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[References: 47 tit.)]

Purpose Both constant and intermittent acute aerobic exercises have been found to decrease arterial stiffness. However, direct comparisons of these two types of exercise are sparse. It is not known which type of exercise has the greatest effect. Methods We evaluated the haemodynamic responses in 15 males (age 48.5±1.3 years; BMI 27.5±0.8 kg m-2) following acute constant (CE) and intermittent cycling exercise (IE). Duration and heart rate were matched during both exercises (131.8±3.2 bpm for CE and 132.0±3.1 bpm for IE). Central and peripheral arterial stiffness was assessed through pulse wave velocity (PWV). Plasma concentrations of nitric oxide (NO), atrial natriuretic peptide (ANP), blood lactate, noradrenaline, and adrenaline were measured before and after each exercise. Results Central (+1.8±7.4 and -6.5±6.8% for CE and IE) and upper limb PWV (+2.7±6.2 and -8±4.6% for CE and IE) were not significantly altered although a small decrease (small effect size) was observed after IE. However, lower limb PWV significantly decreased after exercises (-7.3±5.7 and -15.9±4% after CE and IE), with a larger effect after IE. Conclusions Greater decrease in lower limb PWV occurred after IE despite greater heart rate. This may be due to the higher blood levels of lactate during IE, while NO, ANP, noradrenaline, and adrenaline levels remained not statistically different from CE. These results underlined the importance of lactate in triggering the post-exercise vascular response to exercise, as well as its regional characteristic.