Effect of resistance training on changes in lymphocyte subpopulation during head-down-tilt bed rest

Head-down-tilt (HDT) bed rest imitates microgravity-like conditions for a supine human body on the ground. On the other hand, resistance training is used to eliminate unfavorable physical changes in astronauts under a microgravity environment during spaceflight. Twelve healthy males voluntarily participated in a 20-day -6 degrees HDT bed rest study. The ratio of CD3-positive peripheral blood lymphocytes were analyzed by immunofluorescence staining. Volunteers who undertook resistance-training during HDT bed rest were designated as the resistance training group (RTG), and those who did not as non-resistance-training group (N-RTG). We could not observe significant differences in the ratio of CD3-positive peripheral blood lymphocytes between RTG and N-RTG. Thus, resistance training during HDT bed rest might not have a significant effect on changes in the ratios of CD3-positive PBL.