Effects of shelf bar assistance on kinetic control during sit-to-stand in healthy young and elderly subjects

A comparison of minimum segment models for the estimation of centre of mass position and velocity for slip recovery during a bathtub transfer task

BACKGROUND

Exploring the use of minimum marker sets is important for balancing the technical quality of motion capture with challenging data collection environments and protocols. While minimum marker sets have been demonstrated to be appropriate for evaluation of some motion patterns, there is limited evidence to support model choices for abrupt, asymmetrical, non-cyclic motion such as balance disturbance during a bathtub exit task.

RESEARCH QUESTION

How effective are six models of reduced complexity for the estimation of centre of mass (COM) displacement and velocity, relative to a full-body model.

METHODS

Eight participants completed a bathtub exit task. Participants received a balance perturbation as they crossed the bathtub rim, stepping from a soapy wet bathtub to a dry floor. Six reduced models were developed from the full, 72-marker, 12 segment 3D kinematic data set. Peak displacement and velocity of the body COM, and RMSE (relative to the full-body model) for displacement and velocity of the body COM were determined for each model.

RESULTS

Main effects were observed for peak right, left, anterior, posterior, upwards and downwards motion, and peak left, anterior, posterior, upwards and downwards velocity. Time-varying (RMSE) was smaller for models including the thighs than models not containing the thighs. In contrast, inclusion of upper arm, forearm, and hand segments did not improve model performance. The model containing the sacrum marker only consistently performed the worst across peak and RMSE metrics.

SIGNIFICANCE

Findings suggest a simplified centre of mass model may adequately capture abrupt, asymmetrical, non-cyclic tasks, such as balance disturbance recovery during obstacle crossing. A reduced kinematic model should include the thighs, trunk and pelvis segments, although models that are more complex are recommended, depending on the metrics of interest.

Efficacy of Installation of Temporary Bathing Transfer Aids by Older Adults

Grab bars facilitate bathing and reduce the risk of falls during bathing. Suction cup handholds and rim-mounted tub rails are an alternative to grab bars. The objective of this study was to determine whether older adults could install handholds and tub rails effectively to support bathing transfers. Participants installed rim-mounted tub rails and suction cup handholds in a simulated bathroom environment. Installation location and mechanical loading performance were evaluated. Participant perceptions during device installation and a bathing transfer were characterized. While 85% of suction cup handholds met loading requirements, more than half of participants installed the suction cup handhold in an unexpected location based on existing guidance documents. No rim-mounted tub rails were successfully installed. Participants were confident that the devices had been installed effectively. Suction cup handholds and rim mounted tub rails are easy to install, but clients may need additional guidance regarding where, and how to install them.

Circumstances of Falls During Sit-to-Stand Transfers in Older People: A Cohort Study of Video-Captured Falls in Long-Term Care

OBJECTIVE

To characterize the circumstances of falls during sit-to-stand transfers in long-term care (LTC), including the frequency, direction, stepping and grasping responses, and injury risk, based on video analysis of real-life falls.

DESIGN

Cohort study.

SETTING

LTC.

PARTICIPANTS

We analyzed video footage of 306 real-life falls by 183 LTC residents that occurred during sit-to-stand transfers, collected from 2007 to 2020. The mean age was 83.7 years (SD=9.0 years), and 93 were female (50.8%).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

We used Generalized Estimating Equations to test for differences in the odds that a resident would fall at least once during the rising vs stabilization phases of sit-to-stand and to test the association between the phase of the transfer when the fall occurred (rising vs stabilization) and the following outcomes: (1) the initial fall direction; (2) the occurrence, number, and direction of stepping responses; (3) grasping of environmental supports; and (4) documented injury.

RESULTS

Falls occurred twice as often in the rising phase than in the stabilization phase of the transfer (64.0% and 36.0%, respectively). Falls during rising were more often directed backward, while falls during stabilization were more likely to be sideways (odds ratio [OR]=1.95; 95% confidence interval [CI]=1.07-3.55). Falls during rising were more often accompanied by grasping responses, while falls during stabilization were more likely to elicit stepping responses (grasping: OR=0.30; 95% CI=0.14-0.64; stepping: OR=8.29; 95% CI=4.54-15.11). Injuries were more likely for falls during the stabilization phase than the rising phase of the transfer (OR=1.73; 95% CI=1.04-2.87).

CONCLUSION

Most falls during sit-to-stand transfers occurred from imbalance during the rising phase of the transfer. However, falls during the subsequent stabilization phase were more likely to cause injury.

Influence of handrail height and knee joint support on sit-to-stand movement

Handrail height and knee joint support both significantly influence sit-to-stand (STS) movement. However, research on the associations between handrail height, knee joint support, and their cumulative effect on STS kinematics and changes in plantar pressure distribution during STS under different handrail heights and knee joint support is still unclear. The main objective of this study was to examine the influence of handrail height and knee joint support on the kinematics and the distribution of plantar pressure in healthy adults during STS. Twenty-six healthy adult subjects aged 23 to 58 years participated in this experiment. The subjects carried out STS movement experiments under 7 conditions: 6 experimental conditions of 3 different heights of handrail, with and without knee joint support, and 1 control condition of standing up naturally. The motions of the markers were recorded using cameras operating at 60 Hz, and total movement time, the percentage of movement time of each phase, trunk tilt angle, joint angle, plantar pressure, and the time from hindfoot to forefoot peak pressure were analyzed and compared. Handrail height significantly influences the percentage of movement time at phase I (P = .015) and the maximum trunk tilt angle (P < .05), knee joint support significantly influences the maximum trunk tilt angle and ankle angle (P = .033), and handrail height and knee joint support have an interaction on the time from hindfoot to forefoot peak pressure (P < .001). Subjects' STS performance was improved with the use of assistant devices but showed particular improvement under the condition of with knee joint support when the handrail height was middle handrail.

Effect of different handrail types and seat heights on kinematics and plantar pressure during STS in healthy young adults

Handrail type and seat height both significantly influence sit-to-stand (STS) movement. However, research on the associations between handrail type, seat height, and their cumulative effect on STS kinematics and changes in plantar pressure distribution during STS under different handrail types and seat heights is insufficient.The main objective of this study was to investigate the effect of different handrail types and seat heights on the kinematics and plantar pressure in healthy adults during STS.The study was conducted on 26 healthy young adults. Six conditions were tested: low seat (LS) and vertical handrail; LS and horizontal handrail (HH); LS and bilateral handrail; high seat (HS) and vertical handrail; HSHH; HS and bilateral handrail. The movement time, trunk tilt angle, and time from hindfoot to forefoot peak pressure were analyzed and compared.A significant difference was found in handrail type (P < .001) and seat height (P < .02) for the total movement time of STS. A significant difference was also found for the maximum trunk tilt angles (P < .001) in handrail types. There was an interaction between handrail type and seat height for the time from hindfoot to forefoot peak pressure of STS (P = .003).Using HSHH could take less time to accomplish STS movement; it also reduced the maximum trunk tilt angle and thus reduce the risk of falling; the time from hindfoot to forefoot peak pressure when using HSHH was short and subjects could accomplish STS movement easier.

Effects of seat height on whole-body movement and lower limb muscle power during sit-to-stand movements in young and older individuals

Sit-to-stand (STS) movements from low seat height are not easily executed by older individuals. Although young individuals increase their lower limb muscle power (LLMP) based on the product of the ground reaction force (GRF) and center of mass velocity (CoMv) during STS movement from a low seat height, it remains unclear whether seat height has an effect on LLMP during STS movement in older individuals. The present study aimed to investigate differences in the LLMP during STS movements when seat height is lowered between young and older individuals. Twelve older and twelve height-matched young individuals were instructed to perform STS movements from low (20 cm), middle (40 cm), and high (60 cm) seat heights. STS movement and GRF were obtained by a motion analysis system and force plates. In the low-seat-height condition, the forward and upward LLMPs and the upward CoMv were significantly lower in older individuals than those in young individuals, but the forward CoMv was not. The completion time of STS movement from a low seat height was significantly longer in older individuals than in young individuals. Our findings suggest that the slower upward CoMv due to the lower upward LLMP extends the completion time of STS movement from a low seat height in older individuals. Furthermore, in the low-seat-height condition, older individuals may move their center of mass (CoM) forward in a different way when compared with young individuals, and they may not use forward LLMP for moving CoM forward.