Increased serum levels of adiponectin upon a single bout of exhaustive exercise in amateur athletes

Adiponectin is a serum hormone that plays a significant role in the prevention of metabolic disorders, such as obesity, type 2 diabetes, coronary heart disease, and metabolic syndrome.1 It is secreted from white adipose tissue into circulation in three different oligomeric forms: trimers (low molecular weight, LMW), hexamers (medium molecular weight, MMW), and high-molecular-weight (HMW) oligomers. The HMW form of adiponectin is the most active in the regulation of body weight and energy balance.2,3 Since previous studies indicated that exercise leads to higher levels of circulating adiponectin, in this work we investigated serum concentrations of this hormone after a single bout of exhaustive exercise on a cycle ergometer in 25 male amateur athletes. Participants were divided into young adults (YA) and middle-aged adults (MA), and total adiponectin was measured at baseline, upon 15 minutes and 24 h post-exercise, using ELISA. HMW oligomer levels were assessed at baseline and at 24 h post-exercise by western blotting analysis. A significant increase in total adiponectin levels was found both upon 15 minutes and 24h after the exercise protocol, especially in the YA group. Considering all participants HMW oligomers also increased 24 h post-exercise, but when analyzed separately this increase was found only in YA subjects. Correlation analyses revealed that adiponectin concentration is associated with VO2peak and Powerpeak levels in YA subjects, highlighting a positive relationship between its regulation and exercise capacity. Moreover, baseline adiponectin negatively correlated with VO2peak and Powerpeak suggesting adaptation mechanisms of adipose tissue. In conclusion, a single bout of exhaustive exercise evokes a significant, rapid, and lasting increase in adiponectin serum levels in healthy subjects, particularly due to an increase in HMW oligomers.