Dose-response relationships between energy availability and bone turnover in young exercising women
Dose-response relationships between energy availability and bone turnover in young exercising women
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DOI：
10.1359/jbmr.040410
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发表时间：
2004-08-01
影响因子：
6.2
通讯作者：
Loucks, AB
中科院分区：
文献类型：
--
作者：
Ihle, R;Loucks, AB
为了帮助完善军人女性的营养指南，我们在控制了29名年轻女性的能量供应后，评估了骨转换。与增加骨吸收相比，限制对骨形成的损害较轻。介绍：我们对29名有规律经期、习惯久坐、身体成分正常的年轻女性进行了能量供应(定义为膳食能量摄入减去运动能量消耗)和选定的骨转换指标之间的剂量-反应关系。材料和方法：在间隔至少2个月的两个月经周期的早期卵泡期，受试者在监督下以70%的有氧能力进行15kcal/kgLBM/天的运动，并控制临床膳食产品的消耗量(45kcal/kgLBM/天)和三种限制(10，20，20，3种限制之一)中的一种或30千卡/千克/天)能量利用率处理按随机顺序进行。每隔10分钟采血，24小时取尿，测定血浆骨钙素(OC)、血清I型前胶原羧基末端肽(PICP)和尿N-端肽(NTX)。结果：每天服用10kcal/kgLBM，NTx浓度(P<；0.01)和骨吸收/形成解偶联指数(Z(NTx-OC)和Z(NTx-PICP；P<；10(-4))均升高。所有限制能量供应的处理都抑制了OC和PICP浓度(所有P<；0.05)。随着能量的供应，PICP线性下降(P<；10(-6))，而OC的大部分抑制发生在20-30kcal/kgLBM/天之间(P<；0.05)。结论：这些剂量-反应关系与同一实验中发现的和先前报道的特定生殖和代谢激素非常相似：NTX和雌二醇；PICP和胰岛素；OC，三碘甲状腺原氨酸(T-3)和胰岛素样生长因子(IGF)-I。严重限制的能量供应使骨吸收和堡垒分离，如果任其继续下去，可能会导致骨密度不可逆转的减少，而不那么严格的限制对骨形成的抑制可能会阻止年轻女性实现其峰值骨量的遗传潜力。需要更长时间的实验来确定长期限制能量供应和骨转换之间的剂量-反应关系。
To help refine nutritional guidelines for military servicewomen, we assessed bone turnover after manipulating the energy availability of 29 young women. Bone formation was impaired by less severe restrictions than that which increased bone resorption. Military servicewomen and others may need to improve their nutrition to avoid these effects.Introduction: We determined the dose-response relationship between energy availability (defined as dietary energy intake minus exercise energy expenditure) and selected markers of bone turnover in 29 regularly menstruating, habitually sedentary, young women of normal body composition.Materials and Methods: For 5 days in the early follicular phase of two menstrual cycles separated by at least 2 months, subjects expended 15 kcal/kgLBM/day in supervised exercise at 70% of aerobic capacity and consumed controlled amounts of a clinical dietary product in balanced (45 kcal/kgLBM/day) and one of three restricted (either 10, 20, or 30 kcal/kgLBM/day) energy availability treatments in random order. Blood was sampled at 10-minute intervals, and urine was collected for 24 h. Samples were assayed for plasma osteocalcin (OC), serum type I procollagen carboxy-terminal propeptide (PICP), and urinary N-telopeptide (NTX).Results: NTX concentrations (p < 0.01) and indices of bone resorption/formation uncoupling (Z(NTX-OC) and Z(NTX-PICP); both p < 10(-4)) were increased by the 10 kcal/kgLBM/day treatment. OC and PICP concentrations were suppressed by all restricted energy availability treatments (all p < 0.05). PICP declined linearly (p < 10(-6)) with energy availability, whereas most of the suppression of OC occurred abruptly between 20 and 30 kcal/kgLBM/day (P < 0.05).Conclusions: These dose-response relationships closely resembled those of particular reproductive and metabolic hormones found in the same experiment and reported previously: similar relationships were observed for NTX and estradiol; for PICP and insulin; and for OC, triiodothyronine (T-3), and insulin-like growth factor (IGF)-I. The uncoupling of bone resorption and fort-nation by severely restricted energy availability, if left to continue, may lead to irreversible reductions in BMD, and the suppression of bone formation by less severe restrictions may prevent young women from achieving their genetic potential for peak bone mass. More prolonged experiments are needed to determine the dose-response relationships between chronic restrictions of energy availability and bone turnover.