, lower prevalence of diabetes and current smoking, had lower BMI, systolic and diastolic blood pressure, HbA1C and higher low-density lipoprotein (LDL) cholesterol levels compared to participants who did not have CAC scores.

Figure 1.

Inclusion and exclusion of study participants

Evaluation of PA

Evaluation of PA in JHS has been previously described.¹⁸ Evaluation of PA was performed at Visit 1 and Visit 3, but we only used the Visit 1 data because of a lack of some important covariates during Visit 3. At Visit 1, participants completed an interviewer-administered PA survey. Metabolic equivalent levels for each activity were taken from the most current version of the National Compendium of PA. The average time per week spent engaged in all activities at either a vigorous or moderate level was calculated and each participant was classified into one of the three American Heart Association (AHA) recommended levels of PA: 1) Ideal: 150 min/week of moderate activity or 75 min/week of vigorous activity or 150 min/week of moderate +vigorous activity; 2) Intermediate: 1–149 min/week of moderate activity or 1–74 min/week of vigorous activity or 1–149 min/week of moderate + vigorous activity; 3) Poor: 0 min/week of PA. Scores for three different domains of PA (Sport index, Home/Yard index, and Active index) were also computed; Sport index rates PAs from sports and formal exercise. The frequency, duration and intensity of each of the activities were taken into account and scored. Home/Yard index rates PAs in the home that involve care giving, preparing and cleaning up from meals, routine and major house cleaning, gardening/yard work, and heavy outdoor and house hold labor. Active index rates PAs during leisure time including walking and biking for leisure and transportation, but not including sports or formal exercise. These three components and PA at work constitute the total PA described above. Change of AHA PA category from Visit 1 to Visit 3 was available for 3170 participants and remained unchanged for 48% of JHS participants (Supplementary Figure 1).

Outcomes

The primary outcome was incident CHD, including myocardial infarction and fatal CHD, from enrollment through December 31, 2015. CHD events were ascertained through direct patient queries during annual telephone follow-up and ongoing surveillance of hospitalizations, and subsequently confirmed through the review of hospital records and death certificates.¹⁹

High-Sensitivity C Reactive Protein

Blood samples were collected according to the National Committee for Clinical Laboratory Standards as previously described.²⁰ High-sensitivity C reactive protein (hs-CRP) was measured using the immunoturbidimetric CRP-Latex assay (Kamiya Biomedical Company, Seattle, WA) with a Hitachi 911 analyzer (Roche Diagnostics).²¹

Coronary Artery Calcium Score

CAC score was measured at visit 2 in randomly selected participants. In this study, 2420 participants’ CAC score data were available. The research CT protocol included the heart using a 16-channel multidetector CT system equipped with cardiac gating (Lightspeed 16 Pro; GE Healthcare, Milwaukee, WI) as previously described.²² CAC was quantified utilizing Agatston scoring, modified to account for slice thickness. Calcified artery plaque was computed by multiplying each lesion by a weighted attenuation score on a TeraRecon Aquarius Workstation (TeraRecon, San Mateo, CA); scoring was in Hounsfield units.

Clinical Covariates

BMI was calculated as body weight (kg) / (height (m))². Current smoking and alcohol drinking status were defined as yes or no based on self-report at the time of the baseline exam. Hypertension was defined as blood pressure ≥140/90 mmHg or use of blood pressure-lowering medication. Venous blood samples were drawn from each participant after more than eight hours of fasting at Visit 1. Fasting plasma glucose, hemoglobin A1c, and LDL cholesterol concentration were assessed using standard laboratory techniques. Diabetes mellitus was defined as the use of diabetes medications, a hemoglobin A1c ≥ 6.5%, or a fasting blood glucose ≥ 126 mg/dL at baseline. Education level was determined as each participants’ highest level of schooling completed, and it was classified into three categories: “less than high school”, “high school graduate”, or “college”.

Statistical Analysis

Baseline characteristics of the study population were summarized by categories of PA. Data were summarized using frequencies (proportions) for categorical variables, and means ± (standard deviations) or medians ± (interquartile ranges) for continuous variables. Chi-squared test, ANOVA, and Kruskal-Wallis testing were used for comparison across PA categories where appropriate.

Cross-Sectional Analysis

Linear regression analysis was performed to examine the relationship between PA variables and hs-CRP levels. Logistic regression analysis was used to examine the association between PA variables and coronary calcium score where participants were divided into two groups as Agatston score <100 or ≥100.⁶ Two models, minimally- and further-adjusted models were constructed to evaluate associations of PA with CAC score. Model 1 included adjustment for age and sex, while model 2 additionally included BMI, systolic blood pressure, anti-hypertensive medication use, history of diabetes, total cholesterol / high density lipoprotein cholesterol ratio, current smoking status, current drinking status and education levels based on previous studies.^{23, 24} We performed another model based on the Model 2. Model 3 additionally included hs-CRP in the analysis of CAC. To visualize the relationship between the PA index of several domains and CAC score (Agatston score), restricted cubic spline curves were used. The analysis was adjusted using multiple covariates (Model 2), and we used 3 knots. Knots were located at median, 25th, and 75th percentiles of each index.

Longitudinal Analysis

To illustrate the effect of PA on outcomes, Kaplan-Meier curves for cumulative survival free from CHD was constructed for three groups of participants and log-rank test was used for comparison. Cox proportional hazards models after testing for proportionality assumption were used to estimate the hazard ratios of incident CHD. The three models used in the cross-sectional analysis were also used for longitudinal analysis.

All analyses were performed using STATA version 14 (STATA Corp, College Station, TX). A two-sided p value <.05 was considered significant.

Results

Baseline Characteristics

Table 1 shows the demographic characteristics of the study cohort based on AHA PA category. Those with higher PA levels were younger, more likely men, current alcohol drinkers and had higher achieved education levels. They also were less likely to be current smokers and had lower mean BMI, systolic blood pressure, HbA1C, hs-CRP and CAC score. Diastolic blood pressure and total cholesterol / HDL cholesterol ratio were not different among groups.

Table 1.

Baseline Characteristics Based on the AHA PA Categories

Variables	Overall (n=4132)	Poor (n=1959)	Intermediate (n=1346)	Ideal (n=827)	P for Trend
Age, years	54 ± 13	57 ± 12	53 ± 12	51 ± 13	<.001
Male, n (%)	1496 (35)	672 (33)	450 (32)	374 (44)	<.001
BMI, kg/m2	31.7 ± 7.2	32.1 ± 7.5	31.7 ± 7.2	30.8 ± 6.4	<.001
Waist, cm	100 ± 16	102 ± 17	99 ± 16	98 ± 14	<.001
SBP, mmHg	127 ± 17	129 ± 17	126 ± 16	124 ± 16	<.001
DBP, mmHg	76 ± 9	76 ± 9	76 ± 8	76 ± 8	.18
BP meds, n (%)	1970 (48)	1004 (51)	625 (46)	341 (41)	<.001
Diabetes, n (%)	743 (18)	414 (21)	231 (17)	98 (12)	<.001
T-chol/HDL ratio	4.1 ± 1.3	4.1 ± 1.3	4.1 ± 1.3	4.1 ± 1.3	.22
HbA1C, %	5.9 ± 1.2	6.0 ± 1.2	5.9 ± 1.2	5.7 ± 1.0	<.001
Hs-CRP, mg/dL	0.51 ± 0.93	0.58 ± 1.13	0.47 ± 0.68	0.41 ± 0.68	<.001
Current smoker, n (%)	500 (12)	287 (15)	135 (10)	78 (9)	<.001
Current drinker, n (%)	1949 (47)	802 (41)	671 (50)	476 (58)	<.001
Education level
Less than high school	739 (18)	499 (25)	165 (12)	75 (9)	<.001
High school graduate	735 (18)	409 (21)	226 (17)	100 (12)
College	2658 (64)	1051 (54)	955 (71)	652 (79)
CAC (Agatston) score	127 ± 372	161 ± 436	99 ± 301	99 ± 311	<.001
Sport Index	2.0(1.0, 3.3)	1.0(1.0, 1.0)	3.0(2.5, 3.5)	3.8(3.3, 4.3)	<.001
Home/Yard Index	2.3 ± 0.6	2.2 ± 0.6	2.3 ± 0.6	2.5 ± 0.6	<.001
Active Index	2.0(1.5, 2.8)	2.1(1.7, 2.6)	2.3(1.9, 2.7)	2.4(2.0, 2.9)	<.001
Follow up, years	12.8(11.8, 12.6)	12.7(11.8,13.6)	12.9(11.8, 13.6)	12.8(11.9,13.6)	.04

^aBMI = body mass index, BP meds = anti-hypertensive medication use, CAC = coronary artery calcium DBP = diastolic blood pressure, Hs-CRP = high sensitivity c reactive protein, PA = physical activity, SBP = systolic blood pressure, T-chol/HDL = Total cholesterol / High density lipoprotein cholesterol

^bThe baseline characteristics was obtained at visit 1 (2000–2004). CAC score was obtained at visit 2 (2005–2008). Study median follow-up time was 12.8 years (interquartile range, 11.8 – 13.6 years).

^cFor the follow up duration, the p-value was for no difference and used the analysis of variance.

PA and hs-CRP

Multivariate linear regression analysis revealed that higher PA level category was associated with lower hs-CRP levels after adjusting for possible confounding factors (Model 2, Intermediate PA versus Poor PA: β-coefficient, −0.07; 95%CI, −0.13~−0.01,Ideal PA versus Poor PA: β -coefficient, −0.08; 95%CI, −0.15~−0.002) (Table 2). All the PA index of different domains were also associated with lower hs-CRP levels after adjustment (Table 2).

Table 2.

PA and High-Sensitivity C Reactive Protein

Variable	Model	PA Category
		Poor (n=2043)	Intermediate (n=1398)	Ideal (n=855)
hs-CRP	1	Ref (1)	−0.11 (−0.17, −0.05)†	−0.14 (−0.21, −0.06)†
	2	Ref (1)	−0.07 (−0.13, −0.01)*	−0.08 (−0.15, −0.002)*
Variable	Model	PA Index of Different Domains
		Sport Index	Home/Yard Index	Active Index
hs-CRP	1	−0.047 (−0.069, −0.024)†	−0.075 (−0.120, −0.030)†	−0.082 (−0.117, −0.047)†
	2	−0.026 (−0.048, −0.003)*	−0.062 (−0.106, −0.019)†	−0.051 (−0.085, −0.016)†

^ahs-CRP = high-sensitivity C reactive protein, PA = physical activity

^bAll results were expressed as β and 95% confidence interval.

^cModel 1: adjusted for age and sex; Model 2: adjusted for age, sex, body mass index, systolic blood pressure, anti-hypertensive medication use, diabetes, total cholesterol / high density lipoprotein cholesterol ratio, current smoking status, current alcohol drinking status, and education level

^d*: p<.05, †: p<.01

PA and Coronary Calcium Score

Multivariate logistic regression analysis was conducted to determine the relationships between PA and CAC score. After adjusting for possible confounding factors, ideal PA level was associated with a lower prevalence of CAC Agatston score ≥100, while intermediate PA level was not (Model 2, Intermediate PA versus Poor PA: Odds ratio, 0.87; 95%CI, 0.67~1.14, Ideal PA versus Poor PA: Odds ratio, 0.70; 95%CI, 0.51~0.96) (Table 3). All the PA index of different domains were also associated with lower prevalence of CAC after adjustment (Table 3, Figure 2). After additionally adjusting for hs-CRP levels, Home/Yard index became insignificant (Supplementary Table 3).

Table 3.

PA and Coronary Artery Calcification

Variable	Model	PA Category
		Poor (n=1108)	Intermediate (n=794)	Ideal (n=518)
CAC score ≥100	1	Ref (1)	0.85 (0.66, 1.08)	0.65 (0.49, 0.88)*
	2	Ref (1)	0.87 (0.67, 1.14)	0.70 (0.51, 0.96)*
Variable	Model	PA Index of Different Domains
		Sport Index	Home/Yard Index	Active Index
CAC score ≥100	1	0.87 (0.79, 0.95)*	0.82 (0.69, 0.98)*	0.80 (0.70, 0.92)†
	2	0.90 (0.82, 0.99)*	0.82 (0.69, 0.99)*	0.84 (0.73, 0.97)*

^aCAC score = coronary artery calcification score (Agatston score), PA = physical activity

^bAll results were expressed as odds ratio and 95% confidence interval.

^cModel 1: adjusted for age and sex; Model 2: adjusted for age, sex, body mass index, systolic blood pressure, anti-hypertensive medication use, diabetes, total cholesterol / high density lipoprotein cholesterol ratio, current smoking status, current alcohol drinking status, and education level

^d*: p<.05 †: p<.01

Figure 2. Several domains of physical activity and coronary calcium score.

CACS: coronary artery calcium scores

PA and Incident CHD

Over a median follow-up 12.8 years (interquartile range, 11.8 – 13.6 years), there were 164 incident CHD events (incidence rate, 3.3/1000 person-years). Ideal PA level was associated with a lower rate of incident CHD (log-rank p<.001) (Figure 3). After adjustment for conventional risk factors, ideal PA level was associated with lower rate of incident CHD compared with poor PA level (model 2, ideal PA level versus poor PA level: HR 0.55; 95% CI, 0.31–0.98) (Table 4). All the different domains PA indices were not associated with incident CHD after adjustment (Table 4). After additionally adjusting for hs-CRP levels, the relationships between PA variables and incident CHD did not change significantly (Supplementary Table 4).

Figure 3. Kaplan Meier survival curves.

CHD: coronary heart disease

Table 4.

PA and Incident CHD

	PA Category
Model	Poor (n=1959)	Intermediate (n=1346)	Ideal (n=827)
Model 1	Ref (1)	1.19 (0.85, 1.66)	0.47 (0.27, 0.83)†
Model 2	Ref (1)	1.25 (0.90, 1.75)	0.55 (0.31, 0.98)*
	PA Index of Different Domains
Model	Sport Index	Home/Yard Index	Active Index
Model 1	0.91 (0.80, 1.04)	1.00 (0.78, 1.29)	0.82 (0.67, 1.01)
Model 2	0.95 (0.83, 1.09)	1.02 (0.79, 1.32)	0.86 (0.70, 1.05)

^aPA = physical activity

^bModel 1: adjusted for age and sex; Model 2: adjusted for age, sex, body mass index, systolic blood pressure, anti-hypertensive medication use, diabetes, total cholesterol / high density lipoprotein cholesterol ratio, current smoking status, current alcohol drinking status, and education level

^d*: p<.05 †: p<.01

Discussion

In this analysis of a large African American cohort free of cardiovascular disease at baseline, higher PA level category by American Heart Association’s Life Simple 7 metrics was associated with a lower hs-CRP level, a lower prevalence of CAC score ≥100, and a lower rate of incident CHD. PA index of three different domains were also inversely associated with hs-CRP levels and the prevalence of CAC after adjustment. However, these indexes were not associated with incident CHD.

Previous reports have demonstrated an inverse relationship between PA and CV events. However, there have been discrepant results in the few studies among African Americans which have been limited by relatively small numbers, and lack of gender diversity.^{2–4, 25} The JHS is a large, contemporary, prospective observational study of African Americans; therefore, our study adds important data supporting the CV benefits of PA in African Americans. Our findings can be compared to other contemporaneous cohorts including the Atherosclerosis Risk in Communities (ARIC) Study, a biracial multi-center cohort which demonstrated participants with ideal PA levels had a significantly lower risk for incident CHD compared to those with poor PA levels (HR 0.79, 95% CI 0.72–0.86).²⁶ We observed an even lower risk (HR 0.55) for incident CHD in African Americans of JHS getting ideal PA. The ARIC Study included both white and African American participants; therefore, it is possible that PA may be an even more important risk modifier in African Americans. Further investigation of this relationship and how it may mediate subsequent risk for heart failure is also warranted, specifically in African Americans who are at disproportionately high risk.

In the present analysis, PA was dose-dependently and inversely associated with CAC in African Americans. The relationship between CAC and PA has been investigated in some reports;^{6, 27} however, there have been mixed results and few of these included African Americans. Hamer and colleagues reported that objectively measured PA using accelerometers for a week was not associated with the presence of detectable CAC (Agatston score >0) after adjustment for conventional risk factors in 443 healthy cohort participants.²⁷ On the other hand, Imran and colleagues reported that walking was inversely associated with CAC in 2971 participants without CHD.⁶ Our study results were in line with this latter report. The cause of the discrepancy between our study results and Hamer’s study are not clear, but relatively smaller participant numbers, older age (mean age = 66±6 years), relatively active as a whole, and racial differences might have contributed to the differences.

Immunity and inflammation have been reported to play a role in the pathogenesis of atherosclerosis.¹³ A recently published meta-analysis of exercise intervention trials showed exercise interventions reduced hs-CRP levels in adults irrespective of the presence of heart disease.¹⁴ In the present study, PA levels were inversely associated with hs-CRP levels. The results of our observational study are consistent with previous interventional studies and are novel given the absence of other studies assessing this relationship in a large cohort of African Americans. However, although PA levels were inversely associated with hs-CRP, the β coefficients (effect sizes) were small and further study is warranted to examine whether this relationship is clinically meaningful.

In the analyses of CAC and incident CHD, after additionally including the hs-CRP in the model, the results were not changed significantly. These results suggest that there may be another mediator in the relationships between PA and lower prevalence of CAC or lower rate of incident CHD. We could not additionally adjust for CAC in the analysis of incident CHD because the number of participants who underwent coronary CT and had CHD events was small. However, based on several other studies which have demonstrated strong relationships between CAC and CHD, we think the relationships between higher PA levels and lower incident CHD might be mediated through attenuated CAC.

In the present study, intermediate PA level was not associated with lower CAC and lower rate of incident CHD compared with poor PA levels. This may be because a wide range of PA levels are included in the intermediate PA category. However, these results do not necessarily suggest modest PA is meaningless to maintain healthy coronary arteries.

African Americans have been reported to be less physically active than other ethnic groups, and this may be one of the contributing factors to CVD health disparities in African Americans.^{15, 28} The results suggest that higher PA levels may lead to lower prevalence of increased CAC and lower rate of incident CHD. Although we did not test PA as an intervention, our findings provide more compelling scientific rationale for recommendations specific to African Americans.

Our study has a few limitations. First, PA levels were evaluated at baseline based on self-report which could lead to a recall bias and possibly misclassification. Second, this study was performed only in African Americans and our results may not be generalizable to other racial/ethnic groups. Third, in the definition of diabetes, the fasting glucose was assessed only one time based on American Diabetes Association guidelines and there is a possibility that some participants may have been misclassified. Fourth, there were differences in baseline characteristics between participants who underwent the CAC analysis and those who were excluded for lack of CAC measures (Supplementary Table 2). Therefore, the results of the CAC analysis might not completely reflect the population used in this study. Fifth, PA levels might have changed throughout the study and the PA levels at Visit 1 may not reflect the current PA levels when the events happened. Finally, the present study is a prospective observational study; therefore, there is a possibility that the lower PA levels may reflect the process of unrecognized disease, which may be associated with inflammation, CAC and incident CHD. Although participants included in this study were generally healthy and we excluded those with CHD at baseline and adjusted for possible confounding factors, we should be careful in interpreting the present study results. On the other hand, our study has several strengths. First, to our knowledge, this is the largest report examining the relationship between PA and inflammation, CAC and incident CHD in a community-based cohort of African Americans. The JHS is the largest US-based cohort with contemporary data on CV risk factors among African Americans, a population with a greater burden of CV morbidity and mortality^{29, 30}. Second, data were prospectively collected using standardized methods for assessment of blood pressure and covariates at baseline. All CHD events in the JHS were adjudicated by clinical reviewers, reducing the potential for event misclassification.

Conclusions

Ideal PA levels were associated with lower inflammation levels, a lower prevalence of CAC, and a lower rate of incident CHD in a community-based African American cohort. Interventions to increase PA levels may reduce CV events in African Americans.

Perspectives.

African Americans are also more likely to have unhealthy behaviors such as physical inactivity/sedentariness compared to whites. Our study findings suggest that promotion of ideal PA among African Americans may be very important to prevent the development of CHD, and further prospective studies to determine if ideal PA prevents the development of CHD are warranted.

Abbreviations:

PA

physical activity

CHD

coronary heart disease

CV

cardiovascular

JHS

Jackson Heart Study

CAC

coronary artery calcification

BMI

body mass index

LDL

low-density lipoprotein