INTRODUCTION: Circulating progenitor cells (CPCs) are a heterogeneous population of stem/progenitor cells in peripheral blood that participate in tissue repair. CPC mobilization has been well characterized in able-bodied persons, but has not been previously investigated in wheelchair racing athletes. The purpose of this study was to characterize CPC and CPC sub-population mobilization in elite wheelchair racing athletes in response to acute, upper-extremity aerobic exercise to determine if CPC responses are similar to ambulatory populations.
METHODS: Eight participants (3 female; age=27.5+/-4.0 years; supine height=162.5+/-18.6cm; weight=53.5+/-10.9kg, VO2peak=2.4+/-0.62 L/min; years post injury=21.5+/-6.2 years) completed a 25 km time trial on a road course. Blood sampling occurred before (Pre) and immediately post (Post) exercise for quantification of CPCs (CD34+), HSPCs (CD34+/CD45dim), HSCs (CD34+/CD45dim/CD38-), CD34+ adipose tissue-derived (AT)-MSCs (CD45-/CD34+/CD105+/CD31-), CD34- bone marrow-derived (BM)-MSCs (CD45-/CD34-/CD105+/CD31-), and EPCs (CD45dim/CD34+/VEGFR2+) via flow cytometry. Blood lactate was measured Pre- and Post-trial as an indicator of exercise intensity.
RESULTS: CPC concentration increased 5.7 fold post-exercise (P=0.10). HSPCs, HSCs, EPCs, and both MSC populations were not increased post exercise. Baseline HSPCs were significantly positively correlated to absolute VO2peak (Rho = 0.71, P<0.05) with HSCs trending to positively correlate to VO2peak (Rho = 0.62, P=0.10). AT-MSCs were trending to be negatively correlated to baseline VO2peak (Rho = -0.62, P=0.058). The change in CPCs, EPCs, and AT-MSCs Pre-Post exercise significantly positively correlated to the change in lactate concentrations (Rho = 0.91 p = 0.002, 0.71 p = 0.047, 0.81 p = 0.02, respectively, all P<0.05).
CONCLUSION: These data suggest that CPC content in wheelchair racing athletes is related to cardiorespiratory fitness and responses to exercise are positively related to exercise intensity.
(C) 2017 American College of Sports Medicine