<p>The present thesis examined the acute and chronic (training) hemodynamic
responses to the unique exercise stimulus of high-intensity "sprint" interval exercise or
training (SIT). Previous research has characterized the muscle metabolic and exercise
performance adaptations to both short and medium term SIT, however the cardiovascular
adjustments and adaptations have not been examined. As part of this thesis two studies
were designed to permit evaluations of the chronic cardiovascular responses to a six-week
SIT intervention protocol, while two separate studies examined the acute impact of
a sprint exercise session on indices of vascular structure and function. Comparisons were
made between the SIT and traditional endurance exercise training (ET) in the two
exercise training studies, while comparisons were made between a single sprint and that
of multiple sprints in the acute exercise studies. The subject population examined in this
research was young healthy participants.</p>
<p>Our general hypothesis regarding the training adaptations was that similar
changes of artery stiffness, vascular endothelial function, blood flow kinetics and oxygen
uptake kinetics would occur following SIT compared to ET. Regarding the acute effects
of a sprint exercise, we expected arterial stiffness to decrease in the exercising limbs and
increase in the central arteries, similar to the responses observed previously immediately
following endurance exercise, while we hypothesized that endothelial function would be
decreased immediately following the exercise session because of the intense nature of the
exercise. The overarching hypothesis guiding these specific hypothesis is that we believe
that individual bouts of exercise impact on the arterial wall through the generation of a
shear stimulus related to cyclic increases in blood flow and blood pressure. In the short-term the acute response of the artery depends on the composition of the arterial wall and
the local stimulus. Over time, functional and structural adjustments occur to normalize
the impact of shear forces.</p>
<p>Training adaptations in vascular structure and function to SIT were similar to
those observed with ET. Both exercise training methods stimulated improved peripheral
artery stiffness and endothelial function. The rate of increase in oxygen uptake (kinetic
response) was not improved with either training method. However, estimated myocardial
demand was reduced with ET but not SIT, which indicates more favourable adaptation in
central hemodynamics with ET.</p>
<p>Acute sprint exercise markedly reduced peripheral artery stiffness in the exercised
limbs well into recovery (~45 minutes), which may benefit central hemodynamics after
exercise completion. Sprint exercise also acutely decreased endothelial function, likely
because of high oxidative stress generated during the exercise bout and may provide the
ideal stimulus for endothelial adaptation.</p>
<p>In summary, this thesis highlights the chronic and acute effects of sprint interval
exercise and training in young health individuals. The notion that sprint interval exercise
provides equivalent benefits to the cardiovascular system as endurance exercise may be
true in the peripheral circulation. However, further study focusing is required before the
general acceptance of more favorable central hemodynamic effects from endurance
exercise training.</p> / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/16717 |
| Date | 09 1900 |
| Creators | Rakobowchuk, Mark |
| Contributors | MacDonald, Maureen J., Gibala, Martin J., McCartney, Neil, Kinesiology |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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