Katsunori Fujii

Analysis of the velocity curve for height by the wavelet interpolation method in children classified by maturity rate.

The Wavelet Interpolation Method (WIM) developed by Meyer ([1992] Wavelets and Operators. Cambridge: Cambridge University Press) has been proposed as an analytical method for the accurate description of longitudinal growth velocity in height and identification of the age at maximum peak velocity (MPV) in the curve. The distance curve in height was determined by interpolating the longitudinal records of 98 boys and 88 girls, 6–17 years old, with the WIM. The distance curve was then differentiated to obtain a velocity curve. Age at MPV estimated from the velocity curve was utilized as a criterion of maturity rate (timing), and five maturity groups (early, little early, average, little late and late) were defined in both sexes. Four type models were derived from the occurrence of secondary peaks (mid‐growth spurt and after‐growth spurt): type model A, appearance of a mid‐growth spurt and MPV; type model B, appearance of an after‐growth spurt and MPV; type model C, appearance of a mid‐growth spurt, an after‐growth spurt and MPV; and type model D, appearance of MPV only. The individual growth data of boys and girls classified by maturity rate were sorted into the four type models. The frequency of occurrence of the four type models in groups classified by maturity rate was then analyzed, and the characteristics of height growth velocity was examined in boys and girls. Am. J. Hum. Biol. 11:13–30, 1999.

Confirmation of delayed menarche based on regression evaluation of age at menarche for age at MPV of height in female ball game players.

A general delay in menarche in female athletes has been confirmed based on comparisons of mean ages between athletes and non-athletes; however, it has not been possible to judge such delays individually. If delayed menarche could be evaluated for an individual, the athlete could be advised as to necessary precautions. In this study, the age at maximum peak velocity (MPV) of height, adopted as an index of physical maturation, was identified by the wavelet interpolation method (WIM). The relationship between the age at menarche and age at MPV of height in female athletes and non-athletes was then examined. For the athlete group, health examination records of 90 female ball game players in the first year of university in the Tokai area, all of whom had participated in national level competitions, were reviewed for the period from the first grade of elementary school until the final year of high school (from 1985 to 1996). A similar examination was conducted for the control group, among whom a final group of 78 female non-athletes were selected. The age at menarche was determined by questionnaires, and the longitudinal data for height and weight were obtained from the health examination records. Based on a comparison of the difference between the age at MPV of height and age at menarche in ball game players and the control group, a tendency was seen for the difference between the two ages to narrow as the age at MPV of height rose. A corrected regression evaluation of age at menarche against age at MPV of height was derived in the control group, and the evaluation system was applied to ball game players. The delay in menarche in ball game players could be individually evaluated.

Validity of fat percentage evaluation for fat-thin judgement derived from standard weight in preschool children

In the present study, we measured body composition of boys and girls aged 3–5 years and investigated changes with age. We also composed regression polynomials of body weight against height from the data and the data for young children obtained similarly in the present study, determined the valid order for the polynomial, and developed a regression evaluation. Obesity was determined from the regression evaluation for body weight against height and compared with obesity determined from the body fat percentages obtained in this study to investigate the validity of body composition measurements of young children. A comparison was then made of children whose fat-thin level was judged from height and weight in this way and determinations of fat-thin level judged from statistical values for fat percentage measured in this study. In boys both distributions show essentially the same trends, whereas in girls the distribution shows a marked change toward “somewhat thin”. Fat percentage judgements were more common in “somewhat thin”, and overall there was a greater trend toward obesity in judgements from weight vs. height regression evaluation charts.

Relationship between body composition and BMI in preschool children

Childhood obesity is one of the most serious public health challenges of the 21st century. Obesity is a state in which body fat accumulates to an abnormal degree, and detailed information about body composition is necessary to investigate the problems of obesity in children. In the present study, we measured body composition using equipment based on the multifrequency bioelectrical impedance analysis method to measure lean body mass and the quantity of fat. We evaluated differences in body composition in young children from 3 to 5 years old, including differences in relation to gender, and correlated them with measured values of BMI. The fat percentages in girls were higher than in boys, and the muscle percentages (muscle mass/weight × 100) were the opposite. These results show that there were differences in relation to gender. Our evaluations were based on regression analysis of fat percentages in relation to BMI and muscle percentages. A high correlation was found between BMI and fat percentage. The relationship between BMI and muscle percentage was the opposite of the relationship between BMI and fat percentage, and there was a high negative relationship between boys and girls. A significant regression tendency was confirmed from the results of the regression analysis of fat and muscle percentages for BMI in preschool children. This suggests that BMI can also be used to evaluate the fatness or thinness of a preschool child. In short, BMI can be used as an index that can be used to evaluate fat and muscle percentages from early childhood.

Secular trends in physical growth indicators in infants and young children

There have been no analyses in Japan that have used mathematical functions to investigate changes over time in physical growth records of infants and young children. In this study, we investigated secular changes in physical growth velocity of infants and young children using the wavelet interpolation method, and examined secular changes in physical growth indicators. The subject data were physical growth survey records for young boys and girls published by the Ministry of Health, Labor and Welfare in 1960 and 2000. The physical growth indicators used in the study were height, weight, chest circumference and head circumference. The wavelet interpolation method was applied to these indicators for the period from age 0 to 6 years, and the derived growth distance curves and growth velocity curves were analyzed. The values at birth were higher in 1960 than in 2000 for both boys and girls, but after 6 months of age the values for 2000 exceeded those for 1960. The largest peak velocity soon after birth, obtained from the analysis of the growth velocity curve, did not show clear secular changes in either boys or girls. However, a clear increasing trend was seen in the largest peak velocity for all indicators in both boys and girls in 2000, compared with 1960. The age at first local peak velocity remained unchanged in boys in 2000 compared with 1960, but in girls slightly earlier trends were seen in all indicators in 2000. Thus, this investigation of the secular changes in physical growth indicators in infants and young children indicated that in 2000 children were slightly smaller at birth, but then matured more quickly, and grew larger than children in 1960.

Changes in Psoas Major and Quadriceps Cross Sectional Area in Elderly People after 12 Weeks of Exercise

The purpose of this study was to investigate whether 12-weeks of movement training would increase the psoas major cross-sectional area (CSA) in senior men and women. Fifty eight men and women aged 65 to 80 years old (69.6±3.7, 30 male, 28 female) were divided into a control (n=19) and exercise group (n=39). Subjects were assessed before and after the training program for stature, body mass, and magnetic resonance imaging of the psoas major and the quadriceps muscle. The experimental group performed exercises using machines designed to improve the movement of the hip at a frequency of twice every week, with a total of 23 trainings in 12-weeks. Magnetic resonance images of both thighs and the abdomen and psoas major were obtained, aimed at 50% of the length of the greater trochanter and the lower edge of the femur and between the fourth (L4) and fifth (L5) lumbars. A 9.4% increase in the psoas major CSA in the training group was observed. In the male and female breakdown, a 11.5% and 8.4% change was observed in males and females, respectively. In the quadriceps, there was no significant statistical improvement in either males or females. Furthermore, in the control group, there was no significant change seen in either the psoas major or the quadriceps. As a result of conducting training that enables upkeep of posture and smooth linkage of the lumbar spine, the pelvis and thighbone, the psoas major CSA of older adults were improved in a short period of time. For this reason, the possibility of improving the psoas CSA, which decreases remarkably with increased age, by improving the linkage of the body trunk is also suggested.

Confirmation of physical growth pattern in children with a slim body type: analysis of longitudinal data in Korean youth

There is little research carried into physical growth in obesity, and there is even less carried out into physical growth in slimness. In this study, using data on Koreans, who are racially similar to Japanese, we classified subjects into slim and medium types, and analyzed longitudinal growth data for height and weight in these two groups. The study groups comprised 600 boys and 501 girls in the final year of high school selected from schools in Busan, South Korea, and in a suburb of Busan. We identified the age at maximum peak velocity (MPV) in growth during puberty derived from the growth velocity curves for height using the wavelet interpolation method, and determined the levels of maturity. We also retrospectively analyzed the rate of appearance of the slim and moderate types back to the first year of elementary school, and investigated genetic elements by examining the proportion of slim children who remained slim. The proportions of boys and girls classified as slim in grade 1 were 26% and 38%, respectively, in relation to those classified as slim in the final year. The ages at MPV for height were 14.11 years (SD 1.07) among medium-type boys and 14.68 years (SD 1.01) among slim boys. The ages at MPV for height were 12.05 years (SD 1.30) among medium-type girls and 12.18 years (SD 1.36) among slim girls. The ages at MPV for height were significantly different (P < 0.05) between slim and medium-type boys, but were not significantly different in girls.

Effect of alkali ion water intake before and after exercise on water volume in the blood during recovery phase

Physical condition begins to feel abnormal with a water loss of several percent of body weight. In this study subjects drank alkali ion water and neutral water before and after exercise, and the water volume in the blood and serum osmotic pressure dynamics were evaluated. The usefulness of alkali ion water intake before and after exercise in recovering from dehydration due to exercise was investigated. The subjects were ten healthy male university students. The drinks used were commercially available alkali ion water as the experimental drink and neutral water as the placebo. Exercise was done for 30 min on a bicycle ergometer. Water volume in the blood and serum osmotic pressure were determined using blood component tests. The water volume in blood was higher in the alkali ion water group than in the neutral water group, indicating the effectiveness of alkali ion water in maintaining the amount of water in the blood. In addition, in the alkali ion water group serum osmotic pressure showed a significant decrease, and the amount of water in the blood increased. The rate of absorption was therefore high and considered to be effective in maintaining a sufficient water volume in the blood. It is possible that increases in the amount of plasma may also be expected with alkali ion water intake, suggesting the effectiveness of alkali ion water in the recovery of water volume in the blood following dehydration due to exercise.

Construction of a delayed menarche evaluation system for South Korean female athletes by the wavelet interpolation model

As an evaluation system for delayed menarche has not been established in South Korea, the Author determined the interval between age at menarche and the age at the maximum peak velocity (MPV) for height in individual Korean female athletes and used the wavelet interpolation method to derive such as system. It is necessary to identify female athletes in whom delayed menarche occurs in order to elucidate the effects of regular training on menarche. The evaluation system was derived from regression analysis of age at menarche in relation to age at MPV for height. Health examination records of 154 Korean female athletes in their second year at high school who had participated in national level competition were reviewed from the first grade of elementary school until the second year of high school. The longitudinal data for height were obtained from the health examination records. The age at menarche and the history of athletic sports training were researched by questionnaire and interview. Non-athletes were used as a control group similar to the athletes, and 330 were randomly selected to construct the criteria for evaluation of delayed menarche. Least-squares approximation polynomials for age at menarche in relation to age at MPV for height from the first to the third order were constructed, and the regression equation for the cubic polynomial was valid. The cubic regression polynomial was therefore applied to each athlete. From the regression evaluation a score was derived for each athlete, and a positive score was found for athletes participating in each athletic sport except archery. The results indicate that Korean athletes have a strongly delayed menarche.