2026-09-23T09:00:24.896875467Zhttps://repository.nwu.ac.za/server/oai/requestoai:repository.nwu.ac.za:10394/412062023-05-05T01:04:00Zcom_10394_26463col_10394_26473
Strydom, G.L.
Steyn, H.S.
Dreyer, Lukas Ignatius
10172521 - Strydom, Gert Lukas (Supervisor)
2023-05-04T07:33:14Z
2023-05-04T07:33:14Z
1996
http://hdl.handle.net/10394/41206
PhD, North-West University, Potchefstroom Campus
Research has indicated that coronary risk factors are interrelated in a complex manner.
The purpose of this study was firstly, to determine if physical activity can influence the
atherogenity of the individual risk factors by changing the relationship that exists between
the coronary risk factors, and secondly to determine if this interrelationship between the
risk factors had any effect on physical activity's relationship with the individual risk
factors.
Executives (N = 325) of 20 different companies were evaluated with regard to participation
in physical activity, smoking habits, lifestyle as well as some morphological and
biochemical parameters. The biochemical analysis included measures of total cholesterol,
triglycerides, HDL-cholesterol and glucose. The LDL-cholesterol and TC/HDL-ratio
values were calculated. Blood pressure measurements and a physical work capacity170 test
on a Monark cycle ergometerwas also done on each of the respondents. The relationship
between a total of 17 coronary risk factors was investigated by means of cluster, stepwise
multiple regression and two-way analyses of variance. For the purpose of the two-way
analyses of variance the respondents were placed into tertiles (low, moderate, high) with
regard to participation in physical activity, total cholesterol, LDL-cholesterol, HDLcholesterol,
triglycerides, systolic and diastolic blood pressure as well as percentage body
fat, age, smoking habits and lifestyle. Intergroup differences were determined with the
Newman-Keuls follow-up test and practical significance with the effect size calculation of
Cohen.
Body weight and the Quetelet-index showed the strongest relationship with each other
in the cluster analysis. Total cholesterol and LDL-cholesterol were strongly related to
each other as was HDL-cholesterol and the physical activity index (PAI) and systolic and
diastolic blood pressure. In the stepwise multiple regression analyses the other coronary
risk factors contributed 4.5%, 36.7%, 11.1 % and 10.3% to the respective variances of a
family history of heart disease, the Belloc and Breslow-index, age and smoking. The
other coronary risk factors showed better relationships with LDL-cholesterol, TC/HDLratio,
HDL-cholesterol and total cholesterol and contributed 95.6%, 87.9%, 81.2% and
95.6% to their respective variances. With regard to the effect of physical activity on these
relationships, the stepwise multiple regression analyses indicated that among inactive
participants, the other coronary risk factors contributed more to the variances of
percentage body fat (60.9% vs 45.1%), the Belloc and Breslow-index (44.0% vs 23.9%)
and smoking (21.5% vs 7.9%) than was the case when the same analyses were done on
the highly physically active respondents. These results seem to indicate that physical
activity may lower the atherogenity of the above mentioned coronary risk factors through
the effect it (physical activity) has on their respective relationships with the other
coronary risk factors.
The results of the two-way analyses of variance that were done support this conclusion.
It was found that the effect of physical activity on the relationships between the coronary
risk factors was of such nature that it would lower the atherogenity of all the coronary
risk factors that were used in this study. It has become clear that the interrelationship
and interdependence that exists between the different coronary risk factors has to be
taken into consideration when physical activity's relationship with the individual risk
factors is studied.
Doctoral
other
North-West University (South Africa)
Coronary risk factors
Physical activity
Blood pressure
Lipoproteins
Lipids
Executive fitness
Die effek van inoefening op enkele koronêre risikofaktore en hulle onderlinge verwantskap by Suid-Afrikaanse bestuurslui
Thesis
open.access