Cardiovascular disease begins to develop in childhood. Physical activity positively impacts cardiovascular health and lowers cardiovascular disease risk in school-aged children and adults; however, there is insufficient evidence to determine the effects of physical activity on cardiovascular health during early childhood. The specific dose of physical activity required for favourable cardiovascular health in this age group is also unknown. The purpose of this thesis was to explore the relationships between physical activity and cardiovascular health indicators during early childhood. In the first study, we found that physical activity engagement has beneficial effects on cardiovascular fitness, blood pressure, autonomic function, and arterial stiffness during early childhood. We then determined in the second study that to avoid unfavourable cardiovascular health, preschool-aged children should engage in at least 240 minutes of activity at any intensity, 80 minutes of moderate-to-vigorous physical activity, or 8700 steps per day. Finally, in the third study we evaluated a novel technique for examining arterial wall properties, carotid artery longitudinal wall motion, and determined that it was weakly associated with an established indicator of arterial stiffness (pulse wave velocity) in early childhood. These findings highlight that the benefits of physical activity on cardiovascular health begin in early childhood and the minimal amount of activity to avoid unfavourable cardiovascular health is higher than current recommendations. For the most part, physical activity benefited boys and girls similarly, although it is unclear if the physical activity targets apply equally to boys. We also determined that carotid artery longitudinal wall motion may not be an indicator of arterial stiffness in young children. Future studies should determine if the favourable effects of physical activity on cardiovascular health during early childhood carry over to later years and if achieving the physical activity targets determined in this thesis are associated with additional health benefits. / Thesis / Doctor of Philosophy (PhD) / Heart disease develops slowly over time, starting in childhood. This thesis explored if physical activity can begin to prevent heart disease even in preschoolers, and how much physical activity preschoolers need in order to keep their hearts and blood vessels healthy. We found that preschool-aged children who were more active had better heart health, including better blood vessel health and higher fitness. While all activity was good, more intense, moderate-to-vigorous physical activity (sometimes called energetic play) was more beneficial and slowed down the stiffening of their blood vessels as the children grew. We determined that preschool-aged children should engage in at least 4 hours of physical activity at any intensity or 80 minutes of moderate-to-vigorous physical activity every day to avoid poor heart health. The findings in this thesis highlight the importance of regular physical activity participation to promote heart health even in preschool-aged children.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/25231 |
| Date | January 2020 |
| Creators | Proudfoot, Nicole A. |
| Contributors | MacDonald, Maureen J., Kinesiology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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