Observations upon metabolic changes during and after exercise

Walton, John L (1970) Observations upon metabolic changes during and after exercise. MSc(R) thesis, University of Glasgow.

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This thesis examines the effect of examines on the blood concentrations of various metabolites with particular reference to differences between subjects who were athletically trained and others who were not in a state of athletic training. In the first two chapters the biochemical techniques that have been used are described and normal values for the blood levels of acetoacetate and 3-hydroxybutyrate reported. Chapter 3 describes the response of athletes and non-athletes to strenuous exercise (11/2 hour's of running). The untrained subjects had more marked changes in lactate and pyruvate levels during the initial period of exercise than the trained, subjects, After exercise the untrained subjects also had higher concentrations of plasma free fatty acids and total ketone bodies. Similar differences were obtained between fit and unfit subjects exercising for a shorter period (11/2 hour) at similar work loads on a bicycle ergometer. The development of post-exercise ketosis is negatively correlated with an individual's fitness as measured by the Harvard Step Test, but not with his percentage body fat, although ketone bodies are degradation Products of fat metabolism (Chapter 4). The degree of ketosis which develops depends on the duration of exercise (Chapter 5) and upon the amount of training that an individual has carried out; thus athletes who are out of training become ketotic after exercise. Post-exercise ketosis in unfit subjects is diminished by the administration of glucose and the resulting hyperglycaemia is accompanied by decreases in free fatty acids and glycerol (Chapter 6). A similar pattern of metabolite changes was observed after administration of glucose to subjects undergoing a prolonged fast. These findings suggest that the increased concentration of free fatty acids results in a continued high rate of ketone body formation, which together with the decreased utilisation after exercise shows itself as post-exercise ketosis. The raised free fatty acid concentrations after exercise also cause inhibition of glucose utilisation resulting in a change in the shape of the glucose tolerance curves after exercise with a higher peak and a delayed fall. The experimental production of ketosis by the oral administration of sodium acetoacetate is described in Chapter 7. This indicates that the resistance to ketosis seen in the fitter subjects is not due to any differences in the rates of utilisation of ketone bodies. When acetoacetate is given during exercise there is an increase in tolerance indicating that during the exercise ketone bodies are being used a fuel. This supports observations (Chapter 5) showing that a second period of running is accompanied by a fall in the blood concentrations of ketones. After exercise tolerance to acetoacetate is markedly reduced in untrained subjects but little changed in the trained subjects. These observations suggest that post-exercise ketosis in the untrained subjects develops because production exceeds utilisation. In the last Chapter the effect of exercise on the secretion of growth hormone is compared in fit and unfit subjects. The latter are shorn to have a more pronounced and long-lasting rise in secretion. The phenomenon however cannot wholly account for differences in fat metabolism between the two groups because subjects with hypopituitarism (and hence no increase in growth hormone levels with exercise) also developed post-exercise ketosis.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Adviser: Ralph H Johnson
Keywords: Kinesiology, Physiology
Date of Award: 1970
Depositing User: Enlighten Team
Unique ID: glathesis:1970-73196
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56
URI: https://theses.gla.ac.uk/id/eprint/73196

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