The purpose of the present study was to determine by simulation whether oxygen deficit kinetics in decrement-load exercise (DLE) starting from a low exercise intensity is related to the oxygen uptake (Vo2) kinetics. In this simulation, work rate in DLE was separated into steps that were regarded as constant-load exercises (CLEs). It was assumed that Vo2 kinetics behaved exponentially at the onset and offset of each CLE, respectively. Vo2 at the onset of CLEs increases at the same time and becomes a recovery phase step-by-step corresponding to the decrement of work rate. The sum of Vo2 values at the onset of CLEs at a given time (nt-Vo2) corresponds to Vo2 excluding oxygen debt in DLE. The sum of Vo2 values at the offset of CLEs at a given time (dt-Vo2) corresponds to Vo2 related to oxygen debt in DLE. The total of net- and dt-Vo2 values is equivalent to Vo2 actually observed in DLE (gs-Vo2). As the oxygen requirement level is a steady-state value of Vo2 in CLE, the oxygen deficit level can be obtained by subtracting Vo2 at the onset of CLE from the steady-state value. The oxygen deficit level at a given time was added in all CLEs. This is oxygen deficit per unit time (df-Vo2). Oxygen debt and oxygen deficit were calculated by integrating df-Vo2 and dt-Vo2 from the start of exercise to a given time, respectively. Gs-Vo2 increased, reached a peak, and decreased linearly until the end of the DLE. Oxygen deficit increased rapidly and showed a steady state. Oxygen debt increased linearly after a time lapse. The difference between oxygen deficit and oxygen debt changed like gs-Vo2 kinetics. Therefore, it is concluded that if we consider the repayment of oxygen debt in the oxygen deficit in DLE, the kinetics of the oxygen deficit becomes similar to gs-Vo2 kinetics in the simulation.
The purpose of the present study was to determine the degree of fitting an approximation equation for oxygen uptake (Vo2) in decrement-load exercise (DLE). Work rate was started from 120 watts and was decreased by a rate of 15 watts per min. The initial work rate of DLE corresponded to 72±10% of the work rate at anaerobic threshold determined in incremental-load exercise (ILE). Vo2 in DLE increased rapidly, reached a peak, and decreased linearly until the end of the exercise. Vo2 in DLE was higher than that in ILE at the same work rate except in the early periods in ILE and DLE. This difference ranged from 300 to 400 ml/min. This difference is a result of repayment of oxygen debt in DLE and from the oxygen deficit induced by the delay of response of Vo2 in ILE. As work rate in DLE can be obtained by the difference between work rates in constant-load exercise (CLE) and ILE, we postulated that the approximation equation for Vo2 kinetics in DLE could be expressed by a combination of approximation equations in CLE and in ILE. When time delay was taken into consideration in this equation, the fitting of data obtained by using the equation was better than that of data obtained by using the equation without a parameter of time delay. The degree of fitting ranged from 94 to 98% (r2). Thus, it seems that Vo2 including oxygen debt in DLE can be approximated by the equation used in this study.
The purpose of this study was to investigate the changes of maximal oxygen consumption, left ventricular function and serum lipids after 36 weeks of aerobic exercise in elderly women without the influence of drugs. Eight elderly women were studied by M-mode and Doppler echocardiography to assess left ventricular size, mass and function. Maximal oxygen consumption (VO2max) was determined for each subject by administering a treadmill exercise test. The training intensity was decided by heart rate reserve. Subjects performed exercise for 40minutes a day, 3days a week at 50–60% of the heart rate reserve during the 36 weeks. Exercise capacity was assessed by VO2max with a graded exercise test of the treadmill. Weight and % body fat decreased after training. Cardiorespiratory function improved because of the increase in VO2max and VO2max normalized for body weight after training. Systolic blood pressure significantly decreased. There are no significant difference in all left ventricular's parameters (end-diastolic dimension, end-systolic dimension, end-diastolic volume, end-systolic volume, stroke volume, cardiac output, ejection fraction, fractional shortening) after 36 weeks. Exercise training did not induce left ventricular (LV) enlargement as evidence of an absence of increase in left ventricular end-diastolic volume. The total cholesterol level and triglyceride level decreased after training. High density lipoprotein-cholesterol significantly increased and low density lipoprotein-cholesterol significantly decreased, atherogenic index (AI) significantly decreased and apolipoprotein A-I increased and apolipoprotein B decreased after training. In conclusion, although there was no significant change in left ventricular function, aerobic training showed a positive influence on body composition, maximal oxygen consumption and serum lipids.
The purpose of this study was to investigate the ADL ability characteristics of the elderly by comparing the characteristics to achieve basic activities between the independent and institutionalized dependent elderly from the viewpoints of gender and age differences. The subjects were 697 Japanese dependent elderly living at welfare institutions for the aged, and 482 independent elderly living at home. Seventy-four activities were selected from nine ADL domains. The survey for the independent elderly was conducted in health or culture education classes, and for the elderly without these classes, a general delivery survey was conducted. The independent elderly provided their own data. The survey for the dependent elderly was conducted in welfare institutions and the staff working at the subjects' institutions responded. In two-way ANOVA of rates of items, significant gender differences were found in some changing and holding posture activities in the independent elderly group, and in activities using upper extremities in the dependent elderly group. ADL ability in the independent elderly group significantly decreases with aging, but this trend is unclear in the dependent elderly group. In the independent elderly group, indications of a decrease appear in activities with lower limbs from the 70s, and appear in the most of basic activities from the 80s. Furthermore, differences in achievement levels of each activity with aging were found in both elderly groups. These findings may suggest that there are remarkable individual differences in ADL ability of the elderly with aging.
This study was conducted to obtain basic data in improving the health of Koreans, saving energy and protecting environments. This study investigated the effects of wearing thermal underwear for keeping warm in the office in winter where temperature is not as low as affecting work efficiency, on thermoregulatory responses and subjective sensations. In order to create an environment where every subject feels the same thermal sensation, two experimental conditions were selected through preliminary experiments: wearing thermal underwear in 18°C air (18-condition) and not wearing thermal underwear in 23°C air (23-condition). Six healthy male students participated in this study as experiment subjects. Measurement items included rectal temperature (Tre), skin temperature (Tsk), clothing microclimate temperature (Tcm), thermal sensation and thermal comfort. The results are as follows: 1) Tre of all subjects was maintained constant at 37.1°C under both conditions, indicating no significant differences. 2) (Tmacr)sk under the 18-condition and the 23-condition were 32.9°C and 33.7°C, respectively, indicating a significant level of difference (p<0.05). 3) Among local skin temperature, trunk part (forehead and abdomen) did not show significant differences. After 90-min exposure, the skin temperature of hands and feet under the 18-condition was significantly lower than that under the 23-condition (p<0.001). 4) More than 80% of all the respondents felt comfortable under both conditions. It was found (Tmacr)sk decreased due to a drop in the skin temperature of hands and feet, and the subjects felt cooler wearing only one layer of normal thermal underwear at 18°C. Yet, the thermal comfort level, Tre and Tcm of chest part under the 18-condition were the same as those under the 23-condition. These results show that the same level of comfort, Tre and Tcm can be maintained as that of an environment about 5°C higher in the office in winter, by wearing one layer of thermal underwear. In this regard, this study suggests that lowering indoor temperature by wearing thermal underwear in winter can contribute to saving energy and improving health.
The purposes of this study were 1) to estimate biological age score (BAS) in Japanese healthy women based on the 4–7 years longitudinal data for physiological, hematological and biochemical examinations and 2) to examine the rate of aging changes in adult women based on the estimated BAS. The samples consisted of cross-sectional (n=981) and longitudinal (n=110) groups. Out of 31 variables examined, five variables (forced expiratory volume in 1.0 s, systolic blood pressure, mean corpuscular hemoglobin, glucose, albumin/globulin ratio) that met the following criteria: 1) significant cross-sectional correlation with age; 2) significant longitudinal change in the same direction as the cross-sectional correlation; and 3) assessment of redundancy, were selected as candidate biomarkers of aging. This variable set was then submitted into a principal component analysis, and the first principal component obtained from this analysis was used as an equation for assessing one's BAS. Individual BAS showed a high longitudinal stability of age-related changes, suggesting high predictive validity of our newly developed aging measurement equation. However, changes in the aging rate based on the estimated BAS were not constant. The mean slopes of the regression lines of BAS for the three age groups (age<45, 45≤age<65 yrs, 65≤age) were 0.095, 0.065, 0.138, respectively. One-way analysis of variance detected a significant difference (F=5.14, p<0.01) among the three age groups. These results suggest that the rate of aging in adult women is relatively slower until 65 years of age, but after 65, the rate of aging shows a rapid increase. We concluded that the longitudinal method used for selection of variables to compute the BAS was useful and theoretically valid compared to those obtained from cross-sectional data analysis.
Body fat distribution and abdominal fatness are indicators of risks for coronary heart disease. However, the relationships between resting energy expenditure (REE) and the body fat distribution or the abdominal fatness are unclear. We examined the relationships of REE with whole-body fat distribution (waist, hip and waist-to-hip ratio: WHR) and abdominal fatness (intra-abdominal fat: IF and subcutaneous fat: SF) after adjustment for body composition. 451 men and 471 women were subdivided into two groups, 40–59 years: middle-aged group and 60–79 years: elderly group. REE was measured by an indirect calorimetry system. Percentage of fat mass (%FM), fat mass (FM) and fat-free mass (FFM) were assessed by a dual-energy x-ray absorptiometry method. The IF area (IFA) and SF area (SFA) at the level of the umbilicus were measured using computed tomography. Circumference of waist and hip were measured in a standing position. The WHR, waist circumference and SFA did not significantly (p>0.05) associate with the REE after adjusting for FM, FFM and age in any of the groups. The adjusted REE was significantly and inversely correlated with hip (r=−0.159, p<0.05) and IFA (r=−0.131, p<0.05) in the elderly men. These results suggest that lower REE may contribute to greater hip and IFA rather than WHR and waist in elderly men.
The purpose of this study is to find out the differences in physical activity (PA), energy expenditure (EE) and energy intake (EI) under free-living conditions between Japanese prepubertal obese and nonobese boys. The subjects were 15 prepubertal obese boys (Age: 11.7±0.4 years old, Body fat: 35.2±1.6%) who do not have obese parents and siblings and 15 prepubertal nonobese boys (Age: 11.8±0.4 years old, Body fat: 18.5±0.8%). We assessed their daily PA by heart rate (HR) monitoring, pedometer step counts (PSC) and time for sedentary activities (SA). We also examined calculated EE from HR-VO2 regression, EI and percentage of macronutrient EI. Results are as follows: Percentage of body fat had significant correlation with weight, BMI, time for SA, percentage EI of protein (positive, p<0.001), VO2max, VO2max per body weight, VO2max per LBM, PSC, TEE per body weight, TEI per body weight (negative, p<0.001), percentage of EI of carbohydrate (negative, p<0.01). The values of the obese were significantly lower in total EE per body weight and in total EI per body weight. EI from dinner was significantly higher in the obese group. The values of the obese were significantly higher in percentage EI from protein and that from carbohydrate. The results of this study showed prepubertal obese boys who do no't have obese parents and siblings have low PA and spend much time for sedentary activities. Obese boys consume higher percentage energy of protein and lower percentage of carbohydrate though differences in EE and EI were found only in total EE per body weight and total EI per body weight between obese boys and nonobese boys.