Identifier

etd-09182013-230111

Degree

Master of Science (MS)

Department

Kinesiology

Document Type

Thesis

Abstract

Recent work suggests repeated cold exposure raises energy expenditure, partly due to sympathetic nervous system stimulation, which indicates repeated cold exposure as a possible strategy to combat obesity without significant behavioral changes. PURPOSE: (1) To examine the acute resting metabolic rate (RMR) response to mild cold exposure of 16° C and the acute autonomic nervous system (ANS) response to two cold exposures of 16° C and 4° C through heart rate variability (HRV) indices; and (2) to examine whether 4 weeks of daily cold exposure would result in adaptations in the metabolic and autonomic responses to acute cold exposure. METHODS: RMR and HRV measurements were used to measure acute cold exposure response at 22° C and prolonged cold exposure response after 90 minutes at 16° C. HRV measurements were also used for acute exposure at 22° C and continuously during 20 minutes of cold exposure at 4° C. RMR and ANS responses to 16° C following 20 sessions (400 minutes) of repeated cold exposure were measured. RMR was measured using a metabolic cart and ANS activity was examined through the measurement of HRV. RESULTS: A significant increase in RMR of 11% (p=0.03) and an increase in Total Power that approached significance (p=0.07) was measured after 90 minutes of exposure to 16° C. Upon exposure to 4° C, significant (p<0.05) increases in Total Power, High Frequency, and RMSSD indices of HRV were measured with Low Frequency approaching significance (p=0.07). No significant findings were measured after repeated cold exposure in comparison to baseline measurements. CONCLUSION: Acute cold exposure of 16° C resulted in a significant increase in RMR of 11% with increased activation of the autonomic nervous system measured at both 16° C and 4° C. Twenty sessions of repeated cold exposure of 4° C did not significantly alter acute responses to cold exposure. There was no evidence of a change in autonomic balance toward a hyper-adrenergic state due to cold exposure. These findings suggest repeated cold exposure may be an effective tool for significantly increasing metabolic rate without changing autonomic balance toward a hyper-adrenergic state.

Date

2012

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Welsch, Michael

Included in

Kinesiology Commons

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