Polarized Aerobic Training and Vascular Adaptations in Apparently Healthy Individuals

This randomized controlled trial will investigate the effects of a 6-week polarized aerobic training intervention on vascular and cardiorespiratory function in apparently healthy sedentary adults aged 30-50 years. Polarized training is characterized by a high proportion of low-intensity aerobic exercise combined with a smaller volume of high-intensity interval exercise, potentially providing complementary haemodynamic and physiological stimuli that support vascular adaptations and cardiovascular health. Although polarized training has been extensively studied in athletic populations, its effects on vascular function in sedentary adults remain insufficiently understood. Thirty participants will be randomly assigned in a 1:1 ratio to either a supervised polarized aerobic training group or a non-exercising control group. The intervention will consist of a 6-week supervised cycle ergometer training program performed three times per week and prescribed according to individual ventilatory thresholds obtained during cardiopulmonary exercise testing. Training sessions will combine low-to-moderate-intensity continuous exercise and high-intensity interval exercise. Participants allocated to the control group will maintain their habitual sedentary lifestyle throughout the study period. The primary outcome will be endothelial function assessed by brachial artery flow-mediated dilation. Secondary outcomes will include arterial stiffness assessed by pulse wave velocity, central haemodynamics, microvascular function, cardiorespiratory fitness, skeletal muscle function, pulmonary function, respiratory muscle strength, and circulating biomarkers related to vascular health. Outcome measures will be assessed at baseline and after completion of the 6-week intervention period. The findings of this study may improve understanding of vascular and systemic adaptations to polarized aerobic training and help inform future exercise-based strategies for cardiovascular risk reduction in apparently healthy sedentary adults.