Purpose: Age-associated changes in arterial structure and function increase risk of cardiovascular disease. Previous studies have found that the body temperature response might influence acute changes in arterial stiffness after exercise. However, the relationship between increased body temperature during warm bathing and arterial stiffness has not been clarified. Therefore, the present study aimed to determine the effects of increases in body temperature by bathing in warm water on arterial stiffness in elderly subjects.  Methods: Healthy elderly 8 subjects (8 males, mean age ± standard error: 61.1 ± 1.1 years) bathed in water at 35°C, 38°C, and 40°C for 15 min. Carotid-femoral pulse wave velocity (aortic PWV) and femoral-ankle PWV (leg PWV), blood pressure, heart rate, and rectal temperature were measured at baseline and at 30 and 60 min after bathing, in a quiet and air-conditioned room at the same time in the morning.  Results: Rectal temperature was significantly increased at 30 and 60 min after bathing at 38°C and 40°C, whereas leg PWV significantly decreased. Heart rate significantly increased at 30 and 60 min after bathing at 40°C. Blood pressure did not change after bathing at any temperature.  Conclusion: The present study showed that leg PWV significantly decreased in elderly subjects after bathing at 40°C, but not at 35°C and 38°C. However the underlying mechanism of the decrease remains unknown and these effects might depend on increased body temperature. Thus, it is suggested that warm bathing might affect the decrease in leg arterial stiffness.

Objective: Aerobic exercise on land decreases arterial stiffness, however, the effect of exercise in water on arterial stiffness has not been clear. This study investigated the effect of a 15-min cycling exercise on land and that in water on pulse wave velocity (PWV) as an index of arterial stiffness. Methods: Nine healthy young men were randomly performed exercise on land and exercise in water equivalent to 50% of each maximum oxygen uptake on separate days. The PWV from carotid to femoral artery (aortic PWV) and femoral to posterior tibial artery (leg PWV) were measured at baseline and 15, 30, 60 min after exercise. Results: The heart rate in water was significantly lower during exercise than that on land. In addition, the carbon dioxide output and respiratory exchange ratio during exercise were significantly greater in water. Body temperature increased after the exercise on land but decreased after the exercise in water. Although the aortic PWV and leg PWV decreased concomitantly with decrease in SBP and DBP after the exercise on land, there were no significant changes after the exercise in water. Conclusion: Although acute exercise on land decreased arterial stiffness after exercise, acute exercise in water of the same exercise load did not. The differences in body temperature and blood pressure after exercise may result in diverse arterial stiffness after exercise.

Objective: To assess LV function during and after warm-water immersion in elderly subjects. Concomitantly with aging, left ventricular (LV) diastolic function decreases. According to results of previous studies, warm-water immersion improves cardiac function in patients with cardiovascular disease. However, its effect in normal elderly is still unclear. Material and Methods: To investigate the effect of acute warm-water immersion on LV function with Doppler echocardiography in elderly subjects, subjects underwent immersion in 40°C water to nipple level for 15 min. Results: The stroke volume (SV), cardiac output (CO), and LV ejection fraction (LVEF) increased significantly during and after warm-water immersion. The ratio of early diastolic mitral inflow (E) and early diastolic mitral annular tissue velocity (E’), an index LV of filling pressure, did not increase during or after immersion. Some LV diastolic function indexes such as E increased during immersion, but after immersion indexes of diastolic function were not different relative to before immersion. Conclusion: These results suggest that LV diastolic function did not correspond to the increased systolic function in elderly subjects, so it might suggest that the LV contraction-relaxation coupling may be interrupted in elderly.