BONE DEMINERALIZATION OF FOOT AND HAND OF GEMINI-TITAN IV, V AND VII ASTRONATUS DURING ORBITAL FLIGHT

Abstract

Roentgenographic densitometry of several appendicular bones of astronauts participating in the Gemini IV, V, and VII orbital space flights revealed the occurrence of small but significant losses of bone mass. The lowest negative bone mass change occurred in the 14. day Gemini VII flight, the highest negative change occurred in the 8 day Gemini V flight, while the 4 day Gemini IV flight produced negative bone mass changes that were intermediate between the two. Thus the length of the space flight did not correlate with the extent of bone mass loss. A statistically significant coefficient of correlation was found between the mean dietary calcium intake of each astronaut during the respective space flights and their losses in bone mass in 6 anatomic sites. In addition to having surpassed the astronauts of Gemini IV and Gemini V in consumption of a substantial portion of the daily diet which was provided for their flight, the crew of Gemini VII participated in a program of isometric and isotonic exercise which was introduced into the Gemini program with their orbital flight, and which was shown in a ground based recumbency study to reduce bone mineral loss.