ABSTRACT
A study was conducted to determine the accuracy of body composition prediction equations using the bioelectrical impedance (BI) method and skinfold thickness (ST) method for predicting longitudinal alterations in the body composition of schoolchildren. Seventeen healthy junior high school boys, aged 12 to 13 yr, participated in the study. Body density (Db) was determined by underwater weighing (UW) . Impedance was measured using a portable four-terminal impedance plethysmograph (800 μA, 50 kHz ; Selco, SIF-891) . Db values by the BI method were estimated from the equations developed for schoolchildren by Watanabe et al. (1993) and Kim et al. (1993) . Db by the ST method was estimated from the equations developed for schoolchildren by Nagamine et al. (1974) and Watanabe et al. (1993), using the sum of skinfold thickness at the triceps and subscapular area. Skinfold thickness was measured on the right side of the body with an Eiken-type skinfold caliper. The changes in Db and body fat measured by UW were small every year. The fat free mass (FFM) measured by UW increased significantly every year. The body composition (average Db, body fat and FFM) values estimated by the BI and ST methods showed no significant differences against average UW values. However, these average values estimated using the equation of Nagamine et al. (1974) were significantly different from the average UW values. The absolute amount of change in FFM (Δ FFM) estimated from BI and ST methods were correlated significantly with absolute amount of change in FFM (Δ FFM) determined by UW. In particular, the accuracy of body composition prediction equations for the BI method (r<SUP>2</SUP>= 0.81 for Watanabe et al., r<SUP>2</SUP> = 0.77 for Kim et al.) was higher than that of body composition prediction equations for the ST method (r<SUP>2</SUP>=0.41 for Nagamine et al., r<SUP>2</SUP>= 0.55 for Watanabe et al) . The findings of this study suggest that the body composition prediction equations based on the BI method are useful for valid assessment of longitudinal alterations in the body composition of schoolchildren.
ABSTRACT
To clarify changes in body temperature during endurance exercise in patients with spinal cord injury (SCI), we measured tympanic temperature (Tty) and skin temperature in the head, arm, chest, thigh, shin and calf in 5 patients with SCI (T6-T 12) and 7 normal controls during 30 minutes arm cranking exercise (20 watts) from 10 minutes before the initiation of exercise until 10 minutes after the termination of exercise in an artificial climate room at a temperature of about 25°C with a relative humidity of about 50%. The Tty in the SCI group was lower than that in the control group from 10 minutes before the initiation of exercise to 10 minutes after the termination of exercise with a significant difference only at the initiation of exercise. The difference in Tty slightly decreased with continuation of exercise. The Tty in the SCI group at rest was 36.05-37.15°C. Four patients in this group showed a decrease of 0.04-0.12°C in the early stage and an increase of 0.66°C±0.19 (mean±SD) at the end of exercise over the value at the initiation of exercise.<BR>The skin temperature was lower in the SCI group than in the control group in all sites excluding the arm. Significant differences were observed in the head in the early stage of exercise and after exercise, in the chest from 10 minutes before the initiation of exercise to 5 minutes after the termination of exercise, in the thigh from 10 minutes before the initiation of exercise to 10 minutes after the termination of exercise, in the shin 10 minutes and 5 minutes before the initiation of exercise, and in the calf from before to 15 minutes after the initiation of exercise. In the SCI group, marked individual differences were observed in the skin temperatures in the thigh, shin, and calf, suggesting specificity of the skin temperature response in and near the paralysis area.<BR>Results in Tty in this study suggested no heat retention in the SCI patients. Therefore, the risk for heat disorders seems to be low during moderate or mild exercise under moderate temperature environment at a temperature of about 25°C with a relative humidity of about 50% even when the skin temperature is low, and thermolysis is not marked.
ABSTRACT
The purpose of this study was to elucidate the relationship between the energy expenditure and the level of physical performance in preschool-age children. Seventy-six boys (5-6 years of age) had motor performance tests (25 m run, soft-ball throw, standing-long-jump, Zig-Zag run, upright handstand jog time, sit-and-reach, one-leg-balance) . Twenty boys were divided into two groups. One consisted of ten boys as the superior group and the other ten boys as the inferior group in results of the motor performance tests.<BR>Energy expenditure was calculated from oxygen intake measured by each child's HR-VO<SUB>2</SUB> regression equation in a treadmill running test and 24-hour heart rate measurement by monitoring recorder. Daily energy uptake was estimated from the weight and kind of food recorded by their parents.<BR>Energy expenditure in kindergarten, at home and in one day for the superior group were found to be higher than those for the inferior group. Energy uptake in the superior group showed a significant-ly higher value than that in the inferior group. It can be concluded that the children of the superior group appeared to be more active, since test and monitoring measurements showed they had more energy expenditure and energy uptake.
ABSTRACT
A study was conducted to clarify the influence of water immersion at different levels on pulmonary response. The subjects, ten healthy men (mean age, 26.2±7.9 years), subjected to measurement of static lung volumes and maximum expiratory flow-volume curves while sitting immersed in water at the level of both the neck and diaphragm. TLC, VC, ERV and FRC for water immersion at the diaphragm level were significantly decreased in comparison with those measured in air. These lung volumes were further decreased upon water immersion to neck level. However, RV did not change significantly upon immersion at either water level. Significant decreases of FEV<SUB>1⋅0</SUB>, FEV<SUB>1⋅0</SUB>%, V<SUB>50</SUB> and V<SUB>25</SUB> were observed upon water immersion at the diaphragm level as compared with those obtained in air. Water immersion to neck level produced further decreases in pulmonary functional parameters. Although peak flow and V<SUB>75</SUB> did not change significantly upon water immersion at either level, V<SUB>50</SUB> and V<SUB>25</SUB> were decreased markedly in comparison with the values obtained in air. A tendency for a marked decrease in pulmonary function parameters was observed upon water immersion to neck level. The changes observed upon water immersion to diaphragm level may have resulted from compression of small airways induced by both an increase of blood volume in the thorax and hydrostatic pressure against the abdomen. The changes induced by water immersion to neck level may have been exacerbated by the two mechanisms described above, in addition to hydrostatic pressure on the chest wall. The present results suggest that the significant reduction of pulmonary functional parameters caused by water immersion may be due to compression of small airways induced by an increase of blood volume in the thorax and hydrostatic pressure on the chest wall and abdomen.
ABSTRACT
The tetrapolar bioelectrical impedance (BI) method has been proposed as a convenient, valid approach for estimating the body composition of normal healthy adults. However, the validity of the BI method has not yet been confirmed for Japanese junior high school boys and girls. The purpose of this study was to develop convenient and useful equations for predicting the body composition in junior high school boys and girls by the BI method. The subjects were 297 healthy boys and girls, aged 12.15 years, all of whom were Japanese. Impedance was measured using a tetrapolar bioelectrical impedance plethysmograph (800 pA, 50 kHz SIF-891) manufactured by Selco. Multiple regression analysis was used to derive prediction equations for Db that were specifically applicable to boys and girls. The effective prediction equations for Db were as follows : 1) Db=1.1860-0.1282 (Wt·Z) /Ht<SUP>2</SUP>, and 2) Db=1.1402-0.0706 (Wt·Z) /Ht<SUP>2</SUP>-0.0007· (abdomen) for boys. 1) Db=1.1337-0.0778 (Wt·Z) /Ht<SUP>2</SUP>, and 2) Db=1.1124-0.0498 (Wt·Z) /Ht<SUP>2</SUP>-0.0006· (subscapular) for girls, where Db=body density (g/ml), Wt=weight (kg), Z =impedance (ohms), Ht=height (cm) . Db estimated by each respective equation was highly correlated with body density measured by underwater weighing (UW-Db) : 1) r=0.881, SEE=0.00868/ml, 2) r=0.902, SEE=0.00788/nil for boys and 1) r= 0.741, SEE=0.0101 g/ml, 2) r=0.775, SEE =0.0095g/ml for girls. Furthermore, in a cross-validation analysis of prediction equations for Db, another sample consisting of 40 boys and 66 girls was used. Db estimated from each respective equation was correlated highly with UW-Db : 1) r=0.856, 2) r=0.887 for boys and 1) r=0.837, 2) r=0.860 for girls. There were no significant differences between the mean Db obtained by the BI method and that by the criterion method. We suggest that the prediction equations proposed in this study are useful for valid assessment of body composition of Japanese junior high school boys and girls aged 12 through 15 years.
ABSTRACT
A study was conducted to investigate the validity of skinfold-based prediction equations for body density (Db, g/m<I>l</I>) developed by Nagamine et al. (1974), and to formulate convenient, useful equations for predicting Db by the skinfold thickness (ST) method in junior high school boys and girls. The subjects of the study were 269 healthy boys and girls, aged 12-15 years. The dependent variable, Db, was determined by underwater weighing (UW) . Independent variables included single skinfold thickness at three sites (triceps, subscapular and abdomen) and the sum of two skinfolds. Db by the ST method was estimated from the equations developed by Nagamine et al. (1974) for boys and girls, using the sum of skinfold thickness at the triceps and subscapular area. Skinfold thickness was measured on the right side of the body with an Eiken-type skinfold caliper. Db estimated by the ST method was correlated significantly with Db determined by UW (r=0.873 for boys and r=0.723 for girls) . However, average Db values estimated by the ST method were significantly lower than those deter-mined by UW (differences in Db values when predicted by the Nagamine equations: 0.0099 for boys and 0, 0114 for girls) . Therefore, we developed linear regression equations for predicting Db. The best-fitting prediction equation for Db was Db=1.0881-0.0010·X for boys, and Db=1.0715-0.0007·X for girls, where X is the sum of the triceps and subscapular skinfold thickness (mm) for boys and girls. Db estimated from the respective equation was correlated significantly with hydrodensitometrically determined Db (r=0.872, SEE=0.0089 for boys; r=0.722, SEE=0.0104 for girls) .<BR>Furthermore, in a cross-validation analysis of prediction equations for Db developed in the present study, Db estimated from the respective equation was correlated highly with hydrodensitometrically determined Db (r=0.887 for boys and r=0.740 for girls) . There were no significant differences between the Db values predicted by the ST method against hydrodensitometrically determined Db values (difference values: 0.0012 for boys and 0.0013 for girls) . The final phase of this study was to develop more stable equations, combining validation and cross-validation samples. On the basis of the final analyses, we recommend the equations Y=1.0875-0.0010X and Y=1.0716-0.0007X, with SEE of 0.0088g/m<I>l</I> for boys and 0.0105g/m<I>l</I> for girls, respectively. It is suggested that the prediction equations finally developed in the present study will be applicable to junior high school boys and girls.
ABSTRACT
Several prediction equations for estimating body composition of Japanese men and women have recently been developed using a linear regression model with a combination of impedance and anthropometric measurements as independent variables. The purpose of this study was to determine the cross-validity of body density (Db) estimated from bioelectrical impedance (BI) and skinfold thickness (ST) methods in comparison with underwater weighing (UW) as a criterion reference method. Percentage body fat (%BF) was derived from Db according to the equation Brozek et al. Fifty-seven healthy Japanese women, aged 19 to 57 years, volunteered to participate in the study. Impedance was measured by use of a portable four-terminal impedance plethysmograph (Selco, SIF-891) . %BF derived from the BI method (r=0.860-0.875) was correlated with hydrodensitometrically determined %BF to a greater extent than %BF obtained using the ST method (r=0.7330.758) or ultrasound method (r=0.536-0.721) . Correlations of various anthropometric indices (r=0.655-0.691) with hydrodensitometrically determined %BF were even lower. It was noteworthy, however, that mean %BF derived from existing BI equations differed significantly from hydrodensitometrically determined mean %BF. Therefore, we attempted to develop a new equation that was applicable to Japanese adult women as follows: Db=1.1613-0.1038 (Wt⋅Z ) /Ht<SUP>2</SUP>, where Wt=weight in kg, Z=impedance in ohms, and Ht=height in cm. The prediction accuracy of this equation was r=0.866 or SEE=0.0077 g/ml. Cross-validation of this equation on a different sample (122 Japanese women, aged 18 to 59 years) revealed a correlation of r=0.869 in terms of %BF, SEE=3.2%, and no significant difference between estimated %BF and the criterion. We suggest that the BI method is one of the most convenient, valid means of assessing human body composition, and that the newly developed BI equation could be useful particularly when the subjects are Japanese adult women in their late teens to fifties.
ABSTRACT
Male mice of dd-strain, at 4 weeks of age were used in the present study. The materials were divided into four groups; namely, mildly, moderately, severely trained and untrained. The treadmill exercise program for mildly, moderately and severely trained groups consisted of running at speeds of 6 m/min, 10m/min and running up a 10% grade at a speed of 12m/min for 10 min 5 times a week, respectively. The collagen content of the skin was measured by means of concentration of hydroxyproline. Moreover, the proportion of neutral salt-soluble (NSC), acetic acid-soluble (ASC) and insoluble collagen (ISC) in the skin was isolated. We attempted to study about the effects of physical activity on the metabolism of collagen by aging. Hydroxyproline concentration of the skin in untrained group increased rapidly until 6 weeks of age. Maximum hydroxyproline concentration was observed at 7 weeks of age in untrianed group. In three trained groups, maximum hydroxyproline concentration was observed at 9 weeks of age. The collagen content of the skin in the three groups was higher than that in untrained group at 9 and 11 weeks of age. The proportion of NSC, ASC and ISC of the skin varied with age in four groups. In the untrained group, the proportion of ISC increased with age and was recognized to reach 81.9% at 15 weeks of age. The proportion of NSC and ASC in both the moderately and severely trained groups indicated approximately 20% increase compared with that in the untrained group. This fact suggests that the degree of maturation of collagen is influenced by physical activity, especially, moderately and severely training. The authors conclude that continuous exercise training control the formation of intramolecular and intermolecular cross-links in skin collagen.
ABSTRACT
In previous assessments of body composition by whole body bioelectrical impedance (BI) analysis, electrodes have almost always been placed on the right side of the body. In fact, the most commonly used equations of Lukaski et al, were developed using BI measurements obtained on the right side of the body. However, in some individuals with traumatic injury or orthopedic problems, it would sometimes be necessary to measure BI on the right left side of the body. In the present study, we investigated the effects of electrode placement on BI and the derived percentage body fat. Subjects were 72 nontrained, healthy adult women : age ; 28.1±12.6 yr (1866), height ; 156.3±6.0cm, weight ; 50.5±7.7 kg, percentage body fat ; 24.4±5.2%. BI was measured for each subject in a supine position by use of a Selco SIF-881 plethysmograph (800 μA, 50 kHz) and ECG electrodes (Nikon Kohden) . The tetrapolar configuration was adopted in order to minimize contact impedance or skin-electrode interation. Eating and exercise were prohibited for at least 3 h prior to assessment. The effects of electrode placement were determined under four conditions: 1) the right arm and right leg (R side), 2) the right arm and left leg (R side-L side), 3) the left arm and right leg (L side-R side), 4) the left arm and left leg (L side) . Body density was predicted from the equation developed by Nagamine et al., and percentage body fat was derived from the body density according to Brozek et al. There were significant differences in BI values among the four conditions. Dominant side BI values were significantly lower than those on the non-dominant side. Percentage body fat values estimated under four different BI test conditions (i, e., R, R-L, L-R, and L) in terms of electrode placement were found to be highly correlated (r= 0.9420-0.956) with hydrodensitometrically determined percentage body fat. However, the mean percentage body fat on the dominant side of the body were significantly lower than that on the non-dominant side. We suggest that electrodes can be placed either on the dominant side or on the non-dominant side of the body for normal individuals, assuming that the lowest value from the four combinations of measurements can be used as the criterion value of BI. When the subjects are athletes, BI values obtained on the dominant side or a mean of the values measured on both sides should be adopted.
ABSTRACT
Recently, bioelectrical impedance analysis systems (BIA) have become available for determination of human body composition. The validity of BIA has been found to be sufficiently in the American population. However, more work is needed to assess the validity and applicability of BIA to the Japanese population. The purposes of this study were (1) to test the validity of body composition measured by BIA in comparison with the underwater weighing criterion method, and (2) to develop a convenient equation that would reliably predict body composition using BIA and anthropometric measurements in Japanese females. The subjects were 226 Japanese women and girls aged 11 to 55 years (23.9±8.3) . Body impedance was measured using a tetrapolar electrode method, with a localized 800-μA and 50-kHz current injection (Selco SIF-881) . The percentage of body fat (%fat) estimated by BIA was significantly correlated with densitometrically determined %fat (r=0.793, Lukaski et al, method ; and r=0.800, Segal et al, method) . The magnitude of these correlations was substantially higher when compared with r=0.615 found between the skinfold thickness method and the criterion method. Absolute %fat values estimated by BIA were, however, significantly lower than those determined by the criterion method, thereby indicating the need for a more accurate method of assessing Japanese body composition. For this, we propose the use of D=1.1303-0.0726 (Wt×R/Ht<SUP>2</SUP>), where D=body density in g/m<I>l</I>, Wt=body weight in kg, R= (R<SUP>2</SUP>+Xc<SUP>2</SUP>) <SUP>0.5</SUP> in ohms, and Ht=body height in cm. Lean body mass (LBM) and %fat predicted from this equation were correlated significantly (r=0.924 and r=0.799, respectively) with values determined by densitometry. The standard error of estimates of LBM and %fat resulted in figures of 1.9 kg and 3.7%, respectively. Thus we suggest that BIA is valid, convenient, and inexpensive, and that the prediction equation proposed in this study is useful for assessment of body composition in Japanese adult females.