Apelin, as a cardiokine/myokine, is emerging as an important regulator of cardiac
and skeletal muscle homeostasis. Loss of apelin signaling results in premature cardiac
aging and sarcopenia. However, the contribution of apelin to peak athletic performance
remains largely elusive. In this paper, we assessed the impact of maximal cardiorespiratory
exercise testing on the plasma apelin levels of 58 male professional soccer players.
Circulating apelin-13 and apelin-36, on average, increased transiently after a single
bout of treadmill exercise; however, apelin responses (Δapelin = peak - baseline values)
showed a striking interindividual variability. Baseline apelin-13 levels were inversely
correlated with those of Δapelin-13 and Δapelin-36. Δapelin-13 showed a positive correlation
with the maximal metabolic equivalent, relative maximal O2 consumption, and peak circulatory
power, whereas such an association in the case of Δapelin-36 could not be detected.
In conclusion, we observed a pronounced individual-to-individual variation in exercise-induced
changes in the plasma levels of apelin-13 and apelin-36. Since changes in plasma apelin-13
levels correlated with the indicators of physical performance, whole-body oxygen consumption
and pumping capability of the heart, apelin, as a novel exerkine, may be a determinant
of peak athletic performance.
