Acute Exercise Increases Systemic Arterial Compliance after 6-Month Exercise Training in Older Women

377 Hypertens Res Vol.31 (2008) No.2 p.377-381 Original Article Acute Exercise Increases Systemic Arterial Compliance after 6-Month Exercise Training in Older Women Seiji MAEDA1),2), Takumi TANABE1), Takeshi OTSUKI2), Jun SUGAWARA3), Ryuichi AJISAKA1), and Mitsuo MATSUDA2) High physical activity or aerobic exercise training increases central arterial distensibility in older humans. However, the effect of a single bout of exercise on central arterial distensibility in older humans is unknown. Furthermore, the effect of exercise training on central arterial distensibility during exercise is unclear. We investigated whether systemic arterial compliance (SAC) changes after acute exercise in older humans, and, if so, whether this change in SAC is enhanced by aerobic exercise training. Seven untrained older women (61–69 years old) participated in a 6-month exercise intervention study. We measured SAC after acute exercise (cycling exercise at 80% of their individual ventilatory threshold for 30 min) before and after 6 months of aerobic exercise training. After exercise training, the individual ventilatory threshold was significantly increased. In addition, both the SAC at rest and that 30 min after acute exercise were significantly increased after the exercise training program. Before exercise training, there was no significant increase in SAC after acute exercise, whereas, after exercise training, the SAC was significantly increased 30 min after acute exercise. The present study suggests that, after aerobic exercise training, SAC increases after acute exercise in older humans, and that the SAC at rest and after acute exercise is enhanced by aerobic exercise training, thereby causing an effective adaptation in increase in cardiac output during exercise. (Hypertens Res 2008; 31: 377–381) Key Words: systemic arterial compliance, aging, acute exercise, exercise training Introduction Large arteries, and central arteries in particular, act as a conduit delivering blood to the tissues and organs, and have a buffering action to level off fluctuations in blood pressure created by cardiac pulsation and intermittent blood flow. A decreased arterial distensibility results in a decline in this buffering capacity, causing increases in systolic blood pressure and left ventricular afterload. The arterial distensibility decreases with advancing age (1, 2). Several studies have reported that central arterial distensibility is higher in physically active humans compared with sedentary humans (2–9). Furthermore, aerobic exercise training induces an elevation of central arterial distensibility (10–13). Many studies have reported that high physical activity or aerobic exercise training induced an increase in central arterial distensibility (2–13). However, there have been few studies on the effects of a single bout of exercise on central arterial distensibility. Kingwell et al. (14) reported that sys- From the 1)Institute of Health and Sport Sciences and 2)Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Japan; and 3) Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan. This work was supported by Grants-in-Aid for Scientific Research (18300215, 18650186) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. Address for Reprints: Seiji Maeda, Ph.D., Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba 305–8577, Japan. E-mail: Received April 26, 2007; Accepted in revised form September 13, 2007. 378 Hypertens Res Vol. 31, No. 2 (2008) Table 1. Age, Height, Body Weight, and BMI before and after Exercise Training in Older Women After training 64±4 152±5 51±6 22±3 — — 51±6 22±3 BMI, body mass index. Values are means±SD. temic arterial compliance (SAC) increased 30 min after acute exercise in their young human subjects. This finding suggests that a single bout of exercise increases SAC, and this elevation may effectively regulate the increase in cardiac output during exercise. However, the effect of acute exercise on SAC in older humans is unknown. Furthermore, the effect of exercise training on SAC during exercise is unclear. We hypothesized that SAC increases after acute exercise, even in older humans who have decreased arterial distensibility, because the elevated SAC may effectively regulate the increase in cardiac output during exercise, and that the acute exercise–induced increase in SAC is reinforced by aerobic exercise training, thereby causing an effective adaptation in increase in cardiac output during exercise. To test our hypothesis, we measured SAC after acute exercise before and after 6 months of aerobic exercise training in older women. Our findings may be helpful to establish guidelines for the use of aerobic exercise training to help prevent cardiovascular diseases in older humans. Methods Subjects Seven untrained older women (61–69 years old) participated in an exercise intervention study. None of the participants had a history of smoking, and none were currently taking any medications. All subjects were free from the signs and symptoms of any overt chronic diseases. The study was approved by the Ethical Committees of the Institute of Health and Sport Sciences of the University of Tsukuba. The study conformed with the principles outlined in the Helsinki Declaration, and all subjects provided their written informed consent before inclusion in the study. Experimental Protocol All seven subjects completed an exercise intervention study. Ventilatory threshold (VT), blood pressure, and SAC were measured before and after 6 months of aerobic exercise training. Blood pressure and SAC were measured before and 30 min after acute exercise. Before they were tested, subjects were asked to refrain from alcohol and caffeine consumption and intense physical activity (exercise) for 24 h to avoid pos- 1200 Ventilatory threshold Age, years Height, cm Body weight, kg BMI, kg/m2 Before training p< 0.01 (mL/min) 1000 800 600 400 200 0 Before training After training Fig. 1. Individual ventilatory threshold during a cycle exercise test before and after 6 months of exercise training in older women (n= 7). Values are the means ± SD. sible acute effects on exercise capacity, blood pressure, and arterial distensibility. All measurements were performed at a constant room temperature (25°C). Exercise Test, Acute Exercise, and Exercise Training The subjects performed a symptom-limited ramp-fashion cycling exercise (after 2 min at 20 W, with 10-W increases every 1 min) until they felt exhausted or reached 85% of the age-predicted maximal heart rate, before and after the exercise training program. Their individual VT was calculated by using regression analysis of the slopes of CO2 production, O2 uptake, and minute ventilation plots (15–18). Before and after the 6-month exercise training program, the subjects performed a stead (...truncated)