Biomechanic Modeling of Sit-to-Stand to Upright Posture for Mobility Assessment of Persons With Chronic Stroke

Effects of Visual-Motor Illusion via Image Videos Showing Increased Exercise Intensity on the Tibial Anterior during Sit-to-Stand Movement: A Study of Healthy Participants

Visual-motor illusion (VMI) elicits kinesthetic sensation from visual stimulation. We have previously performed ankle motion VMI with resistance applied to the ankle joint on the paralyzed side (power-VMI (P-VMI)) and ankle motion VMI without resistance (standard-VMI (S-VMI)) to activate the tibialis anterior (TA) muscle in stroke-paralyzed patients and compared sit-to-stand (STS) durations, but these studies did not measure TA activity during the STS movement. The purpose of this study was to evaluate the effects of different intensities of visual stimuli presented during VMI on TA and STS movement. Healthy right-footed adults (n = 18) observed two different VMI videos of ankle dorsiflexion, including S-VMI and P-VMI, with an observation time of 2 min each. STS movement was evaluated before and after watching each video. Each participant performed both S-VMI and P-VMI interventions on the same day. Only P-VMI enhanced the integrated electromyogram of the TA, increased the angular velocities of the trunk forward inclination and the ankle dorsiflexion, and shortened the STS duration. Our results indicate that P-VMI facilitates the activation of TA during STS, and we believe that we have clarified the intervention mechanism of VMI.

Effects of visual-motor illusions with different visual stimuli on the sit-to-stand of people with hemiplegia following stroke: A randomized crossover controlled trial

BACKGROUND

The objective of this study was to determine the effects of different visual stimuli during visual-motor illusion on sit-to-stand in people with hemiplegia following stroke.

METHODS

This was a randomized crossover controlled trial. Twenty people with hemiplegia following stroke were randomly divided into groups. The video images used for visual-motor illusion were ankle dorsiflexion without resistance (standard visual-motor illusion [standard illusion]) and maximum effort dorsiflexion with resistance (power visual-motor illusion [power illusion]). People with hemiplegia following stroke underwent both illusion interventions with a 1-week washout period in between; group A started with the standard illusion intervention and group B started with the power illusion intervention. Outcomes included the sit-to-stand duration, maximum weight-bearing value, trunk movement during sit-to-stand, ankle joint movement during sit-to-stand, and active ankle dorsiflexion movement on the paralyzed side.

RESULTS

The angular velocity of the trunk and ankle joints increased significantly during sit-to-stand, and sit-to-stand duration decreased significantly in response only to power illusion. In addition, the change in angular velocity of active ankle dorsiflexion was significantly greater in response to power illusion than was the change in response to standard illusion.

CONCLUSION

Power illusion induces a greater improvement in paralyzed ankle dorsiflexion function than standard illusion, resulting in shorter sit-to-stand duration.

Trunk and lower extremity biomechanics during sit-to-stand after stroke: A systematic review

OBJECTIVES

This systematic review aimed to pool available evidence of differences in trunk and lower extremity biomechanics during the different phases of a sit-to-stand (STS) task between persons with stroke and to healthy controls.

METHODS

Four electronic databases (Medline, Web of Science, EMBASE, and Cochrane Library) were systematically searched up to, and including, December 2021. Studies were included if they investigated kinematic, kinetic and/or electromyographic outcome measures of adults with stroke during STS and compared results with healthy controls. Data from eligible studies were categorized according to STS subphases if reported (Phase I: Movement onset to seat-off; Seat-off; Phase II: Seat-off to movement termination; Whole task [if no subtasks reported]). The Newcastle-Ottawa Scale was used to assess risk of bias.

RESULTS

Twenty-one studies were included in this systematic review. Methodological quality ranged from 13% to 75%; mean score was 55%. The findings of this systematic review suggest that after stroke, people rise to stand (phase I) with increased lateral trunk flexion and displacement of the center of pressure (COP) towards the non-paretic side, decreased anterior pelvic tilt, decreased hip flexion and altered timing of lower limb muscle activation. In addition, during phase II, lateral pelvic translation and weight distribution asymmetry was increased, knee extension velocity was decreased and delayed, stabilization was decreased and COP velocity was increased compared with healthy subjects.

CONCLUSIONS

This systematic review clearly showed changes in kinematics, kinetics and muscle recruitment after stroke, with differences between the different phases of STS. Therapeutic interventions should focus on subphases of this functional task to optimize performance in daily living.

Is the Hénon map able to predict the interaction dynamics between the knee and hip joints emerged during sit-to-stand movement?

In this study, the performance of a two-dimensional Hénon map in predicting the interactive dynamics of the knee and hip joints emerging during a normative sit-to-stand movement was evaluated. The instantaneous values of the knee and hip joints were the model inputs, and the next values of the knee and hip joints were predicted by the Hénon map. The map predicted the desired relative behavior of the joints, showing synergetic coordination between the joints. The experimental data were recorded from four healthy participants and used to identify the Hénon map via a genetic algorithm. Model performance was quantitatively assessed by computing the calculated prediction error and analyzing the behavioral dynamics of the state spaces reconstructed via the captured kinematic data. According to the results, there was an obvious similarity between the dynamics of the state space trajectories of the identified model and those of the recorded data, not only in terms of stretching and folding dynamics, but also concerning generalized synchrony. The acceptable performance of the proposed modeling solution can also be demonstrated through these results.

Five-repetition sit-to-Stand test among patients post-stroke and healthy-matched controls: the use of different chair types and number of trials

Background: In 2018, the American Physical Therapy Association (APTA) published a clinical guideline for adults with neurological conditions, which included recommendations for the Five-Repetition Sit-to-Stand test (5STSt). According to the APTA, a standard-height chair should be used, but there is no recommendation regarding seat depth. In addition, the APTA recommended the use of one trial of the test, based on expert opinion.Objectives: (1) Compare the 5STSt scores of patients post-stroke and healthy-matched controls using two types of chairs (one standardized and one adjusted to the individual's anthropometric characteristics); and (2) Verify whether different numbers of trial affect the 5STSt scores.Methods: Eighteen patients post-stroke and 18 healthy-matched controls performed three trials of the 5STSt for each type of chair. ANOVA was used for analysis (α = 0.05).Results: No significant interaction between groups and chairs was found. Patients post-stroke showed worsened performances in 5STSt when using both chairs compared to the healthy controls (p = .001). In both groups, the 5STSt scores were lower when using a standardized chair than an adjusted chair (p < .003) and different numbers of trials provided similar 5STSt scores (0.44 ≤ p ≤ 0.98).Conclusion: The 5STSt scores were affected by the physical characteristics of the chair, and an adjusted chair should be used. The APTA recommendation for one trial of the 5STSt is supported by the present results.

Effects of Cane Use and Position on Performance of the Sit-to-Stand Task in Stroke Patients

OBJECTIVE

The aim of the study was to examine the effect of cane use and cane positions on the sit-to-stand performance of stroke patients.

DESIGN

In a crossover study, 30 stroke patients performed sit-to-stand test in seven situations in a random sequence: without a cane, three positions with a regular cane (parallel to the ankle, parallel to the 5th toe, and 10 cm in front of the 5th toe), and the same three positions with a quad cane. The peak vertical ground reaction force and maximum vertical cane support force during sit-to-stand were recorded.

RESULTS

Using a cane significantly reduced the peak ground reaction force by 3% to 9% of body weight compared with that without a cane (P = 0.000-0.023). Different cane positions strongly influenced the maximum cane support force and peak ground reaction force. When the cane was closer to the ankle, the maximal cane support force increased by 6.7% to 8.6% of body weight, which resulted in a decrease in the peak ground reaction force.

CONCLUSIONS

Both types of cane reduced lower limbs' load during sit to stand. When the cane was closer to the trunk, the load on legs was lessened, whereas the load on the upper limb increased. Upper limb's load during sit to stand was greater when using quad cane than using regular cane.

Neuromechanical Differences Between Successful and Failed Sit-to-Stand Movements and Response to Rehabilitation Early After Stroke

BACKGROUND

Recovery of the sit-to-stand (StS) movement early after stroke could be improved by targeting physical therapy at the underlying movement deficits in those people likely to respond.

AIM

To compare the movement characteristics of successful and failed StS movements in people early after stroke and identify which characteristics change in people recovering their ability to perform this movement independently following rehabilitation.

METHODS

Muscle activity and kinematic (including center of mass, CoM) data were recorded from 91 participants (mean 35 days after stroke) performing the StS movement before (baseline), immediately after (outcome), and 3 months after (follow-up) rehabilitation. Three subgroups (never-able [n = 19], always-able [n = 51], and able-after-baseline [n = 21]) were compared at baseline with the able-after-baseline subgroup compared before and after rehabilitation.

RESULTS

The subgroups differed at baseline for quadriceps onset time ( P = .009) and forward body position when quadriceps peaked ( P = .038). Following rehabilitation, the able-after-baseline subgroup increased their forward position ( P < .001), decreased the time difference between bilateral quadriceps peaks ( P < .001) and between quadriceps and hamstrings peaks on the nonhemiplegic side ( P = .007). An improved performance in the always-able subgroup was associated with a number of baseline factors, including forward positioning ( P = .002) and time difference between peak activity of bilateral quadriceps ( P = .001).

CONCLUSIONS

This neuromechanical study of StS before and after rehabilitation in a sample of people early after stroke identified the importance of temporal coupling between forward trunk movement and quadriceps and hamstrings' activity. These findings advance the science of stroke rehabilitation by providing evidence-based therapy targets to promote recovery of the StS movement.

Is there a relationship between postural alignment and mobility for adults after acquired brain injury? A systematic review

PRIMARY OBJECTIVE

To examine the relationship between postural alignment and mobility skills for adults after acquired brain injury (ABI).

METHODS

Systematic review of the literature. Seven electronic databases, grey literature and reference lists of the shortlisted publications were searched. Studies were included if participants were adults with ABI, both postural alignment and mobility were measured and analysis included a relationship between alignment and mobility. Those that met the inclusion criteria were assessed with a critical appraisal tool. The review was registered with PROSPERO, registration number CRD42015019867.

RESULTS

Seven observational studies were included that had examined a relationship between postural alignment and mobility after ABI. Critical appraisal scores were moderate to strong. While some studies reported that improved postural alignment was related to improved mobility after ABI, results varied and there was insufficient evidence to answer the primary question. Heterogeneous study designs did not allow meta-regression.

CONCLUSIONS

A small amount of observational evidence exists for a relationship between postural alignment and mobility after ABI. Results vary, with some studies reporting that a more stable, upright trunk correlates with better mobility, and others providing conflicting or ambiguous results. Further research is needed to establish the relationship between postural alignment and mobility skills after ABI.

Validation of an optimized algorithm to use Kinect in a non-structured environment for Sit-to-Stand analysis

The aim of this work is to obtain reliable kinematic measures relative to the execution of the Sit-to-Stand functional evaluation test, by low-cost and widely diffused instrumentation, that even non-experienced users can adopt in non-structured environments, like ambulatory or domestic settings. In particular, the paper refers to a low cost RGB-Depth sensor widely used in the gaming scenario like the Microsoft Kinect sensor. An algorithm is proposed that allows a reliable measure of human motion in a sagittal view. The performance of the proposed algorithm is compared to other two classic commercial algorithms. Results obtained by all the three algorithms have been compared to kinematic results obtained by the use of a stereophotogrammetric system that represents the gold-standard for kinematic measurement of human movement. Average errors of about 4 degrees, both for the trunk/leg angle and for the knee flexion/extension angle, have been obtained by the proposed algorithm and open the way to its possible adoption in non-clinical environments and further applications.

A novel clinical approach for assessing hop landing strategies: a 2D telescopic inverted pendulum (TIP) model

PURPOSE

Single leg hop for distance is used to inform rehabilitation and return to sport following anterior cruciate ligament reconstruction. However, impairment of landing mechanics may persist after the recommended performance parameter (hop distance) has been met; therefore, alternative methods are required. This study follows the COSMIN guideline to investigate the measurement properties of data from a new instrument (2D TIP). This is a simple motion analysis instrument to assess landing strategy based on more complex biomechanical modelling.

METHODS

Data collected in the clinical setting from 30 subjects with chronic ACL deficiency (mean 15.5, SD 4.3 months following injury) before and 6 months after ACL reconstruction and a healthy control group were analysed. Reliability and measurement error were calculated using two repeated measures from three independent raters. Construct validity was assessed by hypothesis testing, and known groups validity and responsiveness were defined by differences between groups.

RESULTS

The data demonstrate excellent inter-rater (ICC = 0.81-1.00) and intra-rater (ICC = 0.85-1.00) reliability with low measurement error. Of the eight construct validity hypothesis, six were fully and two partially supported. Between-group differences were significant (P < 0.05) supporting the validity and responsiveness hypothesis.

CONCLUSION

2D TIP is a simple and inexpensive instrument for assessing landing strategy that has demonstrated appropriate reliability, validity and responsiveness in the ACL-injured population. The instrument will now be used to identify altered movement strategies and develop novel rehabilitation interventions that target strategy and performance.

LEVEL OF EVIDENCE

Prospective diagnostic study, Level II.

Association of seat height and arm position on the five times sit-to-stand test times of stroke survivors

Objectives. To investigate (1) the association of seat height and (2) the association of arm position on the five times sit-to-stand test (FTSTS) times of individuals with stroke. Design. A cross-sectional study. Setting. University-based rehabilitation centre. Subjects. Patients (n = 43) with chronic stroke. Methods. The times in completing the FTSTS with different seat height (85%, 100%, and 115% knee height) and arm positions (arms across chest, hands on thighs). Results. FTSTS times were significantly different between 85% and 100% seat heights, and between the 85% and 115% seat heights in both arm positions. However, there was no significant difference between the FTSTS times with the two arm positions at any seat height tested. Conclusion. Seat heights lower than the knee height result in longer FTSTS times, whereas arms positions did not significantly affect the FTSTS times.

Demonstration of posturographic parameters of squat-stand activity in hemiparetic patients on a new multi-utility balance assessing and training system

Background

Quantitative evaluation of position control ability in stroke patients is needed. Here we report a demonstration of position control ability assessment and test-retest reliability during squat-stand activity on a new system in hemiparetic patients and controls.

Methods

Sixty-two healthy adults and thirty-four hemiparetics were enrolled.

All of the participants were required to complete five repeated squat-stand activities under three different conditions: partial weight support, standard weight bearing, and resistance. The healthy adults’ test was repeated twice to assess the reliability, while the hemiparetics were tested one time to assess impairments in their position control ability. The healthy participants completed their second test 1 wk after the first. Intraclass correlation coefficients (ICCs) were used to assess test-retest reliability.

Results

During partial weight support, the ICCs ranged from 0.77 to 0.91, which indicated a good reliability. During standard weight bearing and resistance, the ICCs varied from 0.64 to 0.86 and 0.54 to 0.84, respectively, indicating a fair reliability. Compared with the healthy adults, the stroke patients demonstrated poorer position control ability.

Conclusions

The posturography of the squat-stand activity is a new and reliable measurement tool for position control. According to the methods proposed here, hemiparetics can be differentiated from healthy adults using the squat-stand activity. This activity will provide a new evaluation tool and therapy with visual feedback for the stroke patients.

Trial registration

Chinese clinical trial registry, ChiCTR-TRC-10000863

Accelerometry-based prediction of movement dynamics for balance monitoring

This paper proposes a 2D functional evaluation tool for estimating subject-specific body segment parameters, which uses a simple motor task (repeated sit-to-stand, rSTS), recorded with one single-axis accelerometer (SAA) per segment and a force plate (FP). After this preliminary estimation, the accelerometer alone is used to make quasi-real-time predictions of ground reaction force (anterior/posterior, F ( X ), and vertical, F ( Z ), components), center of pressure (CoP) and center of mass (CoM), during rSTS and postural oscillation in the sagittal plane. These predicted dynamic variables, as well as those obtained using anthropometric parameters derived from De Leva, were compared to actual FP outputs in terms of root mean-squared errors (RMSEs). Using De Leva's parameters in place of those estimated, RMSEs increase from 12 to 21 N (F ( X )), from 21 to 24 N (F ( Z )), and from 21.1 to 55.6 mm (CoP) in rSTS; similarly, RMSEs increase from 3.1 to 3.3 N (F ( X )) and from 5.5 to 6.6 mm (CoP) in oscillatory trials. A telescopic inverted pendulum model was adopted to analyze the balance control in rSTS using only predicted CoP and CoM. Results suggest that one SAA per segment is sufficient to predict the dynamics of a biomechanical model of any degrees of freedom.

Analysis of vertical ground reaction force variables during a Sit to Stand task in participants recovering from a hip fracture

BACKGROUND

A Sit to Stand task following a hip fracture may be achieved through compensations (e.g. bilateral arms and uninvolved lower extremity), not restoration of movement strategies of the involved lower extremity. The primary purpose was to compare upper and lower extremity movement strategies using the vertical ground reaction force during a Sit to Stand task in participants recovering from a hip fracture to control participants. The secondary purpose was to evaluate the correlation between vertical ground reaction force variables and validated functional measures.

METHODS

Twenty eight community dwelling older adults, 14 who had a hip fracture and 14 control participants completed the Sit to Stand task on an instrumented chair designed to measure vertical ground reaction force, performance based tests (Timed up and go, Berg Balance Scale and Gait Speed) and a self report Lower Extremity Measure. A MANOVA was used to compare functional scales and vertical ground reaction force variables between groups. Bivariate correlations were assessed using Pearson Product Moment correlations.

FINDINGS

The vertical ground reaction force variables showed significantly higher bilateral arm force, higher uninvolved side peak force and asymmetry between the involved and uninvolved sides for the participants recovering from a hip fracture (Wilks' Lambda=3.16, P=0.019). Significant correlations existed between the vertical ground reaction force variables and validated functional measures.

INTERPRETATION

Participants recovering from a hip fracture compensated using their arms and the uninvolved side to perform a Sit to Stand. Lower extremity movement strategies captured during a Sit to Stand task were correlated to scales used to assess function, balance and falls risk.

Multi-parametric evaluation of sit-to-stand and stand-to-sit transitions in elderly people

The aim of this study was to extract multi-parametric measures characterizing different features of sit-to-stand (Si-St) and stand-to-sit (St-Si) transitions in older persons, using a single inertial sensor attached to the chest. Investigated parameters were transition's duration, range of trunk tilt, smoothness of transition pattern assessed by its fractal dimension, and trunk movement's dynamic described by local wavelet energy. A measurement protocol with a Si-St followed by a St-Si postural transition was performed by two groups of participants: the first group (N=79) included Frail Elderly subjects admitted to a post-acute rehabilitation facility and the second group (N=27) were healthy community-dwelling elderly persons. Subjects were also evaluated with Tinetti's POMA scale. Compared to Healthy Elderly persons, frail group at baseline had significantly longer Si-St (3.85±1.04 vs. 2.60±0.32, p=0.001) and St-Si (4.08±1.21 vs. 2.81±0.36, p=0.001) transition's duration. Frail older persons also had significantly decreased smoothness of Si-St transition pattern (1.36±0.07 vs. 1.21±0.05, p=0.001) and dynamic of trunk movement. Measurements after three weeks of rehabilitation in frail older persons showed that smoothness of transition pattern had the highest improvement effect size (0.4) and discriminative performance. These results demonstrate the potential interest of such parameters to distinguish older subjects with different functional and health conditions.

Wavelet based approach for posture transition estimation using a waist worn accelerometer

The ability to rise from a chair is considered to be important to achieve functional independence and quality of life. This sit-to-stand task is also a good indicator to assess condition of patients with chronic diseases. We developed a wavelet based algorithm for detecting and calculating the durations of sit-to-stand and stand-to-sit transitions from the signal vector magnitude of the measured acceleration signal. The algorithm was tested on waist worn accelerometer data collected from young subjects as well as geriatric patients. The test demonstrates that both transitions can be detected by using wavelet transformation applied to signal magnitude vector. Wavelet analysis produces an estimate of the transition pattern that can be used to calculate the transition duration that further gives clinically significant information on the patients condition. The method can be applied in a real life ambulatory monitoring system for assessing the condition of a patient living at home.

Extraction of information on elder motor ability from clinical and biomechanical data through data mining

This study aimed at evaluating the additional knowledge provided by a biomechanical test coupled with clinical tests for motor ability assessment. A database including clinical test scores and sit-to-stand test variables obtained from 110 medically stable elderly subjects was submitted to data mining by searching for association rules. The presence of rules revealed some redundancies due to sample homogeneity, as mainly observed in the joint analysis of a questionnaire for daily activities assessment (Nottingham test) and the sit-to-stand, and due to similar evaluated information, as resulted from the joint analysis of a balance and gait scale (Tinetti test) and the sit-to-stand. Conversely, when no association rules were found, the tests carried unrelated information. The associations mined while analysing these clinical tests encouraged the integration of biomechanical tests, increasing significantly its clinical applicability and reducing the information redundancy. The information extracted also allowed to highlight rules typical of elderly persons that may serve as a knowledge-based tool for the detection of possible deviation from normality.