One Year of Endurance Exercise Training Does not Improve Vascular Function in Non-Trained Limbs in Healthy...

Regular endurance exercise is widely recognized for its cardiovascular health benefits, with improvements in vascular function particularly relevant for populations with impaired vascular health. However, it is unknown whether prolonged adherence to endurance exercise training in sedentary but healthy young individuals can improve vascular function in non-active limbs. This study investigated the impact of 1 year of supervised endurance exercise on vascular function in previously untrained, healthy young participants. Twelve healthy young adults (25 ± 4 years) were included in a 12-month supervised cycling program, during which maximal aerobic capacity (V̇O₂max) and vascular function were assessed at baseline and after 1, 4, 6, and 12 months of training. Forearm vascular function was assessed using intra-arterial infusions of acetylcholine (ACh; endothelium-dependent vasodilation) and sodium nitroprusside (SNP; endothelium-independent vasodilation) and flow-mediated dilation (FMD). Seven participants completed the 12-month protocol and showed no change in endothelium-dependent or independent vasodilation assessment at any time point during the 12-month training period (p > 0.05), despite a substantial increase in aerobic capacity during the first 6 months of training (baseline: 40.3 vs. 6 months: 50.8 mL·min^-1·kg^-1, p = 0.001), with no further change observed from 6 to 12 months (51.3 mL·min^-1·kg^-1, p > 0.05). One year of endurance exercise training improved aerobic capacity without improving vascular function in non-trained limbs in previously untrained but healthy individuals. These findings support the idea that vascular adaptations to endurance training may reflect a region-specific training effect with vascular remodeling confined to actively engaged limbs and, thus, undetectable in vascular territories not directly involved in exercise training.