Human Health & Performance Directorate, NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX 77058, USA.
Fujii Memorial Institute of Medical Sciences, University of Tokushima, Tokushima 770-8503, Japan.
Bone. 2019 Nov;128:112037. doi: 10.1016/j.bone.2019.07.013. Epub 2019 Aug 7.
Bone loss in astronauts during spaceflight may be a risk factor for osteoporosis, fractures and renal stone formation. We previously reported that the bisphosphonate alendronate, combined with exercise that included an Advanced Resistive Exercise Device (ARED), can prevent or attenuate group mean declines in areal bone mineral density (aBMD) measured soon after ~ 6-month spaceflights aboard the International Space Station (ISS). It is unclear however if the beneficial effects on postflight aBMD were due to individual or combined effects of alendronate and ARED. Hence, 10 additional ISS astronauts were recruited who used the ARED (ARED group) without drug administration using similar measurements in the previous study, i.e., densitometry, biochemical assays and analysis of finite element (FE) models. In addition densitometry data (DXA and QCT only) were compared to published data from crewmembers (n = 14-18) flown prior to in-flight access to the ARED (Pre-ARED). Group mean changes from preflight (± SD %) were used to evaluate effects of countermeasures as sequentially modified on the ISS (i.e., Pre-ARED vs. ARED; ARED vs. Bis+ARED). Spaceflight durations were not significantly different between groups. Postflight bone density measurements were significantly reduced from preflight in the Pre-ARED group. As previously reported, combined Bis+ARED prevented declines in all DXA and QCT hip densitometry and in estimates of FE hip strengths; increased the aBMD of lumbar spine; and prevented elevations in urinary markers for bone resorption during spaceflight. ARED without alendronate partially attenuated declines in bone mass but did not suppress biomarkers for bone resorption or prevent trabecular bone loss. Resistive exercise in the ARED group did not prevent declines in hip trabecular vBMD, but prevented reductions in cortical vBMD of the femoral neck, in FE estimate of hip strength for non-linear stance (NLS) and in aBMD of the femoral neck. We conclude that a bisphosphonate, when combined with resistive exercise, enhances the preservation of bone mass because of the added suppression of bone resorption in trabecular bone compartment not evident with ARED alone.
在太空飞行期间，宇航员的骨质流失可能是骨质疏松症、骨折和肾结石形成的一个风险因素。我们之前曾报道，双膦酸盐阿伦膦酸钠与包括高级抵抗运动设备（ARED）在内的运动相结合，可以预防或减轻在国际空间站（ISS）上进行约 6 个月太空飞行后不久测量的面积骨矿物质密度（aBMD）的群体均值下降。然而，骨密度的这种飞行后益处是否归因于阿伦膦酸钠和 ARED 的个体或联合作用尚不清楚。因此，招募了另外 10 名 ISS 宇航员，他们使用 ARED（ARED 组）而不使用以前研究中类似的药物进行药物治疗，即密度计，生化测定和有限元（FE）模型分析。此外，还将密度计数据（仅 DXA 和 QCT）与在飞行前可使用 ARED 的机组人员（n=14-18）的已发表数据进行了比较（Pre-ARED）。使用飞行前的群体均值变化（±SD％）来评估在 ISS 上依次修改的对策的效果（即 Pre-ARED 与 ARED；ARED 与 Bis+ARED）。各组的飞行时间没有显着差异。Pre-ARED 组的飞行后骨密度测量值明显低于飞行前。如前所述，联合使用 Bis+ARED 可防止所有 DXA 和 QCT 髋关节骨密度和髋关节 FE 强度的估计值下降；增加腰椎的 aBMD；并防止飞行期间尿液骨吸收标志物升高。没有阿伦膦酸钠的 ARED 部分减轻了骨量的下降，但没有抑制骨吸收的生物标志物或防止小梁骨丢失。在 ARED 组中进行的阻力运动并未阻止髋关节小梁 vBMD 的下降，但防止了股骨颈的皮质 vBMD 减少，非线性站立（NLS）的髋关节强度 FE 估计值和股骨颈的 aBMD 减少。我们的结论是，双膦酸盐与阻力运动相结合，由于在单独使用 ARED 时不明显的小梁骨骨吸收的抑制作用，增强了骨量的保存。
