Transfer strategies used to rise from a chair in normal and low back pain subjects

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.

Rollator usage lets young individuals switch movement strategies in sit-to-stand and stand-to-sit tasks

The transitions between sitting and standing have a high physical and coordination demand, frequently causing falls in older individuals. Rollators, or four-wheeled walkers, are often prescribed to reduce lower-limb load and to improve balance but have been found a fall risk. This study investigated how rollator support affects sit-to-stand and stand-to-sit movements. Twenty young participants stood up and sat down under three handle support conditions (unassisted, light touch, and full support). As increasing task demands may affect coordination, a challenging floor condition (balance pads) was included. Full-body kinematics and ground reaction forces were recorded, reduced in dimensionality by principal component analyses, and clustered by k-means into movement strategies. Rollator support caused the participants to switch strategies, especially when their balance was challenged, but did not lead to support-specific strategies, i.e., clusters that only comprise light touch or full support trials. Three strategies for sit-to-stand were found: forward leaning, hybrid, and vertical rise; two in the challenging condition (exaggerated forward and forward leaning). For stand-to-sit, three strategies were found: backward lowering, hybrid, and vertical lowering; two in the challenging condition (exaggerated forward and forward leaning). Hence, young individuals adjust their strategy selection to different conditions. Future studies may apply this methodology to older individuals to recommend safe strategies and ultimately reduce falls.

Gluteus Maximus Muscle Activation Characteristics During a Chair-Rise in Adults With Chronic Stroke

BACKGROUND AND PURPOSE

A successful chair-rise is an important indicator of functional independence post-stroke. Lower extremity electromyographic analyses provide a basis for muscle activation from which clinical intervention protocols may be derived. Gluteus maximus activation during the chair-rise has not been thoroughly researched in the chronic stroke population. This study investigated the magnitude and onset of gluteus maximus activation during the chair-rise comparing adults post-stroke with healthy controls.

METHODS

In this cross-sectional study, adults with chronic stroke (n = 12) and healthy controls (n = 12) completed 4 natural-speed chair-rise trials. Magnitude and onset of bilateral gluteus maximus activation were measured during the movement with secondary comparative data from biceps femoris and vastus lateralis muscles. Kinetic and kinematic measurements were used to quantify chair-rise phases and movement cycle duration.

RESULTS

Significant decreases in paretic ( P = 0.002), and nonparetic ( P = 0.001) gluteus maximus magnitudes were noted post-stroke compared with ipsilateral extremities of healthy adults. Significant gluteus maximus onset delays were noted in paretic extremities compared with nonparetic extremities post-stroke ( P = 0.009) that were not apparent in comparative muscles. Similar onset times were noted when comparing the paretic extremity post-stroke to the ipsilateral extremity of healthy controls ( P = 0.714) despite prolonged movement cycle durations in those with chronic stroke ( P = 0.001). No onset delays were evident in the biceps femoris ( P = 0.72) or vastus lateralis ( P = 0.338) muscles.

DISCUSSION AND CONCLUSIONS

Despite apparent unilateral muscle weakness post-stroke, bilateral decreases in gluteus maximus activation magnitudes and compounding onset deficits of the paretic extremity were observed during chair-rising. Further research is needed to determine whether interventions maximizing bilateral activation magnitudes and improving temporal activation congruency during chair-rising will carry over to functional gainsVideo Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A387 ).

Comparison of Kinematic Movement Patterns Between 2 Subgroups of Females With Low Back Pain and Healthy Women During Sit-to-Stand and Stand-to-Sit

The purpose of study was to compare the kinematic patterns of the thoracic, lumbar, and pelvis segments and hip joints between 2 low back pain subgroups and healthy women during sit-to-stand and stand-to-sit. Kinematic data of 44 healthy women and 2 subgroups of females with low back pain in 2 subgroups of movement system impairment model (rotation-extension [Rot.Ext] and rotation-flexion [Rot.Flex]) were recorded. Participants performed sit-to-stand and stand-to-sit at a preferred speed. Each task was divided into a pre buttock lifted off/on (pre-BOff/n) phase and a post-BOff/n phase. The Rot.Ext subgroup showed greater range of motion in the thoracic during pre-BOff phase of sit-to-stand (P < .001) and pre-BOn phase of stand-to-sit (P = .01) compared to the other 2 groups. The Rot.Flex subgroup displayed limited left hip joint excursion during sit-to-stand pre-BOff (P = .04) and stand-to-sit post-BOn phases (P = .02). The Rot.Flex subgroup showed greater pelvis tilt excursion during sit-to-stand post-BOff (P = .04) and stand-to-sit pre-BOn (P = .01) and post-BOn phases (P = .01). In subgroups of women with chronic low back pain, there were kinematic changes in adjacent body segments/joints of lumbar spine during sit-to-stand and stand-to-sit tasks.

Unsupervised Machine Learning on Motion Capture Data Uncovers Movement Strategies in Low Back Pain

Chronic low back pain (LBP) is a leading cause of disability and opioid prescriptions worldwide, representing a significant medical and socioeconomic problem. Clinical heterogeneity of LBP limits accurate diagnosis and precise treatment planning, culminating in poor patient outcomes. A current priority of LBP research is the development of objective, multidimensional assessment tools that subgroup LBP patients based on neurobiological pain mechanisms, to facilitate matching patients with the optimal therapies. Using unsupervised machine learning on full body biomechanics, including kinematics, dynamics, and muscle forces, captured with a marker-less depth camera, this study identified a forward-leaning sit-to-stand strategy (STS) as a discriminating movement biomarker for LBP subjects. A forward-leaning STS strategy, as opposed to a vertical rise strategy seen in the control participants, is less efficient and results in increased spinal loads. Inefficient STS with the subsequent higher spinal loading may be a biomarker of poor motor control in LBP patients as well as a potential source of the ongoing symptomology.

Spinopelvic movement strategies during sit-to-stand and stand-to-sit in adult spinal deformity

BACKGROUND

Research interest on the impact of adult spinal deformity (ASD) on spinopelvic and whole body motion has increased over the past years. Studies focusing on overground walking, showed that patients with ASD indeed present with functional impairments. Functional tasks challenging the spinopelvic complex, such as sit-to-stand-to-sit, might identify clinically relevant biomechanical parameters and could further increase our insights on how ASD impacts functioning and disability.

RESEARCH QUESTION

Do patients with ASD use different spinopelvic strategies during sit-to-stand (STSt) and stand-to-sit (StTS) compared to healthy controls?

METHODS

In this prospective study, marker-based motion analysis and a subject-specific polynomial fit were used to assess spinopelvic kinematics (thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), trunk, pelvis) during STSt/StTS in 42 patients with ASD and 18 control subjects. All parameters were compared between controls and patients with ASD, divided in three groups based on their sagittal alignment (ASD 1: decompensated sagittal malalignment; ASD 2: compensated sagittal malalignment; ASD 3: scoliosis and normal sagittal alignment). Continuous kinematic and kinetic data were analyzed through statistical parametric mapping.

RESULTS

Patients with ASD showed decreased LL and increased trunk flexion and SVA during STSt/StTS compared to controls. These differences were mainly observed in sagittal deformity patients (ASD 1 and 2). In contrast, coronal patients (ASD 3) did not differ from controls. Dynamic LL and SVA significantly correlated with radiographic LL and SVA, however these relations decreased during the middle third of the motion cycle.

SIGNIFICANCE

Patients with ASD use aberrant spinopelvic strategies during STSt/StTS compared to healthy controls. Only partial correlation to static radiographic parameters suggests other mechanisms need to be identified in addition to spinal malalignment. These might include impaired neuromuscular control or muscle weakness. Further research on movement patterns during functional tasks might ultimately result in treatment strategies that aim to augment activity participation by targeting improvements in movement function.

Dual goals of trunk restriction and stability are prioritized by individuals with chronic low back pain during a volitional movement

BACKGROUND

Individuals with chronic low back pain demonstrate impaired responses to volitional and externally-generated postural perturbations that may impact stability whilst performing activities of daily living. Understanding how balance may be impaired by strategy selection is an important consideration during rehabilitation from low back pain to prevent future injurious balance loss.

RESEARCH QUESTION

This cross-sectional study explored the influence of an active pain episode on volitional movement patterns and stability during a sit-to-stand task in individuals with chronic low back pain compared to those with no low back pain history.

METHODS

Thirteen participants with low back pain who were in an active flare-up and 13 without pain sat on a height-adjusted chair and performed 5 sit-to-stand movements. Sagittal plane kinematics, kinetics, and surface electromyography were used to compute neuromuscular variables across Acceleration, Transition and Deceleration phases. Stability was assessed using times to contact of body centers of mass and pressure to base of support boundaries. Independent samples t-tests were used to examine group effects, and repeated measures analyses of variance assessed within-subjects effects across movement phases.

RESULTS

Individuals with low back pain tended to restrict proximal joint motions through heightened muscle activity while increasing distal joint movement and distal muscle contributions. Individuals with low back pain used a greater driving force, indicated by a longer time to contact of the center of pressure, to achieve comparable center of mass stability. Individuals with low back pain may prioritize trunk restriction and stability through the sit-to-stand movement, possibly related to fear of pain or movement.

SIGNIFICANCE

The tendency for individuals with active low back pain to restrict trunk movements may require additional effort to maintain stability. Further research should examine whether trunk restriction is related to pain-related fear of movement and whether additional cognitive resources are required to maintain movement stability.

A systematic review of movement and muscular activity biomarkers to discriminate non-specific chronic low back pain patients from an asymptomatic population

The identification of relevant and valid biomarkers to distinguish patients with non-specific chronic low back pain (NSCLBP) from an asymptomatic population in terms of musculoskeletal factors could contribute to patient follow-up and to evaluate therapeutic strategies. Several parameters related to movement and/or muscular activity impairments have been proposed in the literature in that respect. In this article, we propose a systematic and comprehensive review of these parameters (i.e. potential biomarkers) and related measurement properties. This systematic review (PROSPERO registration number: CRD42020144877) was conducted in Medline, Embase, and Web of Knowledge databases until July 2019. In the included studies, all movements or muscular activity parameters having demonstrated at least a moderate level of construct validity were defined as biomarkers, and their measurement properties were assessed. In total, 92 studies were included. This allowed to identify 121 movement and 150 muscular activity biomarkers. An extensive measurement properties assessment was found in 31 movement and 14 muscular activity biomarkers. On the whole, these biomarkers support the primary biomechanical concepts proposed for low back pain. However, a consensus concerning a robust and standardised biomechanical approach to assess low back pain is needed.

Does manual therapy affect functional and biomechanical outcomes of a sit-to-stand task in a population with low back pain? A preliminary analysis

Introduction

Manual therapy (MT) hypothetically affects discrepant neuromuscular control and movement observed in populations with low back pain (LBP). Previous studies have demonstrated the limited influence of MT on movement, predominately during range of motion (ROM) testing. It remains unclear if MT affects neuromuscular control in mobility-based activities of daily living (ADLs). The sit-to-stand (STS) task represents a commonly-performed ADL that is used in a variety of clinical settings to assess functional and biomechanical performance.

Objective

To determine whether MT affects functional performance and biomechanical performance during a STS task in a population with LBP.

Methods

Kinematic data were recorded from the pelvis and thorax of participants with LBP, using an optoelectronic motion capture system as they performed a STS task before and after MT from November 2011 to August 2014. MT for each participant consisted of two high-velocity low-amplitude spinal manipulations, as well as two grade IV mobilizations of the lumbar spine and pelvis targeted toward the third lumbar vertebra and sacroiliac joint in a side-lying position; the order of these treatments was randomized. Pelvis and thorax kinematic data were used to derive the time-varying lumbar angle in the sagittal plane for each STS trial. The difference between the maximum and minimum lumbar angles during the STS trial determined the sagittal ROM that was used as the biomechanical outcome. Time to complete each STS trial was used as a functional measure of performance. Pre-MT and post-MT values for the lumbar sagittal ROM and time to completion were statistically analysed using paired samples t-tests.

Results

Data were obtained from 40 participants with 35 useful datasets (NRS = 3.3 ± 1.2; 32.4 ± 9.8 years; 16 females, 19 males). After MT, lumbar sagittal ROM increased by 2.7 ± 5.5 degrees (p = 0.007). Time to complete the STS test decreased by 0.4 ± 0.4 s (p < 0.001).

Discussion

These findings provide preliminary evidence that MT might influence the biomechanical and functional performance of an STS task in populations with LBP. The MT intervention in this study involved a combination of spinal manipulations and mobilizations. Future work will expand upon these data as a basis for targeted investigations on the effects of either spinal manipulation and mobilization on neuromuscular control and movement in populations with LBP.

Kinematic Characteristics of Sit-to-Stand Movements in Patients With Low Back Pain: A Systematic Review

OBJECTIVE

The purpose of this review was to identify different kinematic characteristics between the movements of sit-to-stand-to-sit, sit-to-stand, or stand-to-sit of individuals with and without low back pain (LBP).

METHODS

A systematic search was conducted on scientific databases. The analyzed kinematic variables were duration of the movement, reproduction of the movement, ranges of motion, velocity, and acceleration. The studies were appraised for methodological quality using the Downs & Black scale and for the level of evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach.

RESULTS

After all screening stages, this systematic review comprised 8 cross-sectional studies. When comparing the patients with LBP vs controls, patients with LBP take longer to perform the sit-to-stand-to-sit, sit-to-stand, and stand-to sit movements (eg, 9.33 ± 1.49 seconds vs 8.29 ± 1.23 seconds in the sit-to-stand-to-sit movement), show decreased mobility of the lumbar spine (eg, 26.21° ± 8.76° vs 32.07° ± 6.77° in the sit-to-stand-to-sit movement) and the hip (eg, 51.0° vs 77.25° in the sit-to-stand movement), present decreased velocity of the trunk (eg, 95.31° ± 25.13°/s vs 138.23° ± 23.42°/s in the sit-to-stand-to-sit movement) and the hip (eg, 46° ± 13°/s vs 69° ± 13°/s in the sit-to-stand movement), and decreased overall acceleration of the trunk (eg, 280.19° ± 113.08°/s² vs 460.16° ± 101.49°/s² in the sit-to-stand-to-sit movement), besides presenting greater variability of the trunk (eg, 5.53° ± 0.48° vs 4.32° ± 0.46° in the sit-to-stand movement).

CONCLUSION

There are kinematic alterations in the lumbar spine, the hip, and the trunk of patients with LBP. However, information about pelvic and overall trunk mobility, velocity, and acceleration of the lumbar spine; and mobility, speed, and acceleration of hip and pelvis remain incipient in individuals with LBP. Based on the Grading of Recommendations Assessment, Development, and Evaluation criteria, the results of this review indicate that there is low scientific evidence on the characteristics of the kinematic variables (duration of the movement, reproduction of the movement, range of motion, velocity, and acceleration) of the trunk, lumbar spine, pelvis, and hip in patients with LBP.

Muscle activity and balance control during sit-to-stand across symmetric and asymmetric initial foot positions in healthy adults

BACKGROUND

Rising from a sit to a stand has biomechanical factors that are dependent on initial foot position. Little is known about the effect of initial foot position on leg muscle activation patterns during a sit-to-stand and balance maintenance of stance after a sit-to-stand.

RESEARCH QUESTION

What are the effects of different symmetric and asymmetric initial foot positions on leg muscle activation patterns and balance during and after a sit-to-stand?

METHODS

Three symmetric (neutral; both ankles positioned under the knees at a 90° flexion; one-third; and two-thirds foot length posterior to neutral) and three asymmetric (neutral non-dominant leg with one-third back dominant leg, neutral non-dominant with two-thirds back dominant leg, and one-third back non-dominant leg with two-thirds back dominant leg) initial foot positions were tested. EMG of the lower extremity muscles and sagittal plane kinematic data were measured along with balance assessments in the anterior-posterior and medial-lateral axes.

RESULTS

In the symmetric initial foot positions, a faster forward velocity of the body's center of mass was required for more anterior initial foot positions. Even though the hip extensors activated earlier to decelerate the forward velocity of the body's center of mass before rising, the greater forward velocity caused postural sway following completion of upright stance. In the asymmetric initial foot positions, the posterior leg supported more weight during the sit-to-stand, resulting in balance perturbations in the posterior leg. In the one-third back non-dominant leg with two-thirds back dominant leg asymmetric initial foot position, however, the weight-bearing symmetry was not different from the symmetric initial foot positions during the sit-to-stand. Postural stability after completion of uprising was also improved in this asymmetric initial foot position, showing greater but delayed onset of the tibialis anterior in the anterior leg during the momentum transfer phase.

SIGNIFICANCE

With a neutral symmetric initial foot position, earlier onset of the hip extensors during eccentric lengthening contributed to decelerating the forward velocity of the body's center of mass for balance control during a sit-to-stand. With asymmetric initial foot positions, the weight distribution during a sit-to-stand can be increased by positioning both feet posterior to neutral foot position. Performing a sit-to-stand with this asymmetric initial foot position can improve postural stability after uprising. Thus, this foot position could be used in designing rehabilitation interventions for clinical populations and the frail elderly.

Movement variability in adults with low back pain during sit-to-stand-to-sit

BACKGROUND

Differences in movement variability may be related to a guarded response to pain or a less robust movement pattern, indicating a potential dysfunction in motor control. The study objective was to compare patterns of lumbo-pelvic coordinative variability, during repeated sit-to-stand-to-sit, in individuals with low back pain and healthy adults.

METHODS

Participants were adults with low back pain (n = 16) and healthy controls (n = 21). Kinematics for the T12-L3, L3-S1, and hip segments were measured using electromagnetic motion capture during 10 sit-to-stand-to-sit trials. Continuous relative phase analysis using the Hilbert transform method determined coordination and variability of the Hip-L3S1, and L3S1-T12L3 segments, deconstructed into 4 periods (start/up/down/end). T-tests compared coordination and variability of the full task between groups, and a mixed ANOVA compared the effects of group and period for the two segments.

FINDINGS

Across the full task, the low back pain group demonstrated more variable (mean difference = -6.95, 95% CI = -12.3 to -1.59) and greater out-of-phase behavior (mean difference = -22.6, 95% CI = -39.1 to -6.03) in the LHip-L3S1 segment. Group-period interaction effects revealed greater variability in the start period (mean difference = -0.325, 95% CI = -0.493 to -0.156) and more out-of-phase behavior in the start (mean difference = -0.350, 95% CI = -0.549 to -0.150) and end (mean difference = -0.354, 95% CI = -0.602 to -0.105) periods for the LHip-L3S1 segment.

INTERPRETATION

Excessive variability may relate to reports of poor spinal proprioception in low back pain; however, based on our sample characteristics (low pain and disability) and lack of symptoms during the task, classifying our findings as dysfunctional may not be fully warranted.

Kinematic and Kinetic Validation of an Improved Depth Camera Motion Assessment System Using Rigid Bodies

The study of joint kinematics and dynamics has broad clinical applications, including the identification of pathological motions or compensation strategies and the analysis of dynamic stability. High-end motion capture systems, however, are expensive and require dedicated camera spaces with lengthy setup and data processing commitments. Depth cameras, such as the Microsoft Kinect, provide an inexpensive, marker-free alternative at the sacrifice of joint-position accuracy. In this work, we present a fast framework for adding biomechanical constraints to the joint estimates provided by a depth camera system. We also present a new model for the lower lumbar joint angle. We validate key joint position, angle, and velocity measurements against a gold standard active motion-capture system on ten healthy subjects performing sit to stand (STS). Our method showed significant improvement in mean absolute error and intraclass correlation coefficients for the recovered joint angles and position-based metrics. These improvements suggest that depth cameras can provide an accurate and clinically viable method of rapidly assessing the kinematics and kinetics of the STS action, providing data for further analysis using biomechanical or machine learning methods.

Influence of Cervical Spine Mobility on the Focal and Postural Components of the Sit-to-Stand Task

The aim of this study was to determine the influence of cervical spine mobility on the focal and postural components of the sit-to-stand transition, which represent the preparatory and execution phases of the task, respectively. Sixteen asymptomatic female participants (22 ± 3 years, 163 ± 0,06 cm, 57,5 ± 5 kg), free of any neurological or musculoskeletal disorders, performed six trials of the sit-to-stand task at maximum speed, in four experimental conditions varying the mobility of the cervical spine by means of three different splints. A six-channel force plate, which collected the reaction forces and moments applied at its top surface, was used to calculate the center of pressure displacements along the anterior-posterior and medial-lateral axes. The local accelerations of the head, spine, and pelvis, were assessed by three pairs of accelerometers, oriented along the vertical and anterior-posterior axes. Restriction of cervical spine mobility resulted in an increased duration of the focal movement, associated with longer and larger postural adjustments. These results suggest that restricted cervical spine mobility impairs the posturo-kinetic capacity during the sit-to-stand task, leading to a lower motor performance and a reorganization of the anticipatory postural adjustments. In a clinical context, it might be assumed that preserving the articular free play of the cervical spine might be useful to favor STS performance and autonomy.

Valgus bracing affords short-term treatment solution across walking and sit-to-stand activities

Since activities of daily living do not exist in isolation this prospective study examined biomechanical function during level walking and sit-to-stand activities over two months of brace use by subjects with varying grades of knee osteoarthritis. Kinematic and kinetic data were collected using infrared cameras and force platforms; clinical scores compared perceived and measured functional effects. There was no significant change in pain for any grades of OA but activity levels were significantly higher at one month in the moderate OA grades and at two months for the low OA grades. Mechanical constraints and changes in movement strategies were consistent across tasks and OA grade. This study provides valuable data for further studies aimed at refining the use and optimization of valgus bracing efficacy.

Knee efforts and weight-bearing asymmetry during sit-to-stand tasks in individuals with hemiparesis and healthy controls

The asymmetrical weight-bearing distribution of individuals with hemiparesis rising from a chair might be used to produce similar muscular efforts at the lower limbs. The aim of this study was to determine if individuals with hemiparesis have symmetrical levels of effort at the knee during spontaneous sit-to-stand transfers. Nineteen subjects with hemiparesis and 16 healthy controls participated. Their weight-bearing (WB) distribution during sit-to-stand was assessed with a force platform setup while the knee effort distribution was quantified using electromyographic (EMG) data normalized to maximal EMG values then expressed relative to the sum of the bilateral efforts. The healthy individuals presented symmetrical weight-bearing and knee effort distributions during the sit-to-stand transfer. The participants with hemiparesis, classified in three subgroups based on knee extensors' strength asymmetries (mild, moderate and severe), yielded different results. The mild group (n = 6) behaved like the controls, with almost symmetrical WB and knee efforts. The moderate group (n = 7) had similar WB and effort asymmetries while the severe group (n = 6) exhibited a WB distribution difference between sides but had almost symmetrical knee effort. These results for the severe group suggest that a control is exerted on the levels of effort when rising from a chair, which might be required when a certain threshold of effort is reached on the nonparetic side.

Multi-factorial causative model for back pain management; relating causative factors and mechanisms to injury presentations and designing time- and cost effective treatment thereof

Back pain resolution has not statistically improved over many years with some literature suggesting chronic back pain to be increasing. From a search of literature on causes, events, mechanisms, factors and treatment for back pain, a model is developed that relates causes of back injury to factors that result in pain through two primary mechanisms; muscle fatigue and muscle/tendon/connective tissue strain or sprain with other main mechanisms being diminished reactivity and strength, changes in tendon/tissue mechanical properties and fear of back pain recurrence/fear of movement following a back pain episode. The model highlights the fact that back pain/injury is multi-factorial with numerous circular relationships. Therefore treatment should also be multi-factorial; a combination of physical and psychological therapy with attention to mechanisms at work or in daily living that exacerbate the injury and delay recovery thereof. Exercise is one method that can reduce muscle imbalance, improve resilience to muscle fatigue, and address reactivity and strength. More importantly, eccentric exercise can rectify musculotendinous or connective tissue injury which plays a role in prolonging the back injury cycle. Posture is identified as a causative factor for back pain with the time exposure for posture representing the largest portion of daily activities. From literature and from clinical observation, treatment methods can be improved and incorporated into integrated multi-modal programs. An integrated exercise program that commences with motor control exercise and progresses into functional movement is suggested. Furthermore a modification of the McKenzie extension movement may benefit back injury rehabilitation for a majority of lower back pain patients. Otherwise the sit-to-stand movement is a regular and frequent exacerbating mechanism of back pain and likely continuously tears connective tissue during the movement thus prolonging the cycle of back pain and can be addressed instantly with a modification in sit-to-stand technique.

PRINCIPAL COMPONENT ANALYSIS OF KINEMATIC PATTERNS VARIABILITY DURING SIT TO STAND IN PEOPLE WITH NON-SPECIFIC CHRONIC LOW BACK PAIN

Sit to stand (STS) task requires variability of all body segments to achieve the stability of the important control variables (i.e., center of mass (CM) and head positions). In this study, the possible differences in the variability patterns of various body segments were investigated between 11 chronic low back pain (LBP) and 12 control subjects during STS task through two types of variability analyses; first by calculating the variability of seven limb angles, CM and head positions across 15 trials and second by principal component analysis (PCA) of seven limb angles. Participants performed the task at 3 postural difficulty levels: rigid surface, open eyes (RO), rigid surface, close eyes (RC) and narrow surface, close eyes (NC). The results revealed that LBPs could stabilize the CM and head positions same as controls. Also there was more than 1 synergic combination of whole body segments in both LBP and healthy groups. But the number of PCs accounting for the major part of variance was reduced in the LBPs in the most unstable phase of movement (50%–80% trajectory) in the RO and RC conditions. This may indicate that LBPs have reduced flexibility in the most unstable phase of task.

Individuals with non-specific low back pain use a trunk stiffening strategy to maintain upright posture

There is increasing evidence that individuals with non-specific low back pain (LBP) have altered movement coordination. However, the relationship of this neuromotor impairment to recurrent pain episodes is unknown. To assess coordination while minimizing the confounding influences of pain we characterized automatic postural responses to multi-directional support surface translations in individuals with a history of LBP who were not in an active episode of their pain. Twenty subjects with and 21 subjects without non-specific LBP stood on a platform that was translated unexpectedly in 12 directions. Net joint torques of the ankles, knees, hips, and trunk in the frontal and sagittal planes as well as surface electromyographs of 12 lower leg and trunk muscles were compared across perturbation directions to determine if individuals with LBP responded using a trunk stiffening strategy. Individuals with LBP demonstrated reduced peak trunk torques, and enhanced activation of the trunk and ankle muscle responses following perturbations. These results suggest that individuals with LBP use a strategy of trunk stiffening achieved through co-activation of trunk musculature, aided by enhanced distal responses, to respond to unexpected support surface perturbations. Notably, these neuromotor alterations persisted between active pain periods and could represent either movement patterns that have developed in response to pain or could reflect underlying impairments that may contribute to recurrent episodes of LBP.

Effects of experimentally induced low back pain on the sit-to-stand movement and electroencephalographic contingent negative variation

It is becoming increasingly evident that people with chronic, recurrent low back pain (LBP) exhibit changes in cerebrocortical activity that associate with altered postural coordination, suggesting a need for a better understanding of how the experience of LBP alters postural coordination and cerebrocortical activity. To characterize changes in postural coordination and pre-movement cerebrocortical activity related to the experience of acutely induced LBP, 14 healthy participants with no history of LBP performed sit-to-stand movements in 3 sequential conditions: (1) without experimentally induced LBP; NoPain1, (2) with movement-associated LBP induced by electrocutaneous stimulation; Pain, and (3) again without induced LBP; NoPain2. The Pain condition elicited altered muscle activation and redistributed forces under the seat and feet prior to movement, decreased peak vertical force exerted under the feet during weight transfer, longer movement times, as well as decreased and earlier peak hip extension. Stepwise regression models demonstrated that electroencephalographic amplitudes of contingent negative variation during the Pain condition significantly correlated with the participants' change in sit-to-stand measures between the NoPain1 and Pain conditions, as well as with the subsequent difference in sit-to-stand measures between the NoPain1 and NoPain2 conditions. The results, therefore, identify the contingent negative variation as a correlate for the extent of an individual's LBP-related movement modifications and to the subsequent change in movement patterns from before to after the experience of acutely induced LBP, thereby providing a direction for future studies aimed to understand the neural mechanisms underlying the development of altered movement patterns with LBP.

Prolonged weight-shift and altered spinal coordination during sit-to-stand in practitioners of the Alexander Technique

The Alexander Technique (AT) is used to improve postural and movement coordination and has been reported to be clinically beneficial, however its effect on movement coordination is not well-characterized. In this study we examined the sit-to-stand (STS) movement by comparing coordination (phasing, weight-shift and spinal movement) between AT teachers (n=15) and matched control subjects (n=14). We found AT teachers had a longer weight-shift (p<0.001) and shorter momentum transfer phase (p=0.01), than control subjects. AT teachers also increased vertical foot force monotonically, rather than unweighting the feet prior to seat-off, suggesting they generate less forward momentum with hip flexors. The prolonged weight-shift of AT teachers occurred over a greater range of trunk inclination, such that their weight shifted continuously onto the feet while bringing the body mass forward. Finally, AT teachers had greatly reduced spinal bending during STS (cervical, p<0.001; thoracic, p<0.001; lumbar, p<0.05). We hypothesize that the low hip joint stiffness and adaptive axial postural tone previously reported in AT teachers underlies this novel "continuous" STS strategy by facilitating eccentric contractions during weight-shift.

Perception of weight-bearing distribution during sit-to-stand task in healthy young and elderly individuals

The first objective was to assess whether healthy individuals could accurately estimate their weight-bearing distribution in sit-to-stand transfers. The second was to evaluate the effect of age on weight-bearing perception. 16 young participants (11 women, 5 men; M age 29 yr., SD = 8.7) and 15 elderly participants (7 women, 8 men; M age 65 yr., SD = 3.8) were recruited. Verbal instructions and visual feedback referring to different percentages of weight-bearing distribution to execute were used to quantify weight-bearing perception in sit-to-stand tasks. For the feedback approach, the perception was assessed with a visual analog scale. For the verbal task, the weight-bearing distribution produced was assessed with force plates. Both young and elderly participants had good perception of weight-bearing distribution, with mean absolute errors of 6.4%. Moreover, their perceived and real weight-bearing distribution showed good agreement (ICC > or = .79).

Relação entre percepção e ação durante os movimentos de sentar e levantar em indivíduos idosos

A proposta deste estudo foi analisar o efeito do envelhecimento nos aspectos perceptivos e motores envolvidos com as ações de sentar e levantar de uma cadeira. Indivíduos jovens e idosos foram filmados enquanto sentavam/levantavam de uma cadeira em sete alturas diferentes do assento. Eles julgaram a dificuldade/facilidade encontrada para sentar e levantar em cada altura do assento. Os idosos exibiram mudanças na estratégia de controle usada para sentar na altura mais baixa do assento e superestimaram o nível de dificuldade/facilidade para realizar as tarefas de sentar e levantar. Em síntese, a percepção de execução fácil da tarefa de sentar pelos idosos não concorda com o grau de dificuldade exibido no desempenho motor na altura mais baixa do assento.

Multi-segmental torso coordination during the transition from sitting to standing

BACKGROUND

Research into the multi-segmental mobility of the torso could add to our understanding of the contributions of the head and torso to human movement. The purpose of this study was to determine the motion and temporal coordination of the head and multiple torso segments during the sit-to-stand task.

METHODS

Thirty-two young, healthy participants performed five trials of the sit-to-stand movement and 6s of sitting. Range of motion and patterns of peak flexion and extension of six segments and joints and cross correlation of pairs of the six torso segments were analyzed from 3-D kinematic data.

FINDINGS

Sagittal range of motion for torso joints during the sit-to-stand task was greater than during sitting trials; motion at the lumbar/pelvis joint was greater than at other torso joints. Peak flexion of torso joints occurred earlier than peak extension. Cross correlations at zero lag and time lags of maximum cross correlations varied such that there was greater temporal coordination of intermediate torso segments compared to pairs including the head and pelvis. There was greater temporal coordination of adjacent segment pairs than for pairs that were less proximal to each other.

INTERPRETATION

A high degree of mobility occurs within the torso during the sit-to-stand task. Varying coordination patterns suggest that there are regional differences in movement timing within the torso that may relate to segmental differences in functional roles. Employing multi-segmental torso models may indicate different movement strategies within a healthy population and could highlight differences between clinical populations.

Normalizing temporal patterns to analyze sit-to-stand movements by using registration of functional data

Functional data analysis techniques provide an alternative way of representing movement and movement variability as a function of time. In particular, the registration of functional data provides a local normalization of time functions. This normalization transforms a set of curves, records of repeated trials, yielding a new set of curves that only vary in terms of amplitude. Therefore, main events occur at the "same time" for all transformed curves and interesting features of individual recordings remain after averaging processes. This paper presents an application of the registration process to the analysis of the vertical forces exerted on the ground by both feet during the sit-to-stand movement. This movement is particularly interesting in functional evaluations related to balance control, lower extremity dysfunction or low-back pain.

Transition from sitting to standing after trans-femoral amputation

Standing up is an important and common daily activity. It is essential for independence and a prerequisite for walking. Many elderly and many subjects with impairments have problems with transition from sitting to standing. The aim of the present study was to determine whether there was any difference between the characteristics of standing up in trans-femoral amputees and healthy subjects. Five young trans-femoral amputees and five healthy subjects were included in the study. They were asked to stand up. The body motion was recorded using an Optotrak contactless optical system. The force and moment vectors exerted on the seat were recorded by a JR3 six-axis robot wrist sensor. The force under the feet was recorded by two AMTI force plates. The trans-femoral amputees were found to stand up more slowly than the healthy subjects. The angles of the hip, knee, and ankle joints on the amputated side were different from the angles on the healthy side or in the healthy subjects. There was also a great difference in loading between the healthy and the prosthetic foot. It can be concluded that there are differences in standing up between the trans-femoral amputees and the healthy subjects. These differences may indicate a reason for problems many elderly trans-femoral amputees face when standing up.

Postural control during a sit-to-stand task in individuals with mild Parkinson's disease

Individuals with Parkinson's disease (PD) typically have difficulty rising from a chair. A major contributing factor may be altered anticipatory postural control; this hypothesis has been fueled by reports of altered function of the supplementary motor area in PD, an area linked to the preparation of movements. This study tested the hypothesis that individuals with PD would exhibit altered anticipatory postural control which would include a reduced preparatory hip flexion and decreased forward displacement of the COM prior to lift-off of the buttocks from the chair. Ten male subjects with PD and ten male age-matched controls were instructed to rise from a chair without the use of their arms at their comfortable pace on two separated days during on and off-medication states. Body movements were recorded with an optoelectronic device, in addition to forces under the buttocks and each foot to calculate lower extremity joint angles, joint movements and net body centre of mass displacement (COM). The sit-to-stand (STS) duration was the same for the PD-on and controls, but greater for the PD-off group. The PD groups (on and off) used a hip flexion strategy (greater preparatory hip flexion displacement and forward COM displacement, reduced knee extensor moments) compared to the controls. Contrary to predictions, subjects with PD exaggerated, rather than reduced, the movement preparation of the STS using a hip flexion strategy. Possible underlying causes of this flexion strategy could include compensation for poor lower extremity muscle strength and a need for greater postural stability during the lift-off phase.

Biomechanical analysis of sit-to-stand movement in normal and obese subjects

OBJECTIVE

Main purpose of this study was to develop a biomechanical model for the analysis of sit-to-stand movement in normal and obese subjects.

DESIGN

A biomechanical model describing sit-to-stand was developed using kinetic and kinematic experimental data. Trunk flexion, feet movement, knee and hip joint torques were assumed as sensible indexes to discriminate between normal and obese subjects.

BACKGROUND

Sit-to-stand is a functional task that may become difficult for certain patients. The analysis of its execution provides useful biomechanical information on the motor ability of selected subjects.

METHODS

Sit-to-stand was recorded using an optoelectronic system and a force platform in 40 obese patients and 10 normal subjects. A biomechanical model was developed using inverse dynamics equations.

RESULTS

Kinematic and kinetic indexes evidenced differences in motion strategy between normal and obese subjects. Obese subjects rise from the chair limiting trunk flexion (mean value: 73.1 degrees ) and moving their feet backwards from initial position (mean deviation: 50 mm). Normal subjects, instead, show a higher trunk flexion (mean value: 49.2 degrees, a lower angular value between trunk and the horizontal means increased flexion) and fixed feet position (mean deviation: 5 mm). As for kinetics, obese patients show knee joint torque higher than hip torque (maximum knee torque: 0.75 Nm/kg; maximum hip torque: 0.59 Nm/kg), while normal subjects show opposite behaviour (maximum knee torque: 0.38 Nm/kg; maximum hip torque: 0.98 Nm/kg).

RELEVANCE

We found differences in motion strategy between normal and obese subjects performing sit-to-stand movement, which may be used to plan and evaluate rehabilitative treatments.

Determinants of the Sit-to-Stand Movement: A Review

Background and Purpose. The sit-to-stand (STS) movement is a skill that helps determine the functional level of a person. Assessment of the STS movement has been done using quantitative and semiquantitative techniques. The purposes of this study were to identify the determinants of the STS movement and to describe their influence on the performance of the STS movement. Methods. A search was made using MEDLINE (1980–2001) and the Science Citation Index Expanded of the Institute for Scientific Information (1988–2001) using the key words “chair,” “mobility,” “rising,” “sit-to-stand,” and “standing.” Relevant references such as textbooks, presentations, and reports also were included. Of the 160 identified studies, only those in which the determinants of STS movement performance were examined using an experimental setup (n=39) were included in this review. Results. The literature indicates that chair seat height, use of armrests, and foot position have a major influence on the ability to do an STS movement. Using a higher chair seat resulted in lower moments at knee level (up to 60%) and hip level (up to 50%); lowering the chair seat increased the need for momentum generation or repositioning of the feet to lower the needed moments. Using the armrests lowered the moments needed at the hip by 50%, probably without influencing the range of motion of the joints. Repositioning of feet influenced the strategy of the STS movement, enabling lower maximum mean extension moments at the hip (148.8 N·m versus 32.7 N·m when the foot position changed from anterior to posterior). Discussion and Conclusion. The ability to do an STS movement, according to the research reviewed, is strongly influenced by the height of the chair seat, use of armrests, and foot position. More study of the interaction among the different determinants is needed. Failing to account for these variables may lead to erroneous measurements of changes in STS performance.

Biomechanical analysis of effects of foot placement with varying chair height on the motion of standing up

Individual experience reveals that posterior foot placement enables one to stand up easily from a chair. However, the way in which foot placement affects this motion has not been investigated in detail. This study was performed to examine the effects of foot placement in the initial stage of the dynamics of standing up from a chair. Subjects wearing light-emitting diode markers and surface electrodes stood up from a chair over force plates, and ground reaction force, joint angle, and muscle activity were measured. The motions required to stand up from chairs 30, 40, or 50 cm in height were analyzed with anterior, vertical, and posterior foot placement. With anterior foot placement, the forward-acceleration components of the ground reaction force were recorded with simultaneous and long-sustained activity of the muscles in order to shift the center of gravity of the body forward even more after lift-off. Our findings indicate that the distance between the center of gravity and the point of application of ground reaction force at lift-off are critical factors in the standing-up motion, and that chairs should be of adequate height as well as having sufficient space under the seat to permit the backward movement of the lower legs.

The Oswestry Disability Index

STUDY DESIGN

The Oswestry Disability Index (ODI) has become one of the principal condition-specific outcome measures used in the management of spinal disorders. This review is based on publications using the ODI identified from the authors' personal databases, the Science Citation Index, and hand searches of Spine and current textbooks of spinal disorders.

OBJECTIVES

To review the versions of this instrument, document methods by which it has been validated, collate data from scores found in normal and back pain populations, provide curves for power calculations in studies using the ODI, and maintain the ODI as a gold standard outcome measure.

SUMMARY OF BACKGROUND DATA

It has now been 20 years since its original publication. More than 200 citations exist in the Science Citation Index. The authors have a large correspondence file relating to the ODI, that is cited in most of the large textbooks related to spinal disorders.

METHODS

All the published versions of the questionnaire were identified. A systematic review of this literature was made. The various reports of validation were collated and related to a version.

RESULTS

Four versions of the ODI are available in English and nine in other languages. Some published versions contain misprints, and many omit the scoring system. At least 114 studies contain usable data. These data provide both validation and standards for other users and indicate the power of the instrument for detecting change in sample populations.

CONCLUSIONS

The ODI remains a valid and vigorous measure and has been a worthwhile outcome measure. The process of using the ODI is reviewed and should be the subject of further research. The receiver operating characteristics should be explored in a population with higher self-report disabilities. The behavior of the instrument is incompletely understood, particularly in sensitivity to real change.

Biomechanical analysis of sit-to-stand transfer in healthy and paraplegic subjects

OBJECTIVE

An experimental study of the sit-to-stand transfer in healthy adults with/without arm-support and in paraplegic patients with/without electrical stimulation of the quadriceps muscles was performed. The study was aimed to compare the joint torques, momentum transfer hypothesis, and stability of the sit-to-stand transfer in the healthy and paraplegic subjects.

METHODS

A planar 3-linkage rigid body model was used to compute the body-segmental linear momentum and the reaction forces and torques at the joints from measured data.

RESULTS

In healthy subjects the arm-support enlarged the support base of the body and thus, increased the postural stability. Strong arm-assistance reduced the maximum hip and knee joint torques by more than 50%. It was observed that the healthy participants rising with arm-support used momentum transfer to facilitate the transition from sitting to standing. The paraplegic participants did not apply the momentum transfer strategy and the sit-to-stand transfer was accomplished in a quasi-static manner. Stimulating the quadriceps, the legs could participate partly in the movement dynamics.

CONCLUSION

Our results indicate that some significant differences exist between the maneuver applied by the paraplegic patients to stand up and the strategies used by the healthy adults rising with arm-support.

RELEVANCE

Analysis of the biomechanical factors underlying the sit-to-stand activity is essential in the design of competent closed-loop neuroprosthesis controllers which assist paraplegic patients during rising.

A telescopic inverted-pendulum model of the musculo-skeletal system and its use for the analysis of the sit-to-stand motor task

For field applicability of biomechanical methodologies aiming at assessing motor ability in disabled, or at risk of disablement (e.g. elderly), subjects, measurements must be carried out using a least perceivable to the subject and essential experimental apparatus. Since data thus obtained do not necessarily lend themselves to straightforward interpretation, they should be fed to a model of the portion of the musculo-skeletal system involved that already embodies the invariant aspects of both the modelled system and the motor task. Through such a minimum measured-input model, richer, physiology-related, and thus easier to interpret, information may be expected. In this framework, the present study investigated the sit-to-stand motor task using information obtained only from a force plate located under seat and subject's feet, a seat uniaxial load-cell and basic anthropometric parameters. Data were collected in a sample of 12 able-bodied subjects while executing the motor task at different speeds. The musculo-skeletal system was modelled as a telescopic inverted pendulum (TIP) that could vary its length (shortening or elongation) by effect of a force actuator and its orientation in space by effect of two couple actuators that were looked upon as muscle equivalent effectors. The TIP model output consisted in the kinematics and dynamics of these actuators. It allowed the identification of four functional phases in which the seat-to-stand motor task could be divided, and a detailed description of the relevant mechanics in terms of balance control and centre of mass elevation. Motor strategy modifications associated with speed variation could also be identified. For a global evaluation of the motor act it showed to be no less informative than more demanding multi-segment models. Although it is true that specific musculo-articular functions can only be inferred, the more compact information yielded by the TIP model is expected to facilitate subject and/or disability classification.

Muscle synergies and joint linkages in sit-to-stand under two initial foot positions

OBJECTIVE

The purpose of this study was to investigate the activation pattern of six lower limb muscles during standing up from two initial foot positions and to examine relationships between the onsets of muscle activity and the dynamics of the action. In contrast to earlier studies, an algorithm was used to measure onsets and duration of muscle activity.

METHOD

The activity of biceps femoris, rectus femoris, vastus lateralis, tibialis anterior, lateral gastrocnemius and medial soleus was studied as nine male subjects between the ages of 20 and 35 stood up from two initial foot positions (foot forward, foot back). Subjects sat on a height-adjustable seat with their right foot on a force platform and were videotaped as they stood up.

RESULTS

When the feet were forward there were significant increases in movement duration, displacement and velocity of trunk segment flexion at the hips reflecting the increased distance the body mass must be moved forward. The sequence of onsets and the duration of muscle activity, however, were consistent across the two conditions. Onsets of extension at hip, knee and ankle, however, correlated with different muscle activity depending on the foot position.

CONCLUSION

The results suggest that muscles working over different joints are temporally linked and that different muscle linkages may be utilised in the lower limb to coordinate the sit-to-stand action under different functional demands.

The use of artificial neural networks to identify patients with chronic low-back pain conditions from patterns of sit-to-stand manoeuvres

OBJECTIVE: To investigate whether artificial neural networks (ANNs) can categorize healthy subjects, chronic low-back-pain (LBP) patients, and subjects pretending to have low-back pain problems, based upon patterns of stand-sit-stand manoeuvres. DESIGN: A non-invasive laboratory study of human subjects. BACKGROUND: Normal strategies for sit-stand manoeuvres are modified in cases of chronic LBP. Subtle changes and many parameters are unsuitable for conventional statistics. METHODS: Fourteen healthy subjects, 10 chronic LBP patients, and 12 subjects pretending to have LBP participated. Forces and centres of pressure at the feet and knees, plus hip and lumbar movements provided inputs into a three-layer feed-forward ANN with sigmoidal transfer functions. The ANN was trained with data from 35 of the 36 subjects, and its ability to classify the left-out subject was tested. This was repeated with each subject omitted from training in turn. RESULTS: The ANN correctly classified 31 of 36 subjects. The subjects were also classified by nine physiotherapists from videos of the manoeuvres. Their success rate was significantly lower that that of the ANN, which is not surprising for an unusual procedure without training. CONCLUSIONS: ANNs should be considered as additional tools in assessment and possible diagnosis of pathological movements. RELEVANCE: The capacity of ANNs to discriminate patterns of human movement offers a technique that may prove to be a useful tool for assessment and diagnosis.

Trunk movements in older subjects during sit-to-stand

Sitting to standing (STS) is an activity that is performed many times during the course of a day and is an important prerequisite to the achievement of many functional goals. This article presents the results from a pilot study, the purpose of which was to develop a method for investigating the activity of sit-to-stand. The study describes STS timing and patterns of trunk movement during standing up in a population of 30 normal older adult subjects (mean age, 61.6 years; SD, 7.7 years). Data were gathered using a three-dimensional movement analysis system, CODA-3. Time taken to stand up was recorded, as were the trunk movements of pelvic and shoulder rotation, trunk lateral flexion, pelvic and shoulder lateral shift, and backward shoulder movement to achieve stance. Results show that normal subjects stood up quickly (mean, 1.67 sec; SD, .27 sec; range, 1.26 to 2.13 sec), and despite large amounts of trunk forward flexion and upward motion necessary to achieve the task of standing up, only small amounts of trunk rotation, trunk lateral flexion, and trunk lateral shift were measured during the activity. The identification of these movements characteristics may be beneficial in assisting with analysis of the STS movement pattern.