The effect of endurance training and subsequent physical inactivity on glycaemic control after oral glucose load and physical exercise in healthy men

Physical inactivity during space flight has a profound effect on glucose metabolism. The aim of this study was to test whether endurance training (ET) may improve a negative effect of subsequent -6∘-6∘ head-down bed rest (HDBR) on glucose metabolism. Fourteen healthy males completed the study consisting of 6 weeks lasting ET followed by 6 days HDBR. Treadmill exercise at 80% of pre-training VO2maxVO2max and 75 g oral glucose tolerance test (OGTT) were performed before and after ET as well as after HDBR. ET increased VO2maxVO2max by 11%. ET significantly lowered while HDBR had no effect on fasting and OGTT plasma glucose levels. ET had no effect while HDBR was followed by an augmentation of insulin and C-peptide response to OGTT. Insulin sensitivity tended to increase after ET and to decrease during HDBR, however, mostly without statistical significance. Plasma glucose, insulin and C-peptide response to exercise were elevated after HDBR only. Our study shows that antecedent physical training could ameliorate a negative effect of simulated microgravity on insulin-mediated glucose metabolism.