Differences In Step Length Research Articles

Spatiotemporal Gait Parameters That Predict Gait Function Based on Timed Up and Go Test Performance in the Hemiplegic Stroke Patients

The purpose of this study was to determine which spatiotemporal gait parameters obtained during hemiplegic walking could be a predictive factor for the Timed Up and Go test (TUG). Two hundreds nine subjects who had suffered a stroke were recruited for this study. They were participated in two assessments; the TUG test and gait analysis. The relationship between the TUG test and spatiotemporal parameters was analyzed using Pearson's correlation coefficients. In addition, to predict the spatiotemporal gait parameters that correlated most with the TUG scores, we used multiple linear regression analyses (stepwise method). The results show that the normalized velocity was strongly correlated with the TUG performance (r=-.72, p<.001). Additionally, single support percentage (SSP), double support percentage (DSP), step time difference (STD), and step length difference (SLD) significantly were correlated with the TUG test. Normalized velocity, STD, DSP of affected side, and SSP of non-affected side explained 53%, 8%, 3%, 2%, of variance in the TUG test respectively. In conclusion, an increase in gait velocity and a decrease in STD would be effective indicators of improvement on the functional mobility in the stroke rehabilitation.

Effects of the Elastic Walking Band on gait in stroke patients

This study investigated how stroke patients improve the walking patterns by using the Elastic Walking Band, which was included with a long elastic band and four pierced plastics as fixed points. Fifteen patients with stroke were recruited. Participants were nine males and six females. Gait parameters were measured with the GAITRite system to analyze the spatial and temporal parameters of walking by stroke patients. The Elastic Walking Band had no significance in cadence, swing time and stance on both limbs. However, the Elastic Walking Band significantly improved velocity in stroke patients. Furthermore, there was a significant difference in step length of the less-affected limb between the two conditions, but no significant difference in the affected side. When the patients walked with the Elastic Walking Band, affected and less-affected stride length were also significantly increased as compared with barefoot walking. There were significant differences of velocity, less-affected step length, both stride length between walking with and without the Elastic Walking Band. Consequently, the Elastic Walking Band can be used as an assistive walking device that is lighter and less expensive for stroke patient gait training in the clinic.

Learning to be economical: the energy cost of walking tracks motor adaptation

Many theories of motor control suggest that we select our movements to reduce energy use. However, it is unclear whether this process underlies short-term motor adaptation to novel environments. Here we asked whether adaptation to walking on a split-belt treadmill leads to a more economical walking pattern. We hypothesized that adaptation would be accompanied by a reduction in metabolic power and muscle activity and that these reductions would be temporally correlated. Eleven individuals performed a split-belt adaptation task where the belt speeds were set at 0.5 and 1.5 m s(-1). Adaptation was characterized by step length symmetry, which is the normalized difference in step length between the legs. Metabolic power was calculated based on expired gas analysis, and surface EMG was used to record the activity of four bilateral leg muscles (tibialis anterior, lateral gastrocnemius, vastus lateralis and biceps femoris). All participants initially walked with unequal step lengths when the belts moved at different speeds, but gradually adapted to take steps of equal length. Additionally, net metabolic power was reduced from early adaptation to late adaptation (early, 3.78 ± 1.05 W kg(-1); and late, 3.05 ± 0.79 W kg(-1); P < 0.001). This reduction in power was also accompanied by a bilateral reduction in EMG throughout the gait cycle. Furthermore, the reductions in metabolic power occurred over the same time scale as the improvements in step length symmetry, and the magnitude of these improvements predicted the size of the reduction in metabolic power. Our results suggest that increasing economy may be a key criterion driving locomotor adaptation.

Comparison of the effects of solid versus hinged ankle foot orthoses on select temporal gait parameters in patients with incomplete spinal cord injury during treadmill walking

Ankle foot orthoses (AFOs) are usually used for patients with incomplete spinal cord injury (ISCI) to provide support in walking. The aim of this study was to compare the effect of AFOs, with and without ankle hinges, on specific gait parameters during treadmill training by subjects with ISCI. Quasi-experimental. Five patients with ISCI at the thoracic level participated in this study. Gait evaluation was performed when walking 1) barefoot 2) wearing a solid AFO and 3) wearing a hinged AFO. The mean step length when walking barefoot was 26.3 ± 16.37 cm compared to 31.3 ± 17.27 cm with a solid AFO and 28.5 ± 15.86 cm with a hinged AFO. The mean cadence for walking barefoot was 61.59 ± 25.65 steps/min. compared to 50.94 ± 22.36 steps/min. with a solid AFO and 56.25 ± 24.44 steps/min with a hinged AFO. Significant differences in cadence and step length during walking were only demonstrated between the barefoot condition and when wearing a solid AFO. Significant difference was not observed between conditions in mean of ankle range of motion. The solid AFO was the only condition which improved cadence and step length in patients during ISCI gait training. Clinical relevance A solid AFO could be used permanently to compensate for impaired ankle function or it could be used while retraining stepping.

Gait characteristics of individuals with transtibial amputations walking on a destabilizing rock surface

Individuals with transtibial amputation (TTA) have a high incidence of falls during walking. Environmental factors, such as uneven ground, often play a contributing role in these falls. The purpose of this study was to quantify the adaptations TTA made when walking on a destabilizing loose rock surface. In this study, 13 young TTA walked over a rock surface and level ground at four controlled speeds. Subjects successfully traversed the rock surface by adopting a conservative gait characterized by shorter and wider steps. They also took shorter steps with their prosthetic limbs and exhibited greater variability in foot placement when stepping onto their intact limb. Between-limb differences in step length and width variability increased at faster walking speeds. TTA increased hip and knee flexion during initial stance, which contributed lowering the whole-body center of mass. TTA also increased hip and knee flexion during swing, enabling them to significantly increase their toe clearance on the rock surface compared to level ground. Toe clearance on the prosthetic side was aided by increased ipsilateral hip flexion. The results suggest that TTA were able to adapt their gait to overcome the challenge imposed by the rock surface. These adaptations were asymmetric and initiated proximally.

Subjects with hip osteoarthritis show distinctive patterns of trunk movements during gait-a body-fixed-sensor based analysis

BackgroundCompensatory trunk movements during gait, such as a Duchenne limp, are observed frequently in subjects with osteoarthritis of the hip, yet angular trunk movements are seldom included in clinical gait assessments. Hence, the objective of this study was to quantify compensatory trunk movements during gait in subjects with hip osteoarthritis, outside a gait laboratory, using a body-fixed-sensor based gait analysis. Frontal plane angular movements of the pelvis and thorax and spatiotemporal parameters of persons who showed a Duchenne limp during gait were compared to healthy subjects and persons without a Duchenne limp.MethodsA Body-fixed-sensor based gait analysis approach was used. Two body-fixed sensors were positioned at the dorsal side of the pelvis and on the upper thorax. Peak-to-peak frontal plane range of motion (ROM) and spatiotemporal parameters (walking speed, step length and cadence) of persons with a Duchenne limp during gait were compared to healthy subjects and persons without a Duchenne limp. Participants were instructed to walk at a self-selected low, preferred and high speed along a hospital corridor. Generalized estimating equations (GEE) analyses were used to assess group differences between persons with a Duchenne limp, without a Duchenne limp and healthy subjects.ResultsPersons with a Duchenne limp showed a significantly larger thoracic ROM during walking compared to healthy subjects and to persons without a Duchenne limp. In both groups of persons with hip osteoarthritis, pelvic ROM was lower than in healthy subjects. This difference however only reached significance in persons without a Duchenne limp. The ratio of thoracic ROM relative to pelvic ROM revealed distinct differences in trunk movement patterns. Persons with hip osteoarthritis walked at a significantly lower speed compared to healthy subjects. No differences in step length and cadence were found between patients and healthy subjects, after correction for differences in walking speed.ConclusionsDistinctive patterns of frontal plane angular trunk movements during gait could be objectively quantified in healthy subjects and in persons with hip osteoarthritis using a body-fixed-sensor based gait analysis approach. Therefore, frontal plane angular trunk movements should be included in clinical gait assessments of persons with hip osteoarthritis.

Muscular and Gait Abnormalities in Persons With Early Onset Multiple Sclerosis

Muscular and gait abnormalities are common complaints among persons with multiple sclerosis, even in the early stages of the disease. Our aim was to evaluate peak isometric strength, major lower limb muscle fatigue, and spatiotemporal gait parameters in persons with a first neurological event suggestive of multiple sclerosis, defined as a clinically isolated syndrome (CIS). Fifty-two individuals (36 women, 16 men) with CIS, aged 35.2 (SD = 7.2) with an Expanded Disability Status Scale score of 1.7 (SD = 1.3), participated in the study. Peak isometric torque and fatigue index were measured at the knee and ankle bilaterally as well spatiotemporal parameters of gait. Twenty-eight age- and gender-matched healthy subjects served as controls. The CIS group demonstrated increased muscle fatigue, and greater ankle muscle torque asymmetries compared with the control group. The overall fatigue index scores intensified on an average of 40% in the CIS group (27% vs 19% in controls). Participants in the CIS group walked with a larger step length difference, longer step time difference, wider base of support, and prolonged double support period compared with the control group. Positive correlations were identified between double support period and some muscle parameters. At this early stage of clinically isolated syndrome, evidence of a reduction in lower limb motor performance can already be identified. The possibility of early identification and potential for developing an intervention program that may alter treatment outcome warrants further exploration.

Longitudinal Change in Gait and Motor Function in Pre-manifest Huntington’s Disease

The purpose of this study was to examine longitudinal change in gait and motor function in pre-manifest Huntington’s disease (HD).We examined ten pre-manifest subjects at baseline, one and five years. Quantitative gait data were collected with an electronic mat (GAITRite®). We analyzed measures related to speed (velocity, step length, cadence), asymmetry (step length difference), dynamic balance (percent time in double support, support base) and variability in stride length and swing time. Motor function was assessed with the motor component of the Unified Huntington’s Disease Rating Scale.Gait velocity decreased (p=0.001), whereas step length difference (p=0.006), stride length variability (p=0.0001) and swing time variability increased (p=0.0001) from baseline to year five. Step length difference (p<0.05) and swing time variability (p<0.05) increased marginally in one year from baseline. UHDRS Total motor score increased over five years (p=0.003), though the increase in one year was not significant (p=0.053). Of the individual motor domain scores (eye, hand movements, gait and balance, chorea) only dystonia worsened over five years (p=0.02). Total motor score (r2= 0.49, p<0.001) and swing time variability (r2= 0.22, p<0.009) were correlated with estimated years to diagnosis.Our results present the longest longitudinal follow up of gait in pre-manifest HD thus far. Despite the small sample size, quantitative gait analysis was able to detect changes in gait speed, symmetry and variability. Swing time variability was particularly important because it increased in one year from baseline and was correlated with estimated time to diagnosis. Our results highlight the importance of predictive outcomes such as gait variability using quantitative analysis.

Comparison Of Step Length Between Motorized And Non-motorized Treadmills During Walking, Jogging, Or Running

Non-motorized treadmills are becoming increasing popular with athletes and the general population for training and fitness purposes. A non-motorized treadmill requires the individual to propel the treadmill belt in order for the exercise to be performed. Although more non-motorized treadmills are becoming available, the advantages and disadvantages over a motorized treadmill are still being investigated. PURPOSE: The purpose of this study was to examine if differences occur in step length at various speeds between motorized and non-motorized treadmills. METHODS: Nine healthy college-aged individuals (n=9; 5 males, 4 females) walked at 1.34 m/s, jogged at 2.23 m/s, and ran at 3.13 m/s on three different treadmills: a belt driven (BT), a slatted (ST), and a non-motorized treadmill (CT). The participants achieved the prescribed speed and then the time to complete 25 steps was measured. Average step length was calculated for each speed on each treadmill. Statistical analysis was performed using repeated measures ANOVA with a post hoc Tukey test to determine where significant differences occurred (P < 0.05). RESULTS: There were no significant differences in step length between the three treadmills at the walking, jogging, or running speeds, though the differences between speeds were all significantly different. CONCLUSION: There appears to be no difference with the individuals step length between treadmills at a given speed. Whether or not this is due to the construction of this particular CT remains to be investigated.Table

Age-related differences in locomotor targeting performance under structural interference

to determine if there are age-related differences in locomotor targeting (LT) performance and step length (SL) regulatory behaviour under structural interference. forty older (n = 20, mean age = 77.9) and younger (n = 20, mean age = 25.2) participants walked 11.6 m while stepping on a target positioned at the 9.5 m point. Participants completed seven trials under each of three conditions, including the control (C) (no structural interference), low structural interference (L) and high structural interference (H). The structural interference conditions required participants to engage in LT while simultaneously verbally identifying letters that were visually presented on one of two monitors. One monitor was located near the target (low interference), while the other monitor was elevated to require participants to direct their gaze further away from the target to identify a letter (high interference). Outcome measures included LT error, SL, SL variability and the distribution of SL adjustment. structural interference had a detrimental effect on the LT accuracy of the older group (2.75 cm mean increase in absolute error) but not on the younger group (1.05 cm mean increase in absolute error), even though the interference caused the older group alone to adopt a more conservative gait pattern involving shorter SLs. The older participants exhibited shorter mean SL with each increase in structural interference (conditions C vs. L, P = 0.004; conditions L vs. H, P = 0.050), whereas the younger participants' mean SL did not differ across conditions. The manner in which older and younger participants distributed SL adjustment across the steps in advance of the target did not differ. the results confirmed that LT demands more attention from older adults than it does from younger adults, and revealed that a consequence of this age difference is a decline in LT accuracy among older adults. The study implicates age-related impaired visual attention switching as a potential source of impaired walking performance among older adults.

Specific surface free energy and the morphology of synthesized ruby single crystals

Ruby single crystals were synthesized from Mo- or Pb-based fluxes. The specific surface free energy of crystal was experimentally obtained using contact angle of liquid droplets on the crystal surface, and compared with the equilibrium grown length of each face. The proportion of the specific surface free energy and the equilibrium grown length was constant for the different faces of each individual ruby crystal, which looks to satisfy Wulff’s relationship. The relationship between specific surface free energy of the faces of the individual crystal with the same index and the equilibrium grown length of the face was linier. The difference in the specific surface free energy for the face of the same index can be explained by the difference in step length.

Balance recovery after an evoked forward fall in unilateral transtibial amputees

Falls are a common and potentially dangerous event, especially in amputees. In this study, we compared the mechanisms of balance recovery of 17 unilateral transtibial amputees and 17 matched able-bodied controls after being released from a forward-inclined orientation of 10%. Kinematic analysis revealed statistically significant differences in response time and knee flexion at heel-strike between both groups. However, there were no statistically significant differences in step length of the leading and trailing limb, swing time of the leading limb, and maximal knee flexion during swing. In the amputees, we found spatial and temporal differences when recovering with the sound versus prosthetic limb first. When leading with the prosthetic limb, they responded faster and also the interval between heel-strike of the leading and trailing limb was shorter. Furthermore, amputees made a longer step and showed less knee flexion at heel-strike when leading with the prosthetic limb. Interestingly, amputees as a group had no specific limb preference, prosthetic or sound, to recover after a forward fall, despite the asymmetry in their locomotor system. Analyses of dynamic stability (extrapolated center of mass) revealed that the amputees were equally efficient in recovering from an impending fall as controls, irrespective whether they lead with their prosthetic or sound limb. We suggest that in amputee rehabilitation, balance recovery after a fall should be trained with both sides, as this can increase confidence in fall-prone situations.

Mechanics of the West Point Bionic Foot During Walking: A Case Study

PURPOSE: To investigate the differences in walking gait kinematics and kinetics when using passive versus active (West Point Bionic Foot) foot-ankle prosthetic devices in a transtibial amputee. METHODS: Kinematic (step length, step time) and kinetic (passive peak and active peak forces) variables were measured during treadmill walking in a male transtibial amputee (age 26 years, height 185.0 cm, mass 72.4 kg). A Kistler Gaitway treadmill was utilized to collect kinematic and kinetic data. Prior to data collection, the subject underwent a 30 min treadmill walking familiarization session using both his passive foot and the active foot. He then performed 10-15 min walking trials for each of three conditions: 1) passive foot, self-selected speed (5.6 km/h), 2) active foot, matched speed with passive foot (5.6 km/h), and 3) active foot, self-selected speed (6.0 km/h). RESULTS: There were significant (p < 0.0001) decreases in step length, step time, and passive peak and active peak forces in the prosthetic leg as compared to the unaffected leg in all three conditions. While there were no differences in step length and step time between the passive foot and active foot during the matched speed condition, there were significantly (p < 0.0001) smaller active peak forces when using the active foot. The results for the prosthetic leg are presented in the table below (mean ± SD).TableCONCLUSION: The West Point Bionic Foot allowed the subject to achieve a faster, self-selected comfortable walking speed. In addition, the active foot permitted the subject to maintain a given walking speed while producing smaller active peak forces with no concurrent changes in step length and step time. Supported by AMEDD Advanced Medical Technology Initiative Grant 2008011723.

Changes to Control of Adaptive Gait in Individuals with Long-standing Reduced Stereoacuity

Gait during obstacle negotiation is adapted in visually normal subjects whose vision is temporarily and unilaterally blurred or occluded. This study was conducted to examine whether gait parameters in individuals with long-standing deficient stereopsis are similarly adapted. Twelve visually normal subjects and 16 individuals with deficient stereopsis due to amblyopia and/or its associated conditions negotiated floor-based obstacles of different heights (7-22 cm). Trials were conducted during binocular viewing and monocular occlusion. Analyses focused on foot placement before the obstacle and toe clearance over it. Across all viewing conditions, there were significant group-by-obstacle height interactions for toe clearance (P < 0.001), walking velocity (P = 0.003), and penultimate step length (P = 0.022). Toe clearance decreased (approximately 0.7 cm) with increasing obstacle height in visually normal subjects, but it increased (approximately 1.5 cm) with increasing obstacle height in the stereo-deficient group. Walking velocity and penultimate step length decreased with increasing obstacle height in both groups, but the reduction was more pronounced in stereo-deficient individuals. Post hoc analyses indicated group differences in toe clearance and penultimate step length when negotiating the highest obstacle (P < 0.05). Occlusion of either eye caused significant and similar gait changes in both groups, suggesting that in stereo-deficient individuals, as in visually normal subjects, both eyes contribute usefully to the execution of adaptive gait. Under monocular and binocular viewing, obstacle-crossing performance in stereo-deficient individuals was more cautious when compared with that of visually normal subjects, but this difference became evident only when the subjects were negotiating higher obstacles; suggesting that such individuals may be at greater risk of tripping or falling during everyday locomotion.

Adult age differences in familiarization to treadmill walking within virtual environments

We assessed age-related differences in adults in familiarization to treadmill walking within virtual environments (VE), and examined whether treadmill walking after familiarization resembles overground walking. Seventeen younger and 17 older adults walked at preferred speed on an overground walkway and afterwards walked at the same speed for 20 min on a treadmill coupled to a VE. A motion capture system was used to measure spatio-temporal gait parameters. On the treadmill, both younger and older adults initially displayed decreased step length and increased step width, cadence, and time in double support relative to overground walking. Except for time in double support, step characteristics approached overground walking-behavior with a negatively accelerated trend. After 15 min of treadmill walking, changes became minor corresponding to less than 1% deviations to individuals’ overground walking. At the end of familiarization, average differences in step length, cadence, and double support relative to overground walking were reduced to less than 5 percent in both age groups. For step width, younger adults approximated overground walking after 20 min more closely than older adults, probably reflecting larger initial differences between treadmill and overground walking among older adults. We conclude (a) that 20 min of familiarization to treadmill walking in a VE are sufficient to reach stable walking patterns resembling those observed in overground walking, but that some differences between the two settings remain, especially in older adults; (b) that sufficient familiarization to the treadmill is needed to ascertain the validity and generalizability of comparisons between younger and older adults.

Effect of prosthetic ankle units on the gait of persons with bilateral trans-femoral amputations

In able-bodied individuals, the ankle joint functions to provide shock absorption, aid in foot clearance during the swing phase, and provides a rocker mechanism during stance phase to facilitate forward progression of the body. Prosthetic ankles currently used by persons with lower limb amputations provide considerably less function than their anatomical counterparts. However, increased ankle motion in the sagittal plane may improve the gait of persons with lower limb amputations while providing a more versatile prosthesis. The primary aim of this study was to examine and quantify temporal-spatial, kinematic, and kinetic changes in the gait of four male subjects with bilateral trans-femoral amputations who walked with and without prosthetic ankle units. Two prosthesis configurations were examined: (i) Baseline with only two Seattle LightFoot2 prosthetic feet, and (ii) with the addition of Endolite Multiflex Ankle units. Data from the gait analyses were compared between prosthetic configurations and with a control group of able-bodied subjects. The amputee subjects' freely-selected walking speeds, 0.74 +/- 0.19 m/s for the Baseline condition and 0.81 +/- 0.15 m/s with the ankle units, were much less than that of the control subjects (1.35 +/- 0.10 m/s). The amputee subjects demonstrated no difference in walking speed, step length, cadence, or ankle, knee, and hip joint moments and powers between the two prosthesis configurations. Sagittal plane ankle range of motion, however, increased by 3-8 degrees with the addition of the prosthetic ankle units. Compared to the control group, following initial contact the amputee subjects passively increased the rate of energy storage or dissipation at the prosthetic ankle joint, actively increased the power generation at the hip, and increased the extension moment at the hip while wearing the prosthetic ankle configuration. The amputee subjects increased the power generation at their hips, possibly as compensation for the reduced rate of energy return at their prosthetic ankles. Results from subject questionnaires administered following the gait analyses revealed that the prosthetic ankle units provided more comfort during gait and did not increase the perceived effort to walk. The subjects also indicated that they preferred walking with the prosthetic ankle units compared to the Baseline configuration. The results of the study showed that the prosthetic ankle units improved sagittal plane ankle range of motion and increased the comfort and functionality of the amputee subjects' prostheses by restoring a significant portion of the ankle rocker mechanism during stance phase. Therefore, prosthetic ankle mechanisms should be considered a worthwhile option when prostheses are prescribed for persons with trans-femoral amputations.

Active and passive contributions to joint kinetics during walking in older adults

The objectives of this study were to characterize the active and passive contributions to joint kinetics during walking in healthy young and older adults, and assess whether isokinetic ankle strength is associated with ankle power output during walking. Twenty healthy young (18–35 years) and 20 healthy older (65–85 years) adults participated in this study. We measured subject-specific passive-elastic joint moment–angle relationships in the lower extremity and tested maximum isokinetic ankle strength at 30 deg/s. Passive moment–angle relationships were used to estimate active and passive joint moment, power, and work quantities during walking at 80%, 100% and 120% of preferred walking speed. There were no significant differences in walking speed, step length, or cadence between the older and young adults. However, the older adults produced significantly more net positive work at the hip but less net positive work at the ankle at all walking speeds. Passive contributions to hip and ankle work did not significantly differ between groups, inferring that the older adults generated the additional hip work actively. Maximum isokinetic ankle strength was significantly less in the older adults, and correlated with peak positive plantar-flexor power at both the preferred and fast walking speeds. The results of this study suggest that age-related shifts in joint kinetics do not arise as a result of increased passive hip joint stiffness, but seem to be reflected in plantar-flexor weakness.

Variáveis espaço-temporais da marcha de crianças com paralisia cerebral submetidas a eletroestimulação no músculo tibial anterior

Spatiotemporal gait variables of children with cerebral palsy undergoing electrostimulation in the anterior tibial muscle Objective: This study had the objective of describing spatiotemporal gait variables of four to five-year-old children with spastic hemiplegic cerebral palsy, before and after sessions of electrostimulation of the anterior tibial muscle on the paralyzed side. Method: Five children underwent 12 sessions of electrostimulation (three times a week). To collect biomechanical data, the gait was analyzed using the Peak Motus system, version 7.0, with two S-VHS video cameras with an acquisition rate of 60 Hz. Threedimensional reconstruction of the movements was performed using the direct linear transformation (DLT) method. Results: Following the intervention, all the children presented smaller differences in step length between the paralyzed and non-paralyzed sides (p= 0.009). Four children presented increased cycle amplitude. Two children presented increased cadence, speed and single support time on the paralyzed side. Thus, it was found that there was an improvement in gait symmetry in relation to the step lengths seen before and after the intervention, although the increase in the spatiotemporal variables did not occur in the same way for all the children. Conclusion: Despite the difficulties in defining larger and more homogeneous samples for studies of this type, the present data suggest the need for identification of and greater control over the variables that affect gait and its treatment among children with cerebral palsy.

Is there an effect of prenatal breech position on locomotion at 2.5 years?

The long-term effects of intra-uterine breech position on postnatal development of motor functions have not been systematically investigated. The aim of the present study was to investigate the possible effect of prenatal breech position on locomotion. Two complementary studies were conducted. Firstly, a gait analysis was carried out. Secondly, in a functional task the children were challenged to cross a gap until their maximum attainable crossing distance was reached. The mean age of the twenty-one children who participated in this study was 32.1 months (SD = 4). Children who lied in prenatal breech position ( n = 10) had a walking pattern comparable to the control group ( n = 11). There were no differences in step length, step width, foot rotation, foot rotation asymmetry, hip flexion, hip extension and range of motion of the hip. Thus, prenatal breech position, although a long-term effect was found, does not seem to have functional consequences on locomotion. However, the total amount of extra hip motion during the gap crossing was significantly smaller in children who lied in breech position compared to the control group. This was due to significant less extra hip flexion at the side of the leading leg. Nevertheless, comparable maximum gaps were crossed in both groups. Apparently, these children had a different solution of the challenging task of gap crossing. They compensated the lack of extra hip flexion by applying more extra hip extension.

CHARACTERIZATION AND VALIDATION OF VIRTUAL REALITY WALKING SIMULATOR

Purpose/Hypothesis: Virtual Reality (VR) has been proposed as a strategy for rehabilitation. To measure the potential of new VR devices they need to be characterized and compared to their real world counterparts. The primary purpose of this study was to characterize and validate the gait of individuals who walked on a VR walking simulator (WS) by comparing it to the kinematics and velocity of overground walking. The secondary purpose was to determine if the presence of the virtual environment (VE) modified walking characteristics. We hypothesized that walking velocity would be greater overground and slowest without the VE. Number of Subjects: Ten healthy subjects (2 male and 8 female) ages 24–53 without musculoskeletal injuries or neuromuscular pathology participated. Materials/Methods: Gait step length and velocity were collected (three trials) as participants walked at their self selected speed on a Gait Rite mat. Participants wore a harness and refective markers on the foot, ankle, knee, hip and trunk. They stood on the WS with each foot secured on a robotic platform, a harness attached to an unweighing frame, facing a screen. Unweighed 40% of their body weight they practiced walking on the WS (2–8 min.) until achieving the criterion gait pattern. Data were collected for four street crossing trials, walk without VE (2), walk with VE (2). An auditory tone or the VE green light prompted participants to begin walking. Kinematics were acquired using a 6 camera Peak system at 60 Hz. Joint angles were calculated for push of and initial contact by averaging the peak angle of three steps. Velocity data were averaged from the x-translation plots of the ffth metatarsal. Joint excursions from push of to initial contact-loading response were compared to normative data. Differences between overgound walking velocity and step length relative to the mobility simulator with and without the VE were assessed using a repeated measures ANOVA (alpha level= .05). Results: Walking velocity and step length were significantly greater for overground walking (1.5 m/sec; .79 m) compared with the mobility simulator with (.22 m/sec; .17 m) and without (.21 m/s; .18 m) the VE. The average joint excursions on the mobility simulator for push of to initial contact-loading response were 34 (knee) and 18 (ankle) degrees; compared to a range from push of to initial contact-loading response of 22–40 (knee) and 10–20 (ankle) degrees in normal gait. Conclusions: Walking in the VE resulted in pronounced decreases in temporal distance measures of gait however joint excursions were comparable to normal gait. There were no differences in gait velocity, step length or joint excursions when walking on the mobility simulator with and without the VE. The mechanics of the robot limit step length however, changing street crossing time in the VE may increase walking velocity. Clinical Relevance: Selected aspects of gait were preserved in the WS while others were not. Transfer of training from the walking simulator to real world walking still needs to be determined.