| dc.description.abstract | Cardiorespiratory fitness (CRF) is a strong and independent predictor of
cardiovascular health, and currently the only known major risk factor for
cardiovascular disease (CVD) that is not routinely assessed in clinical practice.
Determination of reference values for CRF and consensus on clinically relevant cutoffs
that associate with higher health risk for various populations are particularly
lacking for older adults, who are typically underrepresented in large population
studies. Sedentary behavior and adiposity are closely linked to adverse health
outcomes and negatively affect the risk of CVD. The potentially mediating effect of
CRF previously shown in younger populations, however, has not yet been adequately
addressed in older adults.
Given the anticipated increase in the number of older adults, improved understanding
of the complex interplay of behavioral and cardio-metabolic risk factors for CVD will
generate basic knowledge to implement effective, individualized intervention
strategies for the older population. Therefore, the primary objectives of this thesis
were to provide reference values for directly measured CRF and cardiorespiratory
function in a large and diverse sample of older Norwegian women and men, and to
investigate how high CRF modifies cardiovascular risk factors associated with
sedentary behavior and adiposity.
Study I presents directly measured CRF (VO2peak) and cardiorespiratory function in
1567 women and men aged 70-77 years, representing the currently largest reference
data in an older population worldwide. Additionally, differences in physiological
response to cardiopulmonary exercise testing between women and men, and subgroups
of CVD patients and healthy individuals are discussed. In Papers II and III, we
demonstrate a robust inverse association of high age-specific CRF and risk factors for
CVD, independent of levels of sedentary time, physical activity, body mass index and
body composition. Having high CRF attenuated the adverse association of prolonged
sedentary time and the clustering of cardiovascular risk factors, even in participants
not meeting the current recommendations for physical activity. Furthermore, we
demonstrated that low CRF and adiposity cumulatively associate with higher
likelihood of having an unfavorable cardiovascular risk factor profile. These findings
emphasize the importance of including both CRF and measures of adiposity in the
assessment of cardiovascular risk and health promotion efforts. In this context, CRF
below 25.7 mL·kg-1·min-1 in women and 30.7 mL·kg-1·min-1 in men represented
critical thresholds for unfavorable cardiovascular risk factor levels in older adults.
The findings of this thesis provide novel information on CRF and cardiorespiratory
function for researchers and clinicians to interpret data from cardiopulmonary
exercise testing in older adults, and demonstrate the benefits of having high agespecific
CRF on cardiovascular health. | nb_NO |
