Exploration of the Independent and Combined Effects of Energy and Estrogen on Bone Metabolism, Bone Structure, and Estimated Bone Strength in Young Exercising Women

Open Access
- Author:
- Southmayd, Emily
- Graduate Program:
- Kinesiology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- March 15, 2019
- Committee Members:
- Mary Jane De Souza, Dissertation Advisor/Co-Advisor
Mary Jane De Souza, Committee Chair/Co-Chair
Nancy Williams, Committee Member
Lorah D Dorn, Committee Member
Rebecca Jane Mallinson, Outside Member
Allison Altman Singles, Committee Member - Keywords:
- Female Athlete Triad
Bone Health
Exercising Women
Bone Mineral Density
Nutrition
Bone Turnover
Amenorrhea - Abstract:
- The Female Athlete Triad (Triad), a syndrome of low energy availability, menstrual dysfunction, and low bone mineral density (BMD), affects up to 60% of exercising girls and women. As such, understanding the physiology underlying the Triad is imperative in order to identify therapeutic targets and develop effective treatment strategies to prevent long-term health detriments in afflicted women. Bone health is a major clinical outcome of concern in female athletes and exercising women with the Triad, as bone loss or suboptimal peak bone mass development may predispose women to osteoporosis and related fractures later in life. To garner a better understanding of factors contributing to bone health and to inform guidelines for treatment targets in female athletes and exercising women with the Triad, this purpose of this dissertation was 1) to assess the unique and combined effects of energy status and estrogen status on volumetric BMD (vBMD), bone geometry, and estimated bone strength in exercising women, 2) to assess the unique and combined effects of energy status and estrogen status on bone turnover in exercising women, 3) to evaluate predictors of change in bone turnover dynamics across a 12-month nutritional intervention in women with exercise-associated menstrual disturbances, and 4) to determine if bone turnover dynamics at baseline impact BMD outcomes in women with exercise-associated menstrual disturbances participating in a nutritional intervention. Key findings of the studies that made up this dissertation implicate that energy status is a main driving factor dictating vBMD, bone geometry, estimated bone strength, and bone metabolism in exercising women. The results indicate that improving energetic status will not only improve bone turnover at the cellular level, but that bone turnover favoring bone formation over bone resorption will also predict improved BMD in the following year. The findings support the guidelines put forth by the Female Athlete Triad Coalition that endorse nutritional therapy as the first line of treatment for the Triad, as low energy availability is the root cause of the clinical sequelae, including menstrual dysfunction and compromised bone health.