Takashi Kinugasa

Walking Patterns and Finger Rhythm of Older Adults

Walking patterns and rhythmic movement of the fingers were examined in a total of 1,134 male and female community residents 65 years of age and over. Walking patterns were characterized according to the ratio of step length divided by step rate (cadence), called the Walk Ratio, during level walking at preferred and maximum speeds. The walking pattern tended to change according to age; older subjects walked with shorter steps (smaller Walk Ratio). Rhythmic movement was examined using the finger-tapping test in time to the sound of a 4-Hz metronome. Hastened tapping or finger festination, in which the subject tapped faster than requested (constant error of 3 msec. and over in the intertap interval), was characteristic of aging; 16.8% of the subjects exhibited finger festination and the occurrence increased with age, especially among those in their eighties (29.3%). Finger festination was accompanied by walking patterns with an increased step rate, or a smaller Walk Ratio. These characteristics of aging were discussed as similar to extrapyramidal symptoms of walking and rhythm production in patients with Parkinsons disease.

Longitudinal Change in the Physical Performance of Older Adults in the Community

The primary purposes of this study were 1) to confirm age-related deterioration of physical performance in older adults longitudinally, and 2) to predict future functional status and mortality by initial level of physical performances. The subjects were 517 older adults examined both in 1992 and 1996 in the Tokyo Metropolitan Institute of Gerontology, Longitudinal Interdisciplinary Study on Aging. The same battery consisting of muscle strength, balance, walking, and manual speed was administered to the subjects in the baseline and follow-up examinations. A significant longitudinal decline was observed in all physical performances except for grip strength. The age-related decline accelerated with aging for preferred walking velocity. Inter-subject variability in walking velocity significantly increased for 4 years period. Maximum walking velocity was a common predictor for functional status and mortality. The results suggest that physical performance measures, especially maximum walking velocity, is a valid means for physical therapy to evaluate physical functioning of community-living older persons.

Postcontraction Influences on Reaction Time

Abstract The purpose of this study was to compare reaction time (RT) and fractionated RT components (premotor and motor times) between normal and postcontraction conditions. Twelve participants performed 20 trials each of control and postcontraction RT conditions. For the control condition, participants executed a learned, rapid, knee-extension contraction response to an auditory stimulus. The postcontraction condition was identical to the control condition except that the participants performed a 3-s isometric contraction of the knee extensor muscles prior to an auditory stimulus. Muscle activity was recorded from the quadriceps muscle group. Results indicated that the postcontraction condition was significantly faster than the control condition for the average RT, premotor time, and motor time. It was concluded that reaction time, processing time, and muscle contraction time for a learned task could be significantly reduced following an isometric contraction.

Sequence of preparatory set for response movement.

Electromyographic reaction times (EMG-RTs) of the right biceps brachii muscle were examined for two movement patterns, elbow flexion and forearm supination, in 8 healthy male subjects under simple and complex RT conditions with varied preparatory intervals (PIs): 0, 200, 400, 600, and 800 msec. In the simple RT condition, the subject was informed of the movement patterns to be performed prior to beginning the trials. In the complex RT condition the subject had to choose one of the two movement patterns at the time of the presentation of a warning signal. The results indicated that: (1) compared with the simple RT condition a delay of about 100 msec. in over-all mean EMG-RT was observed at PI = 0 msec. in the complex RT condition; (2) the difference of over-all mean EMG-RT between the two RT conditions disappeared when PI = 400 msec.; and (3) the difference in EMG-RTs between flexion and supination in the complex RT condition became the same as that in the simple RT condition when PI = 700 msec. It is assumed that the preparatory set for response movements is organized in an order, resulting in the differentiation of RT.

Factorial invariance of the physical performance measures in longitudinal study of aging: A simultaneous analysis approach

In this study, we examined the factorial structure of the physical performance measures and the longitudinal invariance of elderly people in the community. The subjects were investigated in Akita as part of TMG‐LISA. Data used in this study were from 463 older adults who participated in all the physical performance tests, both in the baseline (1992) and the 4‐year follow‐up (1996) investigation. The test battery consisted of six items (hand power, walking, and balance). There were longitudinal aging changes in gender and age in all of the measurements between the baseline research and the follow‐up research, except for the one‐leg standing with eyes closed test. The factorial invariance of the structure in these measures taken in 1992 and 1996 was confirmed through the confirmatory factor analysis (CFA) of the structural equation modeling, controlled for gender and age. As a preliminary step for analysis of factorial invariance, we analyzed the fitting basic motor ability model to cross‐sectional data of the baseline and follow‐up. As a result of the analysis, the fitness levels of each data of the models were good. Then, we applied simultaneous analysis and analyzed longitudinal changes in the factorial structure of measurements. The results were that there were the same factors in the factorial structure model of physical performance measured in both the baseline and follow‐up investigation, and that their arrangements were identical. Furthermore, we find that there was no difference in all factor‐loading in both models being investigated. These results statistically indicated that there were no signs of aging changes in factorial structure of the measures between the baseline investigations and the follow‐up 4 years later in spite of the longitudinal decline of the values of physical performance tests. Moreover, it was indicated that the simultaneous analysis, which this research used, was applicable for statistical analysis procedure of factorial invariance of various repeated measures on studies of aging, as a longitudinal study.

We have two strategies to attain healthy aging

To attain healthy and successful aging, we emphasized the importance in making the most of easily available, rather traditional ways, such as swimming, as well as in developing a new strategy, such as the ‘working‐high sleeping‐low body temperature’ strategy.