Schneider V S, McDonald J
Calcif Tissue Int. 1984;36 Suppl 1:S151-44. doi: 10.1007/BF02406149.
Maintenance of a skeleton capable of resisting the stresses of everyday life is dependent on the mechanical forces applied to the skeleton during normal activity in a 1-G environment. When the effects of 1-G on the longitudinal skeleton are removed, as with space travel or inactivity, bone and bone mineral are lost because bone resorption is greater than bone formation. Ninety healthy young men were studied during 5-36 weeks of continuous bed rest. During inactivity, urinary calcium increases rapidly and by the sixth week of bed rest, output has risen by 100 mg/day, plateaus for several weeks, and then decreases but remains above ambulatory baseline thereafter. This occurred even though they received vitamin D supplements throughout the study. Calcium balance becomes negative after 2 weeks and by the end of the first month, 200 mg/day is lost. The loss continues at this rate for at least 36 weeks. Calcaneal mineral loses 5% of its mass each month. Attempts to prevent disuse osteoporosis with both mechanical and biochemical means, including exercise, skeletal compression, increased hydrostatic pressure to the lower body, supplemental calcium and/or phosphorus, calcitonin, or etidronate were not successful.
维持一个能够抵抗日常生活压力的骨骼系统，依赖于在1-G环境下正常活动期间施加于骨骼的机械力。当去除1-G对纵向骨骼的影响时，比如太空旅行或缺乏活动，骨和骨矿物质会流失，因为骨吸收大于骨形成。对90名健康年轻男性进行了为期5至36周的连续卧床休息研究。在缺乏活动期间，尿钙迅速增加，到卧床休息第6周时，排出量已上升至100毫克/天，持续几周保持平稳，然后下降，但此后仍高于活动时的基线水平。即便在整个研究过程中他们都补充了维生素D，这种情况仍会发生。两周后钙平衡变为负值，到第一个月末，每天流失200毫克。这种流失以该速率至少持续36周。跟骨矿物质每月流失其质量的5%。尝试通过机械和生化手段预防废用性骨质疏松，包括运动、骨骼压迫、增加下半身静水压力、补充钙和/或磷、降钙素或依替膦酸，但均未成功。
