Influence of Gender and Aerobic Training Background on Exercise-Induced Increase in Adiponectin

Abstract

Adipose tissue secretes the adipokine, adiponectin (ADPN), which is insulinsensitizing, anti-inflammatory, and anti-atherogenic. Exercise training improves insulin sensitivity and lowers the risk of cardiovascular complications. As some of the metabolic effects of exercise training and ADPN overlap, exercise training has been proposed to increase ADPN. However, most single bout exercise, or short-term (ï‚£3 months) and constant-effort (fixed session duration, fixed number of sessions/week, and fixed intensity) exercise protocols do not produce increases in ADPN in untrained and trained cohorts. Furthermore, most exercise studies were conducted on male-female mixed gender cohorts or male/female single gender cohorts. As a result, no direct comparison of male and female subjects pertaining to the effect of exercise on ADPN levels has been reported. Our governing hypothesis is that long-term aerobic exercise increases ADPN, and the increase in ADPN is influenced by gender and exercise training background. We tested two specific hypotheses using different cohorts of human volunteers. Hypothesis 1 states that ADPN levels will increase significantly in previously untrained, middle-aged males and females in response to a long-term, progressive aerobic training protocol. Hypothesis 2 states that ADPN levels in multi-year trained female marathoners will increase significantly in response to a long-term, progressive aerobic training, but not in comparably trained males. We compared ADPN levels in trained marathoner males (n=10) and females (n=8) subjects and untrained males (n=9) and females (n=11) subjects in a 6-mo aerobic training intervention study. Fasting plasma samples were collected at the beginning and end of the 6-mo training period and analyzed. ADPN levels increased significantly in both trained and untrained females and untrained males, but non-significantly in trained males. Ours is the first study to compare changes in ADPN in mean age and BMI-matched male and female groups with two non-overlapping exercise training backgrounds in response to the same long-term, progressive aerobic training. The insight provided by the results of the two studies will help in understanding gender differences in ADPN