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Physical activity, cardiorespiratory fitness, and abdominal obesity in relation to cardiovascular disease risk: epidemiological studies
Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.ORCID iD: 0000-0002-3901-7833
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Karolinska Institutet , 2013.
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Research subject
Medicine/Technology
Identifiers
URN: urn:nbn:se:gih:diva-2989ISBN: 978-91-7549-309-1 (print)OAI: oai:DiVA.org:gih-2989DiVA: diva2:659512
Public defence
2013-11-15, Aulan, GIH, Lidingövägen 1, Stockholm, 09:00 (English)
Opponent
Supervisors
Available from: 2013-10-25 Created: 2013-10-25 Last updated: 2015-09-18Bibliographically approved
List of papers
1. Fitness and abdominal obesity are independently associated with cardiovascular risk.
Open this publication in new window or tab >>Fitness and abdominal obesity are independently associated with cardiovascular risk.
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2009 (English)In: Journal of internal medicine, ISSN 1365-2796, no 21 MayArticle in journal (Refereed) Published
Abstract [en]

Objectives. To examine the relationship between cardiovascular fitness (VO(2)max) and abdominal obesity (waist circumference) and individual cardiovascular disease (CVD) risk factors, as well as a clustered risk factor profile, and to study the impact of gender, age and smoking on these relationships. Design. Cross-sectional. Setting. Astrand Laboratory of Work Physiology, Swedish School of Sport and Health Sciences, Stockholm, Sweden. Subjects. Men (n = 781) and women (n = 890) from two random population-based samples of Swedish women and men aged 20 to 65 years. Main outcomes. Odds ratios. Results. Each unit of higher fitness was associated with a decrease in all individual risk factors ranging from 2% to 4% independent of waist circumference, each unit of higher waist circumference was associated with an increased risk ranging from 2% to 5% independent of fitness. For clustering of three or more of the risk factors, each unit of fitness was associated with a 5% decrease in risk and each unit of waist circumference with a 5% increase in risk. The clustered risk was higher in unfit participants who were older or smoked daily, regardless of waist circumference. Obese participants were at higher risk if they were men or older, regardless of fitness level. However, neither a higher fitness level nor lean status reduced the risk associated with smoking. Conclusions. Higher fitness and lower waist circumference are each independently associated to a similar extent with a lower CVD risk. Simultaneous evaluation of both fitness and abdominal obesity status in clinical practice is important.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:gih:diva-965 (URN)10.1111/j.1365-2796.2009.02131.x (DOI)19563391 (PubMedID)
Available from: 2009-09-24 Created: 2009-09-24 Last updated: 2017-03-31Bibliographically approved
2. Independent associations of physical activity and cardiovascular fitness with cardiovascular risk in adults.
Open this publication in new window or tab >>Independent associations of physical activity and cardiovascular fitness with cardiovascular risk in adults.
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2010 (English)In: European Journal of Cardiovascular Prevention & Rehabilitation, ISSN 1741-8267, E-ISSN 1741-8275, Vol. 17, no 2, 175-80 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Uncertainty still exists whether physical activity (PA) and cardiovascular fitness (CF) contribute separately to cardiovascular disease (CVD) risk. This study examined the associations of PA and CF on individual as well as clustered CVD risk factors. DESIGN: Cross-sectional. METHODS: Seven hundred and eighty-one men and 890 women, aged 20-65 years, from two random population-based samples of Swedish women and men were included. PA was assessed by questionnaire and CF was predicted by a submaximal cycle ergometry test. Waist circumference, blood pressure, and fasting levels of blood lipids were assessed and dichotomized by conventional cut-off points. RESULTS: Participants reporting high PA level benefited from lower triglycerides and atherogenic cholesterol levels, regardless of CF. Higher CF level was, regardless of PA, associated with lower risk for all risk factors. With regard to clustering of risk factors, each higher CF level was associated with a gradually reduced risk by half or more, independent of PA. Furthermore, being unfit but reporting high PA was associated with a 50% lower risk compared with being unfit and inactive. Furthermore, high reported PA was associated with an additional reduced risk among fit participants. In addition, an excess risk of interaction was found for waist circumference, triglycerides, and the clustered CVD risk between neither being sufficiently active nor being fit. CONCLUSION: This study suggests that both PA and CF are independently associated with lower cardiovascular risk, and that both variables should be taken into account when CVD risk is estimated.

National Category
Public Health, Global Health, Social Medicine and Epidemiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-1430 (URN)10.1097/HJR.0b013e32833254f2 (DOI)19809331 (PubMedID)
Available from: 2010-11-02 Created: 2010-11-02 Last updated: 2017-03-31Bibliographically approved
3. A new submaximal cycle ergometer test for prediction of VO(2max).
Open this publication in new window or tab >>A new submaximal cycle ergometer test for prediction of VO(2max).
2014 (English)In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, no 2, 319-326 p.Article in journal (Refereed) Published
Abstract [en]

Maximal oxygen uptake (VO(2max) ) is an important, independent predictor of cardiovascular health and mortality. Despite this, it is rarely measured in clinical practice. The aim of this study was to create and evaluate a submaximal cycle ergometry test based on change in heart rate (HR) between a lower standard work rate and an individually chosen higher work rate. In a mixed population (n = 143) with regard to sex (55% women), age (21-65 years), and activity status (inactive to highly active), a model included change in HR per unit change in power, sex, and age for the best estimate of VO(2max) . The association between estimated and observed VO(2max) for the mixed sample was r = 0.91, standard error of estimate = 0.302 L/min, and mean measured VO(2max)  = 3.23 L/min. The corresponding coefficient of variation was 9.3%, a significantly improved precision compared with one of the most commonly used submaximal exercise tests, the Åstrand test, which in the present study was estimated to be 18.1%. Test-retest reliability analysis over 1 week revealed no mean difference in the estimated VO(2max) (-0.02 L/min, 95% confidence interval: -0.07-0.03). The new test is low-risk, easily administered, and valid for a wide capacity range, and is therefore suitable in situations as health evaluations in the general population.

National Category
Medical and Health Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-2480 (URN)10.1111/sms.12014 (DOI)23126417 (PubMedID)
Projects
Långvarigt stillasittande
Available from: 2012-11-19 Created: 2012-11-19 Last updated: 2017-03-31Bibliographically approved
4. The importance of non-exercise physical activity for cardiovascular health and longevity.
Open this publication in new window or tab >>The importance of non-exercise physical activity for cardiovascular health and longevity.
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2014 (English)In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 48, 233-238 p.Article in journal (Refereed) Published
Abstract [en]

Background Sedentary time is increasing in all societies and results in limited non-exercise physical activity (NEPA) of daily life. The importance of low NEPA for cardiovascular health and longevity is limited, especially in elderly.                                

Aim To examine the association between NEPA and cardiovascular health at baseline as well as the risk of a first cardiovascular disease (CVD) event and total mortality after 12.5 years.

Study design Cohort study.                                

Material and methods Every third 60-year-old man and woman in Stockholm County was invited to a health screening study; 4232 individuals participated (78% response rate). At baseline, NEPA and exercise habits were assessed from a self-administrated questionnaire and cardiovascular health was established through physical examinations and laboratory tests. The participants were followed for an average of 12.5 years for the assessment of CVD events and mortality.                                

Results At baseline, high NEPA was, regardless of regular exercise and compared with low NEPA, associated with more preferable waist circumference, high-density lipoprotein cholesterol and triglycerides in both sexes and with lower insulin, glucose and fibrinogen levels in men. Moreover, the occurrence of the metabolic syndrome was significantly lower in those with higher NEPA levels in non-exercising and regularly exercising individuals. Furthermore, reporting a high NEPA level, compared with low, was associated with a lower risk of a first CVD event (HR=0.73; 95% CI 0.57 to 0.94) and lower all-cause mortality (0.70; 0.53 to 0.98).                                

Conclusions A generally active daily life was, regardless of exercising regularly or not, associated with cardiovascular health and longevity in older adults.                                

Keyword
NEPA, Health, Exercise, Human
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-2988 (URN)10.1136/bjsports-2012-092038 (DOI)
Projects
Långvarigt stillasittande
Note

At the time of Elin Ekblom Bak's dissertation the article was accepted for publication.

Available from: 2013-10-25 Created: 2013-10-25 Last updated: 2017-03-31Bibliographically approved

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