Cardiovascular Journal of Africa: Vol 31 No 6 (November/December 2020)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 6, November/December 2020

304

AFRICA

Relationship between physical activity and carotid

intima–media thickness among teachers in South Africa:

the SABPA study

Tamrin Veldsman, Mariette Swanepoel, Makama A Monyeki, Johanna S Brits, Leoné Malan

Abstract

Objective:

To determine the relationship between objectively

measured physical activity (PA) and carotid intima–media

thickness (CIMT) in teachers in South Africa.

Methods:

A cross-sectional study was conducted among

215 teachers aged 25 to 65 years (mean age 49.67 ± 8.43

years) who participated in the Sympathetic Activity and

Ambulatory Blood Pressure in Africans (SABPA) prospec-

tive cohort study. Ultrasound CIMT imaging was done using

the SonoSite Micromaxx over seven consecutive days. Other

measurements obtained included body mass index (BMI),

waist circumference, 24-hour ambulatory blood pressure, and

C-reactive protein (CRP) and fasting blood total cholesterol

levels. Data were analysed using Statistical Package for Social

Sciences (SPSS) version 25.

Results:

The prevalence of obesity according to BMI and

sedentary behaviour was above30%; hypertension was 38.9%

and low-grade inflammation (CRP) was 41.1%. Male teach-

ers showed higher mean values for CIMT than female teach-

ers (0.75 ± 0.16 vs 0.66 ± 0.12 mm;

≤ 0.05). A borderline

negative association existed between CIMT and mean seven-

day awake metabolic equivalent of task (

= –0.19;

= 0.08)

in female teachers in the light-PA group. CIMT was inversely

associated with total energy expenditure (

= –0.31;

= 0.05)

in sedentary male teachers.

Conclusion:

Participation in light PA was associated with

lower CIMT values in female teachers. Given the health

implications of cardiovascular disease risk among teachers,

PA intervention studies are recommended to determine effec-

tive interventions to provide information on how to decrease

the progression of subclinical atherosclerosis in this popula-

tion.

Keywords:

carotid intima–media thickness, physical activity,

South Africa

Submitted 30/1/20, accepted 23/6/20

Published online 23/7/20

Cardiovasc J Afr

2020;

: 304–313

www.cvja.co.za

DOI: 10.5830/CVJA-2020-024

Undeniable evidence exists about the protective role of regular

physical activity (PA) in the development of chronic diseases;

1-4

however, high levels of physical inactivity continue to be a

major public health concern in the 21st century.

The global

recommendation for adult participation in PA is at least 150

minutes of accumulated moderate-intensity activity per week

for at least 10 minutes continuously.

One in five adults globally

does not meet the PA recommendations.

In South Africa, more

than one-third (38.2%) of the population does not participate

in sufficient PA,

and in a 51-country survey, the country

was ranked as having the third-highest prevalence of physical

inactivity.

Physical inactivity, obesity and hypertension are

directly associated with the risk of developing cardiovascular

disease (CVD) and atherosclerosis.

10-12

Atherosclerosis is an active inflammatory process involving

changes in cell behaviour and lipid accumulation in arteries and

can be considered as one of the underlying causes of coronary

heart disease events.

13-16

Additionally, C-reactive protein (CRP),

as a biomarker for atherosclerosis,

has been linked to an

increase in carotid intima–media thickness (CIMT) progression.

Weingärtner and colleagues

also revealed that serum cholesterol

was positively associated with CIMT among the healthcare

workers at the Saarland University Hospital in Homburg/Saar,

Germany. Of concern are the results of a study by Laurence and

colleagues

in 489 teachers from Cape Town, which reported

18.7% of the teachers to be at a high risk of developing a heart

attack or stroke within 10 years.

Using left CIMT, a non-invasive sonographic measurement

of atherosclerosis, may enable the prediction of future vascular

events such as stroke and myocardial infarction

before they

happen. Koolhaas

et al.

conducted the population-based

Rotterdam Study, including 5 344 adults, and suggested that

the beneficial impact of regular PA on CVD might outweigh

the negative effect of high body mass index (BMI) among

middle-aged and older adults. Conversely, a study by Zulkepli

et al.

using subjective measures of PA revealed no significant

correlation between PA level and CVD risk factors. One

study found that higher levels of moderate-to-vigorous PA

was associated with lower CIMT, and participants who were

sedentary had an increased CIMT.

A study in Caucasian men

and women indicated a positive association between CIMT and

time spent sedentary, and a negative association with light PA,

while another study in Danish adolescents did not find any

Physical Activity, Sport and Recreation Research Focus

Area (PhASRec), Faculty of Health Sciences, North-West

University, Potchefstroom, South Africa

Tamrin Veldsman,MSc,

Tamrin.Veldsman@nwu.ac.za

Mariette Swanepoel, PhD

Makama A Monyeki, PhD

Hypertension in Africa Research Team (HART), North-West

University, Potchefstroom, South Africa

Johanna S Brits, PhD

Leoné Malan, RN, PhD