Changes in the effects of 18 month endurance run training on aerobic work capacity in young children / 体力科学

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 (VO<SUB>2</SUB>) during the course of the training period.<BR>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 (VO<SUB>2</SUB>max⋅ TBW<SUP>-1</SUP>) 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.

A study on the effect of endurance running on circulorespiratory function in young children / 体力科学

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⋅<I>l</I><SUP>-1</SUP> of blood lactate concentration (LA) were maintained for at least 3-4 min⋅m<SUP>-1</SUP>. The control group was given no special training.<BR>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 (Vo<SUB>2</SUB>) and blood lactate concentration (LA) at all steps.<BR>From the above mentioned procedure, the following findings were obtained :<BR>1) After the 6-month endurance run training, Vo<SUB>2</SUB>max/TBW was significantly (p<0.05) increased from 47.5 to 50.4 m<I>l</I>⋅kg<SUP>-1</SUP>⋅min<SUP>-1</SUP> and also the peak LA was significantly (p<0.05) increased from 5.41 to 6.36 mmol⋅<I>l</I><SUP>-1</SUP>in the experimental group. On the other hand, no significant increases were observed in the control group.<BR>2) Running velocity in the final stages (Vmax) was significantly (p<0.001) improved from 190.0 to 205.0 m⋅min<SUP>-1</SUP>in 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.<BR>3) Submaximal V, HR, and Vo<SUB>2</SUB>/TBW equivalent to 3 and 4 mmol⋅<I>l</I><SUP>-1</SUP> 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.

A study on physical activity levels of young children in the nursery school / 体力科学

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.<BR>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.<BR>Analyses of physical activity patterns were tried by relating heart rate levels to circulorespiratory variables which were equivalent to 3 or 4 mmo<I>l</I>/<I>l</I> blood lactate concentration (3m MLA or 4m MLA) .<BR>By so doing, the following results were obtained:<BR>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.<BR>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.<BR>The corresponding relative values of oxygen uptakes were 85.2% Vo<SUB>2</SUB>max-3 m MLA and 94.3% Vo<SUB>2</SUB>max-4 m MLA for males and 89.7% Vo<SUB>2</SUB>max-3 m MLA and 96% Vo<SUB>2</SUB>max-4 m MLA for females.<BR>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.<BR>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) .<BR>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.<BR>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.<BR>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.

The studies on aerobic work capacities of preparatory school children (IV) / 体力科学

The objectives of the present study were to find out peculiar cardiorespiratory adjustments of young children against relatively short duration of exhaustive run.<BR>Young four male and four female children, aged four or five years, ran on the flat treadmill firstly with the velocity where they could continue to run at least for five minutes (140m/min for male children and 120m/min for female children) and thereafter with three different kinds of velocities where they were forced to cease running because of their exhaustion (160, 180 and 200m/min for male children and 140, 160 and 180m/min for female children) .<BR>Increase rates and recovery rates converted from absolute values of of HR (bpm) and Vo<SUB>2</SUB> (1/min) in each phase were used for analysis.<BR>The results obtained were as follows;<BR>1) Also for young children changes of increase rates and recovery rates of HR and Vo<SUB>2</SUB> to the time course showed the exponential inclinations.<BR>2) Fifteen seconds after the commencement of running the increase rates of HR ranged from 56.0 to 65.0% and those of Vo<SUB>2</SUB> ranged from 42.5 to 53.3% for male children and on the other hand for female children ranged from 49.0 to 58.2% and 38.9 to 43.5% respectively.<BR>The increase rates of HR were, therefore, steeper than those of Vo<SUB>2</SUB> for both sexes.<BR>Significant differences were found in the velocities of 160, 180 and 200m/min for male children and 140 and 180m/min for female children.<BR>3) The increase rates of HR attained fifteen minutes after the start of running corresponded to one the second or two the third of 82.0 to 91.0% and 81.6 to 87.3% which were attained one minute after the start of running for male and female children respectively.<BR>4) In spite of the absolutely and relatively greater range of adjustment, which means the larger difference between values at rest and maximal effort, the increase rates of Vo<SUB>2</SUB> reached or surpassed those of HR one minute after the start of running.<BR>5) The ranges of adjustment of HR and Vo<SUB>2</SUB> were higher for male children, but the both increase rates exhibited till one minute after the start of running, though no significant differences were found, were higher for male children.<BR>6) On the contrary to the case of increase rates the recovery rates of Vo<SUB>2</SUB> were significantly higher than those of HR at least till two minutes after the cessation of running for both sexes.<BR>Vo<SUB>2</SUB> returned to the level of rest only five minutes after the cessation of running, but HR lied a little higher above the resting level even fifteen minutes later.<BR>7) The higher acceleration of increase rate and deceleration of recovery rate for young children are presumably much due to the smaller range of adjustment. Accordingly the experiments sould be designed by unifying exhaustion time.

THE STUDIES ON AEROBIC WORK CAPACITIES OF PREPARATORY SCHOOL CHILDREN (III) / 体力科学

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.<BR>The expired airs were collected at rest and whole through the treadmill running.<BR>Heart rates were also continuously registered not only at rest but also during the treadmill running.<BR>The following results were obtained:<BR>1) At the velocities of 100m/min, 120m/min and 140m/min apparent steady states of heart rates and Vo<SUB>2</SUB> were established within the three miuntes both for boys and girls.<BR>But boys showed lower heart rates and higher Vo<SUB>2</SUB> during the steady states at a given velocity than girls did.<BR>2) At the last velocity of 200m/min Vo<SUB>2</SUB>max were attained 30 seconds after the start of running for boys and also at the last of 180m/min girls reached Vo<SUB>2</SUB>max 60 seconds after the beginning.<BR>It was, therefore, confirmed that if the work intensity was sufficiently high, Vo<SUB>2</SUB> max could be reached at the latest between 30 and 60 seconds after the start of work for young children.<BR>3) At the one step lower velocity than the last, namely, 180m/min for boys and 160m/min for girls, the plateaus of Vo<SUB>2</SUB>max were found for the last minute.<BR>4) The heart rates simultaneously observed with Vo<SUB>2</SUB>max 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.<BR>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.<BR>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.

THE STUDIES ON AEROBIC WORK CAPACITIES OF PREPARATORY SCHOOL CHILDEREN (II) / 体力科学

Maximal oxygen uptakes were determined by means of ground run for 53 male and 56 female subjects aged from 3 to 5 years.<BR>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.<BR>The following results were obtained:<BR>1) Male absolute values of maximal oxygen uptakes (<I>l</I>/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.<BR>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.<BR>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.<BR>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;<BR>y=52.723 logx-44.071 (n=53, r=.487)<BR>y=44.095 logx-33.980 (n=56, r = .445) .<BR>4) The regression equations of absolute maximal oxygen uptakes (<I>l</I>/min) to body weights (kg) were the following ;<BR>y=0.51x-.125 (n=53, r=.729) for males<BR>y=0.043x+.007 (n=56, r=.747) for females.<BR>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.<BR>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.<BR>The regression equations of 5 minute run (m) and maximal oxygen uptakes related to body weight (ml/kg/min) were<BR>y=5.034x+576.680 for mals<BR>y=5.009x+558.408 for females.

THE STUDIES ON AEROBIC WORK CAPACITIES OF PREPARATORY SCHOOL CHILDREN (I) / 体力科学

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:<BR>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.<BR>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.<BR>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.<BR>4) Correlation coefficients between body weights and absolute values of maximal oxygen uptakes were .8986 for males and .5626 for females.<BR>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.