Effect of Endurance Exercise Training on Serum Adiponectin Concentration

Adiponectin, a cytokine released by adipose tissue, has insulin-sensitizing and anti-atherosclerotic properties. PURPOSE: Since circulatory concentrations of adiponectin are typically lower in obese subjects, this study was performed to determine if endurance exercise training-induced reduction of adiposity resulted in increased serum adiponectin concentration in a sample of black and white men and women aged 17 to 65 years (n=667). METHODS: Serum adiponectin concentrations from before and after a 20-week endurance exercise program were analyzed via enzyme-linked immunoassay. RESULTS: After adjustment for age, serum adiponectin at baseline was not related to VO2max in any race/sex group (range: r=−0.153 in black men, r=−0.016 in white women, p>0.05). Unexpectedly, although mean subcutaneous and intra-abdominal fat area decreased, adiponectin decreased with exercise training (before vs. after: 7.45±0.18 vs. 6.39±0.17 ugmL1, p<0.001). Training-induced change in intra-abdominal fat area was not related to change in adiponectin (r=−0.009, p>0.05). Changes in fat mass and subcutaneous abdominal fat area were inversely related to serum adiponectin change (r=−0.107 and −0.098, respectively, p<0.05), i.e., a larger reduction in adiposity was associated with a slightly smaller decrease in adiponectin. These relationships were small and only significant in black women and white men. In addition, change in VO2max was not related to adiponectin change in any of the race/sex groups (overall r=−0.055, p>0.05). At baseline, adiponectin was related to fasting insulin concentration (r=−0.264, p<0.001) and insulin sensitivity derived from minimal modeling following an intravenous glucose tolerance test (r=+0.266, p<0.001). Although fasting insulin decreased and insulin sensitivity increased in response to exercise training, changes in neither of these vabiables were related to the decrease in adiponectin (r=−0.006 and −0.017, respectively, p>0.05). CONCLUSIONS: Although adiposity decreased slightly, twenty weeks of exercise training resulted in an unexpected decrease in serum adiponectin concentration. Relationships between changes in adiposity indices and adiponectin were very modest. Furthermore, since insulin sensitivity increased in spite of the decrease in adiponectin, adiponectin does not appear to play a major role in the improved insulin sensitivity found with exercise training. Funded by the American Heart Association (Mid-Atlantic Affiliate) and multiple grants from NIH-NHLBI.