Plasma apelin levels in overweight/obese adults following a single bout of exhaustive exercise: A preliminary cross-sectional study.

Introduction: Physical activity is beneficial for preventing metabolic diseases. Here, the circulatory level of apelin, one of the myokines, was assessed in patients with obesity to examine the effects of body composition, metabolic parameters, and physical fitness on apelin secretion following an exercise program.

Methods: A total 60 subjects [34 women (21 lean and 13 overweight/obese) and 26 men (8 lean and 18 overweight/obese)], age 30-59 years, with body mass index (BMI) of 18-30kg/m were recruited based on the guidelines for Korean obesity therapy in a clinical trial. Body composition, biochemical parameters, and physical fitness test were conducted. A single bout of exhaustive exercise was performed following Bruce protocol. Relationships among exercise-induced apelin, metabolic factors, and physical capacity were then analyzed. Independent/paired t-test between groups/time points and Pearson correlations were performed.

Results: There were significant positive correlations in post-exercise apelin and lean mass (P=0.006), homeostatic model assessment of insulin resistance (HOMA-IR; P=0.004), HOMA insulin secretion (HOMA-%B; P=0.005), lactate dehydrogenase (LDH; P=0.002), grip strength (P=0.004), and isokinetic knee flexion and extension tests in 60° and 240°/s (all variables, P<0.05), but these parameters were not correlated with pre-exercise apelin. Exercise was more effective in increasing apelin level in men compared to women.

Conclusion: Acute exercise increased circulating apelin, which was more effective in obese compared to healthy men, while no effect in women regardless of obesity status. Thus, apelin secretion after a single exercise is dependent on gender and metabolic status of subjects.