Aerospace Medicine and Human Performance · Oct 2026
Hip Bone Mineral Density Loss Grades with Age and Mission Length in NASA Astronauts
By Salman SG, Phadke RA, Ahmed AS et al.
INTRODUCTION: Spaceflight-induced bone mineral density (BMD) loss is a known crew-health risk. Prior single-cohort analyses have examined age and mission duration separately in the 94-astronaut Lifetime Surveillance of Astronaut Health dual-energy x-ray absorptiometry cohort, but their joint dose-response has not been tested. METHODS: We analyzed 94 astronauts with paired preflight and postflight scans, including 89 with complete hip data. Per-astronaut changes in hip, spine, and whole-body BMD were compared across four age × mission-duration groups: age <45 vs. ≥45 yr and mission duration <6 vs. ≥6 mo. Group sizes were 14, 14, 39, and 22. Kruskal-Wallis tests were performed at each skeletal site, with Bonferroni correction across three sites. Dunn post hoc testing with Bonferroni correction across six comparisons was applied for the hip. RESULTS: Hip BMD loss showed a stepwise gradient, from the youngest, shortest-mission group (mean change, −0.018; −1.8%) to the oldest, longest-mission group (−0.038; −3.8%). The omnibus hip comparison was significant and remained significant after Bonferroni correction. Post hoc testing showed greater hip loss in the oldest, longest-mission group compared with the youngest, shortest-mission group and the older short-mission group. Spine and whole-body changes were not significant. DISCUSSION: Postflight hip BMD loss showed a graded association across age and mission-duration strata, supporting prospective confirmation. Salman SG, Phadke RA, Ahmed AS, Deveza L, Fiedler B. Hip bone mineral density loss grades with age and mission length in NASA astronauts . Aerosp Med Hum Perform. 2026; 97(10):872–878.