Effects of physical training and adiposity on glucose metabolism and 125I-insulin binding

Eighteen young male subjects, aged 18-30 yr, with maximal oxygen intake (VO2max) varying between 36 and 80 ml.kg-1.min-1, were studied. Between 20 and 120 min after injection, tolerance to iv glucose (20 g/m2) was not affected by VO2max but the insulin response was very significantly reduced in the better trained subjects. 125I-insulin binding to monocytes was found to be greater in the best trained subjects. Simple correlation analysis indicates that both VO2max and adiposity are related to plasma glucose and plasma insulin levels as well as to 125I-insulin binding. Because VO2max is negatively correlated to percent of body fat, a partial correlation analysis was made. Results indicate that the differences observed in athletes with regard to glucose and insulin levels and 125I-insulin binding are related to reduced adiposity rather than to enhanced VO2max.