Mediolateral Trunk Research Articles

Toward ambulatory balance assessment: Estimating variability and stability from short bouts of gait

Stride-to-stride variability and local dynamic stability of gait kinematics are promising measures to identify individuals at increased risk of falling. This study aimed to explore the feasibility of using these metrics in clinical practice and ambulatory assessment, where only a small number of consecutive strides are available. The concurrent validity and reliability were assessed compared to more continuous walking. Twenty young adults walked continuously for 500m, as well as 36 bouts of 20m while wearing an accelerometer (DynaPort MiniMod) on the trunk. Within-day reliability was high for stride time variability, mediolateral trunk variability and local dynamic stability, while between-day reliability was low for both variability estimates and moderate for local dynamic stability. Stride time variability and mediolateral trunk variability were increased when walking short bouts and did not correlate well with the longer walking trials. Local dynamic stability did correlate highly between the long and short bouts trials, and 15 bouts of eight strides appeared to be sufficient for valid estimation. These results imply task-specific differences and low reliability of variability estimates rendering them unsuitable for application to short bouts of gait, while local dynamic stability can be readily employed.

Energy cost of balance control during walking decreases with external stabilizer stiffness independent of walking speed

Human walking requires active neuromuscular control to ensure stability in the lateral direction, which inflicts a certain metabolic load. The magnitude of this metabolic load has previously been investigated by means of passive external lateral stabilization via spring-like cords. In the present study, we applied this method to test two hypotheses: (1) the effect of external stabilization on energy cost depends on the stiffness of the stabilizing springs, and (2) the energy cost for balance control, and consequently the effect of external stabilization on energy cost, depends on walking speed. Fourteen healthy young adults walked on a motor driven treadmill without stabilization and with stabilization with four different spring stiffnesses (between 760 and 1820Nm−1) at three walking speeds (70%, 100%, and 130% of preferred speed). Energy cost was calculated from breath-by-breath oxygen consumption. Gait parameters (mean and variability of step width and stride length, and variability of trunk accelerations) were calculated from kinematic data. On average external stabilization led to a decrease in energy cost of 6% (p<0.005) as well as a decrease in step width (24%; p<0.001), step width variability (41%; p<0.001) and variability of medio-lateral trunk acceleration (12.5%; p<0.005). Increasing stabilizer stiffness increased the effects on both energy cost and medio-lateral gait parameters up to a stiffness of 1260Nm−1. Contrary to expectations, the effect of stabilization was independent of walking speed (p=0.111). These results show that active lateral stabilization during walking involves an energetic cost, which is independent of walking speed.

Walking Smoothness Is Associated With Self-Reported Function After Accounting for Gait Speed

Gait speed has shown to be an indicator of functional status in older adults; however, there may be aspects of physical function not represented by speed but by the quality of movement. The purpose of this study was to determine the relations between walking smoothness, an indicator of the quality of movement based on trunk accelerations, and physical function. Thirty older adults (mean age, 77.7±5.1 years) participated. Usual gait speed was measured using an instrumented walkway. Walking smoothness was quantified by harmonic ratios derived from anteroposterior, vertical, and mediolateral trunk accelerations recorded during overground walking. Self-reported physical function was recorded using the function subscales of the Late-Life Function and Disability Instrument. Anteroposterior smoothness was positively associated with all function components of the Late-Life Function and Disability Instrument, whereas mediolateral smoothness exhibited negative associations. Adjusting for gait speed, anteroposterior smoothness remained associated with the overall and lower extremity function subscales, whereas mediolateral smoothness remained associated with only the advanced lower extremity subscale. These findings indicate that walking smoothness, particularly the smoothness of forward progression, represents aspects of the motor control of walking important for physical function not represented by gait speed alone.

The effectiveness of voluntary modifications of gait pattern to reduce the knee adduction moment

It has been suggested to use gait modifications in the retraining of patients with knee osteoarthritis (OA), in order to reduce the external knee adduction moment (KAdM). This study focused on the effect of walking speed, foot position and trunk sway, and on the 3D knee moments. Gait analyses of fourteen healthy volunteers were performed in a gait laboratory. Subjects walked at three different speeds in their normal gait pattern, as well as with toe-in and toe-out gait and with medio-lateral trunk sway at a self-selected speed.Fast walking speed increased the KAdM (17–30%) and flexion moment (32%). A slower walking speed did not decrease the KAdM. Toe-in mainly decreased the KAdM (45%) and the transverse moment (38%) during early stance. Toe-out decreased the KAdM during late stance (56%), but increased the KAdM during early stance and midstance (21–24%), due to decreased endorotation of the hip with knee flexion. Trunk sway decreased the KAdM during early stance and midstance (31–33%). Gait modifications mainly affected the KAdM, but changes in sagittal and transverse knee moments and kinematics were also observed. This indicates that, when estimating knee load, taking only the frontal plane kinetics into consideration may lead to erroneous simplifications. No conclusive beneficial effects were found in any of the gait modifications throughout the entire stance phase.

Sulf1 modulates BMP signaling and is required for somite morphogenesis and development of the horizontal myoseptum

Heparan sulfate proteoglycans (HSPGs) are glycosylated extracellular or membrane-associated proteins. Their unbranched heparan sulfate (HS) disaccharide chains interact with many growth factors and receptors, modifying their activity or diffusion. The pattern of HS sulfation can be altered by the enzymes Sulf1 and Sulf2, secreted extracellular 6-O endosulfatases, which remove specific sulfate groups from HS. Modification by Sulf enzymes changes the binding affinity of HS for protein such as ligands and receptors, affecting growth factor gradients and activities. The precise expression of these sulfatases are thought to be necessary for normal development. We have examined the role of the sulf1 gene in trunk development of zebrafish embryos. sulf1 is expressed in the developing trunk musculature and as well as in midline structures such as the notochord, floorplate and hypochord. Knockdown of sulf1 with antisense morpholinos results in poor differentiation of the somitic trunk muscle, loss of the horizontal myoseptum, lack of pigmentation along the mediolateral stripe, and improper migration of the lateral line primordium. sulf1 knockdown results in a decrease in the number of Pax7-expressing dermomyotome cells, particularly along the midline where the horizontal myoseptum develops. It also leads to decreased sdf1/cxcl12 expression along the mediolateral trunk musculature. Both the Pax7 and cxcl12 expression can be restored by inhibition pharmacological inhibition of BMP signaling, which also restores formation of the myoseptum, fast muscle development, and pigmentation patterning. Lateral line migration and neuromast deposition depend on sdf1/cxcl12 and FGF signaling respectively, both of which are disrupted in sulf1 morphants. Pharmacological activation of FGF signaling can rescue the spacing of neuromast deposition in these fish. Together this data indicate that sulf1 plays a crucial role in modulating both BMP and FGF signaling along the developing myoseptum to coordinate the morphogenesis of trunk musculature, associated pigment cells, and lateral line neuromasts.

Amplitude and Phasing of Trunk Motion is Critical for the Efficacy of Gait Training Aimed at Reducing Ambulatory Loads at the Knee

The purpose of this study was to determine the contribution of changes in amplitude and phasing of medio-lateral trunk sway to a change in the knee adduction moment when walking with increased medio-lateral trunk sway. Kinematic and kinetic data of walking trials with normal and with increased trunk sway were collected for 19 healthy volunteers using a standard motion analysis system. The relationship between the change in first peak knee adduction moment (ΔKAM) and change in trunk sway amplitude (ΔSA; difference between maximum contralateral trunk lean and maximum ipsilateral trunk lean) and phasing (SP; time of heel-strike relative to time of maximum contralateral and time of maximum ipsilateral trunk lean) was determined using nonlinear regression analysis. On average, subjects increased their SA by 9.7 ± 3.6 deg (P < 0.001) with an average SP of 98.8 ± 88.8 ms resulting in an average reduction in the first peak knee adduction moment of -55.2 ± 30.3% (P < 0.001). 64.3% of variability in change in peak knee adduction moment with the increased trunk sway condition was explained by both differences in SA and SP, and the relationship among these parameters was described by the regression equation ΔKAM = 27.220-4.128 [middle dot] ΔSA-64.785 [middle dot] cos(SP). Hence, not only the amplitude but also the phasing of trunk motion is critical. Not only lower limb movement but also lumbar and thoracic lateral flexion should be considered in the decision making process for an optimal intervention aimed at reducing the load on the medial compartment of the knee during walking. However, these promising findings originated from studies on healthy subjects and their relevance for gait training interventions in patients with presumably painful knee osteoarthritis remains to be determined.

Familiarisation to body weight supported treadmill training for patients post-stroke

Introduction Walking on a treadmill with body weight support (BWS) may require familiarisation. Patients post-stroke fatigue easily and the time needed to reach stable walking is important. However, even if body weight supported treadmill training (BWSTT) is commonly used in gait rehabilitation for patients post-stroke, it is not known how much time that is needed before stable walking is reached in this population. The objective of this study therefore, was to investigate if patients post-stroke manage to stabilise walking patterns during a 5-min familiarisation-trial on the treadmill with BWS. Method 35 patients post-stroke walked on a treadmill at preferred speed and with 20 percent BWS during a 5-min familiarisation-period. A body-worn sensor assessed trunk acceleration. Intraclass correlation coefficient (ICC) was used for pairwise comparisons of successive 30 s intervals during familiarisation, and one-way repeated-measures analysis of variance was used to investigate if there were linear trends between intervals. Results Mean ICCs across all variables stabilised above 0.90 after 3 min. Across intervals, walk ratio, cadence and step length obtained mean ICCs that were high, while interstride trunk regularity and trunk asymmetry obtained lower ICCs. However, except for mediolateral trunk acceleration, there was no linear trend after the first 3 min indicating that differences between intervals during the last 2 min were random. Discussion and conclusion This was the first study investigating familiarisation to BWSTT for patients post-stroke. Findings revealed that most of the familiarisation occurred within the first 3 min of walking, and therefore relatively stable walking could be achieved within a 5-min walking trial on the treadmill with BWS.

Criteria of gait asymmetry in patients with hip osteoarthritis

Gait symmetry is often a goal for physiotherapy in patients with hip osteoarthritis and after total hip replacement. However, there is no agreement on criteria for pathological gait asymmetry. In this study we investigated discriminative abilities of trunk and footfall gait symmetry measures, and thereafter assessed whether a 10% cutoff value is valid as a general criterion of pathological gait asymmetry across measures. Anteroposterior, vertical, and mediolateral trunk symmetry, single support, and step length symmetry were obtained simultaneously by trunk accelerometry and an electronic walkway in 37 patients with end-stage hip osteoarthritis and 56 controls. Subjects walked six times along a 7-meter walkway at slow, preferred, and fast speed, before data were normalized for gait velocity. Anteroposterior, vertical, and single support symmetry measures showed best discriminating abilities. The general 10% criterion of gait asymmetry and optimal cutoff criteria calculated for each symmetry measure showed approximately equal total classification ability. However, the optimal cutoff criteria classified a high number of controls as having pathological gait asymmetry. The general criterion of 10% is valid with high total classification ability, does not classify asymmetry in able-bodied subjects as pathological, and is feasible for use on individual patients in the clinic as well as in research.

Changes in gait symmetry, gait velocity and self-reported function following total hip replacement

To investigate the magnitude of change at different time points in measures of gait symmetry, gait velocity and self-reported function following total hip replacement. Longitudinal with test occasions pre-surgery and 3, 6 and 12 months post-surgery. Thirty-four patients with hip osteoarthritis (mean age 63 years, standard deviation 11 years). Subjects walked back and forth along a 7-m walkway at slow, preferred and fast speed. Anteroposterior, vertical and mediolateral trunk symmetry was assessed by accelerometry, while single support symmetry, step-length symmetry and gait velocity was simultaneously assessed by an electronic walkway. Self-reported function was assessed by Hip disability and Osteoarthritis Outcome Score. Gait symmetry data were normalized for gait velocity. Changes between test occasions were reported as effect size. All measures showed effect sizes > 0.30 from pre-operative to 12-months postoperative assessments, and improvements were significant (p < 0.05) in all measures, except mediolateral symmetry. In general, gait symmetry and gait velocity improved most 6 and 12 months postoperatively, while self-reported function improved most 3 months postoperatively. Early improvements were seen in self-reported function, suggesting immediate relief from stiffness and pain, while gait symmetry and velocity improved later postoperatively, suggesting that gait quality and performance require prolonged rehabilitation with postoperative guidance, muscular strengthening and motor relearning.

Is standing balance control in adolescent idiopathic scoliotic girls associated to the horizontal body and trunk center of mass offset?

Though adolescent idiopathic scoliosis (AIS) is characterized by a lateral deviation of the spine with resulting geometric changes in the trunk and rib cage standing imbalance was reported. The type and location of the spinal deformity was shown to perturb balance control while the interaction between standing posture and balance in AIS suggest a dysfunction in the postural regulation system of scoliotic subjects. Postural responses appear to be dependent on body somatotypes and in particular that ectomorphic girls have a tendency to lean further back favoring a hypokyphotic trunk attitude and increasing the risk of spinal deformity progression. These observations on spinal deformity and body shape alterations that modify trunk COM position imply a change in the body center of mass position as well that could perturb standing balance. In scoliotic girls, postural imbalance was attributed to a sensory rearrangement of the motor system on the representation of the body in space. The objectives of this study were to test if the antero-posterior (AP), medio-lateral (ML) and resultant body-head and trunk center of mass (COM) horizontal offsets were similar in able-bodied and scoliotic girls and if these offsets were related to the center of pressure displacements.

황해 참서대(Cynoglossus joyneri) 자어의 형태기재

Four specimens of Cynoglossus larvae (3.2-7.3 mm in notochord length, NL) collected from the middle Yellow Sea in August, 2008 were identified as Cynoglossus joyneri larvae based on morphological characteristics; (1) the two elongated dorsal fin rays on the parietal region, (2) protruded abdomen, (3) no melanophores on the mediolateral trunk and tail. Larva of 3.2 mm NL is compressed with a little big head and tapering, long tail. Larva of 7.0 mm NL has 115 dorsal fin and 85 anal fin rays, which are the same to those of adult. Larva of 7.3 mm NL tended to have concave part in the fringe of forehead, in which left-side eye may move to the other side.

Altered vision destabilizes gait in older persons

This study assessed the effects of dim light and four experimentally induced changes in vision on gait speed and footfall and trunk parameters in older persons walking on level ground. Using a quasi-experimental design, gait characteristics were assessed in full light, dim light, and in dim light combined with manipulations resulting in reduced depth vision, double vision, blurred vision, and tunnel vision, respectively. A convenience sample of 24 home-dwelling older women and men (mean age 78.5 years, SD 3.4) with normal vision for their age and able to walk at least 10 m without assistance participated. Outcome measures were gait speed and spatial and temporal parameters of footfall and trunk acceleration, derived from an electronic gait mat and accelerometers. Dim light alone had no effect. Vision manipulations combined with dim light had effect on most footfall parameters but few trunk parameters. The largest effects were found regarding double and tunnel vision. Men increased and women decreased gait speed following manipulations ( p = 0.017), with gender differences also in stride velocity variability ( p = 0.017) and inter-stride medio-lateral trunk acceleration variability ( p = 0.014). Gender effects were related to differences in body height and physical functioning. Results indicate that visual problems lead to a more cautious and unstable gait pattern even under relatively simple conditions. This points to the importance of assessing vision in older persons and correcting visual impairments where possible.

Lower trunk motion and speed-dependence during walking

BackgroundThere is a limited understanding about how gait speed influences the control of upper body motion during walking. Therefore, the primary purpose of this study was to examine how gait speed influences healthy individual's lower trunk motion during overground walking. The secondary purpose was to assess if Principal Component Analysis (PCA) can be used to gain further insight into postural responses that occur at different walking speeds.MethodsThirteen healthy subjects (23 ± 3 years) performed 5 straight-line walking trials at self selected slow, preferred, and fast walking speeds. Accelerations of the lower trunk were measured in the anterior-posterior (AP), vertical (VT), and mediolateral (ML) directions using a triaxial accelerometer. Stride-to-stride acceleration amplitude, regularity and repeatability were examined with RMS acceleration, Approximate Entropy and Coefficient of Multiple determination respectively. Coupling between acceleration directions were calculated using Cross Approximate Entropy. PCA was used to reveal the dimensionality of trunk accelerations during walking at slow and preferred speeds, and preferred and fast speeds.ResultsRMS acceleration amplitude increased with gait speed in all directions. ML and VT trunk accelerations had less signal regularity and repeatability during the slow compared to preferred speed. However, stride-to-stride acceleration regularity and repeatability did not differ between the preferred and fast walking speed conditions, partly due to an increase in coupling between frontal plane accelerations. The percentage of variance accounted for by each trunk acceleration Principal Component (PC) did not differ between grouped slow and preferred, and preferred and fast walking speed acceleration data.ConclusionThe main finding of this study was that walking at speeds slower than preferred primarily alters lower trunk accelerations in the frontal plane. Despite greater amplitudes of trunk acceleration at fast speeds, the lack of regularity and repeatability differences between preferred and fast speeds suggest that features of trunk motion are preserved between the same conditions. While PCA indicated that features of trunk motion are preserved between slow and preferred, and preferred and fast speeds, the discriminatory ability of PCA to detect speed-dependent differences in walking patterns is limited compared to measures of signal regularity, repeatability, and coupling.

Executive Functions Are Associated With Gait and Balance in Community-Living Elderly People

Cognition influences gait and balance in elderly people. Executive functions seem to play a key role in this mechanism. Previous studies used only a single test to probe executive functions, and outcome measures were restricted to gait variables. We extend this prior work by examining the association between two different executive functions and measures of both gait and balance, with and without two different cognitive dual tasks. This is a cross-sectional study with randomly selected community-living elderly people. Executive functions were tested with the Trail Making Test Parts A and B and the Stroop Color Word Test; memory with Cambridge Neuropsychological Test Automated Battery (CANTAB) subtests. Patients walked without and with two dual tasks (subtracting serial sevens and animal naming). Main outcomes focused on gait (velocity, stride length, and stride time variability), measured on an electronic walkway, and balance, measured as trunk movements during walking. Associations were assessed with multiple regression models. One hundred elderly people, with a mean age 80.6 years (range 75-93 years) participated. Both dual tasks decreased gait velocity and increased variability and trunk sway. Executive functions were associated with only stride length variability and mediolateral trunk sway during performance of animal naming as the dual task. Memory was not associated with the gait and balance variables. In community-living elderly people, executive functions are associated with gait and balance impairment during a challenging dual-task condition that also depends on executive integrity. Next steps will be to explore the value of executive functions in defining fall-risk profiles and in fall-prevention interventions for frail patients.

Should trunk movement or footfall parameters quantify gait asymmetry in chronic stroke patients?

The purpose of this study was to investigate gait asymmetry in chronic stroke patients in comparison with subjects with no known asymmetries. Further, we wanted to decide which gait symmetry parameter has the best ability to discriminate between the two groups. Twenty subjects with hemiplegia (mean age 58 years, S.D. = 8 years) and 57 subjects with no known gait asymmetry (mean age 77 years, S.D. = 5 years) walked six times along a 7-m walkway at slow, preferred and fast speed. Measures of vertical, anteroposterior, and mediolateral trunk asymmetry were assessed from triaxial accelerometry data. The footfall parameters of single support (% of stride time) and step length (m) asymmetry were assessed from data obtained using an electronic walkway. Vertical ( p < 0.001), anteroposterior ( p = 0.01), mediolateral ( p = 0.01) trunk movement and single support ( p = 0.03) showed significant differences in asymmetry between the two groups. No difference in step length asymmetry was found between the two groups. Neither single support asymmetry nor step length asymmetry showed the ability to discriminate subjects with hemiplegic gait from subjects in the comparison group. Measures of trunk movement asymmetry, however, were able to discriminate between the two groups ( p ≤ 0.001). The results indicate that trunk movement should be included in the assessment of gait asymmetry in chronic stroke patients.

Physical Fatigue Affects Gait Characteristics in Older Persons

Fatigue affects self-reported functioning in older persons. Balance and gait problems increase fall risk. The effect of physical fatigue in the elderly population in general, and on balance control during walking in particular is not well known. This study investigates how a repeated sit-to-stand task affects gait control in older persons. Twenty-two persons (mean age 78 years) took part in a fatigue group (FG), and 22 persons (mean age 80 years) in a matched control group (CG). Participants walked back and forth on a walkway at different walking speeds. Gait data were adjusted for pretest-posttest differences in walking speed. The FG participants were physically fatigued by a repeated sit-to-stand task. Trunk data were obtained by a triaxial accelerometer and foot level data by an electronic walkway. There were no group differences in preferred gait speed (p =.96) or in step length (p =.47) following the fatiguing task, but there were significant increases in step width (p =.023) and in mediolateral trunk acceleration amplitude (p =.038) in the FG group. Step-length variability (p =.004) and interstride trunk acceleration variability in the vertical direction (p =.002) increased, and tended to increase in the anteroposterior direction (p =.10) and to decrease in the mediolateral direction (p =.10) in the FG only. Gait changes following a physical fatiguing task agree with changes previously found in older persons at risk of falling, suggesting that physical fatigue may represent a risk factor for falls in elderly persons.

Implications of increased medio-lateral trunk sway for ambulatory mechanics

The purposes of this study was to test a mechanism to reduce the knee adduction moment by testing the hypothesis that increased medio-lateral trunk sway can reduce the knee adduction moment during ambulation in healthy subjects, and to examine the possibility that increasing medio-lateral trunk sway can produce similar potentially adverse secondary gait changes previously associated with reduced knee adduction moments in patients with knee osteoarthritis. Nineteen healthy adults performed walking trials with normal and increased medio-lateral trunk sway at a self-selected normal walking speed. Standard gait analysis was used to calculate three-dimensional lower extremity joint kinematics and kinetics. Knee and hip adduction moments were lower (−65.0% and −57.1%, respectively) for the increased medio-lateral trunk sway trials than for the normal trunk sway trials. Knee flexion angle at heel-strike was 3° higher for the increased than for the normal trunk sway trials. Knee and hip abduction moments were higher for the increased medio-lateral trunk sway trials, and none of the other variables differed between the two conditions. Walking with increased medio-lateral trunk sway substantially reduces the knee adduction moment during walking in healthy subjects without some of the adverse secondary effects such as increased axial loading rates at the major joints of the lower extremity. This result supports the potential of using gait retraining for walking with increased medio-lateral trunk sway as treatment for patients with degenerative joint disease such as medial compartment knee osteoarthritis.

The effect of gait speed on lateral balance control during walking in healthy elderly.

The aim of this paper was to investigate the effect of speed dependency on lateral gait parameters. In 36 healthy elderly (mean age=72.5 years, S.D.=3.2 years), walking at four different self-administered speeds, mediolateral trunk acceleration and step width (SW), but not step-width variability (SWV), were found to have quadratic relations to gait speed. Normalizing for speed by curvilinear interpolation, and controlling for subject characteristics, disclosed smaller SW (adjusted R2=0.41, P<0.001), but larger SWV (adjusted R2=0.26, P=0.01) with increasing age in multiple regression models. These relations were camouflaged at preferred speed.

Fingertip touch improves postural stability in patients with peripheral neuropathy.

The purpose of this work was to determine whether fingertip touch on a stable surface could improve postural stability during stance in subjects with somatosensory loss in the feet from diabetic peripheral neuropathy. The contribution of fingertip touch to postural stability was determined by comparing postural sway in three touch conditions (light, heavy and none) in eight patients and eight healthy control subjects who stood on two surfaces (firm or foam) with eyes open or closed. In the light touch condition, fingertip touch provided only somatosensory information because subjects exerted less than 1 N of force with their fingertip to a force plate, mounted on a vertical support. In the heavy touch condition, mechanical support was available because subjects transmitted as much force to the force plate as they wished. In the no touch condition, subjects held the right forefinger above the force plate. Antero-posterior (AP) and medio-lateral (ML) root mean square (RMS) of center of pressure (CoP) sway and trunk velocity were larger in subjects with somatosensory loss than in control subjects, especially when standing on the foam surface. The effects of light and heavy touch were similar in the somatosensory loss and control groups. Fingertip somatosensory input through light touch attenuated both AP and ML trunk velocity as much as heavy touch. Light touch also reduced CoP sway compared to no touch, although the decrease in CoP sway was less effective than with heavy touch, particularly on the foam surface. The forces that were applied to the touch plate during light touch preceded movements of the CoP, lending support to the suggestion of a feedforward mechanism in which fingertip inputs trigger the activation of postural muscles for controlling body sway. These results have clinical implications for understanding how patients with peripheral neuropathy may benefit from a cane for postural stability in stance.