The oxidation of low-density lipoproteins (LDL) is considered a key step in the development and progression of atherosclerosis. Single bouts of aerobic exercise cause transient increases in free radical production that may enhance the susceptibility of LDL to oxidation and create a more atherogenic LDL particle. In contrast, chronic exercise has often been considered an effective tool in improving metabolic profile through changes in aerobic capacity, lipid profile, fuel utilization and oxidative stress in both healthy and disease populations. Despite this, less is known about how it may benefit the prevention of LDL oxidation and the mechanisms by which this may occur, particularly in aged and patients with type II diabetes who have oxidative stress. The primary aim of the work contained in this thesis, is to examine the effects of aerobic exercise on the susceptibility of LDL to oxidation in both young, aged and type II diabetic subjects. The findings of study 1 demonstrate that an acute bout of moderate intensity exercise can increase the susceptibility of LDL III in both young and aged subjects regardless of any change in LDL lipid composition. Study 2 demonstrates that chronic aerobic exercise of moderate intensity is effective at improving the resistance of the LDL I sub fraction against oxidation, as shown by an increase in T1I2max, despite no change in LDL lipid composition. This intervention was also beneficial in altering maximal aerobic capacity in both young and aged subjects. Study 3 demonstrates that chronic low and moderate intensity aerobic exercise has no effect on LDL oxidative susceptibility. However, chronic moderate intensity exercise increased catalase activity and decreased protein oxidation. The collective findings of this work provide evidence that acute exercise may increase LDL oxidation while chronic exercise may prevent the oxidation of LDL particularly in aged subjects. Further research with greater subject numbers is required to determine the precise mechanism by which exercise influences the susceptibility of LDL oxidation.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:601214 |
| Date | January 2013 |
| Creators | Medlow, Paul Wallace |
| Publisher | University of Ulster |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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