Comparison of serum apelin levels and maximal oxygen consumption in active and inactive obese men

Apelin is an adipokine that may play a significant role in regulating energy metabolism. Obesity and physical activity are factors that affect the concentration of apelin, but it is not known which one is more prominent. Thus, the aim of this study was to compare the serum levels of apelin-13 and the maximal oxygen consumption (VO2max) in men who are inactive normal-weight, active and inactive obese. Forty-five healthy men (age range, 34-46 years) were assigned to one of the following groups. 1) active-obese: body mass index (BMI)=28-33.9 kg/m2, 3-5 score in the physical activity rate questionnaire (PAR-Q) and n=16; 2) inactive-obese: BMI = 28-33.9 kg/m2, 1 in PAR-Q and n=18; 3) inactive normal-weight: BMI=18.5-24.9 kg/m2, 1 in PAR-Q and n=11. Blood samples were collected from the subjects in a fasting state; then, the serum level of apelin-13 was measured by the ELISA method. The VO2max was estimated by the non-exercise method and based on the PAR-Q. One-way ANOVA showed that there was no significant difference in the serum levels of apelin-13 between the groups (P=0.73). It was found that VO2max was significantly lower in the inactive-obese group compared to the other groups (P≤0.001); however, no significant difference was noted between the active-obese and inactive normal-weight groups (P=0.14). Findings of this study show that the moderate physical activity and type 1 obesity could not be effective in apelin-13 concentration. In addition, it can be suggested that the obesity and physical activity indices have the same reciprocal effects in maximal oxygen consumption.