The purpose of this study was to compare age and gender differences of lower limb muscle thickness among healthy young children. Five hundred and sixty-one healthy young children aged 3 to 8 years old (284 boys and 277 girls) participated in this study. Anterior thigh, posterior thigh, and calf muscle thicknesses (MTa, MTp, MC) were determined using a B-mode ultrasound. The thickness of each muscle increased significantly as age increased, except in the MTa in the 5-year-old boys' group. A significantly main effect was found in MTa, and there was a higher value in girls than boys, except in the 4-year-old group. A significant age × gender interaction was also observed in MTa, with higher values found in boys than girls, except in the 3- and 5-year-old groups. There was no significant gender different in MC. In addition to the Mt/Tmt ratio, the ratio of each muscle thickness to the total amount of MTa, MTp, and MC was calculated. As a result, in girls, the Mt/Tmt ratio remained constant as age increased in all muscles. On the other hand, in boys, MTa decreased and MTp increased as age increased. From these results, it was suggested that gender differences exist in lower limb muscles thickness among healthy young children aged between 3 and 8 years old. It was also suggested that the muscle development of MTa and MTp was different in boys, while lower limb muscle development in girls stayed constant.

The purpose of this study was to clarify the effects of lower limb muscle mass growth on sprinting ability in children aged 3 to 8 years. The subjects were 514 unimpaired children (266 boys and 248 girls). We measured their lower limb muscle thickness (anterior thigh: MTa, posterior thigh: MTp, and calf: MTC) and 25 meter sprinting time. Muscle thickness was measured using a B-mode ultrasound diagnostic imaging unit. From the 25 meter sprint, we measured the following characteristics in relation to sprinting ability: results, maximum velocity, stride and pitch. The results revealed that sprinting ability significantly correlated with MTp and MTC in both boys and girls. This suggests that, in addition to morphological development, lower limb muscle mass growth contributes to an increase in stride (m/step) and affects sprinting ability during the period from infancy to early childhood. However, no relationship was seen between sprinting ability and anthropometric characteristics (body height and mass) or lower limb muscle thickness among 8-year-old boys. It is possible that lower limb muscle quality and power as well as improvement in elements such as sprinting movement have a stronger influence on sprinting ability than morphological elements such as physique and muscle mass in boys around that age. In contrast, a significant relationship was seen between lower limb muscle thickness and sprinting ability in girls of all age groups, suggesting that, unlike boys, innate lower limb muscle mass influences sprinting ability for girls.

A study was performed to evaluate the physical capacity of elite female volleyball players from Kyushu Bunka Gakuen Senior High School (Kyu. B. G.) . Twenty-four players were examined for body composition (underwater weighing), cardiorespiratory function (VO₂max and O₂debtmax by treadmill exercise test) and skinfold thickness, from 1988 to 1989.
These measurements were compared with those of 16 second-class players from Nagasaki Prefecture, and also with the results of other investigations.
The results were as follows :
1. The mean parameters for the Kyu. B. G, players were : age, 17.5 yr ; height, 168.3 cm ; weight, 59.8 kg ; percentage body fat (%Fat ), 17.9% ; lean body mass ( LBM), 49.0 kg ; LBM/ Ht, 29.1 kg/m ; sum of eight skinfold thicknesses, 109.1 mm ; VO₂max, 2.71 l/min, 45.7 ml/kg· min ; O₂debtmax, 5.69l, 94.8 ml/kg.
2. The average %Fat of the Kyu. B. G, players was significantly lower than that of the second-class players from Nagasaki Prefecture.
3. The average VO₂max (ml/kg·min) and O₂debtmax (l, ml/kg) of the Kyu. B. G, players were significantly higher than those of the second-class players.
4. The average %Fat and VO₂max (ml/kg·min) of the Kyu. B. G, players were similar to those of Japan League and All Japan volleyball players.
5. When the progress of physiological function due to training for 11 months was examined in five Kyu. B. G, players, the average VO₂max (ml/kg·min) showed a significant increase of approximately 8%.
These results indicated that the Kyu. B. G, players had a superior body composition, aerobic work capacity and anaerobic work capacity, equal to those of top volleyball players in Japan.

A study was performed to evaluate the physiological function of elite senior high school soccer players (Kunimi) . Forty-six players were evaluated for cardiorespiratory function (maximum oxygen uptake : Vo₂max, maximum oxygen debt : Max O₂ debt), body composition (underwater weighing) and skinfold thickness, all parameters being measured four times over a two-year period.
The following means were recorded : age, 17.8 yr ; height, 173.0 cm ; weight, 65.8 kg ; percentage body fat (%Fat), 10.0%; lean body mass (LBM kg), 59.2 kg ; LBM/Ht (kg/m), 34.2 ; sum of eight skinfold thicknesses, 63.5 mm ; Vo₂max, 60.0 ml/kg⋅min ; maximum ventilation (V_Emax, BTPS), 136.8l/min ; maximum oxygen debt ; 8.2l, 124.8 ml/kg.
Results for percentage body fat, Vo₂max (ml/kg⋅min) and Max O₂ debt (ml/kg) were compared with values found in other soccer players at various levels.
In summary, one of the most outstanding attributes of the Kunimi senior high school soccer players was a high level of both aerobic power and anaerobic power.

A study was conducted to evaluate the physique, body composition, ⁴⁰K (body potassium content; K) and skinfold thickness of severely handicapped children and adults. Seventy-two subjects were classified by physical activity level into four categories, and these categories were combined into an ACTNE GROUP and an INACTIVE GROUP.
The handicapped children and adults were evaluated for body height, body weight, percentage body fat (skinfold method and ⁴⁰K method), lean body mass (LBM), K (g), K/Wt (g/kg), and skinfold thickness, all parameters being measured in 1985. The parameters were compared with values found between males and females, cerebral palsy (CP) and mentally retarded (MR), and the active group (AG) and the inactive group (NG) .
The following mean values were recorded: ACTNE GROUP (AG) , age 16, 9 yr; height 132.5 cm; weight 27.9 kg; percentage body fat %Fat (Nagamine) 17.8%; %Fat (Forbes) 31.2%; LBM 22.7 kg; K (g) 49.3 g ; K/Wt (g/kg) 1.79 g. INACTIVE GROUP (NG) , age 17.0 yr; height 132.7 cm; weight 22.9 kg ; percentage body fat %Fat (Nagamine) 15.6%; %Fat (Forbes) 35.2%; LBM 19.1 kg; K (g) 36.5 g; K/Wt (g/kg) 1.68 g.
The values of body composition (%Fat, LBM) estimated using the formulae of Forbes, Garrow and Behnke, by the ⁴⁰K method were compared with those estimated by the skinfold method (Nagamine) .
Results for physique, percentage body fat, LBM (kg), K (g) and K/Wt were compared between males and females, CP and MR, and AG and NG. One of the most outstanding characteristics of handicapped AG was that body weight, LBM (kg) and K (g) were greater than in handicapped NG.

A study was conducted to evaluate dietary intake, food intake pattern and blood composition in athletes over a 4-year period from 1988 to 1991. We measured the mean daily intakes (energy and nutrient intakes, PFC rates, minerals and vitamins) from 3-day dietary records for 110 highly trained male athletes (swimming, track & field, canoeing, soccer, cycling and weight-lifting) and 87 female athletes (swimming, track & field, canoeing, basketball and volleyball) living in Nagasaki Prefecture. We compared these measurements with the recom-mended dietary allowances (RDA) for normal Japanese. Energy, fat, calcium and iron intakes were below the RDA, especially for most female athletes and male weight-lifters.
The following mean values were obtained
[MALE] SOCCER (Senior High School boys) : Energy intake 3241 kcal ; Protein 106.2 g ; Fat 88.6g ; PFC rates P (13.2%), F ( 25.0%), C (61.8%) . CANOEING (Senior High School boys) : Energy 2830 kcal ; Protein 99.2g ; Fat 83.9g ; PFC rates P (14.1%), F (26.3%), C (59.6%) . TRACK & FIELD (Adults) : Energy 2870 kcal ; Protein 105.4 g ; Fat 89.3 g ; PFC rates P (13.2%), F (25.0%), C (61.8%) .
[FEMALE] BASKETBALL (Adults) : Energy 1866 kcal ; Protein 70.0 g ; Fat 51.9 g ; PFC rates P (15.0%), F (25.1%), C (59.9%) . BASKETBALL (Senior High School girls) : Energy 2421 kcal ; Protein 88.9 g ; Fat 90.9 g ; PFC rates P (14.8%), F (34.0%), C (51.1%) . VOLLEYBALL (Senior High School girls) : Energy 2290 kcal ; Protein 71.6g ; Fat 72.1 g ; PFC rates P (12.6%), F (28.4%), C (59.0%) .