Characteristics of Aquatic Exercise / 日本温泉気候物理医学会雑誌

The purpose of this lecture is to introduce how aquatic exercise is an attractive training method, especially for maintaining the cardiovascular fitness, during recovery from musculos-keletal injuries of the lower legs and/or from obesity. Though the energy expenditure of vertical movement in water is less than that on land due to the effect of buoyance, walking/running in water increases the energy metabolism largely enough to maintain the cardiovascular fitness level. In addition, water running on the spot with flotation device is capable of eliciting metabolic responses comparable to treadmill running on land. Therefore, comfortable and useful facilities for aquatic exercise should be constructed in each province for both healthy and injured persons to maintain and improve their cardiovascular fitness.

The explosive leg extensor power output and its evaluation with the function of sex and age / 体力科学

The explosive power output of both legs during extension movement was assessed in 271 male (aged 16-84 yr) and 248 female (aged 16-82 yr) subjects, and the table of evaluation for the value obtained was prepared with the function of sex and age. From a sitting position on a seat, leg extension movement was performed toward the foot plate in the forward, to which the body mass of each subject was applied as a resistance. The reliability of the power measurement was ascertained from the result that the coefficients of variation were under 5 x 10<SUP>-2</SUP> when the power output of 6 subjects was measured once a day for 10 days. On both sexes, the power output per body mass declined linearly with age. The regression equations between age (x) and the power output per body mass (y) were as follows.<BR>male: y=-0.22 x+28.38 (r=.659, n=271; p<0.001)<BR>female: y=-0.13 x+18.36 (r=.583, n=248; p<0.001)<BR>For all groups classified by 10 years, the male indicated greater value than the female in corresponding groups. The ratio of the value for the female relative to that for the male was between 64.8% and 72, 0%. These results suggested that the power output for the male decreased at a higher rate, and the sex difference of it decreased as the age increased.

Effect of exercise at ventilatory threshold on magnitude and duration of excess post-exercise O2 consumption / 体力科学

Resting O<SUB>2</SUB> consumption following exercise at ventilatory threshold (VT) intensity was measured in order to investigate the magnitude and duration of excess post-exercise O<SUB>2</SUB> consumption in untrained men. Nine untrained males (mean age 24.8±1.5 years) exercised for one hour at VT intensity (58.2±1.7% of VO<SUB>2</SUB>max) on a cycle ergometer, and then rested for 12 h sitting in a comfortable armchair (post-exercise) . On a separate day the subjects rested for 12 h but without preceding exercise (non-exercise) . O<SUB>2</SUB> uptake (VO<SUB>2</SUB>) and heart rate (HR) were measured for 5 min every 30 min throughout the 12 h rest period and again at 24 h following the exercise. High-carbohydrate meals (carbohydrate 112.8±5.1 g, protein 9.7±0.4 g, fat 1.8±0.1 g) were given to the subjects at 2, 7 and 12 h following the exercise. The total energy intake per day was 1591.7±71.8 kcal. V0<SUB>2</SUB> and HR were significantly higher, and respiratory quotient (RQ) was significantly lower at most of the measured time-points for post-exercise than for non-exercise. Total energy consumption for the 12 h rest period was 957.3±25.5 kcal for post-exercise and 840.3±15.8 kcal for non-exercise, respectively. After 24 h no difference was observed in VO<SUB>2</SUB> and HR between post-exercise and non-exercise, but RQ was significantly lower in the former than in the latter (0.86±0.05 vs. 0.90±0.04, p<0.05) . These results suggest that exercise for one hour at VT intensity enhances resting VO<SUB>2</SUB> for at least 12 h, and elevates the rate of fat utilization for at least 24 h.

Estimation of body fat by near infrared spectroscopic technique / 体力科学

Near infrared spectroscopy has been used to determine the chemical composition of food stuffs, i, e., the protein, fat, and moisture content. Recently in the U. S. A, this technique was applied to the estimation of human body composition, and a portable instrument was developed. This study was designed to determine the prediction equation of body fat for Japanese people. 69 men and 52 women, aged 18 to 58 years, covering a wide range of percent fat levels, physiques, physical activity levels, had body fat estimated by hydrostatic weighing (HW), skinfold thicknesses (SF) and near infrared spectroscopy. Near infrared interactance spectra were measured on the anterior midline of the biceps halfway (between the anticubital fossa and acromion), the spectral data from which gave best correlation with HW and SF compared the other sites, using the wavelength of 947 nm. The spectral values and percent fat values obtained from HW about 1/2 of subjects were used to develop a prediction equation. This equation was then used to predict % body fat of the other 1/2 subjects. The correlation coefficient between % body fat as predicted by the near infrared method and as predicted by the HW technique was 0.88 (p<0.001, SEE=3.2) . This correlation value was similar to the value between % body fat as predicted by HW and as predicted by SF. In the American data, the correlation coefficients were higher when the other variables were added ; height, weight, age, but in the Japanese they did not almost change even when the other variables were added. There was not a difference between the spectra of right and left arm values. In the results, the prediction equation of % body fat for the Japanese population was determined as follows:<BR>% body fat =54.14-29.47× (the spectral data at 947 nm) [r=0.88, p<0.001, SEE=3.2] (for right arm) .

Comparison of equilibrium and extrapolation methods of CO2 rebreathing for determining the mixed venous CO2 pressure / 体力科学

The purpose of this study was to compare two methods of CO<SUB>2</SUB> rebreathing-equilibrium method (Collier, 1965) and extrapolation method (Defares, 1958) -for determining the mixed venous CO<SUB>2</SUB> pressure (PvCO<SUB>2</SUB>) during exercise. Following a sitting rest for 5 min, five healthy males performed upright bicycle ergometer exercises with work rate of 100 and 150W for 5 min. During both at rest and in exercise, PvCO<SUB>2</SUB> was measured twice to evaluate the reproducibility of both methods. The equilibrium method was performed according to that by Jones & Campbell (1982) . In the extrapolation method, instead of using the graphical analysis described by Klauaen (1965), PvCO<SUB>2</SUB> was directly calculated by applying the modified exponential equation (Defares, 1958) . In the duplicate tests, coefficient of variation was lower while correlation coefficient was higher, with increasing work rate in both methods. It was noted that these tendencies were more pronounced in the extrapolation method than in the equilibrium method. It was concluded that in contrast to the results of Auchincloss et al. (1980), the extrapolation method was more reproducible than the equilibrium method.

Altitude training for improving swimming performance at sea level / 体力科学

The present study was designed to investigate the effects of low altitude training on swimming performance with setting the same duration (3-wk) and the same level of altitude (2, 300m) . Eight male (Gm<SUB>1</SUB>) swimmers aged 13 to 19 years and four male (Gm<SUB>2</SUB>) and eight female (Gf<SUB>2</SUB>) swimmers aged 13 to 18 years sent to Mexico City, and they conducted swimming work outs. All of them were top Japanese swimmers of various events. They repeated the swimming training twice a day continuously for four days with one day rest. Hemoglobin concentration (Hb), red blood cell count (RBC) and hematocrit (Hct) were determined before, during and after the altitude training several times. The values of Hb, RBC and Hct of all three groups increased significantly from before training to after training except Hb in Gm<SUB>1</SUB>. On the other hand, these three variables did not necessarily increase during the altitude training. Gm<SUB>1</SUB> and Gf<SUB>2</SUB> tended to increase Hb and RBC during the training. As for swimming performance at sea level, the individual best swimming records were improved significantly in 200m events, but not in 100m events in Gm<SUB>1</SUB>. Therefore, it may be concluded that 3-wk altitude (2, 300m) training possibly improve swimming performance in the events equal to or longer than 200m at sea level.

Relationship between maximal aerobic power and the fatiguability during repeated isokinetic contractions / 体力科学

To investigate the relationship between maximal aerobic power (VO<SUB>2</SUB>max) and fatigu-abililty during repeated isokinetic contractions, 39 male speed skaters (mean 20.8 years) served as subjects. They were divided into two groups according to their VO<SUB>2</SUB>max levels ; high VO<SUB>2</SUB>max group (HI, n=19) and low VO<SUB>2</SUB>max group (LO, n=20) . VO<SUB>2</SUB>max was measured in all subjects during incremental exercise on a bicycle ergometer and body composition was determined by densitometry. Cross-sectional area (CSA) of the leg extensor muscles was evaluated using ultrasonic method. Fatiguability was assessed during the fatigue test consisting of 50 repeated isokinetic knee-extensions at an angular velocity of 180 deg⋅sec<SUP>-1</SUP>. Remark-able findings include :<BR>1. There were no significant differences in body composition and thigh composition between the two groups except for high subcutaneous fat in group LO.<BR>2. There were significant differences in VO<SUB>2</SUB>max between group HI (3.93<I>l</I>⋅min<SUP>-1</SUP>, 67.3 m<I>l</I>⋅kg LBM<SUP>-1</SUP>⋅min<SUP>-1</SUP>) and group LO (3.59<I>l</I>⋅min<SUP>-1</SUP>, 59.9 m<I>l</I>⋅kg LBM<SUP>-1</SUP>⋅min<SUP>-1</SUP>) .<BR>3. In the fatigue test, the average initial values did not differ, however, the average final values were higher in group HI. Also, a significant difference was observed in per unit CSA between the two groups.<BR>4. Higher peak forces (kg) in group HI were observed after the initial 30 dymanic contractions per unit CSA and % of peak values (% peak force) .<BR>5. A close relationship was demonstrated between VO<SUB>2</SUB>max per LBM and the fatigue index, i. e., the mean decline in peak force with 50 contractions (r=-0.37, p<0.05) .<BR>Based on the present findings it is suggested that maximal aerobic power (VO<SUB>2</SUB>max) influences the rate of fatigue development even during short-term maximal isokinetic contractions, and that there may be some physiological cross-linkages between cardiopulmonary regulation and the metabolic properties of skeletal muscles. This finding is also in conformity with earlier results indicating the importance of oxygen delivery as a limiting factor for muscle performance.

Lactate oxidation in rats after strenuous exercise / 体力科学

Oxidation of lactate at rest (RE, n=4), or after short strenuous exercise (EX, n=6) was investigated in rats. Food and water were given ad libitum before experiment. In EX, rats ran to exhaustion at the speed of 80-100 m·min<SUP>-1</SUP>. Immediately after exercise, 4 μCi of (U-<SUP>14</SUP>C) lactate was injected into aorta through an indwelling catheter. In RE, (U-<SUP>14</SUP>C) lactate was injected into the rats at rest. Expired gas was collected by a Brooks type bottomless chamber on treadmill belt for 120 min. In EX, exercise duration was 109±18 sec (mean±SE), and maximum blood lactate concentration after the exercise was 23.7±2.1 mM (mean±SE) . Cumulative percent recovery of <SUP>14</SUP>C as <SUP>14</SUP>CO<SUB>2</SUB> for 120 min was 48.5±2.8% for EX and 61.7±0.9% for RE (mean±SE) . Significant difference was found between these two rates (p<0.01) . After 50 min of recovery, mean volume of <SUP>14</SUP>CO<SUB>2</SUB> expired per min in RE was significantly greater than that in EX (p<0.01) . Mean volume of <SUP>14</SUP>CO<SUB>2</SUB> expired per min per VCO<SUB>2</SUB> in RE was always greater than that in EX, and significant difference was found at 7.5 min of recovery (p<0.01) . It is concluded that although the rate of recovery of <SUP>14</SUP>C as <SUP>14</SUP>CO<SUB>2 </SUB>after exercise is lower than that at rest, the major pathway of lactate metabolism after short strenuous exercise is oxidation.

ASTHMATIC CHILDREN AND SWIMMING / 体力科学

In 31 asthmatic children, we investigated the change of the structure on the time of living, an amount of exercise by pedmeter and measured pulmonary ventilatory function during 28 weeks swimming training.<BR>The result showed 58.07% of contribution factor to the structure on the time of living on children with asthma and dynamic play time after school were significantly shorter in asthmatic than non-asthmatic children (p<0.05) . After 28 weeks, we could not find any significantly differences of dynamic play time between asthmatic and nonasthmatic children.<BR>An amount of exercise in daily life from the point of view of walking step number by pedmeter were significantly less in aged 6-9 years boys and girls, and aged 10-12 years boys than non-asthmatic children (respectively, p<0.05, p<0.01) . However, after 28 weeks, we could not find any differences between asthmatic and non-asthmatic children.<BR>Forced vital capacity (FVC) and rate of forced expiratory volume on one second (% FEV<SUB>1.0</SUB>) were increased after 28 weeks than the begining of swimming, and we found the strength of their breathing muscles.<BR>On according to perform the great swimming distances (averages 220m in boys, 325m in girls), all asthmatic children became very lively and actively.

CHANGES OF BODY TEMPERATURE AT REST AND DURING EXERCISE IN WATER / 体力科学

The metabolic rate, HR and thermal responses of 26 children, aged 7-8 years (6 boys, 7 girls) and aged 9-11 years (7 boys, 6 girls), were measured during head-out immersion in water. In the water bath, a bicycle ergometer was set and water temperature wes maintained at 26±1°C. Thirty minutes measurements of heat production (cal⋅min<SUP>-1</SUP>⋅m<SUP>-2</SUP>), HR, rectal (T<SUB>re</SUB>) and skin (T<SUB>sk</SUB>) temperatures were obtained under experimental conditions of resting and bicycling in water.<BR>The rate of decrease in HR and T<SUB>re</SUB> were significantly greater in the younger group than the older, irrespective of sex, in resting condition (P<0.001, P<0.01, respectively), but any differences could not be found in bicycling condition.<BR>Heat conductanc (K) from body surface were calculated. In resting condition in water, older girl group showed K=94.1 (cal⋅m<SUP>2</SUP>⋅°C ⋅min<SUP>-1</SUP>) and younger boy group K=142.2 and in bicycling condition in water they were 213.8 and 276.9, respectively.

RESPIRATORY-CARDIOVASCULAR SYSTEM OF OBESE MEN RELATED TO VO<SUB>2max</SUB> AND BODY COMPOSITION / 体力科学

In order to investigate an effect of the excess fat of obese men on the respiratory-cardiovascular system, VO<SUB>2</SUB>max was measured for seven obese, 16 ordinary and seven lean men. All subjects were university students, ages 18 to 25 years. Body composition was determined by densitometry. Furthermore, six non-obese young men participated in an added-weight experiment so as to estimate an effect of the excess fat of obesity. Results showed that there were no statistically significant differences in the absolute values of VO<SUB>2</SUB>max, VEmax, and HRmax among the groups. Concerning the relative value of VO<SUB>2</SUB>max to body weight, the obese group showed a significantly lower value of 40.4 ml/kg-min than the lean and ordinary group values of 51.5 and 48.8 ml/kg-min, respectively. However, no significant difference was found between the relative values of VO<SUB>2</SUB>max per lean body mass of any of the groups. VO<SUB>2</SUB>max for the obese group was 54.0 ml/kg-min, 56.0 for the lean group and 57.7 for the ordinary group. Such trends were very similar to the results of the added-weight experiment. Based on the values for the subjects in this study, this leads to the conclusion that the excess fat of obese men might act only as an inactive load and might not affect the ability of the respiratory-cardiovascular system. Besides, the threshold of obesity for men proposed by Behnke and Wilmore might be reasonable from the viewpoint of the absolute and the relative values of VO<SUB>2</SUB>max.

PULMONARY DIFFUSING CAPACITY, PULMONARY MEMBRANE DIFFUSING CAPACITY AND PULMONARY CAPILLARY BLOOD VOLUME AT REST AND DURING EXERCISE / 体力科学

Oxygen intake, pulmonary diffusing capacity (DL), pulmonary membrane diffusing capac ity (DM) and pulmonary capillary blood volume (Vc) were measured at rest and during maximal and submaximal work, with Filley's steady state technique on 3 athletes (middle distance runners) and 5 non-athletes. The results obtained in this study were as follows<BR>(1) At rest, DL, DM, Vc in athletes were 28.3±3.7 ml/min/mmHg, 52.2±5.3 ml/min/ mmHg, 124.1±41.8 ml respectively, and in non-athletes were 25.6±1.0 ml/min/mmHg, 47.5±7.5 ml/min/mmHg, 114.7 ± 25.9m1 respectively.<BR>(2) During submaximal works, DL, DM and Vc increased together with oxygen intake. At the same level of VO<SUB>2</SUB> athletes showed greater DL, DM and Vc than those of non-athletes. Contact time exponentially decreased as oxygen intake increased.<BR>(3) At maximal work, athletes showed significantly greater max VO<SUB>2</SUB> DL, DM and Vc than those of non-athletes. But, contact time of athletes was not significantly greater than that of non-athletes.<BR>(4) The results demonstrate that a higher DL, DM and Vc is accompanied by a higher aerobic capacity, a larger ventilatory capacity, and a larger cardiac output.

MAXIMUM OXYGEN INTAKE AND ITS RELATION TO BODY WEIGHT —JAPANESE ATHLETES— / 体力科学

The present study was intended to determine max. Vo<SUB>2</SUB> and its relation to body weight of Japanese athletes. The subjects in this study were 151 male and female athletes who were Japanese excellent or good runners and swimmers.<BR>Max. Vo<SUB>2</SUB>2 was determined during the maximum running on the treadmill. Treadmill test was made with a constant slope of 8.6%. During the first 2 minutes, the treadmill was set in motion at a certain speed (180 or 200 m/min for male and 160 m/ min for female), and then the speed was increased by 10 m/min every succeeding minute until exhaustion. Expired air during running was collected in Douglas bag every 1 minute upto exhaustion. The sampling gas was analyzed by means of a Beckman oxygen and carbon dioxide analyzer.<BR>The results obtained in this study were as follows ;<BR>1) The regression equations were calculated between max. Vo<SUB>2</SUB> and body weight in relation to sex and sports (Table 1) .<BR>2) Max. Vo<SUB>2</SUB> per body weight of the male swimmers ranges from 50 to 70 and that of the male runners is 70 ml/kg/min. For the female swimmers max. Vo<SUB>2</SUB> is between 40 and 60 and the female runners approximately 60 ml/kg/min.<BR>3) The regression equation was calculated between the mean speed of 5000 m running as performance (Y) and max. Vo<SUB>2</SUB> per body weight as physical resources (X) for the runners.<BR>Y=0. 0431X+2.50±0.232

MAXIMUM OXYGEN INTAKE AND ITS RELATION TO BODY WEIGHT—JAPANESE ORDINARY ADOLESCENTS— / 体力科学

The purpose of this study was to determine maximum oxygen intake and its relation to body weight of Japanese ordinary adolescents who consisted of 266 boys and 280 girls (12-18 years of age) living in Nagoya City.<BR>The progressive treadmill exercise test was chosen as a work stimulus. Treadmill test was made with a constant slope of 8.6%. During the first 2 minutes, the treadmill was set in motion at a certain speed (160m/min for boys and 140m/min for girls), and then the speed was increased by lOm/min every succeeding minute until exhaustion. Expired air during running was collected in Douglas bag every 1 minute upto exhaustion. Then sampling gas was analyzed by means of a Beckman oxygen and carbon dioxide analyzer. The heart rate was calculated from ECG during running and the respiratory rate was determined with the aid of thermister attached to the inside of the mask. All experiments were performed in the afternoon (PM 3 : 00-5: 00) during the winter seasons from 1968 to 1970.<BR>The results obtained in this study were as follows;<BR>1) The mean value of maximum oxygen intake of the boys remarkably increased with age until 18 years of age. The maximum value was 2.81 l/mmn at 18 years of age. On the other hand, the mean value of the girls was almost constant over a wide range of ages from 12 to 18 except between 16 and 17. The maximum value was 1.941/min at 17 years of age.<BR>2) The correlation coefficients and the regression equations were calculated between maximum oxygen intake and body weight.<BR>Boys r=0.883 Y= 0.0457X+ 0.0902 ± 0.3094 (n; 260)<BR>Girls r=0.595 Y=0.0149X+1.0648±0.2565 (n; 288)<BR>Where Y is maximum oxygen intake in l/min and X is body weight in kg. The same correlation coefficients and regression equations were calculated relating to sex and age. As for boys, the coefficients of “X” in the regression equations increase with age from 0.0227 at 12 years of age to 0.0468 at 18 years of age. On the other hand, there was no distinct inclination in the regression equations of the girls.

A STUDY ON HEART RATE AND SWIMMING SPEED IN THE VARIOUS INTERVAL TRAININGS OF SWIMMING / 体力科学

The purpose of this study is to conduct the examination of heart rate and speed variations with respect to the various interval trainings of swimming. One trained, one post-trained and one untrained swimmers were employed for this study. The experiment was conducted during the summer of 1968. The temperature of atomosphere varied from 30°C to 33°C and that of water from 27°C to 29°C.<BR>The data of heart rate were obtained from the record of ECG. Two electrodes or ECG consisting of silver cups of 10mm in diameter were attached to the skin over sternum. In order to avoid mechanical and electrical disturbances, the electrodes were tightly fixed through the following procedures;<BR>1) The electrodes were pasted on cleaned skin with ECG jelly.<BR>2) The adhesive plaster was placed over the electrodes.<BR>3) The adhesive plaster was coated with wax.<BR>The wire of 20 meters was used to connect the electrodes and the recorder. On trial of interval training was consisted of two phases; 1) The active phaseTo swim 50 meters according to his swimming ability. 2) The rest phase.To take a 0, 5, 10, 20, 30, 45 or 60 seconds interval between each 50 meters swimming. Each trial of training was repeated ten times.<BR>Results are as follows;<BR>1) The longer the rest period is, the higher the swimming speed is.<BR>2) All swimmers swim 50 meters at 60-80% of their maximum speed and the percent of the trained is higher than that of the untrained.<BR>3) Maximum heart rates of the trained, the post-trained and the untrained during tenth swimming are 188, 180 and 173 respectively, which are the same in every trial.<BR>4) Decreasing rates of heart rate during the rest period are 10 under in 5-10 seconds interval, 15-25 in 20-30 seconds interval and 20-50 in 45-60 seconds interval,