Impact of a single bout of high-intensity interval exercise on lower limb vascular function in young triathletes and sedentary men

This study aimed to compare the acute changes in lower limb arterial function, left ventricular characteristics, and blood pressure following high-intensity interval cycling exercise in young male triathletes and sedentary adults, addressing whether habitual training influences vascular responses immediately after exercise.Six male triathletes and nine sedentary male adults performed 33 minutes of high-intensity interval cycling exercise, consisting of alternating moderate-intensity (3 minutes) and high-intensity (4 minutes) intervals.Lower limb arterial indices, left ventricular parameters, and blood pressure were assessed at baseline, immediately post-exercise and 1 and 2 hours after exercise, using ultrasound imaging and blood pressure analyses.At rest, triathletes exhibited significantly greater left ventricular end-diastolic volume, stroke volume, and superficial femoral artery diameter than sedentary participants.In the linear mixed model analysis, a significant global group × time interaction among lower-limb hemodynamic indices was observed only for superficial femoral artery vascular conductance.However, planned post hoc analyses showed that lower-limb hemodynamic indices, including superficial femoral artery blood flow and vascular conductance, were higher immediately after exercise in triathletes than in the sedentary group, whereas no group differences were observed at later time points.Conversely, sedentary participants experienced greater increases in systolic blood pressure and pulse pressure immediately after exercising.This study suggests that triathletes may exhibit greater lower limb arterial responses immediately following high-intensity interval exercise compared with sedentary participants.These findings suggest that greater lower-limb blood supply during the early recovery period after high-intensity exercise may represent a vascular feature associated with the habitual training of triathletes.