Prior, J. C. (2018). Innovations in Women's Bone Health-Appreciating Important "Bone Variables" Besides Estrogen. Int J Environ Res Public Health, 15(9), E1929. https://doi.org/10.3390/ijerph15091929
Prior JC. Innovations in Women's Bone Health-Appreciating Important "Bone Variables" Besides Estrogen. Int J Environ Res Public Health. 2018;15(9):E1929. doi:10.3390/ijerph15091929
Prior, J. C. "Innovations in Women's Bone Health-Appreciating Important "Bone Variables" Besides Estrogen." Int J Environ Res Public Health, vol. 15, no. 9, 2018, pp. E1929.
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Guthardt Y et al., 2026·Sci Rep·Free full text on PubMed Central
This systematic review and meta-analysis examined the relationship between menstrual cycle phases and the incidence of muscle injuries in female team sport athletes, following PRISMA 2020 and PERSiST guidelines. A comprehensive search was conducted in PubMed, Scopus, and SPORTDiscus from inception to mid-January 2024. Studies were included if they examined female team sport athletes of reproductive age with regular menstrual cycles and compared the occurrence of muscle injuries across at least two menstrual phases. Studies involving hormonal contraceptive use, medications affecting the menstrual cycle or musculoskeletal system, or menstrual dysfunction were excluded. Three studies met the inclusion criteria, involving 318 participants. Meta-analysis yielded a pooled Risk Ratio of 1.18 (95% CI: 0.75 to 1.86, p = 0.46) for injury risk between the luteal and follicular phases, suggesting no statistically significant association. However, the certainty of the cumulative evidence was rated as very low due to methodological limitations, including inconsistent phase classifications and reliance on imprecise methods for identifying menstrual phases. Consequently, no practical or clinical recommendations can be made at this time. Future research employing standardised, physiologically accurate methods for classifying and detecting menstrual cycle phases is necessary to better understand the potential links between hormonal fluctuations and injury risk.
Seifert-Klauss V et al., 2010·J Osteoporos·Free full text on PubMed Central
Estradiol (E(2)) and progesterone (P(4)) collaborate within bone remodelling on resorption (E(2)) and formation (P(4)). We integrate evidence that P(4) may prevent and, with antiresorptives, treat women's osteoporosis. P(4) stimulates osteoblast differentiation in vitro. Menarche (E(2)) and onset of ovulation (P(4)) both contribute to peak BMD. Meta-analysis of 5 studies confirms that regularly cycling premenopausal women lose bone mineral density (BMD) related to subclinical ovulatory disturbances (SODs). Cyclic progestin prevents bone loss in healthy premenopausal women with amenorrhea or SOD. BMD loss is more rapid in perimenopause than postmenopause-decreased bone formation due to P(4) deficiency contributes. In 4 placebo-controlled RCTs, BMD loss is not prevented by P(4) in postmenopausal women with increased bone turnover. However, 5 studies of E(2)-MPA co-therapy show greater BMD increases versus E(2) alone. P(4) fracture data are lacking. P(4) prevents bone loss in preand possibly perimenopausal women; progesterone co-therapy with antiresorptives may increase bone formation and BMD.
Women's menstrual cycles and bone remodeling are linked in part by their co-dependency on the stressand resource-associated variables that govern both of their cyclical natures. Therefore, it is not surprising that evolution has resulted in the same signaling molecules and pathways that regulate normal ovarian function to be involved in bone remodeling and turnover. This review will first provide an overview of the normal menstrual cycle, its modification by age and ovulatory disturbances, and how it parallels bone remodeling. Epidemiological and clinical evidence will be presented that link bone remodeling, strength, and fractures with women's history of reproductive and menstrual cycle characteristics. This combined evidence will then be presented alongside a synthesis of current concepts derived from basic science investigations focused on understanding the molecular mechanisms underlying the influence of ovarian factors on bone physiology. Osteoporosis is a significant source of morbidity for older women. The data presented in this review suggest that a woman's reproductive cycle and ovulatory characteristics foreshadow the future health of her bones. More importantly, identifying the key mechanisms underlying reproductive and bone health would not only provide essential preventative strategies, but may also uncover attractive targets for the treatment of osteoporosis.
Subclinical ovulatory disturbances (anovulation or short luteal phases within normal-length menstrual cycles) indicate lower progesterone-to-estrogen levels. Given that progesterone plays a bone formation role, subclinical ovulatory disturbances may be associated with bone loss or less than expected bone gain. Our purpose was to perform a meta-analysis of prospective studies in healthy premenopausal women to determine the overall relationship of subclinical ovulatory disturbances to change in bone mineral density. Two reviewers independently identified from serial literature searches 6 studies meeting inclusion criteria: a 2-year study in 114 young adult women, 2006-2009, Vancouver, Canada; a 2-year study in 189 premenopausal women, 2000-2005, Toronto, Canada; a single-cycle study in 14 young women, 1996-1997, Melbourne, Australia; an 18-month study in 53 women, 1990-1995, Santa Clara, California; a 4-year study in 27 women, 1988-1995, Vancouver, Canada; and a 1-year study in 66 women, 1985-1988, Vancouver, Canada. This meta-analysis included a combined sample size of 473 observations in 436 premenopausal women studied over 1-4 years and aged 14-47 years. The percentage of women with ovulatory disturbances varied significantly from 13% to 82%. Women with more frequent ovulatory disturbances had more negative percentage changes in spine bone mineral density (weighted mean difference = -0.86; P = 0.040) for random-effects analysis. There was significant heterogeneity among these 6 studies (I(2) = 80%). In summary, these data show that regularly menstruating women with more frequent ovulatory disturbances experience more negative changes in bone (approximately -0.9% per year). These cycles with silent estrogen/progesterone imbalance may be clinically important.
In their recent article, "Characterization of Perimenopausal Bone Loss," Recker and colleagues present unique longitudinal bone mineral density (BMD) and hormonal data.1 We acknowledge the work involved in recruiting, motivating, and continuing to follow 75 women each for an average of 8 years. The data from this study are an important contribution to our knowledge of bone changes through the natural perimenopausal transition. Unfortunately, these authors have chosen to reduce the complex endocrinological and physiological changes of perimenopause2 to one idea—"estrogen deprivation." Our first concern is that "estrogen deprivation" or "depletion" is not an adequate concept with which to explain the rapid bone loss during perimenopause. The author's own data show that 50% of spinal BMD loss has occurred by 6 months before the final menstrual period at which time estradiol levels are not lower than in the so called "estrogen replete" group. In this study, perimenopausal bone loss appears to begin approximately 3 years before the final menstrual flow, which is about the time when menstrual cycles become irregular.3 Several other studies also show accelerated rates of perimenopausal bone loss.2, 4, 5 During these later phases of perimenopause, estradiol levels can be very high and certainly are not consistently low.2, 6, 7 If estradiol levels are not low in perimenopause, how can we explain the rapid bone loss? First, estradiol levels vary widely.2 Perhaps, acute drops in estradiol levels (often from abnormally high values) cause increased bone resorption much like that which has been shown to occur within seven days of premenopausal ovariectomy.8 A second possibility is that perimenopause causes psychosocial stress.9 Social stress coupled with high estradiol levels in men have been experimentally shown to cause increased cortisol levels10 that are known to be negative for bone. Finally, ovulatory changes that increase as women progress through perimenopause,11 are associated with accelerated cancellous bone loss, despite normal estradiol levels and regular cycles in premenopausal women.12 Replacement of luteal phases with cyclic progestin in a double-blind randomized study in premenopausal women with abnormal cycles caused an important positive change in spinal BMD.13 As a mechanism to allow use of all of their data, the authors labeled "estrogen replete" those women who continued to menstruate as well as those who started hormone therapy before menopause. It seems odd to us to combine data from three women who have undergone ovariectomy and seven women on exogenous hormone therapy with 10 preor perimenopausal women. The estrogen deprivation hypothesis has led the authors to overlook important physiological differences within this group. We request that the data for the 10 untreated preor perimenopausal women be provided and that we be told whether or not they continued to menstruate regularly. In women's life cycle, low levels of estrogen are as natural for menopausal women as for toddlers. To label menopause as a hormone deficiency condition is to ignore the normal hormonal pattern of women's lives. Recker and colleagues suggest that "hormone replacement therapy" should "begin as early as 2 years before the last menstrual period." Although we acknowledge that vasomotor symptoms commonly begin in perimenopause and have a very negative impact on quality of life, we suggest that progesterone would be a more appropriate therapy. Progesterone is truly low at this phase of perimenopause11 and is effective for night sweats/hot flushes. We fear that prescription of estrogen to women in late perimenopause may have negative consequences in both the short and the long-term. In the short term, it may exacerbate symptoms such as breast tenderness, headaches, and fluid retention. In the long term, having experienced side effects from estrogen treatment these women may refuse it when they are menopausal, a time when it has the potential to be valuable therapy. In summary, this important study is flawed because it relies on a clearly inadequate "estrogen deprivation" concept as the sole explanation for differences found in the prospective data from midlife women.
Bone Health › Hormones and Bone › Estrogen and Bone
Jerilynn C Prior
J Prior
PMID 30189600 30189600 DOI 10.3390/ijerph15091929 10.3390/ijerph15091929 Prior et al. 2018, Prior 2018
Cite this article
Prior, J. C. (2018). Innovations in Women's Bone Health-Appreciating Important "Bone Variables" Besides Estrogen. Int J Environ Res Public Health, 15(9), E1929. https://doi.org/10.3390/ijerph15091929
Prior JC. Innovations in Women's Bone Health-Appreciating Important "Bone Variables" Besides Estrogen. Int J Environ Res Public Health. 2018;15(9):E1929. doi:10.3390/ijerph15091929
Prior, J. C. "Innovations in Women's Bone Health-Appreciating Important "Bone Variables" Besides Estrogen." Int J Environ Res Public Health, vol. 15, no. 9, 2018, pp. E1929.
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