Thesis defence in the University of Oulu

Doctoral Candidate

Master of Health Sciences Maisa Niemelä

Faculty and research unit

University of Oulu Graduate School, Faculty of Medicine, Research Unit of Medical Imaging, Physics and Technology

Field of study

Medical Physics and Technology

Date and time of the thesis defence

21.11.2019 12:00

Place of the thesis defence

University of Oulu, auditorium F101, Aapistie 7

Topic of the dissertation

Temporal patterns of physical activity and sedentary time and their association with health at mid-life. The Northern Finland Birth Cohort 1966 study

Opponent

Professor Malcolm Granat, University of Salford

Custos

Professor Timo Jämsä, University of Oulu

Temporal patterns of physical activity and sedentary behaviour are associated with cardiovascular health among middle-aged

Doctoral dissertation by MHSc Maisa Niemelä, which will be presented for public defense in the University of Oulu, shows that distinct temporal patterns of physical activity and sedentary time can be used to recognize individuals with the risk of developing cardiovascular disease. The more active the individual was during the day, the lower was the risk of cardiovascular disease. Long bouts of sedentary time were associated with heart rate variability describing the cardiac autonomic function.

The association between total physical activity and sedentary time and cardiovascular disease risk was examined by using machine learning method to recognise distinct physical activity profiles. Study population consisted of those more than 4 500 individuals who were born in 1966 in Northern Finland and participated in the follow-up measurements at 46-years in 2012–2014. Participants filled extensive questionnaires, attended clinical measurements and wore an activity monitor for two weeks on their wrist.

Results showed that four recognised activity profiles were associated with the risk of cardiovascular disease. More active profiles had lower risk of developing cardiovascular disease compared to less active profiles. Long sedentary bouts lasting at least 30 to 60 consecutive minutes were positively associated with heart rate variability. Total sedentary time was not associated with heart rate variability. Self-reported weekly leisure-time physical activity and objectively measured moderate to vigorous physical activity were strongly positively associated with perceived health.

Health benefits of physical activity are substantial. Lately, also the detrimental effects of excessive sedentary time, i.e. time spent in lying or sitting, to health have been recognised. So far there has been only limited knowledge how the temporal patterns of physical activity and sedentary behaviour are associated with health. Based on the results of this study, tailored physical activity profiles can be used to recognise specifically those individuals with risk of developing cardiovascular disease. This information can be utilized when planning actions to promote physical activity and health in individual and population levels.

 

Dissertation

Last updated: 13.11.2019