The role of strength in rising from a chair in the functionally impaired elderly.

Rising from a chair is a task essential for independent living. Many elderly persons have difficult with this task. Previous studies have drawn conflicting conclusions as to the role of strength in limiting the ability to rise from a chair. The purpose of this study is to determine the role of knee extensor strength in rising from a chair in the functionally impaired elderly. It is hypothesized that knee extensor strength limits the minimum chair height from which a subject can rise in the functionally impaired elderly, but not in the young. Studying both young healthy adults and functionally impaired elderly showed that required joint moment increased monotonically with decreasing chair height. Further, the elderly used significantly more of their available strength to rise from any chair height, and their mean required knee moment was 97% of the available strength when rising from the lowest chair height from which they could successfully rise. These data suggest that strength is a limiting factor in determining the minimum chair height from which the functionally impaired elderly may rise.

Mechanics of a constrained chair-rise.

A sit-to-stand task is analyzed by a method which estimates the segmental and whole body center of mass (CoM) kinematics and kinetics using bilateral whole body kinematic data from nine healthy young female subjects. The sit-to-stand, or chair-rise, task is constrained with regard to chair height, pace, initial lower limb position and arm use. The chair-rise maneuver is divided into four phases; (1) the flexion momentum phase; (2) the momentum transfer phase; (3) the vertical extension phase; and (4) the stabilization phase; the first three are examined in detail here. The momentum transfer phase, which immediately follows lift-off from the seat of the chair, is the most dynamic portion of the event, demanding a high degree of coordination. This maneuver is analyzed in order to determine if trunk movement is used only to position the body center of gravity or if the trunk motion generates momentum which is important during the brief but critical period of dynamic equilibrium immediately following lift-off from the chair. Our evidence points to the latter case and indicates that inter-segmental momentum transfer is possible during this period.

Influence of age on dynamics of rising from a chair.

This article describes the sit-to-stand movement in nine healthy elderly adults, ages 61 to 74 years, and compares peak joint angles, torques, and velocities of 11 body segments with data collected from nine young women, ages 25 to 36 years. The subjects in this study rose from a chair under a controlled protocol. An optoelectronic system, two force plates, and two computers were used for data collection and processing. The data are described in relationship to three phases of the task previously described for the young subjects' data. Percentages of difference were calculated for the torques and the velocities. Independent t tests were conducted on maximum angles achieved and total joint excursions. Consistency between groups was demonstrated in the duration of each phase, as well as the body kinematics and kinetics occurring within each phase. There was little difference in maximum torques or velocities. Maximum angles of head-to-trunk extension, head-to-ground flexion, head-to-trunk excursion, and trunk-to-pelvis flexion were significantly different between groups. The differences in head position demonstrated between these two groups may have clinical implications for loss of balance during this task in older patients.

Spinal movement and performance of a standing reach task in participants with and without Parkinson disease.

BACKGROUND AND PURPOSE: Evidence suggests that individuals with early and mid-stage Parkinson disease (PD) have diminished range of motion (ROM). Spinal ROM influences the ability to function. In this investigation, the authors examined available spinal ROM, segmental excursions (the ROM used) during reaching, and their relationships in community-dwelling adults with and without PD. SUBJECTS: The subjects were 16 volunteers with PD (modified Hoehn and Yahr stages 1.5-3) and 32 participants without PD who were matched for age, body mass index, and sex. METHODS: Range of motion of the extremities was measured using a goniometer, and ROM of the spine was measured using the functional axial rotation (FAR) test, a measure of unrestricted cervico-thoracic-lumbar rotation in the seated position. Motion during reaching was determined using 3-dimensional motion analysis. Group differences were determined using multivariable analysis of variance followed by analysis of variance. Contributions to total reaching distance of segmental excursions (eg, thoracic rotation, thoracic lateral flexion) were determined using forward stepwise regression. RESULTS: Subjects with PD as compared with subjects without PD had less ROM (FAR of 98.2 degrees versus 110.3 degrees, shoulder flexion of 151.9 degrees versus 160.1 degrees) and less forward reaching (29.5 cm versus 34.0 cm). Lateral trunk flexion and total rotation relative to the ground contributed to reaching, with the regression model explaining 36% of the variance. DISCUSSION AND CONCLUSION: These results contribute to the growing body of evidence demonstrating that spinal ROM is impaired early in PD.

Chair rise strategies in the elderly.

The elderly often have difficulty with rising from a chair. The purpose of this study was to characterize their rising strategies. A group of 22 elderly adults with a range of functional impairments was asked to rise from chairs of varying heights. Videotape motion analysis was used to identify strategies, estimate centre of mass, and measure time to rise. Three movement strategies were identified, "momentum transfer", "stabilization", and "combined" based on the velocity of trunk movement and base of support rearrangement. "Momentum transfer" uses horizontal momentum developed in the trunk to rise; "stabilization" uses centre of mass and base of support repositioning but very little momentum; "combined" uses elements of both momentum transfer and stabilization. Differences in the time to rise and the centre of mass to base of support separation between the momentum transfer and stabilization strategies were significant at each chair height. The momentum transfer, combined, and stabilization may form a continuum of chair rise strategies.

Chair rise strategy in the functionally impaired elderly.

Many elderly people have difficulty with the common functional activity of rising from a chair. Previous work has identified different strategies that are used to assist the young, the healthy elderly, and the functionally impaired elderly subjects in this activity. For the young and the healthy elderly, modification of these strategies with decreased chair height has been examined. This study examined the changes in chair rise strategy in 18 moderately functionally impaired elderly as the difficulty with rising was increased. The results show that the functionally impaired elderly, when rising from their lowest successful chair compared to a chair of knee height, significantly increase peak hip flexion velocity (11 degrees/sec, p < 0.01) and time to rise (1.25 sec, p < 0.01), and significantly decreased their mean center of mass/base of support (COM/BOS) separation at lift-off (1.96 cm, p < 0.05). These alterations in strategy suggest that while the functionally impaired elderly attempt to increase their momentum in rising by increasing their hip flexion velocity, they simultaneously attempt to increase their stability by taking more time to rise and shortening the distance between their COM/BOS at lift-off. These changes suggest a more conservative strategy with increased difficulty, resulting in decreased success in rising from a chair.

Postural responses to platform perturbation: kinematics and electromyography.

Dynamic postural control may be studied using feedback paradigms which disturb standing balance. In this study the kinematics and electromyography of the reaction to an unexpected slip were examined simultaneously in 16 young, healthy volunteers to characterize the response to postural perturbation in the context of the perturbation characteristics. Kinematically, results showed ankle plantarflexion, knee flexion, hip extension, and shoulder flexion. Electromyographically, sequences of activation of the postural muscles of the leg were primarily anterior distal. Data is presented that supports a new model of the reaction to perturbation which incorporates the timing and type of muscular activity, the type of motion (active or passive), and the perturbation characteristics. RELEVANCE--:Understanding the interplay of the neurophysiological and biomechanical aspects of dynamic postural control gives insight into balance reactions. Simultaneous consideration of the kinematics, muscle activation, and perturbation characteristics allows a more comprehensive view of recovery of balance.