Effect of long-term, community-based daily exercise on the ability to control the dynamic standing balance of Japanese elderly persons in relation to falls.

It is widely accepted that daily exercise improves the dynamic standing balance of elderly persons. In the current study, 77 community-dwelling Japanese elderly persons (aged 71.1 +/- 0.5 years) participated in a daily exercise program to assess its effect on their dynamic standing balance. The daily exercise consisted of walking, stretching, muscle strengthening, and balance exercises. The program ran for 31 months and the dynamic standing balance was assessed at the start of the program and again at 3, 7, 12, 19, 24, and 31 months. In most of the tests of dynamic standing balance, the measured values improved drastically in the first 7 months; thereafter, they either reached a plateau or continued to improve more slowly. These findings can contribute to the future planning of community-based exercise programs; in particular, the length of the program and the timing of changes to the exercise load.

The neural adjustment of postural response through community-based daily exercises in elderly persons.

BACKGROUND: Reflecting the rapidly aging population, community-based interventions in the form of physical exercise have been introduced to promote the health of elderly persons and prevent falls. Postural response is the critical neural response for preventing falls. The objective of this study was to assess the effect of long-term daily exercise on neural adjustment in postural response elucidated by sudden postural perturbation. METHODS: Twenty-six community-based elderly persons (13 men and women; 69.8+/-0.5 years old) participated in this study. Daily exercise was composed of walking for longer than 30 min, stretching, muscle strengthening and balance exercise, and was continued for 3 months. Postural responses were induced by fore or aft horizontal displacement of a platform with a force plate. Center of pressure on the force plate and electromyography of the rectus femoris, tibia anterior, biceps femoris and gastrocnemius were measured in postural response. FINDINGS: Following the 3 months of physical intervention, the amplitude and timing of the center of pressure excursion did not change, whereas the amplitude of muscular activities of the lower leg muscles required for the response significantly decreased. Furthermore, the onset of muscular activation of the lower leg muscles was significantly shortened following the intervention. INTERPRETATION: In conclusion, we showed that a program composed of 3 months of comprehensive exercise modulated the output of the postural response through a neural adjustment in the timing and amplitude of the muscular activation.

The effects of comprehensive exercise program on the adjustments of standing balance in community-dwelling elderly persons.

The objective of this study was to assess the effect of comprehensive exercise program widely accepted as a community-based physical intervention for the prevention of falling in the elderly persons on their controlling standing balance. Twenty-six community-dwelling elderly persons (13 males and females; 69.8 ± 2.8 years old) participated in this study. Daily exercise was comprised of walking for more than 30 min, stretching, muscle strengthening and balance exercise without exercise equipments. The intervention was continued for three months. Indicators of standing balance related to static balance, dynamic balance and postural response were measured before and after the intervention. As an effect of the intervention on static balance, the sway of center of pressure (COP) in the static stance significantly increased. In the dynamic balance, significant improvements were observed in one leg standing time, the 10-m gait time, functional reach. Additionally, the maximal movable length of COP which subjects can move voluntarily to right and left significantly increased. In the postural response, the integrated electromyography (IEMG) induced by postural response for sudden postural perturbation significantly decreased in the lower leg muscles. Since less muscular activities were sufficient to maintain posture, it was suggested that postural response was elicited more efficiently following the intervention. This study suggested that the comprehensive exercise program, which has been widely introduced as community-based interventions for the prevention of falling, have extensive effects on the control of standing balance covering static balance, dynamic balance and postural response in the elderly persons.

Neural adjustment in the activation of the lower leg muscles through daily physical exercises in community-based elderly persons.

Reflecting the rapidly aging population, community-based interventions in the form of physical exercise have been introduced to promote the health of elderly persons. Many investigation studies have focused on muscle strength in the lower leg as a potent indicator of the effect of physical exercises. The objective of this study was to assess the effect of long-term daily exercises on neural command in lower leg muscle activations. Twenty-six community-based elderly persons (13 men and 13 women; 69.8 +/- 0.5 years old) participated in this study. Daily exercise was comprised of walking for more than 30 min, stretching, muscle strengthening and balance exercise, and was continued for three months. Muscle strength and surface electromyography of the tibia anterior, rectus femoris, and biceps femoris were measured in maximum isometric voluntary contraction both before and after the intervention. The mean frequency of the firing of motor units was calculated based on fast Fourier transformation of the electromyography. As the results of the intervention, muscle strength increased significantly only in biceps femoris, whereas the mean frequency of motor units decreased significantly in every muscle, indicating that motor unit firing in lower frequency efficiently induces the same or greater strength compared with before the intervention. Thus, synchronization of motor units compensates for the lower frequency of motor unit firing to maintain muscular strength. In conclusion, long-term physical exercises in the elderly can modulate the neural adjustment of lower leg muscles to promote efficient output of muscle strength.

Progression and direction of contractures of knee joints following spinal cord injury in the rat.

Joint contractures following central nervous system injuries remain a prevalent and significant complication, but no reports are available on evidence of contracture formation over time. The objective of this study was to determine the rate of contracture progression and the direction of loss in joint movement following spinal cord injuries (SCI). Forty-eight female Wistar rats were used. Twenty-four experimental rats underwent a spinal cord transection at the level of T8 and 24 control rats underwent a sham-operation. The animals were studied at each of 5 time points: 2, 4, 8, 12, 16, and 24 weeks after surgical intervention. The degree of contractures was assessed by measuring the femorotibial angle on both hindlimbs with the use of a goniometer. Knee joint motion was measured for flexion and extension direction. Knee flexion contractures developed in all experimental rats. The restriction in motion progressed during the first 12 weeks and plateaued thereafter. The contractures were produced almost exclusively by a loss in the extension range of motion. This study defined the time course that contracture progression was more rapid in the early stage after SCI and stabilized in the later stage of injury. Contractures following SCI occurred in flexion at the knees and resulted from a loss of extension. These findings should help guide timely treatment and provide a better understanding of contracture development.

The Relationship between Postural Deformation and Standing Balance in Elderly Person.

Falling due to unstable standing balance is considered to be the main cause of bone fractures, which lead elderly persons to becoming bedridden. Thus, the standing balance of elderly persons is being given increasingly greater attention. On the other hand, postural deformation caused by deformation in the spine and lower leg joints is considered to have an effect on standing balance. The objective of this study is to clarify the effect of postural deformation on the following three categories of standing balance; 1) the ability to immobilize Center of Gravity (COG) in standing statically, 2) the ability to control COG during movement and 3) the postural response induced by postural sway. Fifty elderly persons (age:77.7 ± 6.4 years old, fifty females) participated in this study. Postural deformation was measured using a Spinal Mouse, a device for non-invasive measurement of spinal curvature and photographic image in sagittal plane. In line with to Nakata's classification of postural deformation, subjects were classified by extension type, S-character deformation type, flexion type, hands on the knee type and normal group. In order to assess the ability to immobilize COG in static standing, Center of Pressure (COP) in static standing was measured for 30 sec. In order to assess the ability to control COG during movement, functional reach, maximal length of stride and the period of 10 m gait were measured. Postural response was induced by fore-aft perturbation of the platform on which the subjects stood. Postural responses were assessed by measuring both COP, and electromyography (EMG) of muscles in the lower legs. There was little significant difference among the five groups concerning postural deformation in every measured item, neither in the ability to immobilize COP in static standing, nor in the postural response induced by postural sway. However, the results of measured items concerning the ability to control COG during movement were significantly worse in flexion type and hands on the knee type compared with the normal group. It was suggested that postural deformation in elderly persons effects exclusively on the ability to control COG during movement in standing balance.