EFFECT OF ENDURANCE EXERCISE TRAINING ON FASTING AND POSTPRANDIAL PLASMA ADIPONECTIN LEVELS

The purpose of this study was to investigate the postprandial response of plasma adiponectin (AN) levels to a high-calorie, high-fat meal, in relatively healthy (free of diabetes, overt heart disease) sedentary 50- to 75-year-old men and women before and after a six-month endurance exercise training program (approximately 70% of VO2 max, three times per week). AN is an adipocyte-released polypeptide ("adipokine") whose physiological significance in insulin sensitivity and other health risk factors is well documented. VO2 max was significantly increased with training in both men and women (men, 27.0 ± 0.9 vs. 32.2 ± 1.2 mL/kg/min, p < 0.0001; women, 23.3 ± 1.0 vs. 27.1 ± 1.4 mL/kg/min, p = 0.0002), while % body fat was decreased (men, 29.9 ± 1.2 vs. 26.0 ± 1.3 %, p = 0.0010 ; women, 42.3 ± 1.5 vs. 39.5 ± 1.8 %, p < 0.0001). Fasting AN levels were higher in women than in men (gender main effect, p = 0.0138), and fasting as well as postprandial adiponectin levels decreased significantly with training in men (p = 0.014) but not in women. No postprandial changes in plasma AN levels were observed in either gender. Stepwise regression analysis showed insulin sensitivity to be the strongest predictor of fasting AN levels. Postprandial AN levels were mainly dependent on fasting AN concentrations. In conclusion, fasting plasma adiponectin levels decreased with exercise training in men in the present study, whereas they remained unchanged in women. Postprandial adiponectin levels did not change following consumption of a high-fat meal either before or after exercise training