The objectives of the present study were to find out peculiar cardiorespiratory adjustments of young children against relatively short duration of exhaustive run.
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) .
Increase rates and recovery rates converted from absolute values of of HR (bpm) and Vo₂ (1/min) in each phase were used for analysis.
The results obtained were as follows;
1) Also for young children changes of increase rates and recovery rates of HR and Vo₂ to the time course showed the exponential inclinations.
2) Fifteen seconds after the commencement of running the increase rates of HR ranged from 56.0 to 65.0% and those of Vo₂ 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.
The increase rates of HR were, therefore, steeper than those of Vo₂ for both sexes.
Significant differences were found in the velocities of 160, 180 and 200m/min for male children and 140 and 180m/min for female children.
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.
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 Vo₂ reached or surpassed those of HR one minute after the start of running.
5) The ranges of adjustment of HR and Vo₂ 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.
6) On the contrary to the case of increase rates the recovery rates of Vo₂ were significantly higher than those of HR at least till two minutes after the cessation of running for both sexes.
Vo₂ 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.
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.

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This study was undertaken to examine whether carbohydrate loading gives a good effect to improve the endurance performance in Japanese subjects who had habitually eaten carbohydrate-rich diets. The glycogen content of the vastus lateralis muscle was determined in 6 healthy male subjects with the aid of the needle biopsy technique by setting different diets after glycogen store was depleted by exhaustive exercise.
Glycogen content of the vastus lateralis muscle after mix, low and high carbohydrate diets was 22.7±2.0, 11.6±1.6 and 36.6±4.5 g/wet muscle⋅kg (mean±SD), respectively, while exhaustive time was 75′39″±10′02″, 67′58″±14′11″and 92′10″±22′10″ (mean±SD), respectively. Thus, a good correlation was noted between muscle glycogen content and work time.
It was therefore concluded that the glycogen content of the working muscle was a determinant factor for the capacity to perform long-term heavy exercise and that carbohy-drate loading attained with low carbohydrate diet and exhaustive exercise followed by high carbohydrate diet had a good effect to perform heavy exercise even in Japanese who lived on carbohydrate-rich diet.

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It has been observed that the premotion silent period (p. s. p.) appears just before a rapid voluntary movement. This phenomenon is believed to be caused by one of the inhibitory discharge from the central nervous system. In the present study, the effect of p. s. p. appearance was investigated by comparing the advanced informations of the fast reactive movement (Fast condition) and the powerful reactive movement (Powerful condition) . Six healthy males aged 19-21 years were subjected to a series of experiment in which they were asked to exert their muscle strength of 15-20% of their maximum elbow extension strength. They were requested to extend their elbow joint responding to a flashing lamp as quickly as possible on the fast condition. On the powerful condition, they exerted their elbow extensor strength as greatly as possible. The EMG activities of triceps brachii and biceps brachii were recorded by bipolar surface electrodes. Mechanical response was simultaneously recorded using a resistance strain gauge transducer, and the mechanogram was analyzed on the following items: A) premotor time (the time from the signal to the onset of the force curve), B) rate of tension rise (the maximum rate of tension rise in the force-time curve) . The following results were obtained from this experiment.
1) The rate of appearance in p. s. p. on the powerful condition (21%) was significantly higher than the fast condition (9%) .
2) The premotor time on the powerful condition (180msec) was significantly later than the fast condition (160 msec) .
3) The rate of tension rise on the powerful condition (258 kg/sec) was significantly greater than the fast condition (177 kg/sec) .
It was suggested from these results that the frequency of appearance in p. s. p. on the fast condition decreased in comparison with the powerful condition. It was also considered that the appearance in p. s. p. produced the increase of the rate of tension rise.

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The purpose of this study was to investigate the kinetics of Vco₂during incremental exercise. The subjects were 7 males, age 21-28 years, exercised at two steady state work loads (540 kpm/min, 810 kpm/min) and incremental work load which was increased stepwise by every 1 min from 180 kpm/min to exhaustion. The Vo₂and Vco₂during steady state exercise (4 to 5 min) were determined by the Douglas bag method and arterialized blood samples were taken for lactate (LA) analysis and blood gas analysis. The Vo₂, Vco₂, and blood lactate were also determined throughout the incremental exercise. At exhaustion, mixed venous Pco₂ (PVco₂) was determined by the CO₂rebreathing method.
1) The Vco₂values at rest and during steady state exercise were linearly related to the Vo₂values. When the regression line was compared with Vco₂during the incremental exercise on the same Vo₂, the Vco₂during the incremental exercise below the anaerobic threshold showed lower values.
2) The total sum of the difference in Vco₂between steady state and incremental exercise was defined as CO₂store. The calculated CO₂store and CO₂store per body weight were significantly related to PVco₂at exhaustion in incremental exercise, respectively (r=0.954, r=0.954) .
3) At work load below the anaerobic threshold, Vco₂was linearly related to Vo₂. If the Vco₂above the anaerobic threshold is estimated from Vo₂using the regression line obtained at work load below the anaerobic threshold, the estimated Vco₂will be lower than the measured Vco₂. The total sum of the difference in the Vco₂was defined as CO₂excess. The CO₂excess and the CO₂excess per body weight were significantly related to ΔLAmax (the difference between LA at 3rd min after exhastion and LA at exercise below the anaerobic threshold), respectively (r=0.870, r=0.930) .
4) HCO₃^-calculated from blood gases (pH and Pco₂) was significantly related to LA (r=-0.902) . The increase of 1 mM/1 in LA was corresponding to the decrease of 0.843 mEq/l in HCO₃^-.
5) From these results, it appeared that the expired Vco₂during the incremental exercise consisted of the stored Vco₂, the exceeded Vco₂, and the produced Vco₂ (Vco₂metabolically produced from Vo₂) .

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