Karolinska Institutet
Browse
Thesis_Elin_Ekblom_Bak_pdf (2.21 MB)
Spikblad_Elin_Ekblom_Bak_pdf (47.38 kB)
1/0
2 files

Physical activity, cardiorespiratory fitness, and abdominal obesity in relation to cardiovascular disease risk : epidemiological studies

thesis
posted on 2024-09-02, 20:39 authored by Elin Ekblom Bak

Although Sweden saw a decline in death rates related to cardiovascular disease (CVD) between 1987 and 2011, it is still the most common cause of death for both women and men. Lifestyle-related factors such as inadequate physical activity (PA), poor cardiorespiratory fitness (CF), and excess body fat are all recognised as important predictors of CVD morbidity and mortality. More recently, studies have highlighted the possible detrimental effects of prolonged sitting, which mainly substitutes for daily non-exercise PA (NEPA). Conversely, more preferable levels of these lifestyle factors are associated with lower CVD risk and increased life expectancy. Despite the extensive research performed within this field, there is still no consensus.

The main objective of this thesis was therefore to examine the interrelationship between different levels of PA, CF, and abdominal adiposity and their association with CVD risk factors, CVD morbidity, and longevity in population-based samples of Swedish men and women of different ages. A second objective was to develop a new and more precise method for estimation of CF in a mixed, healthy, population. The main findings were:

- In a cross-sectional population based random sample of Swedish men (n=781) and women (n=890) aged 20 to 65 years were CF and abdominal obesity each independently and strongly beneficially associated with individual CVD risk factors, as well as to a clustered CVD risk factor profile. For the clustered risk, each unit of fitness (ml·kg-1.min-1) was associated with a 5% decrease in risk and each unit of waist circumference (cm) with a 5% increase in risk. This was seen in women as well as men, younger as well as older people, and daily smokers as well as non-smokers; however, there were some differences within the subgroups.

- In the same population, higher levels of self-reported PA and CF, but mainly the latter, were independently associated in a beneficial way with both individual and clustered CVD risk factors. Furthermore, a notable interaction of excess clustered CVD risk was shown for being insufficiently physical active according to general guidelines in combination with not being fit.

- In a representative cohort of 60-year-old men (n=2039) and women (n=2193) in Stockholm County, a generally active daily life was associated with beneficial metabolic health at baseline and an approximately 30% lower risk for a first-time cardiovascular event and all-cause mortality, respectively, after 12.5 years. These relationships were independent of regular exercise.

- A new submaximal cycle ergometer test for estimation of maximal oxygen uptake was developed. The test is simple, low-risk, and easily administered, and does not require laboratory equipment or expertise. In a mixed population (in terms of age, activity status, and gender), the test showed a significantly increased precision compared with one of the most commonly used submaximal exercise tests today.

In conclusion, these results indicate that in clinical practice it is important to evaluate both PA and CF as well as abdominal obesity status. Regarding PA, it is important to highlight the separate beneficial associations of a daily active life including NEPA on the one hand, and intentional regular exercise on the other.

List of scientific papers

I. Ekblom-Bak E, Hellénius ML, Ekblom O, Engström LM, and Ekblom B. Fitness and abdominal obesity are independently associated with cardiovascular risk. J Intern Med. 2009. 266(6): 547-57.
https://doi.org/10.1111/j.1365-2796.2009.02131.x

II. Ekblom-Bak E, Hellénius ML, Ekblom O, Engström LM, and Ekblom B. Independent associations of physical activity and cardiovascular fitness with cardiovascular risk in adults. Eur J Cardiovasc Prev Rehabil. 2010. 17(2): 175-80.
https://doi.org/10.1097/HJR.0b013e32833254f2.

III. Ekblom-Bak E, Björkman F, Hellénius ML, and Ekblom B. A new submaximal cycle ergometer test for prediction of VO2max. Scand J Med Sci Sports. Epub 6 Nov 2012.
https://doi.org/10.1111/sms.12014

IV. Ekblom-Bak E, Ekblom B, Vikström M, de Faire U, and Hellénius ML. The importance of non-exercise physical activity for cardiovascular health and longevity. Br J Sports Med. [Accepted]
https://pubmed.ncbi.nlm.nih.gov/24167194

History

Defence date

2013-11-15

Department

  • Department of Medicine, Solna

Publisher/Institution

Karolinska Institutet

Main supervisor

Hellénius, Mai-Lis

Publication year

2013

Thesis type

  • Doctoral thesis

ISBN

978-91-7549-309-1

Number of supporting papers

4

Language

  • eng

Original publication date

2013-10-25

Author name in thesis

Ekblom Bak, Elin

Original department name

Department of Medicine, Solna

Place of publication

Stockholm

Usage metrics

    Theses

    Categories

    No categories selected

    Keywords

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC