| dc.description.abstract | Investigating the middle cerebral artery blood velocity (MCAv) kinetic response to exercise can provide insight into the underlying control mechanisms and how the response may by altered by important factors such as age, sex, cardiorespiratory fitness and exercise intensity. However, the MCAv kinetic response to whole-body upright cycling, to exercise above a moderate intensity, and in children and adolescents, has not previously been investigated. The purpose of this thesis was to investigate the utility of kinetic modelling of the MCAv response to moderate and heavy intensity cycling exercise, and the agreement between left and right MCAv responses in adults. Subsequently, the effect of age on the MCAv response to incremental and moderate intensity exercise by comparing children, adolescents and adults was investigated.
Chapter 4 demonstrates that the MCAv response to moderate and heavy intensity cycling can be characterised in healthy adults using a mono-exponential model with a time delay. These data show a greater increase in MCAv during heavy, compared to moderate intensity exercise, with similar time-based response parameters across intensities. Chapter 5 found good agreement between left and right MCAv responses to incremental, moderate and heavy intensity cycling exercise in healthy adults on a group level, but some individual differences were identified. In Chapter 6, a significantly smaller increase in MCAv was observed during incremental exercise in children, compared to both adolescents and adults. Furthermore, the relationships between the intensity-dependent changes in MCAv and end-tidal CO2 (PETCO2) strengthened with increasing age. These findings were then developed further in Chapter 7 investigating the kinetic responses to moderate intensity exercise. Again, a blunted MCAv response was observed in children, compared to adolescents and adults, and the relationships between MCAv and PETCO2 kinetics strengthened with increasing age group.
This thesis provides detailed advancements and evidence-based practical recommendations on the kinetic analyses of MCAv responses to moderate and heavy intensity cycling exercise. Furthermore, this work provides novel data on how age group impacts the MCAv response to exercise, and the strength of the regulatory role of PETCO2 on these responses. | en_GB |
