De Souza Mary Jane, West Sarah L, Jamal Sophie A, Hawker Gillian A, Gundberg Caren M, Williams Nancy I
Women's Exercise and Bone Health Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada; Noll Laboratory, Department of Kinesiology, Penn State University, University Park, PA, USA.
Women's Exercise and Bone Health Laboratory, Department of Exercise Sciences, University of Toronto, Toronto, Ontario, Canada.
Bone. 2008 Jul;43(1):140-148. doi: 10.1016/j.bone.2008.03.013. Epub 2008 Apr 8.
Bone loss in amenorrheic athletes has been attributed to energy deficiency-related suppression of bone formation, but not increased resorption despite hypoestrogenism.
To assess the independent and combined effects of energy deficiency and estrogen deficiency on bone turnover markers in exercising women.
PINP, osteocalcin, U-CTX-I, TT3, leptin, and ghrelin were measured repeatedly, and bone mineral density (BMD) was measured once in 44 exercising women. Resting energy expenditure (REE) was used to determine energy status (deficient or replete) and was corroborated with measures of metabolic hormones. Daily levels of urinary estrone and pregnanediol glucuronides (E1G, PdG), were assessed to determine menstrual and estrogen status. Volunteers were then retrospectively categorized into 4 groups: 1) Energy Replete+Estrogen Replete (EnR+E2R), (n=22), 2) Energy Replete+Estrogen Deficient (EnR+E2D), (n=7), 3) Energy Deficient+Estrogen Replete (EnD+E2R), (n=7), and 4) Energy Deficient+Estrogen Deficient (EnD+E2D), (n=8).
The groups were similar (p>0.05) with respect to age (24.05+/-1.75 yrs), weight (57.7+/-2.2 kg), and BMI (21.05+/-0.7 kg/m2). By design, REE/FFM (p=0.028) and REE:pREE (p<0.001) were lower in the EnD vs. EnR group, and the E2D group had a lower REE:pREE (p=0.005) compared to the E2R group. The EnD+E2D group had suppressed PINP (p=0.034), and elevated U-CTX-I (p=0.052) and ghrelin (p=0.028) levels compared to the other groups. These same women also had convincing evidence of energy conservation, including TT3 levels that were 29% lower (p=0.057) and ghrelin levels that were 44% higher (p=0.028) than that observed in the other groups. Energy deficiency was associated with suppressed osteocalcin, and TT3 (p<0.05), whereas estrogen deficiency was associated with decreased E1G (p<0.02), and lower L2-L4 BMD (p=0.033). Leptin was significant in predicting markers of bone formation, but not markers of bone resorption.
When the energy status of exercising women was adequate (replete), there were no apparent perturbations of bone formation or resorption, regardless of estrogen status. Estrogen deficiency in exercising women, in the presence of an energy deficiency, was associated with bone loss and involved suppressed bone formation and increased bone resorption. These findings underscore the importance of avoiding energy deficiency, which is associated with hypoestrogenism, to avoid bone health problems.
闭经运动员的骨质流失归因于能量缺乏相关的骨形成抑制，尽管雌激素水平低，但骨吸收并未增加。
评估能量缺乏和雌激素缺乏对运动女性骨转换标志物的独立及联合影响。
对44名运动女性重复测量I型前胶原氨基端前肽（PINP）、骨钙素、I型胶原交联C端肽（U-CTX-I）、三碘甲状腺原氨酸（TT3）、瘦素和胃饥饿素，并测量一次骨密度（BMD）。静息能量消耗（REE）用于确定能量状态（缺乏或充足），并通过代谢激素测量进行验证。评估尿雌酮和孕二醇葡萄糖醛酸苷（E1G、PdG）的每日水平，以确定月经和雌激素状态。志愿者随后被回顾性分为4组：1）能量充足+雌激素充足（EnR+E2R），（n = 22），2）能量充足+雌激素缺乏（EnR+E2D），（n = 7），3）能量缺乏+雌激素充足（EnD+E2R），（n = 7），4）能量缺乏+雌激素缺乏（EnD+E2D），（n = 8）。
各组在年龄（24.05±1.75岁）、体重（57.7±2.2 kg）和体重指数（BMI）（21.05±0.7 kg/m²）方面相似（p>0.05）。按照设计，与EnR组相比，EnD组的REE/去脂体重（p = 0.028）和REE:预测静息能量消耗（p<0.001）较低，与E2R组相比，E2D组的REE:预测静息能量消耗较低（p = 0.005）。与其他组相比，EnD+E2D组的PINP受到抑制（p = 0.034），U-CTX-I（p = 0.052）和胃饥饿素水平升高（p = 0.028）。这些女性还有令人信服的能量节约证据，包括TT3水平比其他组低29%（p = 0.057），胃饥饿素水平比其他组高44%（p = 0.028）。能量缺乏与骨钙素和TT3受抑制有关（p<0.05），而雌激素缺乏与E1G降低有关（p<0.02），以及L2-L4骨密度较低（p = 0.033）。瘦素在预测骨形成标志物方面有显著意义，但对骨吸收标志物无显著意义。
当运动女性的能量状态充足（充足）时，无论雌激素状态如何，骨形成或骨吸收均无明显扰动。运动女性在能量缺乏的情况下雌激素缺乏与骨质流失有关，涉及骨形成受抑制和骨吸收增加。这些发现强调了避免与低雌激素血症相关的能量缺乏以避免骨骼健康问题的重要性。
