- Title
- The effects of the menstrual cycle and oral contraceptive cycle on body composition
- Creator
- Hillebrandt, Heidi
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2017
- Description
- Masters Research - Master of Philosophy (MPhil)
- Description
- Throughout their reproductive years, women are exposed to continuously changing female steroid hormone profiles. Large fluctuations of both oestrogen and progesterone are thought to cause many physiological effects on the body. Potential effects on fluid regulation may, in turn, result in changes in body composition over the course of a menstrual cycle or oral contraceptive (OC) cycle. The current research literature is however equivocal concerning the effects of female-specific hormone fluctuations on measures of body composition. Where effects have been observed, limited attention has been given to accurate verification of the menstrual cycle phase. Therefore, the overall aim of this thesis was to investigate the potential changes in body composition over the course of the menstrual cycle (study one) and the oral contraceptive cycle (study two), while including cycle phase verification via hormone analysis. Study one investigated the potential effects of the menstrual cycle on body composition in women of reproductive age (n=10; age: 29.7 ± 7.8 years; height: 164.7 ± 5.0 cm; weight: 66.8 ± 11.0 kg; BMI: 24.6 ± 3.4). Study two investigated the potential effects of the oral contraceptive cycle on body composition in women of reproductive age taking an oral contraceptive (n=9; age: 22.3 ± 3.1 years; height: 166.2 ± 6.8 cm; weight: 63.5 ± 8.1 kg; BMI: 23.0 ± 2.7). Various methods of body composition measurement were used, including weight, girths, skinfolds, bioelectrical impedance analysis (BIA), ultrasound, dual energy xray absorptiometry (DXA), and peripheral quantitative computed tomography (pQCT), resulting in measures of percent body fat (skinfolds, DXA, BIA), fat mass (DXA, BIA), lean mass (BIA), and fat and muscle thickness (ultrasound, pQCT). Furthermore, urine specific gravity (USG) was measured to provide an indication of hydration status. Repeated measures ANOVA was used to compare the changes in body composition variables over the three phases of the menstrual cycle or oral contraceptive cycle. The three phases of the menstrual cycle were defined as early follicular (day 1-4), late follicular (day 10-13) and luteal phase (day 19-23). While the oral contraceptive cycle was split into sugar pill (day 3-6 sugar pill), early OC (day 5-8 hormonal pill) and late OC (day 14-18 hormonal pill). Overall, no significant changes over the menstrual cycle were found for any of the measures of body composition, while for the oral contraceptive cycle only thigh girth showed a change. The main limitation, however, was the small sample sizes in these studies, while the strict menstrual cycle verification used resulted in the exclusion of participants. The high percentage (30%) of anovulation and/or luteal phase deficiency found in study one indicates the need for higher participant numbers in future menstrual cycle research due to the likely need for exclusion of participants. In summary, the current studies purposefully addressed the methodological problems associated with previous research on this topic. Although no significant changes in body composition over the menstrual cycle or oral contraceptive cycle were found, it is very likely that these findings were limited by the relatively small participant numbers. Research on body composition over the menstrual cycle and oral contraceptive cycle is not only of interest to researchers, but also to the general population of women, and especially those involved in sports where body composition has the potential to affect performance and/or team selection. Future research with strict methodological control and high participant numbers is therefore warranted to further investigate the potential effects of the menstrual cycle and oral contraceptive cycle on measures of body composition.
- Subject
- menstrual cycle; oral contraceptive cycle; body composition
- Identifier
- http://hdl.handle.net/1959.13/1354297
- Identifier
- uon:31248
- Rights
- Copyright 2017 Heidi Hillebrandt
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 2 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 438 KB | Adobe Acrobat PDF | View Details Download |