Sprint interval and sprint continuous training increases circulating CD34⁺ cells and cardio-respiratory fitness in young healthy women

Introduction: The improvement of vascular health in the exercising limb can be attained by sprint interval training (SIT). However, the effects on systemic vascular function and on circulating angiogenic cells (CACs) which may contribute to endothelial repair have not been investigated. Additionally, a comparison between SIT and sprint continuous training (SCT) which is less time committing has not been made. Methods: 12 women (22±2 yrs) completed 12 sessions of either SIT (n = 6) or work-matched SCT (n = 6) on 3 days/week. Pre and post-Training assessments included brachial artery endothelial function and peripheral blood analysis for CAC number (CD34⁺/CD34⁺CD45^dim). CAC function was measured by migration and adhesion assays. Cardio-respiratory fitness, carotid arterial stiffness and carotid-radial and brachial-foot pulse wave velocity (PWV) were also evaluated. Results: CD34⁺ CACs increased following training in both groups but CD34⁺CD45^dimdid not (Pre CD34⁺: 40±21/10⁵ leukocytes, Post CD34⁺: 56±24/10⁵ leukocytes, main time effect p,0.05). Brachial artery flow-mediated dilation (FMD) increased following SIT but SCT had no effect (Pre SIT: 5.0±3.4%, Post SIT: 5.9±3.0%, Pre SCT: 7.2±2.7%, Post SCT: 6.5±2.9%; group x time interaction p = 0.08). VVO^2max increased in both training groups (Pre: 34.6±4.6 mlNkgNml²¹, Post: 36.9±5.4 mlNkgNml²¹, main time effect p,0.05). CAC function, carotid arterial stiffness and PWV did not change after training (p.0.05). Discussion: SCT involving little time commitment is comparable to SIT in increasing CD34⁺ cell number and VVO^2max. An increased mobilisation of CD34⁺ CACs suggests that sprint training may be an effective method to enhance vascular repair.