Identifier

etd-09082005-165133

Degree

Master of Science (MS)

Department

Kinesiology

Document Type

Thesis

Abstract

The involvement of the sympathetic nervous system in the pathology of obesity has long been a debate among researchers. Various methods of capturing the resting sympathetic activity as well as the response of the sympathetic activity elicited by the introduction of a meal or a bout of exercise in both lean and obese individuals have been investigated. This study examined the autonomic modulation of the heart following a high carbohydrate liquid meal in various body types. Twenty-five females with body mass indexes [weight (kg)/height2(m)] ranging from 19.3-39.5 were grouped according to relative basal energy expenditure adjusted for lean body mass (High relative basal energy expenditure - HIGH rBEE and Low relative basal energy expenditure -LOW rBEE). Each female consumed ENSURE with Fiber at a calorie level equal to forty percent of her basal energy expenditure. Heart rate variability was measured for 15min at rest, immediately following the meal, and hourly for 5hrs postprandial. The LOW rBEE group at baseline as well as postprandial tended to demonstrate an elevated sympathetic activity when compared to the HIGH rBEE group (LOW rBEE - resting LF/HF ratio 2.36 ± 2.3, peak increase two hours pp LF/HF ratio 3.09 ± 2.9; HIGH rBEE - resting LF/HF ratio 1.93 ± 1.7, peak increase fifteen minutes pp LF/HF ratio 1.98 ± 0.9). Meal induced thermogenesis, measured as changes in sympathetic activity, was higher in the LOW rBEE group. In conclusion, this study has shown that in the pre and postabsorptive state, individuals with a LOW rBEE tend to be more hyperadrenergic when compared to HIGH rBEE individuals, which may signify an adverse cardiovascular risk. The evidence supports the assertion that when the SNS response to a meal in various body types is being investigated, a duration of greater than 5hrs post prandial is necessary.

Date

2005

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Robert Wood

Included in

Kinesiology Commons

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