Effects of Low to Moderate-Intensity Interval Exercise on Arterial Stiffness

Abstract

Recently, it has been reported that high-intensity interval exercise effectively decreases arterial stiffness. However, high-intensity exercise is also associated with some cardiovascular risks, especially for unhealthy people. Interval exercise has the advantage in which exercise-induced subjective fatigue is weakened when compared with continuous exercise. Therefore, if the beneficial effects on arterial stiffness of low to moderate intensity exercise can be made clear, it could be adopted as a new exercise prescription. PURPOSE: The present study aimed to examine and compare the effects of two types of exercise (continuous vs. interval) at low to moderate-intensity on systemic arterial stiffness. METHODS: Eight young men (age, 19.2 ± 0.2 years; height, 172 ± 1.1 cm; weight, 64.4 ± 2.8 kg; body mass index, 21.5 ± 0.8 kg/m2) participated in this study. All subjects were healthy, physically active, unmedicated, non-smokers, and normotensive (blood pressure <140/90 mmHg). They participated in the following four cycle ergometer trials in random order, with each trial separated by at least a day: a trial with a single, 30-min bout of continuous exercise (CE) and a trial with three 10-min bouts of interval exercise separated by 10-min periods of rest (IE) each at 40% and 60% of VO2max. Arterial stiffness was evaluated 2 hours after exercise by cardio-ankle vascular index (CAVI). RESULTS: Although arterial stiffness during the recovery period did not change after CE and IE at 40% VO2max compared with the baseline, it significantly decreased from the baseline in both exercise conditions at 60% VO2max immediately after each exercise (CE, 5.7 ± 0.2 vs. 4.4 ± 0.2, P < 0.05; IE, 5.7 ± 0.2 vs. 4.8 ± 0.1, P < 0.05). Moreover, the decreased CAVI value after exercise in CE was maintained until 30 min after exercise (5.1 ± 0.1, P < 0.05 vs. baseline), and the value was significantly lower than IE (5.1 ± 0.1 vs. 5.4 ± 0.1, P < 0.05). The rating of perceived exertion during exercise was significantly lower in IE than CE in both exercise intensities (P < 0.05). CONCLUSIONS: These results suggest that aerobic exercise at 40% of VO2max was not enough to reduce systemic arterial stiffness for young healthy men. However, it was found that the reducing effect of systemic arterial stiffness after exercise at 60% of VO2max was more effective in CE than IE.