ABSTRACT
The existing adoptive criterion for VO<SUB>2</SUB>max was created for physically fit subjects who were soldiers and/or sportsmen. However, VO<SUB>2</SUB>max is widely used at present as one of the health-related physical fitness determinants from children to aged persons. It might be appropriate to determine the criterion and the critical values for VO<SUB>2</SUB>max in consideration of age and gender.<BR>The present study attempted to determine the reference range and critical values of the criterion for VO<SUB>2</SUB>max using the iterative truncation method. Voluntary VO<SUB>2</SUB>max was measured in 548 healthy volunteers, aged 8 to 82 years, using a treadmill. The % VO<SUB>2</SUB>max was calculated using the equation of %VO<SUB>2</SUB>max=measured VO<SUB>2</SUB>max × 100 gage-estimated VO<SUB>2</SUB>max. Crude data of %VO<SUB>2</SUB>max was applied to the iterative truncation method, and the reference range of %VO<SUB>2</SUB>max (70-130%VO<SUB>2</SUB>max) was determined. Physiological and biochemical parameters, within the values of 70-130%VO<SUB>2</SUB>max, were converted to a percentage using a similar equation of %VO<SUB>2</SUB>max. The value corresponding to 10% of the lower area of the distribution of each parameter was defined as the critical value, which was the minimum level to adopt as the VO<SUB>2</SUB>max. Taking a single or combined application of the critical value of each parameter, the adoptive ratio of VO<SUB>2</SUB>max was investigated.<BR>The present study indicated that there was no difference between VO<SUB>2</SUB>max selected by the iterative truncation method and that obtained by the existing criterion for VO<SUB>2</SUB>max. The combination of the critical value of HRmax and bLAmax was recommended as a criterion of VO<SUB>2</SUB>max. The reference value, critical value of VO<SUB>2</SUB>max and the critical real value of each parameter were shown as a mean of every 5-year interval with the distinction of gender.
ABSTRACT
The effect of ingestion of a chilled carbohydrate and electrolyte solution on metabolic and hormonal responses and water-electrolyte balance was studied after two 5-km runs in hot outdoor conditions (Temp, 30.6-30.9°C ; humidity, 61.3-62.4%) . Eight healthy females (mean age 21.8 years) participated in : 1) a control experiment (Copt) with no fluid intake, 2) an experiment with 500 ml of tap water (WI), and 3) an experiment with 500 ml of sports beverage (SB) containing carbohydrate and electrolytes each of which were given after the 1st 5-km run, followed by a second 5-km run with an equivalent to 68.7-72.3% of VO<SUB>2</SUB>max. In the Cont, decreases in %ΔPV and blood glucose (BS) and increases in serum osmolality (Sosm), free fatty acid (sFFA) and plasma hormone concentrations related to regulation of the water-electrolyte balance in the body persisted after the 2 nd run. The intake of the sports beverage prevented hypoglycemia and ketoacidosis, as shown by an increase in sFFA and positive results for qualitative analysis of ketone body in the urine, and quick recovery of plasma volume following an endurance run under a hot environment. This study suggests that fluid replacement with a sports beverage containing carbohydrate and electrolytes was superior to plain water or no fluid ingestion in terms of metabolic and hormonal responses and the recovery of plasma volume and elevated rectal temperature following an endurance run under hot conditions.
ABSTRACT
We examined the relationship between serum magnesium (sMg) change and urinary Mg (uMg) excretion, lipid metabolism and hormonal responses induced by prolonged physical exercise. Six recreational runners voluntary participated in the study, and their sMg, uMg, serum lipid and circulatory levels of plasma hormones (ACTH, cortisol, ADH, aldosterone) were determined during a 1-week recovery period after a full-marathon race. Immediately after the race, fall of sMg was significant, but recovered to the pre-race level in the next day. Urinary Mg excretion decreased significantly after the race and the tubular reabsorption rate (%TRMg) was elevated for one week. The negative correlation between sMg and %TRMg suggested that a decreased level of sMg enhanced tubular reabsorption of Mg. On the other hand, no correlation was observed between the plasma hormone levels and %TRMg, thus hormonal responses induced by prolonged exercise had less effect on the tubular reabsorption of Mg. Therefore, fall of sMg after the full marathon race may not be a reflection of Mg depletion, but seems to be the result of a Mg shift to other regions (muscle, erythrocytes and adipose cells) from the serum. Increased level of serum FFA after the race suggested enhanced lipolysis, which might be a cause of sMg reduction.
ABSTRACT
The present study was carried out to investigate differences in hormonal and metabolic responses to moderate exercise in the post-absorptive state and during a 33-hour fast. Secretory factors and the roles of regulatory hormones of carbohydrate and lipid metabolism during moderate exercise were assessed baesed on these data. Energy substrates in the blood (glucose, BG; lactate, LA; triglyceride, TG; free fatty acids, FFA; free glycerol, FG) and plasma hormones (ACTH; GH; Cortisol, Corti; glucagon, IRG; insulin, IRI) concentrations were measured from 12 h to 33 h during the fasting period (12: 00, 24: 00, 06: 00, 09: 00), and 3min, 10 min and 30min after moderate treadmill exercise (estimated 70-80% of VO<SUB>2</SUB>max) for 20 min under fasting conditions between 09: 00 and 11: 00. These results (in the fasting experiment, Fast) were compared to the results on a normal diet (N-D) .<BR>The results were as follows:<BR>1. No differences in mean VO<SUB>2</SUB> and respiratory exchange ratio (RER) during exercise were observed between the Fast and N-D experiments. Mean heart rate during exercise in Fast was higher by 3.3±2.2 bpm (p<0.05) .<BR>2. Serum FFA and FG concentrations were significantly higher as a results of 24-hour fasting than the values measured at the same time in N-D. No significant change in serum TG concentrations were observed in Fast. While BG and LA concentrations remained low, and in small changes occurred in then both during Fast.<BR>3. Slightly higher levels of plasma ACTH, GH and IRG were found in Fast, but they were not significantly different from N-D. Plasma Corti concentrations gradually increased after 24 hours of fasting, and were 1.9 times higher at 09: 00 after 33 hours of fasting than on N-D. Plasma IRI levels, however, remained low, and the molecular ratio of IRG to IRI (IRG/IRI) was higher throughout Fast (1.8 to 10.6 times higher than on N-D ) .<BR>4. Plasma ACTH, GH and Corti concentrations increased markedly after exercise, and remained high until 30 min on Fast. No significant change in IRG and depression of insulin secretion were demonstrated after exercise on both treatment.<BR>5. Significant correlation between changes in plasma ACTH and Corti concentrations were observed throughout the experiments (Fast, r=0.562; N-D, r=0.528) .<BR>6. All of the energy substrates except blood TG increased after exercise, and the net increases in LA and FG (Δ) on Fast were significantly higher than on N-D. Significant correlations between the changes in the concentrations of FFA and FG (Fast, r=0.745; N-D, r= 0, 696), LA and BG (Fast, r=0.689; N-D, r=0.623), and FFA and LA (Fast, r=0.579; N-D, r= 0.479) were detected throughout both experiments.<BR>7. The coefficients of correlation between changes in plasma ACTH and FFA, and between BG and LA concentrations were higher on Fast than N-D. However, changes in plasma IRI and IRG concentrations were not directly correlated with any other changes in energy substrates in the blood in either treatment.<BR>The results indicated that moderate exercise for 20 min after a 33-hour fast causes marked responses in ACTH, Corti and GH secretions. It appeared that Corti secretion de-pended on ACTH, and that Corti facilitated fatty metabolism during exercise on Fast. However, secretion factors and the role of GH during exercise remain a matter of conjecture.
ABSTRACT
A study was carried out to confirm the present states of physical training and nutritional condition in sportsmen on the growing stage. Energy expenditure (EE), caloric intake (CI), food items, body weight, running distance for 12 min and hematological and biochemical parameters of blood and urine were measured in 17 high school boys during intense summer baseball training for seven days. EE was estimated from the records by direct observation of activities during the baseball training (RMR method), and CI was calculated from the dietary record supplied each subject for the seven observation day.<BR>Following results were obtained.<BR>1) The average EE was 55.4±7.5 kcal/kg/day, and the CI corresponded to 87.2% of the EE, although no significant reduction of body weight was observed at the termination of the training session.<BR>2) Running distance for 12 min gradually decreased.<BR>3) Significant decreases in serum TG, TP and Hgb concentrations, and a remarkable increase in CPK activity were observed on the 4 th and final days. Urinary excretion of phosphate, urea nitrogen and catecholamines also increased gradually.<BR>4) The greater the increase in negative energy balance (CI-EE), the greater the decrease in TG, TP and Hgb concentrations, and the greater the increase in serum CPK and urinary excretion of catecholamines.<BR>The present results suggest that greater intake of total energy, protein and fat is recommended for development of endurance capacity, baseball techniques and sound growth in occasion such as the present baseball training program in high school boys.
ABSTRACT
The present study was done to elucidate the medical problems and physical fitness of under-weight elementary schoolboys. Eighty nine volunteers, ranging in age from 9 to 12 yrs, were divided into five groups based on the grade of obesity, expressed as % of the standard, taking into account height, age and sex.<BR>The mean grade of obesity for under-weight boys was -12 %, and this group was defined as the experimental group (group I; n=15) . The group III, which contained 23 boys of grade 0 %, and the group V made of 13 boys of grade +33.5 % was defined as the normal control and obese control, respectively.<BR>The measurement of blood pressure, EKG recording, and blood sampling were done in the state of fasting before and after exercise. The exercise was a step test of 5 min duration with a temp of 1 step per 2 seconds, jumping over a bench 25 cm high for 9 years old boys, and 33 cm high for boys of 10 to 12 years. The step test score (PFI) and recovery rate of heart rate (RR (HR) ) were calculated from the EKG. The test battery of physical fitness performance was also done on another experimental day.<BR>The serum levels of total cholesterol (TC), triglyceride (TG), total protein (TP) and hemoglobin (Hgb) were lower in experimental group (EG) than in control groups (CG) . The cholesterol-HDL/TC ratio was conversely higher in EG than in CG. There were no significant differences in the other biochemical measurements between the five groups.<BR>Any abnormal EKG was not recorded before and after exercise throughout the subjects. The frequency of hypertension (above the 135/80 mmHg) was 10.2 % at pre-exercise time. But, none of the boys in EG was found to be hypertensive.<BR>The PFI and physical fitness performance test score showed no differences between EG and group III, however, the score of group V was inferior to that of EG and/or group III. The RR (HR) in EG and over-weight group was lower compared to that for the average-weight boys.<BR>Almost all components in blood measured were elevated after exercise in all the groups. The finding of the highest interest of the exercise-induced elevations of blood constituent levels was an increase in WBC measured as an indicator of stress. The magnitude of increase in WBC (ΔWBC) was higher in EG and the over-weight group than in the average-weight group. In normal subjects, ΔWBC was generally proportional to the work intensity, which, in the present exercise, depended upon the stature and body weight, because the height of bench, tempo and duration of exercise were same for all groups. The work intensity in EG was presumed milder, becasue the mean stature was slightly taller and bodyweight was less heavy compared to those in control groups. But, the greater increase of WBC in EG was observed in spite of a lighter work intensity. According to the Selye's literature, the particular WBC reaction to exercise in the under-weight boys was interpreted as a over-reaction to stress in the state of malnutrition.<BR>From some biochemical parametors, the leaner subjects were assumed to be in a slight malnutrition. And also a later recovery of HR and over-reaction to exercise stress were shown in the under-weight boys group.<BR>It is emphasized that the malnutrition resulting from excessive effort for preventing obesity was unfavourable for children in the growing stage for their healthy growth and development.
ABSTRACT
The purpose of the present study was to assess the effect of commercial sports beverage intake after a thermal exposure on water-electrolytes balance.<BR>Nine healthy male volunteers with a mean age of 26.4 years, not heat acclimated, participated in a control experiment where no fluid was given (C experiment) . Five of them were given 500ml isotonic sports beverage containing Na<SUP>+</SUP>, K<SUP>+</SUP>, Cl<SUP>-</SUP>and glucose (S. B experiment) and/or 500 ml tap water (Wa experiment) immediately after sauna exposure. The nude subjects were exposed to a sauna with 65 to 70°C (r. h. 50 to 60%) for 30 min.<BR>Serum protein, electrolytes (Na<SUP>+</SUP>, K<SUP>+</SUP>, Cl<SUP>-</SUP>), creatinine, plasma aldosterone (Ald), and catecholamines concentrations and excretions of electrolytes and aldosterone into urine were measured before, and 3, 30, 60, and 120 min after the sauna. Serum and urinary osmolalities, blood pressure, rectal temperature (Tr), heart rate, oxygen consumption and weight loss were also measured.<BR>Body weight loss ranged from 50 to 750g. Serum protein, electrolytes and Ald concentrations increased significantly after the sauna. The enhanced levels of these variables and the depression of urine volume, urinary Na<SUP>+</SUP>excretion were maintained throughout the 2h recovery period in C experiment. Hydration associated with a reduced concentration of serum protein and electrolytes was observed at 30 min in S. B, at 60 min in Wa, and a dehydration occured again at 120 min both in S. B and Wa. A peak of urine volume was observed at 60 min in S. B and at 120 min in Wa during recovery. Free water clearance (C<SUB>H2O</SUB>) was -0.98 ml/min/100 ml GFR (Ccr) prior to the exposure. With no fluid administration after the sauna, an excess in negative water balance remained throughout the 2 h recovery. But C<SUB>H2O</SUB>changed from negative to positive at 60 and 120 min after sports beverage and/or water loadings.<BR>A significant elevation of % TRNa (0.33 to 1.14%) was maintained after the sauna in both C and Wa experiment. Plasma Aid concentration and excretion of Aid in urine after the exposure were higher in both C and Wa than in S. B experiment. The increased Tr did not return to the initial level throughout the recovery. No significant differences were observed among the three experiments in heart rate and blood pressure as well as Tr.<BR>The data indicate that salt deficit due to the sauna exposure was attenuated, but not prevented, by sports beverage intake, although the Aid secretion was alleviated. It is suggested that an over loading of sports beverage or water (i. e. 500 ml VS 50 to 750 g weight loss) leads to a marked and prompt water-diuresis, and to another dehydration. The increase of Tr as well as a partly salt deficit can be related to the rises in Ald secretion still observed at 2 h recovery.