Sacerdote reported that there was a decrease in the adrenal ascorbic acid content and an increase in the blood ascorbic acid content of guinea pigs exposed to a gradual reduction in O₂ tension (10.5 to 3.5%) . Teppermann et a1. and Aschan observed the depletion of ascorbic acid in the adrenal cortex of rats exposed to anoxic hypoxia. Furthermore, Wachholder and Podesta, Ratsimamanga and Giroud, Namyslowski, Arai, and Ottowicz et al. observed a highly significant depletion of the adrenal ascorbic acid in rats subjected to experimental muscular exercise.
These reports suggest that ascorbic acid plays an important role in the metabolism of an organism during hypoxia and exercise.
Sayers concluded in his review that, in general, increased adrenocortical activity was associated with a reduction in the concentration of adrenal ascorbic acid.
A number of physiological studies suggest that ascorbic acid plays an important role in adrenal cortex activity. However, the physiological role of ascorbic acid in the metabolic processes of the organ tissues during hypoxia and exercise is unknown. Therefore, this study was carried out in order to determine the relations between the changes in ascorbic acid concentration in various organs under hypoxic conditions as well as during muscular exercise.
Vitamin C (total ascorbic acid : T-AsA) consists of ascorbic acid (C₆H₈O₆ ; AsA) and dehydroascorbic acid (C₆H₆O₆; DHA) . The major purpose of this study was to elucidate the changes in the ratios of AsA and DHA to T-AsA in different organs during hypoxia and exercise.

It was the purpose of this study to elucidate the difference between endurance runners and normal men in respiratory and circulatory adjustments during prolonged exercise, and to evaluate the relationship between the magnitude of the respiratory and circulatory“drift”and the endurance exercise capacity.
Ten male endurance runners (runner group), aged 19-23 years, and nine normal men (control group), aged 19-28 years, exercised on a bicycle ergometer for 60 min at a constant work load requiring 60% of Vo₂max for each subject.
In the control group, VE increased approximately 20% from 10th to 60th min of prolonged exercise (P<0.05), with a corresponding decrease in PAco₂ (P<0.05), whereas in the runner group VE and PAco₂were remained constant throughout prolonged exercise. The above differences of VE and PAco₂responses between the control and the runner group could not be accounted for by a rising body temperature and lactic acidosis, because it was found that the magnitude of the rise in rectal temperature (Tre) and the behavior in lactic acid (LA) were not different for the two groups. On the other hand, we failed to find the difference of the pattern in HR and SV responses to prolonged exercise in the runner group as compared with the control group. At each comparable time period during prolonged exercise, however, the percentage changes from the values at the 10th min in HR and SV were less in the runner group than in the control group. In addition, Vo₂max (ml/kg/min) correlated significantly with the percentage changes in VE (r=-0.534, P<0.05), HR (r=-0.565, P<0.05), and SV (r=0.588, P<0.01) from 10th to 60th min of prolonged exercise.
The results of this study suggest that the endurance training may improve the magnitude of the respiratory and circulatory “drift”, which appears to become a limiting factor to endurance performance.

The present study was aimed to elucidate the relationships between the capacity of oxygen uptake and low atmospheric pressure.
Four anesthetized male dogs were exposed to low pressure of different grades ; 560 mmHg, 460 mmHg, 360 mmHg, and 260 mmHg in a decompression chamber. Blood was drawn from femoral artery and vein through polyethylen tube to outside the chamber. The tube was filled with heparin in order to avoid coagulation when it was not in use. The blood was subjected to determination of oxygen content and oxygen capacity by means of Van Slyke method. Oxygen tension was determined from Hb-Oxygen dissociation curve at pH 7.40.
Arterial and venous oxygen content decreased with lowering the pressure, and the rate of decrease was higher in CaO₂ than in CvO₂. Thus Ca-vO₂ difference decreased from 5.5 vol% (at the control level) to 2.6 vol% (at 260 mmHg.) .
Though the mean oxygen capacity was 20.0 vol% and did not change at 560 mmHg, a significant increase was found at 460 mmHg and 360 mmHg ; they were 20.3 vol% and 20.9 vol% respectively.
PaO₂ fell parallel with lowering of environmental pressure from 92.0 mmHg at 760 mmHg to 29.7 mmHg at 260 mmHg ambient pressure. As venous oxygen tension exhibited a slight decline in contrast to PaO₂, Pa-vO₂ difference became smaller according to lowering the environmental pressure. The difference was 41.4 mmHg at the control level and 4.2 mmHg at 260 mmHg.
In conclusion, we should say that there seems to be two phases in the change of DLO₂ in hypoxic condition. In the first phase, the diffusion gradient decreases lineally with the ambient pressure and VO₂ is unchanged or shows only a slight decrease even in a relatively lower pressure. There may be an increase of DLO₂ accompanied with increase of cardiac output. In much lower ambient pressure, however, there appears the other phase in which QH and also DLO₂ decrease and in turn an apparent decrease of VO₂ can be seen.

To determine the minimum duration of exercise for improving the aerobic capacity of patients with coronary heart disease (CHD), 23 female patients with CHD and/or hypertension, aged 52.8±8.7 years, were studied. After pre-testing, all the patients were conditioned for 4 months in order to elicit improvements in their aerobic capacity and other healthrelated factors. Duration and contents of daily activities were recorded by each patient. After 4 months, oxygen uptake at lactate threshold (VO_2LT) and VO_2peak were increased significantly from 12.9±2.6 to 16.0±3.4ml/kg/min and from 18.5±4.2 to 22.3±5.6ml/kg/min, respectively. Duration of exercise conditioning for the 4 months averaged 23.8±12.2min per day, ranging from 4.6 to 49.7min. Correlational analyses were applied in order to determine the extent to which the improvement in aerobic capacity was associated with the individual mean duration of exercise conditioning. As a result, changes in VO_2LT and VO_2peak correlated significantly with the exercise duration (Pearson's r=0.51, Spearman's rho=0.47 for VO_2LT; Spearman's rho=0.58 for VO_2peak) . Both VO_2LT and VO_2peak tended to improve markedly when daliy exercise duration was 20 min or longer. Furthermore, it was shown that the improvement in aerobic capacity remained almost the same within a range of exercise duration of 20 to 60min. We suggest that the minimum exercise duration for improving the aerobic capacity of cardiac patients is 20 to 30min per day or 140min or more per week.

To estimate how much physical activity is needed to improve overall health status in female patients with ischemic heart disease (IHD), the dose-response relationship between the duration of daily aerobic exercise and change in vital age (VA) was assessed for 4 months of exercise training. VA was considered as an index of physical health status and was computed from various coronary risk facotrs and physical fitness elements. Eighteen female patients with IHD, aged 54.3±9.1 yrs, continued the supervised exercise training 1-2 d/wk and the self-controlled exercise training 1-5 d/wk for 4 months. The intensity of exercise was set at individually determined lactate threshold. Daily duration of aerobic type exercise calculated for each patient averaged 21.1±11.0min/d, rang ing from 4.6 to 46.7 min/d. After the 4-month exercise training, VA decreased from 59.6±12.1 yrs to 54.2±11.8 yrs (P<0.05) . Significant correlation was found between daily duration of exercise and the change in VA (Spearman's rho=-0.60 ; Pearson's r=-0.62) . In this relationship, 10 min/d of exercise induced the decrease in VA and no further decrease in VA was found over the 30 min/d of exercise. In the 11 variables which constitute the equation of VA, oxygen uptake at lactate threshold (Spearman's rho=0.65; Pearson's r=0.64) and balancing on one leg with eyes closed (Spearman's rho=0.48; Pearson's r=0.51) significantly correlated with daily duration of aerobic exercise. From these results, it is suggested that the amount of moderate intensity exercise required to improve physical health status in female patients with IHD may be 10-30 minutes per day.

To estimate the subjective or physiological intensity of work, many index have been employed concerning the functional responses of oxygen transport system. In this study the validity of the index VO₂/VO₂max was discussed.
22 untrained healthy boys aged 16 were selected for the program, and the work was performed with a bicycle ergometer. Work load was increased progressively; 720 kpm/ min (2kp × 60rpm) for the first two minutes, and then increased 180 kpm/min (0.5 kp × 60 rpm) every successive minute to exhaustion. VO₂ and heart rate were measured at each step of load intensity. The expired air was collected in Douglas bag and was analyzed by Sholander apparatus for oxygen and carbon dioxyde.
There were some individual differences in correlation curves of VE to VO₂ and of FEO₂ to VO₂. The differences, however, were reduced and almost the similar curves were obtained when VE and FEO₂ were plotted against VO₂/VO₂ max instead of VO₂.
VO₂/VO₂ max and HR/HR max gave a very high correlation, 0.96. Though the correlation between VO₂ max and total work performed in exercise was 0.68, the correlation between VO₂/VO₂ max and total work was-0.89.
From these results, we should say that the index VO₂/VO₂ max and other functional index using their maximal values as denominator may be quite useful. And also we may assume that the work can be done with the highest efficiency when VO₂, heart rate, FEO₂, VE and probably some other physiological functions are at about 60% of their maximum. At least, we may say that there might occur some changes at this point in physiological conditions relating to the work capacity.

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) .

Ten athletic women (5 normal ovulatory cycles, 5 short luteal phases) and 6 non-athletic women with normal ovulatory cycles were subjected to an investigation of episodic gonadotropin secretion. In the middle follicular phase, blood samples were obtained via an indwelling venous catheter every 15 minutes for 4 hours.
Mean levels of gonadotropins in both athletic groups were lower (p<0.001) than in the control group. LH pulse frequencies in the short luteal group were significantly lower than in the control group (p<0.001) . LH pulse amplitudes were similar in all groups. FSH dynamics were the same as those for LH.
In athletic women, low mean levels and infrequent episodic secretion of gonadotropins were obvious. These data suggest that strenuous athletic activity may cause hypothalamic-pituitary insufficiency, especially that of hypothalamic origin.

Athletic women often exhibit menstrual disorders such as luteal insufficiency, oligomenorrhea and amenorrhea are often seen. It has been suggested that such disorders are related to prolactin release caused by physical activity. To investigate the mechanism by which the disorders are promoted, prolactin secretion was studied in 10 athletic women (5 with normal ovulatory periods, and 5 with short luteal periods) and 6 non-athletic controls. Blood samples were obtained during the early follicular phase of the menstrual cycle through an indwelling venous catheter at 15-minute intervals for 4 hours. The concentration of prolactin was measured by radioimmunoassay.
The mean prolactin concentration in the athletic group was lower than that in the control group (p<0.001), and pulse frequency in the athletic group was higher than that of the control group (p<0.01) . Pulse amplitude in the athletic women with short luteal periods was higher than that of those with normal ovulation. Pulse duration in the athletic women with short luteal periods was significantly longer than that of those with normal ovulation (p<0.01) .
These findings suggest that prolactin is one of the most important factors in menstrual disorders in athletic women.

Biological age based on the assessment of various physiological factors measured in a resting state has been proposed as an appropriate index of aging. We have recently developed an equation for estimation of physical fitness age (PFA), which is composed of eight age-related physical fitness variables. These include oxygen uptake corresponding to lactate threshold (Vo₂@LT), maximal oxygen uptake (Vo₂max), side step, grip strength, vertical jump, foot balance with eyes closed, trunk extension, and trunk flexion. In this study, the validity of PFA as a critical index of physical health and/or aging status was investigated from a longitudinal standpoint on the assumption that exercise habituation does contribute to health promotion. The subjects were 14 Japanese middle-aged and elderly men, aged 50 to 70 years, all of whom were patients with coronary heart disease (CHD) . The subjects participated in a supervised exercise conditioning program for 90 to 120 min each session, 2 times weekly for 4 months. Analyses of the data indicated that the mean PFA of the subjects (66.0±9.0 yr) after conditioning was significantly (P<0.05) lower than the mean PFA (72.8±8.6 yr) obtained before conditioning. After the exercise program, significant increases were documented in Vo₂@LT (17%), Vo₂max (12%), side step (26%), trunk flexion (109%), trunk extension (7%), vertical jump (12%), and foot balance with eyes closed (31%) . Therefore, we conclude that our exercise conditioning program may alter the overall physical fitness of patients with CHD, and that PFA could be a valid physical health and/or aging index.