Significant enhancements in glucose tolerance and insulin action in centrally obese subjects following ten days of training.

Objective: The objective of the study was to determine the effects of short-term exercise on glucose tolerance and insulin response to a glucose load in centrally obese individuals.

Design: 75 g oral glucose tolerance tests (OGTT) were performed prior to participation and 24 hours after the last exercise session. Exercise bouts were 40 minutes in duration and consisted of treadmill walking and cycle ergometry at 70-80% of age-predicted maximum heart rate (APHR(max)).

Participants: Eleven sedentary, centrally obese men [mean (SE): Mass, 119.1 (5.4) kg; BMI, 37.7 (1.8) kg/m(-2); waist-to-hip ratio (WHR), 0.97 (0.01); age 31.7 (2.4) years] were studied before and after 10 days of aerobic exercise training.

Results: No significant change (p >.05) in body mass was noted following 10 days of exercise as compared with preparticipation [119.1 (5.4) kg versus 118.9 (5.4) kg]. Fasting plasma glucose concentration was significantly lower (p < 0.05) following 10 days of exercise as compared with preexercise [5.58 (0.15) mmol/L versus 5.27 (0.12) mmol/L]. No significant change (p > 0.05) in fasting plasma insulin concentration, however, was observed following 10 days of exercise training as compared with preexercise [276.2 (33.7) pmol/L versus 225.3 (35.9) pmol/L]. Plasma insulin concentrations at 60 minutes and 120 minutes were significantly decreased (p < 0.05) when comparing the preexercise to the postexercise OGTT [60: 1264.2 (88.3) pmol/L versus 1103.5 (81.1) pmol/L; 120: 1066.9 (110.5) pmol/L versus 764.1 (106.2) pmol/L]. Plasma glucose concentration at 120 minutes. was also significantly reduced (p < 0.05) after 10 days of exercise as compared with preexercise [6.09 (0.24) mmol/L versus 5.39 (0.22) mmol/L]. Area under the glucose curve was significantly (p < 0.05) reduced after 10 days of exercise as compared with preparticipation [944.6 (44.4) mmol/L/120 min versus 884.4 (43.2) mmol/L/120 min]. Area under the insulin curve was also significantly decreased (p < 0.05) following 10 days of exercise training as compared with preexercise [126,890 (9014.0) pmol/L/120 min versus 109,445 (7,888.9) pmol/L/120 min].

Conclusions: These data suggest that short-term exercise may improve glucose tolerance and insulin response to a glucose load in centrally obese men.