Résumé
High-intensity interval exercise leads to greater improvements in the vascular endothelial function than continuous exercise at moderate intensity. However, few studies have been performed on the effects of repetition exercise consisting of high-intensity exercise followed by complete rest on the arterial function. Therefore, the purpose of this study was to investigate the effects of repetition exercise on the vascular endothelial function determined by flow-mediated vasodilation (FMD). Eleven healthy male subjects completed two exercise sessions on a cycle ergometer in a counterbalanced order. The exercise sessions were 20 min cycling at 50% maximal work rate (Wmax) (continuous exercise, CE) and 20 × 20-sec intervals at 100%Wmax interspersed with 40-sec intervals at complete rest (repetition exercise, RE). Before and after each protocol, the brachial systolic and diastolic blood pressure were measured in the supine position. Relative FMD was assessed at rest and 30 and 60 min after each exercise regimen, and then the normalized FMD (nFMD) was calculated from the peak shear rate. The FMD significantly increased 30 min after RE (8.2 ± 1.5% to 11.5 ± 3.1%, p<0.01) and non-significantly increased 30 min after CE (7.5 ± 1.6% to 8.1 ± 2.1%, n.s.) before returning to baseline at 60 min after both exercise regimens. The FMD value at 30 min after RE was significantly greater than that at 30 min after CE (p<0.01). The nFMD (a.u.) significantly increased 30 min after RE (1.38 ± 0.64 to 2.00 ± 0.94, p<0.05) and non-significantly increased 30 min after CE (1.20 ± 0.54 to 1.49 ± 0.57, n.s.) before returning to baseline at 60 min after both exercise regimens. These results suggest that repetition exercise may lead to an acute improvement in the vascular endothelial function.
Résumé
Endurance exercises such as cycling and running are useful for improving the arterial function and preventing cardiovascular disease (CVD). However, subjects suffering from spinal cord injury (SCI) or lower limb osteoarthritis (OA) cannot perform these kinds of lower limb exercises. Recently, electrical muscle stimulation (EMS) has been shown to be able to increase the muscle strength and blood flow and improve the peripheral circulation. Arm-cranking exercises with EMS may therefore be able to reduce the risk of CVD for patients with SCI and lower OA. However, this point has not been fully clarified. The purpose of this study was to assess the effect of submaximal arm-cranking exercise with EMS on arterial stiffness. Ten healthy young subjects performed submaximal arm-cranking exercise alone (A) and submaximal arm-cranking exercise with EMS (A+E). In the A+E trial, the submaximal arm-cranking exercise was performed at 30%VO2 max for 20 min while EMS was applied to their thigh and calf muscles during the exercise. The brachial-ankle pulse wave velocity (ba-PWV), systolic and diastolic blood pressure (SBP/DBP) and heart rate (HR) were measured before and after each exercise. Immediately after the exercise session, the HR of the subjects in the A+E trial was significantly elevated in comparison to those in the A trial. The SBP and DBP did not differ between the two trials to a statistically significant extent. In the A+E trial, the ba-PWV was significantly reduced immediately after exercise in comparison to the A trial (1082.6 ± 105.9 cm·sec-1 vs. 1191.7 ± 86.7 cm·sec-1, p < 0.05). These findings suggest that arm-cranking exercise with EMS reduces arterial stiffness and might be useful for reducing the risk of CVD.
Résumé
<p>High-intensity interval exercise (IE) leads to greater improvements in the arterial function than continuous exercise at moderate intensity (CE). However, few studies have been performed on the effects of the repetition exercise (RE) on the vascular endothelial function. The purpose of this study was to compare the effects of CE vs. IE vs. RE during aerobic exercise on the vascular endothelial function determined by flow-mediated vasodilation (FMD). Ten healthy male subjects randomly performed 3 trials as follows: CE (20-min cycling at 50%W<sub>max</sub>), IE (10 × 1-min intervals cycling at 75%W<sub>max</sub> interspersed with 1-min intervals cycling at 25%W<sub>max</sub>), and RE (30 × 20-sec intervals cycling at 100%W<sub>max</sub> interspersed with 20-sec intervals at rest). FMD was assessed at rest and 30 and 60 min after each exercise, and then the normalized FMD (nFMD) was calculated from the peak shear rate. The nFMD (a.u.) significant increased 30 min after IE (1.2 ± 0.2 to 3.0 ± 1.0, p<0.05) and increased 30 min after CE (1.0 ± 0.2 to 1.4 ± 0.2, n.s.) and returned to baseline at 60 min after both exercises, while the nFMD decreased 30 min after RE (1.3 ± 0.2 to 1.2 ± 0.1, n.s.) and was sustained at 60 min. The nFMD value at 30 min after IE was significantly greater than that at 30 min after RE (3.0 ± 1.0 versus 1.2 ± 0.1, p<0.05). These results suggest that RE may lead to a less improvement in the vascular endothelial function than CE and IE.</p>
Résumé
Interval training has a beneficial effect for treating the cardiovascular disease. However, it is not clarify the effects of different exercise intensity and duration on arterial function. In the present study, we evaluated the effect of acute short-term high and moderate-intensity interval exercise on pulse wave velocity. Thirteen healthy men were randomly assigned to perform both acute interval exercise (IE; cycling for 24.6 min at 80%VO<sub>2</sub>max and 50%VO<sub>2</sub>max) and acute continuous moderate-intensity exercise (CME; cycling for 30 min at 50%VO<sub>2</sub>max). The IE and CME protocols were designed such that the exercises resulted in the same workload during each session. The brachial systolic and diastolic blood pressure (SBP and DBP), and brachial to ankle pulse wave velocity (baPWV) were obtained in the supine position using an automatic pulse wave form analyzer at pre- and post-exercise. In IE, baPWV at post-exercise decreased significantly compared with pre-exercise value (1181.9±119.2 cm・sec<sup>-1</sup> vs. 1108.4±109.4 cm・sec<sup>-1</sup>, p<0.01). In CME, however, it was not significantly different between pre- and post-exercise values (1173.5±137.1 cm・sec<sup>-1</sup> vs. 1164.8±96.0 cm・sec<sup>-1</sup>, p=ns). No significant differences in SBP and DBP were found both protocols. These results suggest that acute short-term high and moderate-intensity interval exercise was more effective in reducing baPWV compared with acute continuous exercise.