Tokmakidis, S.P. Mitsiou, G. Smilios, I. Nanas, S., Letter to the Editor on: Effects of Exercise Training on the Paracrine Function of Circulating Angiogenic Cells, International Journal of Sports Medicine, (42), 1137-1138, 2021, Georg Thieme Verlag, 0172-4622, 1439-3964