A study was conducted to determine the characteristics of discrimination of force in grip for preschool children. Examination of the new method (NM) designed by Murase & Asami (1991) based on discrimination of force was also carried out by comparing observations obtained by two methods (i. e. modified constant method (CM) and NM) . A total of 12 healthy Japanese preschool children (mean age : 5.4±0, 4yr) volunteered to be subjects for the two methods. The subjects engaged in CM measurements for about 28 days and in NM measurements for 18 to 24 days, The standard stimuli were 3 forces of 1.0kgf (9.8N), 2.0kgf (19.6N) and 3.0kgf (29.4N), and the comparison stimulus was changed at intervals of 0.1kgf. Lower threshold (LT), upper threshold (UT), interval of uncertainty (IU) and percentage of response appearance were selected as variables to represent the characteristics of discrimination of force. The results were also analyzed from the viewpoint of measurement and assessment. The relationships between the percentage of response appearance and each comparison stimulus for 3 standard stimuli matched the cumulative normal distribution functions. It was suggested that a subjective scale of force in grip was established at the age of 5 to 6 years old. LT, UT and IU in the grip increased with a gain in the standard stimulus. The data for the NM were approximately 1.3 to 1.8times larger than those estimated by the CM, and the two observations roughly paired with each other. For the two methods, the tendency of changes in LT, UT and IU, and relative sizes between LT and UT showed similar patterns.

A study was designed in order to determine the patterns and interdependence existing between characteristics of discrimination of force and exerted force in preschool childhood. A total of 28 to 30 preschool children aged approximately 5 to 6 years volunteered to be subjects for each motion, and they discriminated forces in grip, elbow flexion and extension motions. Lower threshold (LT), upper threshold (UT) and interval of uncertainty (IU) were selected as variables representing the characteristic of discrimination of force. Prior to the main examina-tion, unpaired t-test revealed no sex differences in LT, UT and IU for any motions. Therefore, the data derived from boys and girls was pooled for subsequent analysis. The patterns of relationships between variables and exerted force, which was expressed as the percentage of maximal voluntary contraction, generally indicated nonlinear rather than linear combinations, as a result of analysis by simple regression and 2 nd to 5 th degree polynomials. In addition, the interdependency of the relationships was estimated for grip (36.6-44.2%), elbow flexion (26.1-46.8%), and elbow extension (28.1-37.6%) using coefficients of determination in second degree polynomials. Individual differences in the subjects seemed to affect the interdepend-ency during preschool childhood.

This study determined the relationship between health and physical fitness, and the contribution of each element in physical fitness to health for middle-aged and elderly women. A total of 1, 220 females aged 35 to 64 years participated in physical fitness tests and medical check ups. According to health status, the subjects were divided into two groups ; the healthy group (HG) and the unhealthy group (UG) . Multiple discriminant analysis was applied to the multivariate data. Correct discriminant probabilities of multiple discriminant functions to discriminate the HG and UG ranged from 63.9 to 83.3% among 6 age groups. These results suggested that there was a relatively strong relationship between health status and the level of physical fitness for middle-aged and elderly women. The change in correct discriminant probabilities indicated that degree of relationship would decrease stepwise with age. The contribution of each element of physical fitness to health status was also evaluated by Pearson's correlation coefficient. Age-related changes in the correlation coefficients between the discriminant score representing health status and performance on each physical fitness test demonstrated four different patterns. Therefore, special consideration should be given to the degree of contribution of each physical fitness element at each age level when developing exercise programs to promote health among middle-aged and elderly women.

This study was carried out to determine the relationship between health status and physical fitness, and the contribution of each element of physical fitness to the health status of middle-aged and elderly men and women. The subjects were 889 males and females aged 30 to 69 years. Physical fitness tests and medical check ups were performed. According to health status, the subjects were divided into two groups ; the healthy group (HG, n=348) and the unhealthy group (UG, n=207) . Multiple discriminant analysis was applied to the multivariate data. Correct discriminant probabilities of multiple discriminant functions to discriminate the HG and UG were 70.2% and 68.2% for men and women, respectively. These results suggested that there was a relatively strong relationship between health status and the level of physical fitness in both men and women. The contribution of each element of physical fitness to health status was evaluated by correlation coefficients between the discriminant score representing health status, and performance on each element of the physical fitness test and age. Age and muscle endurance contributed significantly to health status in both men and women. In addition, close relationship was seen between health status and elements of cardiorespiratory endurance, balance, and muscle strength in men, while change in physique correlated with health status in women. From these findings, it was concluded that exercise programs for health promotion in middle-aged and elderly people should be provided separately with consideration of the degree to which these specific elements contribute to health status.

The effects of aging on adaptive force control of precision grip while manipulating a small object were compared between older (84.2±8.9 yrs, n=33) and young adults (19.1±0.24 yrs, n=18) from the following perspectives: (1) adaptation to an unfamiliar object with uncertain physical properties during 16 consecutive lifts ; (2) adaptation to an object with a non-slippery (sandpaper) surface during 12 consecutive lifts, followed by 12 consecutive lifts with a slippery (silk) surface ; and (3) adaptation to objects with different weights (0.49, 0.98, 1.96 and 2.94 N) during 24 lifts (6 consecutive lifts for each weight) .During each trial, grip and load forces were monitored. Safety margin force and slip force were evaluated from the data obtained.
The majority of older adults employed a considerably greater safety margin for an unfamiliar object in the initial trials than did young adults, while the minority of the older adults were able to adapt their safety margin force with a few trials, like the young adults. The older adults who overestimated the safety margin force, however, successfully adjusted their grip force to more optimal levels with repeated lifts, suggesting that the adaptive capability of grip force remained even at 90 years of age. The adaptation of older adults, however, was found to be slower (i. e., required more trials) than that of young adults. Upon encountering surface friction change, the safety margin forces in older adults were more strongly affected by the previous surface condition than those in the young adults. In addition, adaptation to a non-slippery surface seemed more difficult than that to a slippery surface with aging. Upon encountering weight change, older adults showed more difficulties in scaling their safety margin forces according to object weights.
Slower adaptation and difficulty in adaptation to the friction or weight change in older adults may reflect the agerelated decline of tactile sensitivity which impaired the signaling of frictional conditions and various discrete events in the hand. In addition, the lift repetition for force adaptation may possibly reflect the age-related deficit or slowing of central processing capacities related to grip force production.