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; ). Ten males (age: 23 ± 3 years; : 61.88 ± 4.68 mL kg min) undertook 1 h of treadmill running at 80% of . 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, CD34CD45) and putative endothelial progenitor cells (CD34CD133, CD34VEGFR2, CD34CD45VEGFR2) were quantified using flow cytometry. Progenitor subpopulations (except for CD34CD45VEGFR2) increased at 0 h (P < 0.05) and returned to pre-exercise levels by 1 h. was positively associated with the exercise-induced progenitor cell response and there were statistically significant time × interactions for CD34, CD34CD45 and CD34+CD133 subpopulations but not VEGFR2-expressing progenitor cells. There were statistically significant correlations between and ingress (r > 0.70, P < 0.025) and egress (r > -0.77, P < 0.009) of progenitor cell subsets (CD34, CD34CD45, CD34CD133), 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.