Eight young girls as an experimental group (E group) and another eight as a control group (C group), (all aged 4-5 years), participated in the present study to observe the effects of training from May 1992 through November 1993. E group performed a 915m endurance run on an agricultural road every day except Sundays for an 18 month training period. No special training was given to C group. In May 1992 (T 1), November 1992 (T 2), May 1993 (T 3), and November 1993 (T 4), both groups underwent treadmill tests in order to check aerobic variables such as heart rate (HR) and oxygen uptake (VO₂) during the course of the training period.
Times required for the run became shorter from summer to fall and from winter to spring (shortening phase), whereas they became prolonged from spring to summer and from fall to winter (prolongation phase) . Therefore, there was a definite seasonality of performance endurance. The rates of shortening in the required times observed from summer to fall were considerably higher than from winter to spring, and this was reflected in the significant improvement of maximal running speed on the treadmill (Vmax) and maximal oxygen uptake in terms of body weight (VO₂max⋅ TBW^-1) from T 1 to T 2 as well as from T 3 to T 4. Thus, significant differences were found between the groups at T 2 and T 4. HR levels during the endurance run were close to 95% HRmax regardless of the phase. Accordingly, the prolongation phases, during which circulatory parameters and ventilatory capacity were least improved, could be regarded as a preparatory period for the following shortening period, during which work load intensities furthermore increased the arteriovenous oxygen differences. Thus, when planning research on the effects of training on aerobic work capacity in the field, special attention should be paid to the season and the training period, and the timing of the examination for training effects, or otherwise, misleading conclusions could be drawn.

Twelve young boys as an experimental group and seven as a control group, aged 5-6 years, participated in a study to clarify whether circulorespiratory trainability exists in young children. The subjects in the experimental group performed a 915 m endurance run on an agricultural road every day except Sundays for six months. During the run, heart rates (HR) equivalent to 3-4 mmol⋅l^-1 of blood lactate concentration (LA) were maintained for at least 3-4 min⋅m^-1. The control group was given no special training.
Before and after the training period, both groups were subjected to increased stepwise running velocity on a flat treadmill till subjective exhaustion to determine circulorespiratory variables such as heart rate (HR), oxygen uptake (Vo₂) and blood lactate concentration (LA) at all steps.
From the above mentioned procedure, the following findings were obtained :
1) After the 6-month endurance run training, Vo₂max/TBW was significantly (p<0.05) increased from 47.5 to 50.4 ml⋅kg^-1⋅min^-1 and also the peak LA was significantly (p<0.05) increased from 5.41 to 6.36 mmol⋅l^-1in the experimental group. On the other hand, no significant increases were observed in the control group.
2) Running velocity in the final stages (Vmax) was significantly (p<0.001) improved from 190.0 to 205.0 m⋅min^-1in the experimental group. Such effects were due partly to the improvement of circulorespiratory function and partly to improved efficiency of running motion. However, no significant differences were found in the control group.
3) Submaximal V, HR, and Vo₂/TBW equivalent to 3 and 4 mmol⋅l^-1 and their values relative to the maximum values showed no significant differences before and after the training period in both groups. The improvement of maximal circulorespiratory variables observed in the experimental group suggests the existence of trainability even in young children.

Six male and seven female children, aged five or six years, ran on the flat treadmill increasing running speeds every two minutes by 20 m/min till their subjective exhaustions. The first steps were started with the speeds of 80 or 100 m/min and the rest periods of 30 seconds were inserted between each successive step for the blood sampling. Expired airs for the determination of oxygen uptakes were collected during the last 30 seconds of every stage. Heart rates were recorded for each subject throughout the whole test session.
Two male and two female subjects were selected in order to determine their physical activity levels in the nursery school. Their heart rates were recorded from Monday to Saturday in a given week.
Analyses of physical activity patterns were tried by relating heart rate levels to circulorespiratory variables which were equivalent to 3 or 4 mmol/l blood lactate concentration (3m MLA or 4m MLA) .
By so doing, the following results were obtained:
1) Mean values of blood lactate concentrations observed immediately after the cessation of the last exhaustive steps were 5.16 m MLA for males and 4.70 m MLA for females.
2) Relative values of heart rate to 3 and 4 m MLA against maximal heart rate (% HRmax-3 m MLA and % HRmax-4 m MLA) were respectively 92.2% HRmax-3 m MLA and 97.5% HRmax-4m MLA for males and 94.9% HRmax-3 m MLA and 98.2% HRmax-4 m MLA for females.
The corresponding relative values of oxygen uptakes were 85.2% Vo₂max-3 m MLA and 94.3% Vo₂max-4 m MLA for males and 89.7% Vo₂max-3 m MLA and 96% Vo₂max-4 m MLA for females.
3) Mean values of heart rate recorded in the nursery through a given week except Sunday ranged from 89 to 114 beats/min for males and 106 to 126 beats/min for females. In the relative value of a heart rate against the heart rate equivalent to 4 m MLA, that is, HR 4 m MLA these values correspond to 44-57% HR 4 m MLA and 57-67% HR 4 m MLA respectively.
4) Accumulated duration time: Their hearts beat higher than 160 beats/min, except in the case of 800 m endurance run (only 0-4 and 0-6 minutes for males and 0-6 and 4-21 (touch of tachycardia) minutes for females) .
Percentages of accumulated duration time lower than 120 beats/min occupied 72-94% and 77-91% of 6 or 7-hour nursing time for males and 51-91% and 51-78% for females.
5) Absolute and relative values of mean heart rates in 800 m endurance run ranged from 183 beats/min (Net 83% HRmax, 90% HR 4 m MLA) to 199 beats/min (Net 98% HRmax, 104% HR 4 m MLA) for males and from 172 beats/min (Net 77% HRmax, 92% HR 4 m MLA) to 196 beats/min (Net 92% HRmax, 96% HR 4 m MLA), though the duration times were short.
6) Optimal intensity of work load was proposed to be the heart rate level of at least 190 beats/min for favourable development and/or improvement of the circulo-respiratory system in young children.

In order to find out the criteria for the determination of maximal oxygen uptakes of very young children, five boys and five girls, aged four or five years, served as the subjects. They ran on the horizontal treadmill once a day for the constant three minutes on different days. The velocity was increased from the first 100m/min by 20m/min till the last where they could endure no longer for the three minutes. As the consequence, the velocities attained were 100m/min, 120m/min, 140m/min, 160m/min, 180m/min and 200m/min for boys and 100m/min, 120m/min, 140m/min, 160m/min and 180m/min for girls.
The expired airs were collected at rest and whole through the treadmill running.
Heart rates were also continuously registered not only at rest but also during the treadmill running.
The following results were obtained:
1) At the velocities of 100m/min, 120m/min and 140m/min apparent steady states of heart rates and Vo₂ were established within the three miuntes both for boys and girls.
But boys showed lower heart rates and higher Vo₂ during the steady states at a given velocity than girls did.
2) At the last velocity of 200m/min Vo₂max were attained 30 seconds after the start of running for boys and also at the last of 180m/min girls reached Vo₂max 60 seconds after the beginning.
It was, therefore, confirmed that if the work intensity was sufficiently high, Vo₂ max could be reached at the latest between 30 and 60 seconds after the start of work for young children.
3) At the one step lower velocity than the last, namely, 180m/min for boys and 160m/min for girls, the plateaus of Vo₂max were found for the last minute.
4) The heart rates simultaneously observed with Vo₂max ranged from 202.4 to 206.4 bpm and also RQ were all above the unit. Accordingly these values could be regarded as the most important critieria for the evaluation of aerobic work capacity of young children.
5) When the velocity was high, the respiratory frequency sharply rises immediately after the start of running. For the first thirty seconds the breath rates reached 60 to 90/min.
6) If the duration of the running on the horizontal treadmill are constantly fixed three minutes, the upper limit of the velocity where the safe aerobic steady state can be established is 140m/min both for boys and girls.

Maximal oxygen uptakes were determined by means of ground run for 53 male and 56 female subjects aged from 3 to 5 years.
Furthermore 38 male and 45 female subjects restricted on the age of 4 and 5 years were chosen and 5 minute run was loaded on them to know their aerobic motor performance.
The following results were obtained:
1) Male absolute values of maximal oxygen uptakes (l/min) avaraged 0.655, 0.789, and 0.904 respectively at the age of 3, 4, and 5 years. The corresponding values for females were 0.523, 0.751, and 0.808.
2) For males mean values of maximal oxygen uptakes in terms of body weight (ml/ kg/min) were 42.60, 47.36, and 51.31 respectively.
For females the corresponding values only reached 35.91, 44.48, and 44.20. The sex differences were found at the age of 3 and 5 years.
3) The developments of relative maximal oxygen uptakes (ml/kg/min) with increasing age (months) were expressed by the following regression equations for males and females respectively;
y=52.723 logx-44.071 (n=53, r=.487)
y=44.095 logx-33.980 (n=56, r = .445) .
4) The regression equations of absolute maximal oxygen uptakes (l/min) to body weights (kg) were the following ;
y=0.51x-.125 (n=53, r=.729) for males
y=0.043x+.007 (n=56, r=.747) for females.
5) During 5 minute run males could cover 798.85m and 844.00m respectively at the age of 4 and 5 years. The corresponding values by females were 779.29m and 785.38m. Males could run significantly faster than females.
6) The correlation coefficients between relative maximal oxygen uptakes (ml/kg/min) and distances covered for 5 minutes (m) were .500 for males and .510 for females respectively.
The regression equations of 5 minute run (m) and maximal oxygen uptakes related to body weight (ml/kg/min) were
y=5.034x+576.680 for mals
y=5.009x+558.408 for females.

According to the past results of Sports Test, it was found that the night part-time high school students showed the significantly lower performance in endurance run than the full-time high school students. This fact may be partly due to the fatigue and the lack of motives necessarily caused by their mental and physical works in day time. This study was attempted to determine their aerobic work capacities (PWC₁₇₀, Vo₂max) in the same experimental condition as used for the full-time high school students and simulteneously comparing them with those of the full-time high school students in the same district. The subjects were 59 male and 38 female, aged from 15 to 19 years.
The results obtained in this study were as follows
1) The mean values of PWC₁₇₀ (kpm/min) for boys increased slightly with increasing ages till 18 years. But girls showed almost same values through the ages. The maximal value were 910kpm/min at the age of 18 years for the boys and 617kpm/min for the girls aged 16 years respectively.
2) For boys the mean values of PWC₁₇₀ (kpm/kg/min) ranged from 14 to 15kpm/ kg/min and ranged from 10 to 11kpm/kg/min for girls.
3) As for the mean values of Vo₂max (l/min) of the boys increased slightly untill the age of 18 years. But girls were same in values through all the ages. The maximal values were 2.71/min at the 18 years for boys and 1.81/min for girls aged 15 years respectively.
4) For boys the mean values of Vo₂max (ml/kg/min) decreased slightly from 49.48 ml/kg/min with ages. The mean values of Vo₂ max (ml/kg/min) ranged from 34 to 35 ml/kg/min for girls.
5) The night part-time high school students were lower than the full-time high school students in PWC₁₇₀ (kpm/min), PWC₁₇₀ (kpm/kg/min), Vo₂max (l/min) and Vo₂max (ml/kg/min) for boys. For girls no significant differences were in these valiables after the age of 16 years.

Maximal oxygen uptakes of 85 preparatory school children (46 for males and 39 for females), aged 5 and 6 years, were determined by means of ground run. Their motor performances such as 25 meter dash run, 50 meter dash run, standing broad jump, 5 minute endurance run and muscle strengths of grip and back were also measured. The following results were obtained:
1) Mean values of maximal oxygen uptakes in terms of body weights were 49.46ml/ kg/min for males and 46.30ml/kg/min for females and the significant difference was found between the sexes.
2) Correlation coefficients between the first and second measurements in the 5 minute endurance run were .9044 for males and .7757 for females, and therefore the reproducibi-lity was higher for males than for females.
3) Correlation coefficients between maximal oxygen uptakes in terms of body weights and the performances of 5 minute endurance run were .4170 for males and .0486 for females.
4) Correlation coefficients between body weights and absolute values of maximal oxygen uptakes were .8986 for males and .5626 for females.
5) Regression equations of absolute values of maximal oxygen uptakes (1/min) to body weights (kg) were y=.051x-.025 for males and y =.024x+.408 for females.

According to the past results of Sport Test held in TOCHIGI Prefecture in 1968, it was certainly found that the endurance run test showed the most characteristic regional trend that adolescents born and reared in mountaineous farm villages, which topographically lie from mountain to plain, obtained significantly better performance than those in commercial and residential streets. The main objectives of the present investigation were to know how much difference, if any, is found concerning endurance capacities between the both adolescents and the study was, therefore, designed in the sphere of physical resources of energy to measure the aerobic work capacities of PWC₁₇₀ and Vo₂ max., and it was assumed that commercial streets represenetd urban districts and on the other hand mountaineous farm villages also represented rural districts. The total number of subjects, aged from 9 to 17 years, who performed the PWC₁₇₀ test of submaximal work load as preliminary one, were 732; 159 in male and 157 in female in urban, and 218 in male and 198 in female in rural districts. But the subjects to be tested in Vo₂ max. of maximal work load were further chosen at random from those who received the PWC₁₇₀ test, and the number of them were 559 in all. The apparatus for the determinations of PWC₁₇₀ and Vo₂ max. was MONARK bicycle ergometer. The three points-four minute method was used in the PWC₁₇₀test and the two-minute stepwise method was adopted for measurement of Vo2 max. The pedalling rate was 50 rpm in the both tests. Every step of work load was increased by 150kpm/min. Concomitantly skinfold thicknesses in the four points of upper arm, scapula, wast, and umbilicus were also measured.
The following results were obtained:
1) Urban adolescents had significantly thicker subcutaneous fats than rural ones.
2) No differences were found in PWC₁₇₀ (kpm) in all the ages between urban and rural adolescents for male, but rural adolescents were significantly superior to urban ones after the age of 12 years in PWC₁₇₀ (kpm/kg) . For female urban adolescents were rather better than rural ones before the 11 years, but on the contrary rural adolescents were significantly higher in PWC₁₇₀ (kpm/kg)
3) The regional differences that rural adolescents were superior to urban ones in aerobic work capacities were recognized earlier in age for PWC₁₇₀ (kpm/kg) than for Vo₂max. (ml/kg), and further appeared in younger ages for female than did for male.
4) In the regression equation y=ax+b, in which x was assumed to express body weight (kg) and y mean PWC₁₇₀ (kpm) or Vo₂ max. (1), and the standard deviation from y, δy, was also calculated, the characteristic regional trend was found in urban and rural districts. Then it could be considered that a was the increase rate of aerodic work capacities to body height and δy was the interpersonal variation. In the case of Vo₂ max. (1) for boys, the higher increase rates were consistently found in rural districts and the smaller variations were also identified. It is apparent that this is partly due to the higher occupation of the activating tissues in body weight increaserate and partly due to their better functioning.
5) According to the allometrical expressions concerning aerobic work capacities, y=b×h^a, obtained by the same mathematical procedure as used by Asmussen, PWC₁₇₀ (kpm) for boys had the same body heights in the two critical points of urban and rural districts, and up to these body heights a was considerably higher in rural boys but almost same α were indicated after the points. As for Vo₂ max. (1), the body heights in the critical points differed in urban and rural districts, that is, the body height in rural boys was about 10cm higher than in urban ones.

The results of Sport Test in TOCHIGI Prefecture in 1964 and 1968 showed the definite and consistent inclination that rural pupils recorded significantly better performance than urban ones in endurance run. This also implies that circulorespiratory capacity, which plays an important role in endurance type of exercise, is much influenced by the environmental conditions necessarily accompanied with each district.
In the present study PWC₁₇₀ kpm/kg as an index of circulorespiratory capacity were measured by means of MONARK bicycle ergometer and ECG in the two couples of urban and rural groups of pupils aged from 12 to 15 years, and the comparisons of urban and rural indicated that rural pupils had considerably better than urban ones with significant difference.
In one couple of the two the pupils of the school surrounded with commercial streets and the ones in mountaneous farm village were contrasted in order to design the ecological research, because the latter was the best and the former the worst in endurance run
85.6% of the pupils in the mountaineous farm village go to school far from home by pedaling bicycle ascending or descending the slopes, and on the other hand all the pupils in the commercial streets walk to school along the horizontal and flat streets nearer than in the mountaineous farm village
In Japan an amount of intraschool physical activities are almost the same in all schools and therefore the differences of daily physical activities, the degree of which brings about the circulorespiratory improvement, depend on the work of attending school long through the years.
In this study the extent of the work load in attending school was estimated by heart rate-oxygen uptake curve on the basis of the mean heart rate derived from telemetering heart beats all through the courses between school and home. This procedure reveals the evidence that mountaineous farm pupils by bicycle are given the work load equivalent to 40% or more of the maximal oxygen uptake, which means the stroke volume reaches its peak and becomes the adequate training stimulus for circulorespiratory improvement, but for the pupils in commercial streets vice versa. And furthermore it was also found that the farther from school, the better the circulo-respiratory capacity in the mountaineous farm district
Though there was found to be the significant difference between them in PWC₁₇₀ as submaximal test, no significant difference was indicated in maximal oxygen uptake (ml/kg, STPD) . This may be due to the fact that in pedaling in step wise method of increasing brake resistance distress or fatigue in leg muscles proceeds the circulorespiratory one.