Effect of Mild Exercise Training on Glucose Effectiveness in Healthy Men

Abstract

OBJECTIVE—To detect whether mild exercise training improves glucose effectiveness (S_G), which is the ability of hyperglycemia to promote glucose disposal at basal insulin, in healthy men.

RESEARCH DESIGN AND METHODS—Eight healthy men (18–25 years of age) underwent ergometer training at lactate threshold (LT) intensity for 60 min/day for 5 days/week for 6 weeks. An insulin-modified intravenous glucose tolerance test was performed before as well as at 16 h and 1 week after the last training session. S_G and insulin sensitivity (S_I) were estimated using a minimal-model approach.

RESULTS—After the exercise training, Vo_2max and Vo₂ at LT increased by 5 and 34%, respectively (P < 0.05). The mild exercise training improves S_G measured 16 h after the last training session, from 0.018 ± 0.002 to 0.024 ± 0.001 min⁻¹ (P < 0.05). The elevated S_G after exercise training tends to be maintained regardless of detraining for 1 week (0.023 ± 0.002 min⁻¹, P = 0.09). S_I measured at 16 h after the last training session significantly increased (pre-exercise training, 13.9 ± 2.2; 16 h, 18.3 ± 2.4, ×10⁻⁵ · min⁻¹ · pmol/l⁻¹, P < 0.05) and still remained elevated 1 week after stopping the training regimen (18.6 ± 2.2, ×10⁻⁵ · min⁻¹ · pmol/l⁻¹, P < 0.05).

CONCLUSIONS—Mild exercise training at LT improves S_G in healthy men with no change in the body composition. Improving not only S_I but also S_G through mild exercise training is thus considered to be an effective method for preventing glucose intolerance.