COSMOS 936, experiment K-208: Spaceflight effects on muscle fibers

摘要

Muscle fiber size and type distribution were studied in the extensor digitorium longus (e.d.1.) muscle of 15 COSMOS 936 rats. The groups studied include 5 flight stationary, 5 synchronous stationary, and 5 vivarium control animals. Of the 3 groups, average fiber diameter was largest in the vivarium control animals and smallest in the flight animals. Flight muscles appeared to be shorter than those of the other groups. Fiber number showed no significant difference. The e.d.1. contains predominantly fast twitch fibers. The slow fiber percentage was quite variable in these animals, and no statistically significant fiber type conversion was noted.