ABSTRACT
The purpose of this study was to examine the relationship between balancing ability during abrupt acceleration and the habitual physical activity level of elderly females. Thirty-one elderly females, aged 65-75 years, volunteered for this study. Changes in the center of foot pressure (CFP) were measured during postural sway following platform acceleration, and the response time and CFP displacement were evaluated. The scores of their daily physical activities (TS) -consisting of house-hold activities (HS), leisure time activities (LS) and sports activities (SS) -were estimated by the modified Voorrips's questionaire method. Response time and CFP displacement correlated significantly with age (p<0.001) . Response time also correlated significantly with the SS, LS and TS scores (p<0.05) . CFP displacement also correlated significantly with the SS and TS scores (p<0.05) . These results suggest that postural balancing ability during abrupt acceleration correlates signifi-cantly with the habitual physical activity levels, especially sports activities in elderly females.
ABSTRACT
A study was conducted to investigate the relationship between long latency activities evoked by a sudden muscle stretch of the right wrist flexor and a peformance during a target match task accompanying wrist movement. The index of performance was the target match time (TMT) from onset of a handle displacement untill the handle position output was matched with a traget line. The standard deviation of TMT (TMT-S.D.) was calculated. Sixteen healthy men, ranging in age from 20 to 27 yr., participated in the study. A DC torque motor was used to generate an angular displacement at the right wrist joint. Analysis of the surface electromyogram recorded from the wrist flexor showed that the short and long latency reflex components (Ml, M 2 and M3) were evoked by muscle stretching. In the target match task, the amplitude of the M 2 and M 3 components for all subjects were significantly smaller than the M 1 component (p<0.01) . In some subjects the M 3 component was not identifiable, since its amplitude was very small in the target match movement. There were significant correlations between the M 2 amplitude and performances (TMT : r=0.857, p<0.01 and TMT-S. D. ; r=0.651, p<0.01) during the target match task. In shoat, the smaller the M 2 amplitude was, the shorter the TMT became and the smaller the TMT-S. D, became. These results suggest that the change in the M 2 component is related to motor control for the target match task.
ABSTRACT
A study was undertaken to investigate whether the amplitudes of reflex EMG components (M1, M2 and M3) induced by sudden muscle stretching in the wrist flexor, are modified according to the reaction movement during wrist flexion, and how the aspects of reflex EMG components are related to premotor time under conditions of stretch stimulus (SS-PMT) and light stimulus (LS-PMT) . Fifteen healthy men, ranging in age from 22 to 28yr, participated in the study. A DC torque motor was used to evoke the reflex EMG activities on the wrist flexor. Analysis of the surface electromyogram recorded from the wrist flexor showed that short and long latency reflex components appeared in response to muscle stretch. In almost subjects, the amplitude of the M2 component was higher during reaction task than during no reaction task. The subjects were classified into two groups (I, II) according to the presence or absence of reflex components and their EMG amplitudes. SS- and LS-PMTs in group I were significantly shorter than those in group II. The amplitude of M2 in group I was significantly higher than in group II. In group I the M3 component was not identified, since the M2 component was followed by a voluntary EMG burst.<BR>These results showed that the amplitudes of long latency reflex components increased during the reaction task in the flexion direction, and suggest that long latency components contribute to the initiation of voluntary movement in subjects with a shorter premotor time.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
The oxygen consumption during physical exercise is necessarily dependent upon the load on the muscle and also on the mass of muscles at work. In the present study maximal work has been performed by legs and arms plus legs in pedaling bicycle ergometer.<BR>Thirteen healty male students were studied. Group A consisted of eight Judoists, aged 18-21 years. Mean maximal oxygen uptake and max O<SUB>2</SUB> uptake/kg for this group were obtained 3.41/min and 44.7 ml/kg/min respectively in legs bicycle exercise. Group B consisted of five long distance runners, aged 19 years, with mean max. O<SUB>2</SUB>-uptake of 3.31/min and max. O<SUB>2</SUB>-uptake/kg of 57.2 ml/kg/min.<BR>In arms plus legs bicycle exercise, max. VO<SUB>2</SUB> and max. VO<SUB>2</SUB>/kg were an average value of 3.81/min and 49.8 ml/kg/min respectively for group A. For group B max. VO<SUB>2</SUB> and max. VO<SUB>2</SUB>/kg averaged 3.61/min and 62.6 ml/kg/min respectively.<BR>Group A 12% significantly higher values for max. VO<SUB>2</SUB> was attained in arms plus legs cycling (P<0.01), but group B 9% higher max. VO<SUB>2</SUB> when arms plus legs cycling than when legs cycling was actually not a regular finding in the group. Max. VO<SUB>2</SUB>/kg in legs cycling was an average 9-11% lower than that on arms plus legs cycling. The differences were statistically significant for group A and group B.<BR>Only in group A was max. VO<SUB>2</SUB> a little higher than in group B for legs cycling, but the differences was not statistically significant. Max. VO<SUB>2</SUB>/kg was statistically significantly higher in arms plus legs cycling with both group. In group A max. heart rate, tidal volume and O<SUB>2</SUB>-pulse were higher in arms plus legs cycling. Then max. heart rate and tidal volume were significantly higher in group A than on group B.