ABSTRACT
This study was carried out in order to compare stride time (gait) variability of walking not only between young and older adults, but also between “fallers” and “non-fallers”. Moreover, this study aimed to clarify the relationship between stride time variability, balance ability, muscular strength and fall experience. The subjects were 12 young women aged 21.2±2.2 years (young group) and 27 older women aged 66.6±4.4 years (older group). The older group included 14 fallers and 13 non-fallers. They wore an accelerometer on their back and walked at a slow, preferred or fast pace. The time of heel contact was detected by acceleration waveform, and stride time was estimated. The stride time variability was computed by the coefficient of variance (CV) of stride time. The subjects underwent balance tests and muscular strength tests. The CV of stride time at the preferred and fast pace were significantly larger in the older group than in the young group, even though there was no difference in any of the gait speeds between the two. The CV of stride time was significantly larger in fallers than in non-fallers at the fast pace. Path analysis showed that fall experience was affected by an increase in the CV of stride time and decreased balance ability, but less affected by decreased muscular strength. Therefore, this study suggested that stride time variability when walking fast is useful as an early assessment of fall risk in middle-aged and elderly people and that fall experience was affected by stride time variability and balance ability.
ABSTRACT
The aim of this study was to compare co-contraction of ankle muscles between older and young adults performing a voluntary sway task, and identify any relationships between co-contraction, balance ability and muscular strength. The task involved displacement of the center of mass backwards and forwards continually during upright stance under three amplitude conditions, large, small and preferred, with sway speeds of slow, medium and fast. The participants comprised 17 older (64.1±2.9 years) and 14 young (21.3±3.3 years) women. Electromyographic recordings were obtained from the tibialis anterior and the medial gastrocnemius muscles during task performance to calculate the co-contraction index (CCI) and evaluate the relative level of co-contraction of antagonist muscle. Additional measurements were obtained from balance tests including body sway tests, functional reach, gait tests, and the EquiTest (Neurocom), and also muscular strength of plantar flexion and dorsiflexion. The CCI was highest under large sway amplitude, but did not differ among sway speeds. The CCI was higher in the older group (23%) than in the young group (15%). Multiple regression analysis revealed that the CCI correlated with body sway in the EquiTest and functional reach, and dorsiflexion strength. Therefore, this study suggested that co-contraction of ankle muscles increased with aging and related to not only static and dynamic balance abilities, but also ankle dorsiflexor strength.
ABSTRACT
This study was to investigate the effects of balance exercises on among static, dynamic and reactive balance ability in community-dwelling older women. Participants comprised 26 community-dwelling older women in Japan, randomized for age and gait speed to the exercise group (n=13) or the control group (n=13). The exercise group performed structured balancing exercises on the sponge and the G ball, once weekly for 24 weeks. The control group performed stretching exercises once per month. Static balance ability was assessed by measuring postural sway and standing on one leg; dynamic balance ability was assessed by measuring functional reach, timed up and go, and gait; and reactive balance ability was assessed using the EquiTest. We also measured knee and ankle strength using an isokinetic machine.At baseline, the two groups were well matched in physical characteristics and in all balance ability and strength tests. After 24 weeks, step length of preferred speed walking (p=0.049) only improved, and peak torque of knee flexion (p=0.050) tended to improve in the exercise group. Any correlations were not found between step length of preferred speed walking and knee flexion strength.These results suggest that these structured balance exercises are effective in improving dynamic, but not static or reactive balance ability. Improvements in dynamic balance ability were not dependent on improved muscle strength.
ABSTRACT
A motor performance test was administered to elderly adults in Koganei City and Nangai Village of Japan as the baseline study of Tokyo Metropolitan Institute of Gerontology, Longitudinal Interdisciplinary Study on Aging (TMIG-LISA) . The participants in this study totaled 405 (183 males and 222 females) aged 65 to 84 from Koganei City, and 734 (295 males and 439 females) aged 65 and over from Nangai Village. The test consisted of measurement of grip strength, one-leg stand-ing, walking at preferred and maximum speeds, and finger-tapping. All motor performances examined were higher among males than females, and they all deteriorated with aging. A regional difference was found in terms of motion speed abilities: finger-tapping rate and walking speed were higher among urban residents than rural residents. Individual differences (coefficient of variation) in the motor ability increased with aging, and reached 106% (maximum tapping rate in female) to 290% (maximum walking speed in female) of those in the twenties. Significant correlations between motor abilities were detected indicating that the specificity of the motor ability found in the young may not account for older adults.
ABSTRACT
A study was conducted to determine the effect of aging on motor ability and to establish a test battery for physical fitness in the elderly. The subjects were 150 men aged 18 to 83 years. The test items examined were selected, according to Fleishman's list of motor abilities; (1) trunk flexion, (2) grip and isometric knee extension strength, (3) postural sway with eyes open and closed, (4) step test, (5) walking test at preferred and maximum speeds, (6) simple visual reaction time, (7) peg-board test, (8) finger tapping test at maximum rate and in time to metronome sounds. Performances for the test items, except for preferred walking speed and coefficient of variation in finger tapping at 5 Hz, showed significant decreases with aging. The decrease in motor performance at age 80 years relative to the level at age 20 years was less than 30% for finger dexterity and reaction time, 40-60% for muscle strength, maximum walking speed and the step test, and over 70% for trunk flexion and postural sway with eyes closed. A test battery composed of trunk flexion, grip strength, knee extension, step test, walking as fast as possible, postural sway with eyes closed, and finger tapping, is therefore recommended for assessing the effect of aging on physical fitness.
ABSTRACT
The purpose of the present study was to determine whetehr differences exist between nine experimental conditions mixing 10°, 40°and 70°of hip joint angles with knee joint angles, when thirteen subjects performed the same response task. In the experiment 1, each subject was asked to stand on the inside two of the four mat switches (500×700 mm) and keep the assigned joint angles during a second of preparatory period. After the period, each subject was asked to respond with a step out on either the right or the left outside mat switch as quickly as possible. Then the data was collected analyzing the whole body choice response time (RESPONSE TIME) defined as the interval time from the signal to respond with step out, the whole body choice reaction time (REACTION TIME) defined as the interval time from the signal to reaction with lifting the leg for responding to the step out, and the movement time (MOVEMENT TIME) defined as the interval time subtracting RESPONSE TIME from REACTION TIME. Moreover, in the experiment 2, the data was collected and analyzed from the onset time of various forces from the two force platforms on which each subject stood instead of the mat switch and EMG which was led from the right side of m. rectus femoris, m, biceps femoris, m. gastrocnemius, m. tibialis anterior and the left side of m. quardriceps femoris, during performance of the response task. The results were as follows:<BR>1. The subjects' posture with each 70°flexion of the hip and the knee joint revealed the shortest RESPONSE TIME, because of the shortened MOVEMNT TIME, compared with the other posture. Conversely, the posture with 70° flexion of the knee joint showed an expanded REACTION TIME.<BR>2. The knee joint angle was an important factor effecting both REACTION TIME and MOVEMENT TIME, rather than the hip joint angle for the task of the experiment, since flexion of the knee joint expanded the REACTION TIME, but shortened the MOVEMENT TIME.<BR>3. The result of the force platform measurements indicated that the posture with each 70°flexion of the hip and the knee joint was shorter than that with each 10°flexion of them at the onset time of the first reaction force after the reaction signal, and that the order of response for the task was beginning at the leg for responding, followed by the other leg for keeping stability.<BR>4. Conclusive evidence for a shortened RESPONSE TIME was found in the facilitation of the central nervous system, which revealed the preliminary muscle activity and the stabilizing of the posture.