Date of Award

2011

Document Type

Thesis - ECU Access Only

Publisher

Edith Cowan University

Degree Name

Masters of Science

School

School of Exercise, Biomedical and Health Sciences

Faculty

Faculty of Computing, Health and Science

First Supervisor

Professor Paul Laursen

Second Supervisor

Dr Greig Watson

Third Supervisor

Dr Matthew Sharman

Abstract

While exercise is essential to reduce chronic disease risk, many individuals do not adhere to exercise recommendations, with the primary reason being ‘lack of time’. In recreationally trained individuals, short-term sprint interval training (SIT) has been shown to induce metabolic and performance adaptations that parallel those of traditional exercise recommendations (TER), and require considerably less time commitment. However, little is known about the effectiveness of short-term SIT in sedentary overweight individuals. This study compared the effects of SIT and TER on metabolic and health-related markers in sedentary and overweight/obese men. Sixteen sedentary overweight men (37.8 ± 5.8 yrs; BMI 32.8 ± 4.7 kg·m-2) were evenly assigned to 2 weeks of either SIT or TER performed on a cycle ergometer (SIT, 6 sessions of 8-12 x 10 s cycle sprints; TER, 10 sessions of 30 min at 65% V̇O2peak). Fasting plasma glucose, insulin and nonesterified fatty acids (NEFA), homeostasis model assessment of insulin resistance (HOMA-IR), body composition and peak oxygen consumption (V̇O2peak) were assessed at baseline and 72 h after the final training bout. Muscle biopsy samples were taken from the vastus lateralis at the same time points, and analysed for proteins associated with glucose uptake and mitochondrial function. No significant changes in BMI, body composition,V̇ O2peak, fasting plasma glucose, insulin and HOMA-IR were observed from pre to post training time points, either within or between groups. A decrease (p < 0.05) in fasting plasma NEFA was found in the TER group post training. Muscle biopsy analysis revealed that total protein content and phosphorylation of specific markers (AS160, COX II, COX IV, GLUT-4, Nur77 or SIRT1) did not change in either training group. Further analysis revealed that 50% of the subjects were classified as having the metabolic syndrome and were grouped to compare against normal subjects. Total protein content and phosphorylation of specific skeletal muscle metabolic markers (AS160, COX IV and Nur77; P < 0.05) were found to increase with exercise training in normal subjects only, while these markers did not change in subjects with the metabolic syndrome. In summary, two weeks of TER elicits minimal training adaptations in sedentary overweight/obese men, while SIT failed to elicit any change. These findings also suggest that short-term skeletal muscle adaptations to training may be impaired in those with the metabolic syndrome. Further research is needed to examine the long-term effects of TER and SIT in sedentary overweight/obese individuals.

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