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Spinal bone loss and ovulatory disturbances
J C Prior1, Y M Vigna, M T Schechter
1Department of Medicine, University of British Columbia, Vancouver, Canada.
The New England Journal of Medicine
|November 1, 1990
Summary
Intense exercise can disrupt ovulation in premenopausal women, leading to accelerated bone loss. These asymptomatic ovulatory disturbances, not physical activity levels, are linked to decreased spinal bone density.
Area of Science:
- Reproductive endocrinology
- Bone metabolism
- Sports medicine
Background:
- Osteoporosis is linked to estrogen deficiency and amenorrhea.
- Bone loss rates in intensely training ovulatory women are not well understood.
Purpose of the Study:
- To investigate bone density changes in premenopausal women with varying exercise habits.
- To determine if exercise intensity or ovulatory disturbances impact bone loss.
Main Methods:
- Quantitative computed tomography (QCT) measured spinal bone density in 66 premenopausal women over one year.
- Participants were categorized by exercise level: marathon training, regular running, and sedentary.
- Menstrual cycle length, luteal phase, diet, exercise, and hormone levels were monitored.
Main Results:
- Overall spinal bone density decreased by 2.0% annually in the study group.
- Ovulatory disturbances, including anovulatory cycles, occurred in 29% of cycles.
- Bone loss was significantly associated with ovulatory disturbances (r=0.54), with anovulatory cycles showing a 4.2% annual bone loss rate.
Conclusions:
- Asymptomatic ovulatory disturbances, not exercise levels, correlated with decreased spinal bone density.
- Premenopausal women experiencing menstrual irregularities may be at risk for accelerated bone loss.