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One identical twin was randomly assigned to the nonexercise control (Con) group, and their sibling was assigned to the exercise (Ex) group. The lumbar spine was significantly more compressible Post-BR compared with Pre-BR in the Con ( P = 0.01). Lumbar spine compressibility Post-BR was not significantly different compared with Pre-BR in the Ex group ( P = 0.89). In both the Con and Ex groups, there were no significant changes Post-BR in lumbar lordosis compared with Pre-BR. Back muscle strength significantly decreased in the Con group Post-BR ( P = 0.002), whereas in the Ex group back muscle strength was not significantly different from Pre-BR values. A significant increase in lumbar spine compressibility in the Con group suggests that spinal deconditioning to gravity occurs during 28-day bed rest. Changes in the mechanical properties of the lumbar spine may be an early indicator of lumbar intervertebral disk degeneration. Supine LBNP treadmill exercise provides axial loads to the lumbar spine and may prevent lumbar spine deconditioning associated with HDT bed rest. <\/jats:p>","DOI":"10.1152\/japplphysiol.00541.2006","type":"journal-article","created":{"date-parts":[[2007,3,29]],"date-time":"2007-03-29T21:04:20Z","timestamp":1175202260000},"page":"2274-2278","source":"Crossref","is-referenced-by-count":38,"title":["LBNP treadmill exercise maintains spine function and muscle strength in identical twins during 28-day simulated microgravity"],"prefix":"10.1152","volume":"102","author":[{"given":"Brandon R.","family":"Macias","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peihong","family":"Cao","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Donald E.","family":"Watenpaugh","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alan R.","family":"Hargens","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"R1","doi-asserted-by":"publisher","DOI":"10.1097\/00007632-198309000-00013"},{"key":"R2","doi-asserted-by":"publisher","DOI":"10.1097\/00007632-197901000-00009"},{"key":"R3","doi-asserted-by":"publisher","DOI":"10.1097\/01.phm.0000163709.70471.42"},{"key":"R4","doi-asserted-by":"publisher","DOI":"10.1097\/00007632-199106000-00008"},{"key":"R5","unstructured":"Brown JW. 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