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

Brain (EEG) and muscle (EMG) activity related to 3D sit-to-stand kinematics in healthy adults and in central neurological pathology - A systematic review

BACKGROUND

The sit-to-stand transfer is a fundamental functional movement during normal activities of daily living. Central nervous system disorders can negatively impact the execution of sit-to-stand transfers, often impeding successful completion. Despite its importance, the neurophysiological basis at muscle (electromyography (EMG)) and brain (electroencephalography (EEG)) level as related to the kinematic movement is not well understood.

OBJECTIVES

This review synthesises the published literature addressing central and peripheral neural activity during 3D kinematic capture of sit-to-stand transfers.

METHODS

A pre-registered systematic review was conducted. Electronic databases (PubMed, CINAHL Plus, Web of Science, Scopus and EMBASE) were searched from inception using search operators that included sit-to-stand, kinematics and EMG and/or EEG. The search was not limited by study type but was limited to populations comprising of healthy individuals or individuals with a central neurological pathology.

RESULTS

From a total of 28,770 identified papers, 59 were eligible for inclusion. Ten of these 59 studies received a moderate quality rating; with the remainder rated as weak using the Effective Public Health Practice Project tool. Fifty-eight studies captured kinematic data of sit-to-stand with associated EMG activity only and one study captured kinematics with co-registered EMG and EEG data. Fifty-six studies examined sit-to-stand transfer in healthy individuals, reporting four dynamic movement phases and three muscle synergies commonly used by most individuals to stand-up. Pre-movement EEG activity was reported in one study with an absence of data during execution. Eight studies examined participants following stroke and two examined participants with Parkinson's disease, both reporting no statistically significant differences between their kinematics and muscle activity and those of healthy controls.

SIGNIFICANCE

Little is known about the neural basis of the sit-to-stand transfer at brain level with limited focus in central neurological pathology. This poses a barrier to targeted mechanistic-based rehabilitation of the sit-to-stand movement in neurological populations.

Between-day reliability of trunk orientation measured with smartphone sensors during sit-to-stand in asymptomatic individuals

BACKGROUND

Trunk kinematics during sit-to-stand is often impaired in individuals with musculoskeletal disorders. Trunk kinematics is commonly assessed in laboratories using motion capture; however, this equipment is often not available outside research centers. Smartphones are widely available and may be a suitable alternative to assess trunk orientation during sit-to-stand remotely.

OBJECTIVES

We investigated whether trunk orientation in the sagittal plane during sit-to-stand can be measured reliably between days when collected remotely using smartphones.

DESIGN

Cross-sectional study.

METHOD

Forty-three asymptomatic participants performed 15 sit-to-stand movements in two separate sessions remotely over videoconferencing. Trunk orientation was measured using each participant's smartphone. Absolute peak trunk orientation in the sagittal plane was extracted during standing, sitting, stand up and sit down. Relative trunk orientation was calculated as the difference between sitting and stand up, or sitting and sit down. Reliability was assessed using Intraclass Correlation Coefficient (ICC_2,k), Standard Error of Measurement (SEM) and Minimal Detectable change (MDC). Between day bias and between-gender differences were assessed using T tests.

RESULTS

All measures showed good reliability (ICC_2,k > 0.80; SEM < 5.6°; MDC < 13.6°) and no between-day bias (p > 0.31). Relative measures were more consistent (ICC_2,k > 0.88; SEM < 3.6°; MDC < 9.9°). No between-gender differences were observed for relative orientation (p > 0.75).

CONCLUSIONS

Sagittal trunk orientation during sitting, standing, and sit-to-stand can be measured reliably when asymptomatic individuals use their own smartphones supervised over videoconferencing. These findings support the use of smartphone sensors for assessing how trunk orientation changes over time, which may assist physiotherapists assess movement patterns of individuals with musculoskeletal disorders remotely.

The 5-STS is a prognostic factor of sub-acute stroke patients who will not become community walkers at discharge from rehabilitation

BACKGROUND

The recovery of community ambulation is a common concern among individuals after stroke.

OBJECTIVES

(1) To develop a potential readily applicable prognostic model able to correctly discriminate stroke patients who will not become independent community walkers at discharge; (2) To investigate the effects of early reassessment during the first month of treatment on the prediction accuracy of this model.

METHODS

This was a prospective cohort study. A consecutive sample of 80 patients at ≤60 days poststroke were assessed at baseline of outpatient physical rehabilitation and reassessed one month later. Non-functional community ambulation was measured.

RESULTS

Seventy-four patients were followed until discharge. Of these, 47 patients were non-functional community walkers at discharge. A prediction model based on baseline performance in the five repetition sit-to-stand [5-STS] test was able to discriminate those patients of the sample (Area-under-curve = 0.956), and again with data from reassessment (AUC = 0.952). A time of 21 s at baseline was a highly prognostic cut-off point for discrimination (sensitivity = 87.2% and 85.1%). The combined use of baseline and reassessment data improved sensitivity (98.1%)CONCLUSION:Early findings of the 5-STS among stroke patients is an independent prognostic factor associated with independent community walking at discharge. It could discriminate individuals who will not become community walkers at discharge.

Effect of Initial Knee angle and Arm Facilitation on biomechanics of the Sit-to-Stand movement

Spinal cord injuries cause loss of muscle function and subsequently reduce independence. Therapeutic interventions such as transcutaneous spinal cord stimulation are increasingly being used to help improve motor functioning however, a comprehensive understanding of the biomechanical elements of movement may help optimize stimulation protocols. Twenty healthy participants completed five sit-to-stand (STS) transitions while initial knee angle and arm facilitation were altered. Electromyography (EMG) activation of four lower limb muscles and centre of pressure dynamics were recorded. Acute initial knee angles resulted in a change in duration of phases within the STS, and restrictive arm positioning caused the time to completion to increase (p=0.04). Muscle activation patterns across phases were compared and showed significant differences between phases in both the Tibialis Anterior and Rectus Femoris (p<0.006). Acute initial knee angles were also found to significantly increase Biceps Femoris activation across multiple phases (p=0.034). Altering the starting position and limb movement result in vastly different temporal and muscular strategies to complete the STS. Thus, joint angle and upper limb facilitation should be considered when designing rehabilitative interventions for clinical cohorts.

Effects of Dynamic Sitting Exercise with Delayed Visual Feedback in the Early Post-Stroke Phase: A Pilot Double-Blinded Randomized Controlled Trial

Sitting ability in the early post-stroke phase affects functional balance ability and other prognoses. We investigated whether dynamic sitting exercise with delayed visual feedback in the mediolateral and anteroposterior directions affected postural control in the early post-stroke phase. In this pilot randomized controlled trial, 27 hemiparetic stroke patients were randomized to experimental (n = 13) and control (n = 14) groups. Dynamic sitting exercise (30 times/day, 5 days/week) in the mediolateral and anteroposterior directions, with 500-ms-delayed (experimental group) or real-time (control group) visual feedback on a computer, was added to usual physical therapy. We evaluated the postural assessment scale for stroke (PASS), static and dynamic sitting balance tasks, the five-times sit-to-stand test, trunk impairment scale, functional ambulation category, and functional independence measure−motor items. In intention-to-treat analysis, the experimental group demonstrated a significant intervention effect on the PASS score (p < 0.05). The mean percentage of body weight on the moving side in the lateral sitting task and the number of successes in the five-times sit-to-stand test were significantly higher in the experimental group than those in the control group (p < 0.05). Thus, the proposed exercise improves postural control, dynamic sitting balance, and sit-to-stand ability in early post-stroke patients.

Biomechanical correlates for recovering walking speed following a stroke. The potential of tibia to vertical angle as a therapy target

BACKGROUND

Recovering independent walking is a priority for stroke survivors. Community walking requires speeds exceeding the average values typically achieved at discharge (0.7 m/s). To improve outcomes there is a need to clarify the factors associated with recovery of functional walking speeds.

RESEARCH QUESTION

Which biomechanical variables correlate significantly with improved walking speed following rehabilitation in acute stroke patients.

METHODS

The study was embedded in a larger clinical trial testing efficacy of a gait training splint. Participants, within 6 weeks of their stroke and exhibiting abnormal gait, were recruited. Using a valid and reliable video-based system, specific kinematic measures were recorded before randomisation (baseline), after a 6-week rehabilitation phase (outcome) and six months after stroke (follow-up). Measures of temporospatial symmetry, knee angular velocity and tibia to vertical angle were added to clinical measures and correlated with change in speed.

RESULTS

23 participants were recruited, (mean age 67.7 ± 16.7 years, 19.2 ± 9.0 days after stroke and 73.9% male), with 20/23 assessed at outcome and 17/23 at follow-up. Drop out was due to withdrawal (3) and technical failure (3). Walking speed increased by 0.15 ± 0.21 m/s (outcome), and 0.21 ± 0.14 m/s (follow-up) from baseline (0.50 ± 0.20 m/s). This increase correlated with an increase in step length (r=0.88) and change in angle of tibia at initial contact (r=-0.59), foot flat (r=-0.61) and terminal contact (r=0.54).

SIGNIFICANCE

This study of gait recovery among acute stroke patients demonstrated modest improvements in walking speed. Walking speed by follow-up (0.71 m/s) classified the group as community walkers (>0.66 m/s) but still too slow to safely use a pedestrian road crossing. Change in step length and tibia to vertical angle significantly correlated with increased walking speed. This finding provides distinctive targets for therapy aimed at improving community walking among stroke survivors. This hypothesis should be tested prospectively in future studies.