Exercise-induced endothelial progenitor cell mobilisation: acute and chronic effects on cardiovascular health in diverse populations

Endothelial dysfunction, a key contributor to atherosclerosis, begins early in life and leads to vascular damage. Endothelial progenitor cells (EPCs), primarily derived from the bone marrow, play a crucial role in endothelial repair and vascular health, while reduced EPC levels are associated with cardiometabolic diseases and elevated cardiovascular risk. Exercise is known to improve endothelial health and influence EPC mobilisation. This thesis investigates the effects of various types of exercise on circulating EPCs, and angiogenic and inflammatory responses, through systematic review approaches and analytical methods. The first systematic review focuses on the acute and chronic effects of exercise in patients with cardiovascular and metabolic diseases, showing that EPC mobilisation is influenced by exercise intensity, particularly high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICON), and the clinical condition. Chronic trials revealed that MICON, alone or combined with resistance exercise (RE) or HIIE, enhances resting EPC levels. The second systematic review focuses on the prospective cohort studies in healthy adults. Acute trials found that prolonged exercise, RE, and maximal exercise significantly increased EPCs, while chronic trials demonstrated improvements in both EPC mobilisation and vascular function following HIIE and MICON. The experimental chapter presents a randomised cross-over pilot study in healthy young males, comparing the effects of HIIE, RE, and MICON on EPC mobilisation, angiogenic factors, and inflammatory markers. Although no significant condition-by-time-point interactions were observed (p = 0.249, η²p = 0.145), exploratory analysis revealed a statistically significant difference, with HIIE eliciting a greater acute response in EPC mobilisation compared to RE at the two-hour time point (78.5 ± 88.7% vs. -2.02 ± 68.4%, p = 0.017). Findings should be interpreted cautiously due to the small sample size and limited blood collection points. Strong associations were observed between exercise-induced EPC responses, endothelial function, and cardiometabolic health markers. The final chapter identifies limitations and proposes future research directions, emphasising the variability of EPC responses based on exercise type and individual health status. This thesis provides valuable insights into exercise as a mechanism to enhance EPC mobilisation and supports its role in cardiovascular health interventions. Future research involving diverse populations is needed to determine optimal exercise protocols for EPC enhancement.