The age-related pattern of body density and body composition in Japanese males (n = 266) and females (n = 318), 11.00 to 18.99 years of age was studied. Body density (BD) as well as height, body weight, and seven skinfold thicknesses were measured. Percentage fat (%Fat) was calculated using the age- and sex-specific equation of Lohman. Fat mass (FM), fat-free mass (FFM), and the body mass index (BMI) were calculated. The trend for BD in males was lowest at 11 years (1.0530 g/ml) and increased to 1.0695 g/ml at 14 years, and then decreased slightly at 15 to 17 years. In female, BD decreased from 1.0530 g/ml at 13 years to 1.0424 g/ml at 17 years. Mean %Fat was highest in males at 11 years (15.8%), and lowest at 14 years (10.1%). The highest mean %Fat in females occurred at 16 years (22.8%), and the lowest at age 11 years (15.2%). Overall, only 6.8% of males and 3.1% of females were classified as obese. Between 11 and 18 years, FFM of males differed by 20.7 kg or 67.9%, whereas females showed a difference of only 10.8 kg or 34.7%. Consequently, age effects explained approximately 60% of the male variance of FFM but only 26% in females. Body density of each sex and age group in this study did not differ significantly from previous Japanese studies, and the pooled BD data for 1,457 Japanese including the present study are reported as a reference.

We investigated the transfer of an arm-positioning movement between the right and left arms of right and left handers. 30 male (15 strong right handers and 15 strong left handers) subjects were asked to perform a constrained criterion movement, 12 cm in length, with right or left arm and a test movement at estimated 6-, 12-, or 24-cm length with the contralateral arm. In the right handers, the constant error of the left arm test movement was near zero, and that of the right arm indicated overshooting. In the left handers, the constant errors of the left arm test movement were farther from zero than those of right arm test movement. Left handers as well as right handers showed manual asymmetry on positioning movement. A plausible explanation for the manual asymmetry on the arm-positioning task is related to interhemispheric transfer of spatial information on positioning movement.

No abstract

The present study measured unimanual kinesthetic discrimination for the right and left thumb angular position of male and female right handers without left handed relatives. Each subject's discrimination threshold and constant error were obtained by the Method of Constant Stimuli. Subjects either made an active movement in assessing the standard thumb angle or were passive while the angle was set by the experimenter. Subjects either reported their decision orally or made a non-verbal movement. A difference was found between the thumbs in the direction of more sensitive kinesthetic discrimination by the left thumb (right hemisphere). The left thumb was found to have smaller discrimination threshold of angular position by about 20% over the right thumb. Sex, passive movement mode, and verbal response were not related to the lateralization effect.

Difference limens and constant errors were obtained by the method of constant stimuli on a task requiring discrimination of the thumb's spatial position for 26 Japanese (13 male and 13 female) and 26 American (13 male and 13 female) college students. The left thumbs of Japanese and American subjects exhibited smaller difference limens, suggesting that both groups show the same hemispheric specialization of spatial perception. Japanese subjects showed smaller difference limens, but no sex difference was observed.