The magnitude of exercise‐induced progenitor cell mobilisation and extravasation is positively associated with cardiorespiratory fitness

CD34⁺ progenitor cells with angiogenic capabilities traffic into blood during exercise and extravasate afterwards but the magnitude of this response varies between people. We examined whether exercise-induced progenitor cell trafficking is influenced by cardiorespiratory fitness (maximum oxygen uptake; V̇O_2max ). Ten males (age:23 ± 3 years; V̇O_2max : 61.88 ± 4.68 mL kg min⁻¹) undertook 1 h of treadmill running at 80% of V̇O_2max. Blood samples were collected before exercise (Pre), in the final minute of exercise (0 h) and afterwards at 0.25, 1 and 24 h. Pan-progenitor cells(CD34⁺, CD34⁺CD45^dim ) and putative endothelial progenitor cells (CD34⁺CD133⁺,CD34⁺VEGFR2⁺, CD34⁺CD45^dimVEGFR2⁺) were quantified using flow cytometry. Progenitor subpopulations (except for CD34⁺CD45^dimVEGFR2⁺) increased at 0 h(P < 0.05) and returned to pre-exercise levels by 1 h. V̇O_2max  was positively associated with the exercise-induced progenitor cell response and there were statistically significant time × V̇O_2max interactions for CD34⁺, CD34⁺CD45^dim and CD34⁺CD133⁺ subpopulations but not VEGFR2-expressing progenitor cells. There were statistically significant correlations between V̇O_2max and ingress (r > 0.70, P < 0.025) and egress (r > −0.77, P < 0.009) of progenitor cell subsets (CD34⁺, CD34⁺CD45^dim, CD34⁺CD133⁺), showing that cardiorespiratory fitness influences the magnitude of progenitor cell mobilisation into the blood and subsequent extravasation. These data may provide a link between high levels of cardiorespiratory fitness and vascular health.