A study was carried out to examine the effects of water replacement on cardiovascular function during kendo practice in a hot environment. Five male college kendoists performed moderately severe 30-min kendo practice at a WBGT index of about 27°C with and without water intake. For water replacement, the subjects ingested 700 ml water (500 ml before exercise and 200 ml at 15 min after the start of exercise) . Under both conditions, body weight was decreased significantly, and hematocrit and serum total protein concentration were increased significantly after the exercise. With water replacement, the body weight loss induced by the exercise was similar to that under water deprivation. However, the decrease in body weight from the basal body weight, i. e. body weight measured before water intake, was significantly less with water replacement than under water deprivation. There were no significant differences in the percentage increases of hematocrit and serum total protein concentration between the two conditions, although the percentage change in plasma vasopressin concentration was significantly lower with water replacement than without. In the subjects deprived of water, the left ventricular end-diastolic dimension and left atrial dimension were significantly reduced after the exercise, and stroke volume, ejection fraction, and fractional shortening were also decreased significantly. The ratio of left ventricular end-systolic wall stress to left ventricular end-systolic volume index was increased significantly after the exercise without water intake. With water replacement, however, the percentage decreases in cardiac dimensions, stroke volume, ejection fraction, and fractional shortening were significantly lower than those under water deprivation. There was no significant change in the ratio of left ventricular end-systolic wall stress to left ventricular end-systolic volume index before and after the exercise with water intake. It is suggested that 700 ml water replacement before and during kendo exercise in a hot environment prevents depletion of stroke volume and deterioration of cardiovascular function, although it might not improve significantly the plasma volume loss after exercise.

To study the effects of prolonged kendo practice in a hot environment on cardiovascular function, certain hemodynamic parameters were measured in 5 male college kendo fencers before and after 1 hour of kendo practice performed at a dry bulb temperature of 30.4t and wet bulb temperature of 26.2°C After kendo practice, body weight was significantly decreased and both hematocrit and blood viscosity were significantly increased. The left ventricular end-diastolic dimension and the left atrial dimension, measured by echocardiography, were significantly reduced after kendo practice, and stroke volume, ejection fraction, and fractional shortening were also significantly decreased after practice. The same fencers were subjected to lower body negative pressure testing designed to reduce the left ventricular end-diastolic dimension to the same degree as kendo practice, and comparable decreases in stroke volume, ejection fraction, and fractional shortening were observed. The ratio of end-systolic wall stress to end-systolic volume index was significantly increased during both kendo practice and lower body negative pressure testing. We conclude that prolonged kendo practice in a hot environment impairs cardiac pump function by reducing preload in parallel with the decrease in venous return, that myocardial contractility may not deteriorate despite marked hemoconcentration, and that fluid intake during practice may prevent deterioration of cardiovascular function.

To investigate the effect of intense exercise on immunological factors in saliva, we measured secretory immunoglobulin A (sIgA), lactoferrin and fibronectin. We used a reliable saliva collection method that has already been reported. Timed saliva samples were obtained from 16 healthy young males. Samples were collected before, immediately after, 1 day after and 5 days after endurance running (42.195 km) . The concentrations (μg/ml) of sIgA, lactoferrin and fibronectin were measured by ELISA, and the secretion rates (μg/min) of each were calculated. Immediately after the exercise, the concentration of total protein in saliva increased significantly, but the sIgA secretion rate decreased to 53%. The secretion rates of both lactoferrin and fibronectin did not change significantly. The local immune system plays an important role in mucosal surface defense against upper respiratory tract infection. The sIgA level in the oral cavity was temporarily decreased after intense exercise. A decreased sIgA secretion rate might partly explain the increased susceptibility to upper respiratory tract infection after endurance exercise.

It is generally accepted that secretory immunoglobulin A (sIgA) is a major effector of local immunity in the oral cavity. The salivary sIgA level is known to be temporarily decreased after an acute single bout of intense exercise. On the other hand, the effect of continuous exercise training on salivary sIgA has been controversial. In the present study, we collected timed saliva samples from collegiate kendoists using the reliable saliva collection method that has already been reported. The collection was performed before, during and after a traditional high-intensity 10-day training camp during the coldest part of the winter. We investigated the effect of repetitious intense exercise training on resting sIgA levels in saliva.
The subjects were 19 males and 8 females (age: 19.9±0.5 years) who took part in the camp. We obtained saliva samples before the camp, on the first and the 10th days of the camp, and 4 and 10 days after the camp at 5 p. m. The concentration of sIgA was measured by ELISA, and the sIgA secretion rate was calculated.
The resting sIgA secretion rate decreased significantly during the camp. It remained at a lower level 4 and 10 days after the camp compared to the initial level, although it tended to recover gradually. Prolonged suppression of the resting sIgA secretion rate during a traditional winter kendo training camp might be induced by repetition of high-intensity training.