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The effects of the menstrual cycle and hormonal contraceptives on the central thermoeffector threshold temperatures and width of the interthreshold zone

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dc.contributor.author Dies, Natalie. en_US
dc.date.accessioned 2010-01-28T15:55:29Z
dc.date.available 2010-01-28T15:55:29Z
dc.date.issued 2009-01-28T15:55:29Z
dc.identifier.uri http://hdl.handle.net/10464/2874
dc.description.abstract Basal body temperature (BBT) and thermoeffector thresholds increase following ovulation in many women. This study investigated if solely central thermoregulatory alterations are responsible. Seven females in a non-contraceptive group (NCG) were compared with 5 monophasic contraceptive users (HCG) on separate accounts: pre-ovulation (Trial I; d 2-5) and post-ovulation (Trial 2; 4-8 d post-positive ovulation) for NCG, and active phase for HCG (d 2-5, d 18-21). During immersion in 28°C water to the axilla, participants exercised for 20-30 min on an underwater ergometer. After steadily sweating, immersion continued until metabolism increased two-fold due to shivering. Rectal (Tre) BBT was not different between trials for neither NCG (1: 37.34±0.16°C; 2: 37.35±0.27°C) nor HCG. At exercise termination, Tre forehead sweating cessation increased (P<0.05) in trial 2 irrespective of group (1: 37.55±0.39°C; 2: 37.90±0,46°C). Tre shivering onset did not increase (P>0.05) in trial 2 (1: 36.91±0.50°C; 2: 37.07±0,45°C). The widths of the interthreshold zone increased (P<0.05) in trial 2 (1: 0.64±0.22°C; 2: 0.82±0.37°C) due to the increased sweating threshold only. HCG cooled quicker (1: -l.15±0,43°C; 2: -1.00±0.50°C) than NCG participants (1: - 0.58±0.22°C; 2: -0.52±O.29°C), and tympanic (Tty) sweat thresholds were significantly (P<0.05) decreased (1: 34.76±0.54°C; 2: 35.39±0.61°C) versus NCG (l: 35.57±0.77°C; 2: 35.89±1.04°C). Lastly, Tre and Tty thresholds were significantly different (P<O.05) for all thresholds within the same trial. In conclusion, BBT is not a reliable indicator of ovulation, only the central thermoregulatory drive for sweating is altered by menstrual phase, contraceptive users have enhanced thermal sensitivities, and Tty opposed to Tre provides different measures of core temperature. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Body temperature. en_US
dc.subject Basal metabolism. en_US
dc.subject Menstrual cycle. en_US
dc.subject Contraceptives. en_US
dc.subject Ovulation--Detection. en_US
dc.title The effects of the menstrual cycle and hormonal contraceptives on the central thermoeffector threshold temperatures and width of the interthreshold zone en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name M.Sc. Applied Health Sciences en_US
dc.degree.level Masters en_US
dc.contributor.department Applied Health Sciences Program en_US


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