The direct effect of bathing on R-R interval was examined in six healthy men (mean age, 40±11 years).
Bathing at 37-38°C produced signifficant shortening of mean R-R intervals (mRR) during usual and deep breathing (6times/min), and signifficant decrease of their coefficients of variation (CV; SD/mRR×100) during deep breathing.
In ten minutes after the end of bathing, mRR recovered, but not CV.
These data suggest that the bathing at those temperature might stimulate the sympathetic drive and suppress the parasympathetic drive to the heart.

The finger skin temperatures at ventral tip of both sides were examined in 8 normal subjects and 20 patients with vibration disorder, during one hand 45°C-water immersion test of 10 minutes.
In normal cases, the figer skin temperatures of the immersion side increased immediately and then waved from time to time during the immersion. The mean temperature at the time of 4.5 minutes was significantly higher than those of 2.5 minutes and 8.0 minutes and did not come near the 45°C graduary.
In the patients with vibration disorder who had got Raynauds' phenomenon with in a recent year, the skin temperatures did not so waved as which did in normal cases and became near the 45°C in the later half of the immersion. After the immersion, the warmed skin temperatures returned more slowly to their previous values than the normal cases.
The finger skin temperatures of the non-immersion side showed transient but significant falls initialy and then got up gradualy during the immersion in the normal cases.
In the patients with vibration disorder who had got Raynauds' phenomenon, within a recent year, the mean skin temperature of the non-immersion side was significantly lower than the normal value almost before, through and after the immersion especialy in the later half of the immersion and for several minutes after the immersion. The initial fall of skin temperatures were not so obvious as they were in the normal cases.
These data suggest that the hot water immersion test is useful to asess the peripheral circulatory disturbance in patients with vibration disorder.

This study examined acute effects of hot water immersion on the secretion of human alpha-atrial natriuretic peptide (ANP), cyclic GMP (c-GMP), arginine vasopressin (AVP), plasma renin activity (PRA) and aldosterone in venous blood. Ten healthy subjects (mean age: 20.5yr.) underwent hot water immersion (IM) of 40°C for ten minutes by quiet sitting, which simulates usual bathing among Japanese. ANP rose from 19 to 34pg/ml with the peaked value at ten minutes of IM (p<0.001), and remained signifcantly elevated during 10 to 30 minutes after IM. Then they qradually returned to the pre-immersing level by 50min. c-GMP showed similar timed responeses as ANP. Between those parameters significantly positive linear correlation (p<0.001) was observed. AVP did not change immediately after IM, but tended to rise at 20 minutes after IM. PRA and aldosterone increased in rates of the changes later at 15 to 30 minutes, but less significantly as ANP. Those results suggested that the secretion of ANP by water immersion was enhanced by thermal stimuli in spite of short duration of central hypervolemia by water immersion. Suppressing effects of water immersion on AVP and renin-aldosterone system were small. On the contrary, hot water stimuli exerted rebounding increases on them. c-GMP seemed to be one of the indicative factors relating to the change of ANP.

The effect of underwater exercise on respiratory resistance (Rrs) was examined in 12 patients with chronic obstructive pulmonary disease (COPD). Rrs was measured while the patients were sitting on land with quiet respiration, while immersed in water (at 38°C) up to the upper abdomen and upper chest in standing position, and while sitting on land with quiet respiration after mild underwater exercise. The mean Rrses in each condition were 0.37, 0.37, 0.42, 0.33kp/1/s. Rrs increased by 14% (p<0.005) after immersion in water up to the upper chest and decreased by 12% (p<0.001) after underwater exercise. The change after exercise showed a popitive correlation with FEV_1.0/FVC on spirogram. Although water immersion or underwater exercise of these COPD patients caused a slight load in ventilation, no significant aggravation of the subjective symptom was found.
The above results suggested that uoderwater exercise was beneficial as a physical treatment for mild cases of COPD.

Cold pressor tests were examined on the eight wintering members (mean age 35±SD 4years old) of the 28th Japanese Antarctic Research Expedition to study their autonomic adaptation to local severe cold stress.
Tests were carried out 6 times with 3 month intervals through the expedition.
The first test was done on the ship in the Indian Ocean, on November 24, 1986 (Test-1). The second (Test-2), third (Test-3), fourth (Test-4) and fifth test (Test-5) were done at the Japanese Antarctic Asuka Base on February 24, 1987, May 20, 1987, August 18, 1987 and November 11, 1987, respectively. The last sixth test (Test-6) was done on the ship in the Antarctic Ocean on February 29, 1988.
The left hand was immersed in the ice floated water for three minutes for cold pressor test. Systolic and diastolic blood pressure (SBP, DBP), heart rate (HR) and variation coefficient of R-R intervals (CV_(R-R)) were examined, before immersion (F), at the beginning of immersion (A1), at the end of immersion (A2) and 2 minutes after immersion (A3).
An usual sphygmomanometer was used for blood pressure measuring and
CARDIMAX FX-102A (FUKUDA) was used for electrocardiogram. HR and CV_(R-R) were calculated from each 50 R-R intervals of ECG. Student's paired t-test was used for statistical evaluation.
SBP (A1, A2, A3), DBP (A2) and HR (A1) rose significantly (p<0.05-0.001) in Test-1. The increases in SBP (A3) and DBP (A2) were not observed in Test-2 and those after. The increase in SBP (A1) was observed in Test-2 but not after Test-3. The increase in HR (A1) was observed in Test-2 and Test-4 but not in Test-3 and after Test-5.
CV_(RR) (A1, A3) in Test-2 and CV_(RR) (A2, A3) in Test-4 decreased significantly (p<0.05-0.01). CV _(RR) (F) was relatively higher in these tests than others and was within normal range at the Test-3, Test-5 and Test-6.
The sympathetic adaptation to local severe cold seems to have advanced in 2 months and completed within 5 months in their Antarctic life. The parasympathetic function might have been excited when the sympathetic adaptation was unstable.

Psychological tests were undertaken on the eight wintering members of the 28th Japanese Antarctic Research Expedition (mean age 35±SD 4years old) with about 4 month intervals through the expedition.
The first test was done on the ship to Antarctica on November 24, 1986 (Test-1), and the second (Test-2), the third (Test-3) and the fourth test (Test-4) were done at the Japanese Antarctic Asuka Base on March 28, 1987, July 17, 1987 and October 11, 1987, respectively. The last fifth test (Test-5) was performed on the ship to Japan on February 29, 1988.
For psychological tests, MAS (manifest anxiety scale), CMI (Cornell Medical Index) and SRQ-D (Self-rating Questionaire for Depression) were used.
The mean scores of MAS-A, CMI-T (S, I, J+M-R) showed a tendency to become high in Test-2 and Test-3 and become low after Test-4. The mean scores of SRQ-D exhibited a tendency to become high in Test-3 and the high score continued after Test-4.
The psychological stress seems to have reached a peak point at Test-3, in July, 1987, when was the last session of winter with no sunshine at Antarctic Base.
Some management for mental health might be needed in this season for the wintering members of the Japanese Antarctic Research Expedition.