Biomechanics of overground vs. treadmill walking in healthy individuals

Validation and reliability testing of a new, fully integrated gait analysis insole

Background

A new tool (OpenGo, Moticon GmbH) was introduced to continuously measure kinetic and temporospatial gait parameters independently through an insole over up to 4 weeks. The goal of this study was to investigate the validity and reliability of this new insole system in a group of healthy individuals.

Methods

Gait data were collected from 12 healthy individuals on a treadmill at two different speeds. In total, six trials of three minutes each were performed by every participant. Validation was performed with the FDM-S System (Zebris). Complete sensor data were used for a within test reliability analysis of over 10000 steps. Intraclass correlation was calculated for different gait parameters and analysis of variance performed.

Results

Intraclass correlation for the validation was >0.796 for temporospatial and kinetic gait parameters. No statistical difference was seen between the insole and force plate measurements (difference between means: 36.3 ± 27.19 N; p = 0.19 and 0.027 ± 0.028 s; p = 0.36). Intraclass correlation for the reliability was >0.994 for all parameters measured.

Conclusion

The system is feasible for clinical trials that require step by step as well as grouped analysis of gait over a long period of time. Comparable validity and reliability to a stationary analysis tool has been shown.

Commercial Motion Sensor Based Low-Cost and Convenient Interactive Treadmill

Interactive treadmills were developed to improve the simulation of overground walking when compared to conventional treadmills. However, currently available interactive treadmills are expensive and inconvenient, which limits their use. We propose a low-cost and convenient version of the interactive treadmill that does not require expensive equipment and a complicated setup. As a substitute for high-cost sensors, such as motion capture systems, a low-cost motion sensor was used to recognize the subject’s intention for speed changing. Moreover, the sensor enables the subject to make a convenient and safe stop using gesture recognition. For further cost reduction, the novel interactive treadmill was based on an inexpensive treadmill platform and a novel high-level speed control scheme was applied to maximize performance for simulating overground walking. Pilot tests with ten healthy subjects were conducted and results demonstrated that the proposed treadmill achieves similar performance to a typical, costly, interactive treadmill that contains a motion capture system and an instrumented treadmill, while providing a convenient and safe method for stopping.

Effect of walking speed on gait sub phase durations

Gait phase durations are important spatiotemporal parameters in different contexts such as discrimination between healthy and pathological gait and monitoring of treatment outcomes after interventions. Although gait phases strongly depend on walking speed, the influence of different speeds has rarely been investigated in literature. In this work, we examined the durations of the stance sub phases and the swing phase for 12 different walking speeds ranging from 0.6 to 1.7 m/s in 21 healthy subjects using infrared cinematography and an instrumented treadmill. We separated the stance phase into loading response, mid stance, terminal stance and pre-swing phase and we performed regression modeling of all phase durations with speed to determine general trends. With an increasing speed of 0.1m/s, stance duration decreased while swing duration increased by 0.3%. All distinct stance sub phases changed significantly with speed. These findings suggest the importance of including all distinct gait sub phases in spatiotemporal analyses, especially when different walking speeds are involved.

Knee joint motion and muscle activation patterns are altered during gait in individuals with moderate hip osteoarthritis compared to asymptomatic cohort

BACKGROUND

Knee replacements are common after hip replacement for end stage osteoarthritis. Whether abnormal knee mechanics exist in moderate hip osteoarthritis remains undetermined and has implications for understanding early osteoarthritis joint mechanics. The purpose of this study was to determine whether three-dimensional (3D) knee motion and muscle activation patterns in individuals with moderate hip osteoarthritis differ from an asymptomatic cohort and whether these features differ between contra- and ipsilateral knees.

METHODS

3D motions and medial and lateral quadriceps and hamstring surface electromyography were recorded on 20 asymptomatic individuals and 20 individuals with moderate hip osteoarthritis during treadmill walking, using standardized collection and processing procedures. Principal component analysis was used to derive electromyographic amplitude and temporal waveform features. 3D stance-phase range of motion was calculated. A 2-factor repeated analysis of variance determined significant within-group leg and muscle differences. Student's t-tests identified between group differences, with Bonferroni corrections where applicable (α=0.05).

FINDINGS

Lower sagittal plane motion between early and mid/late stance (5°, P=0.004, effect size: 0.96) and greater mid-stance quadriceps activity was found in the osteoarthritis group (P=0.01). Compared to the ipsilateral knee, a borderline significant increase in mid-stance hamstring activity was found in the contra-lateral knee of the hip osteoarthritis group (P=0.018).

INTERPRETATION

Bilateral knee mechanics were altered, suggesting potentially increased loads and knee muscle fatigue. There was no indication that one knee is more susceptible to osteoarthritis than the other, thus clinicians should include bilateral knee analysis when treating patients with hip osteoarthritis.

Assessment of the effects of body weight unloading on overground gait biomechanical parameters

BACKGROUND

Gait rehabilitation with body weight unloading is a common method of gait rehabilitation for clinical subjects with neurological and musculoskeletal impairments. However, the efficiency of this method was hard to assess given the confounding variables walking modality (treadmill vs. overground) and subjects' inability to maintain a comfortable speed when pulling a body weight unloading system by which they were suspended. By controlling the gait modality (overground) and devising a mechanical device that pulled the system at a constant speed, this study could examine the unique effects of body weight unloading on the biomechanical parameters of healthy subjects walking overground at comfortable speed.

METHODS

Ten healthy subjects were instructed to walk overground under a control (no suspension vest) and three (0%, 15%, 30%) body weight unloading experimental conditions. Hip, knee and ankle spatiotemporal, kinematic, and kinetic measures were recorded for all conditions (six trials per condition).

FINDINGS

ANOVA showed no changes in cadence, speed and stride length, a reduction in double limb support and increase in single limb support. Pairwise comparisons of gait parameters under 0%,15% and 30% body weight unloading conditions indicated significant reductions in lower joint kinematics and kinetics with increased body weight unloading. Additionally, despite changes in the peak values of kinematic and kinetic measures, the curvature patterns remained unchanged.

INTERPRETATION

This study shows that overground gait with up to 30% body weight unloading reduces joint loads without modifying gait curvature patterns or the plantarflexion angle. Several clinical applications for gait reeducation conducted in situ with unloading are enumerated.

Supervised vs unsupervised exercise for intermittent claudication: A systematic review and meta-analysis

BACKGROUND

Supervised exercise (SE) is widely accepted as an effective therapy for intermittent claudication (IC), but its use is limited by cost. Unsupervised exercise (UE) represents a less costly alternative. We assessed the comparative effectiveness of SE vs UE in patients with IC.

METHODS AND RESULTS

We searched PubMed, EMBASE, and the Cochrane Database of Systematic Reviews and identified 27 unique studies (24 randomized controlled trials, 4 observational studies) that evaluated the comparative effectiveness of SE vs UE in 2074 patients with IC. Compared with UE, SE was associated with a moderate improvement in maximal walking distance at 6 months (effect size 0.77, 95% CI 0.36-1.17, P < .001) and 12 months (effect size 0.56, 95% CI 0.34-0.77, P < .001). Supervised exercise also improved claudication distance to a moderate extent compared with UE at 6 months (effect size 0.63, 95% CI 0.40-0.85, P < .001) and 12 months (effect size 0.41, 95% CI 0.18-0.65, P = .001). There was no difference in the Short Form-36 quality of life at 6 months (effect size -0.05, 95% CI -0.50 to 0.41, P = .84) or walking impairment questionnaire distance (effect size 0.24, 95% CI -0.03 to 0.50, P = .08) or speed (effect size 0.26, 95% CI -0.06 to 0.59, P = .11).

CONCLUSIONS

In claudication patients, SE is more effective than UE at improving maximal walking and claudication distances, yet there is no difference in general quality of life or patient-reported community-based walking. Further studies are needed to investigate the relationship between functional gain and disease-specific quality of life.

Walking stability during cell phone use in healthy adults

The number of falls and/or accidental injuries associated with cellular phone use during walking is growing rapidly. Understanding the effects of concurrent cell phone use on human gait may help develop safety guidelines for pedestrians. It was shown previously that older adults had more pronounced dual-task interferences than younger adults when concurrent cognitive task required visual information processing. Thus, cell phone use might have greater impact on walking stability in older than in younger adults. This study examined gait stability and variability during a cell phone dialing task (phone) and two classic cognitive tasks, the Paced Auditory Serial Addition Test (PASAT) and Symbol Digit Modalities Test (SDMT). Nine older and seven younger healthy adults walked on a treadmill at four different conditions: walking only, PASAT, phone, and SDMT. We computed short-term local divergence exponent (LDE) of the trunk motion (local stability), dynamic margins of stability (MOS), step spatiotemporal measures, and kinematic variability. Older and younger adults had similar values of short-term LDE during all conditions, indicating that local stability was not affected by the dual-task. Compared to walking only, older and younger adults walked with significantly greater average mediolateral MOS during phone and SDMT conditions but significantly less ankle angle variability during all dual-tasks and less knee angle variability during PASAT. The current findings demonstrate that healthy adults may try to control foot placement and joint kinematics during cell phone use or another cognitive task with a visual component to ensure sufficient dynamic margins of stability and maintain local stability.

Achilles tendon loading patterns during barefoot walking and slow running on a treadmill: An ultrasonic propagation study

Measurement of tendon loading patterns during gait is important for understanding the pathogenesis of tendon "overuse" injury. Given that the speed of propagation of ultrasound in tendon is proportional to the applied load, this study used a noninvasive ultrasonic transmission technique to measure axial ultrasonic velocity in the right Achilles tendon of 27 healthy adults (11 females and 16 males; age, 26 ± 9 years; height, 1.73 ± 0.07 m; weight, 70.6 ± 21.2 kg), walking at self-selected speed (1.1 ± 0.1 m/s), and running at fixed slow speed (2 m/s) on a treadmill. Synchronous measures of ankle kinematics, spatiotemporal gait parameters, and vertical ground reaction forces were simultaneously measured. Slow running was associated with significantly higher cadence, shorter step length, but greater range of ankle movement, higher magnitude and rate of vertical ground reaction force, and higher ultrasonic velocity in the tendon than walking (P < 0.05). Ultrasonic velocity in the Achilles tendon was highly reproducible during walking and slow running (mean within-subject coefficient of variation < 2%). Ultrasonic maxima (P1, P2) and minima (M1, M2) were significantly higher and occurred earlier in the gait cycle (P1, M1, and M2) during running than walking (P < 0.05). Slow running was associated with higher and earlier peaks in loading of the Achilles tendon than walking.

Effects of heel base size, walking speed, and slope angle on center of pressure trajectory and plantar pressure when wearing high-heeled shoes

High-heeled shoes are associated with instability and a high risk of fall, fracture, and ankle sprain. This study investigated the effects of heel base size (HBS) on walking stability under different walking speeds and slope angles. The trajectory of the center of pressure (COP), maximal peak pressure, pressure time integral, contact area, and perceived stability were analyzed. The results revealed that a small HBS increased the COP deviations, shifting the COP more medially at the beginning of the gait cycle. The slope angle mainly affected the COP in the anteroposterior direction. An increased slope angle shifted the COP posterior and caused greater pressure and a larger contact area in the midfoot and rearfoot regions, which can provide more support. Subjective measures on perceived stability were consistent with objective measures. The results suggested that high-heeled shoes with a small HBS did not provide stable plantar support, particularly on a small slope angle. The changes in the COP and pressure pattern caused by a small HBS might increase joint torque and muscle activity and induce lower limb problems.

Kinesthetic Force Feedback and Belt Control for the Treadport Locomotion Interface

This paper describes an improved control system for the Treadport immersive locomotion interface, with results that generalize to any treadmill that utilizes an actuated tether to enable self-selected walking speed. A new belt controller is implemented to regulate the user's position; when combined with the user's own volition, this controller also enables the user to naturally self-select their walking speed as they would when walking over ground. A new kinesthetic-force-feedback controller is designed for the tether that applies forces to the user's torso. This new controller is derived based on maintaining the user's sense of balance during belt acceleration, rather than by rendering an inertial force as was done in our prior work. Based on the results of a human-subjects study, the improvements in both controllers significantly contribute to an improved perception of realistic walking on the Treadport. The improved control system uses intuitive dynamic-system and anatomical parameters and requires no ad hoc gain tuning. The control system simply requires three measurements to be made for a given user: the user's mass, the user's height, and the height of the tether attachment point on the user's torso.

Differences in ground reaction forces and shock impacts between nordic walking and walking

The regular practice of Nordic walking (NW) has increased in recent years, in part thanks to the health benefits described by the scientific literature. However, there is no consensus on the effects of shock-impact absorption during its practice.

PURPOSE

The aim of this study was to compare the levels of impact and ground reaction forces (GRF) between NW and walking (W).

METHOD

Twenty physically active and experienced participants were assessed using a dynamometric platform and accelerometry analysis.

RESULTS

The results show statistically significantly higher levels of acceleration in the tibia (12%) and head (21%) during NW compared with W. Equally, GRF were significantly higher (27%) at the instant of strike compared with W, and a reduction of the forces at the instant of takeoff (8%) was observed.

CONCLUSIONS

During NW, shock impacts and GRF levels increased compared with W, an aspect that should be considered when prescribing health improvement programs.

Running shoes increase achilles tendon load in walking: an acoustic propagation study

BACKGROUND

Footwear remains a prime candidate for the prevention and rehabilitation of Achilles tendinopathy because it is thought to decrease tension in the tendon through elevation of the heel. However, evidence for this effect is equivocal.

PURPOSE

This study used an acoustic transmission technique to investigate the effect of running shoes on Achilles tendon loading during barefoot and shod walking.

METHODS

Acoustic velocity was measured in the Achilles tendon of 12 recreationally active males (age, 31 ± 9 yr; height, 1.78 ± 0.06 m; weight, 81.0 ± 16.9 kg) during barefoot and shod walking at matched self-selected speed (3.4 ± 0.7 km·h). Standard running shoes incorporating a 10-mm heel offset were used. Vertical ground reaction force and spatiotemporal parameters were determined with an instrumented treadmill. Axial acoustic velocity in the Achilles tendon was measured using a custom-built ultrasonic device. All data were acquired at a rate of 100 Hz during 10 s of steady-state walking. Statistical comparisons between barefoot and shod conditions were made using paired t-tests and repeated-measure ANOVA.

RESULTS

Acoustic velocity in the Achilles tendon was highly reproducible and was typified by two maxima (P1, P2) and minima (M1, M2) during walking. Footwear resulted in a significant increase in step length, stance duration, and peak vertical ground reaction force compared with barefoot walking. Peak acoustic velocity in the Achilles tendon (P1, P2) was significantly higher with running shoes.

CONCLUSIONS

Peak acoustic velocity in the Achilles tendon was higher with footwear, suggesting that standard running shoes with a 10-mm heel offset increase tensile load in the Achilles tendon. Although further research is required, these findings question the therapeutic role of standard running shoes in Achilles tendinopathy.

Symmetry and order parameter dynamics of the human odometer

Bipedal gaits have been classified on the basis of the group symmetry of the minimal network of identical differential equations (alias cells) required to model them. Primary bipedal gaits (e.g., walk, run) are characterized by dihedral symmetry, whereas secondary bipedal gaits (e.g., gallop-walk, gallop- run) are characterized by a lower, cyclic symmetry. This fact has been used in tests of human odometry (e.g., Turvey et al. in P Roy Soc Lond B Biol 276:4309-4314, 2009, J Exp Psychol Hum Percept Perform 38:1014-1025, 2012). Results suggest that when distance is measured and reported by gaits from the same symmetry class, primary and secondary gaits are comparable. Switching symmetry classes at report compresses (primary to secondary) or inflates (secondary to primary) measured distance, with the compression and inflation equal in magnitude. The present research (a) extends these findings from overground locomotion to treadmill locomotion and (b) assesses a dynamics of sequentially coupled measure and report phases, with relative velocity as an order parameter, or equilibrium state, and difference in symmetry class as an imperfection parameter, or detuning, of those dynamics. The results suggest that the symmetries and dynamics of distance measurement by the human odometer are the same whether the odometer is in motion relative to a stationary ground or stationary relative to a moving ground.

Effects of pivoting neuromuscular training on pivoting control and proprioception

PURPOSE

Pivoting neuromuscular control and proprioceptive acuity may play an important role in anterior cruciate ligament injuries. The goal of this study was to investigate whether pivoting off-axis intensity adjustable neuromuscular control training (POINT) could improve pivoting neuromuscular control, proprioceptive acuity, and functional performance.

METHODS

Among 41 subjects, 21 subjects participated in 18 sessions of POINT (three sessions per week for 6 wk), and 20 subjects served as controls who did their regular workout. Both groups received pre-, mid-, and postintervention evaluations. Propensity score analysis with multivariable regression adjustment was used to investigate the effect of training on pivoting neuromuscular control (pivoting instability, leg pivoting stiffness, maximum internal, and external pivoting angles), proprioceptive acuity, and functional performance in both groups.

RESULTS

Compared with the control group, the training group significantly improved pivoting neuromuscular control as reduced pivoting instability, reduced maximum internal and external pivoting angles, increased leg pivoting stiffness, and decreased entropy of time to peak EMG in the gluteus maximus and lateral gastrocnemius under pivoting perturbations. Furthermore, the training group enhanced weight-bearing proprioceptive acuity and improved the single leg hop distance.

CONCLUSION

Improvement of pivoting neuromuscular control in functional weight-bearing activities and task performances after POINT may help develop lower limb injury prevention and rehabilitation methods to reduce anterior cruciate ligament and other musculoskeletal injuries associated with pivoting sports.

Inter-joint coordination of overground versus treadmill walking in young adults

This study compares the pattern and variability of inter-joint coordination between treadmill and overground walking. Gait analyses of five young adults were performed during preferred speed overground walking (GPS), preferred speed treadmill walking (TPS), and treadmill walking with overground preferred speed (TGS). Continuous relative phase (CRP), derived from the phase portraits of two adjacent joints, was used to examine the inter-joint coordination. Cross-correlation measures and root-mean-square (RMS) differences were used to compare CRP patterns of the GPS condition to those of TPS and TGS conditions respectively. The deviation phase (DP) was used to evaluate the variability of inter-joint coordination during the stance and swing phases over a gait cycle for each condition. The walking speed of TPS was significantly slower than those of GPS and TGS. For the hip-knee CRP pattern, the RMS differences between GPS and TPS were significantly greater than the RMS differences between GPS and TGS. No significant differences between conditions were detected for the cross-correlation measures of hip-knee and knee-ankle CRP patterns. During the stance phase, the hip-knee DP values of TGS were significantly smaller than that of GPS and the knee-ankle DP values of TGS were also significantly smaller than that of GPS and TPS. No significant differences were detected for all three conditions in the swing phase. The findings suggest that the treadmill imposes a systemic regulation on dynamic neuromuscular control during walking, which may need to be considered while interpreting treadmill-based analysis of training to overground walking.

What predicts the first peak of the knee adduction moment?

BACKGROUND

The first peak of the knee adduction moment curve during walking has been shown to be a good clinical surrogate measure of medial tibiofemoral joint loading and osteoarthritis. Defining the relative contributions of the variables that dictate the knee adduction moment, such as center of mass, center of pressure, vertical ground reaction force, and knee adduction angle (i.e. lower limb alignment), has not been formally investigated within the same cohort of individuals. Therefore, the goal of this study was to determine which of these variables is the biggest determinant of the first peak of knee adduction moment curve.

METHODS

Instrumented gait analysis was collected for 30 individuals. Variables significantly correlated with the peak knee adduction moment were input into a stepwise multi-variable linear regression model.

RESULTS

The knee adduction angle predicted 58% of the variance in the first peak knee adduction moment and the vertical ground reaction force magnitude predicted the second most variance (20%).

CONCLUSIONS

The most effective way to modify the peak knee adduction moment may be to change the knee adduction angle (e.g. off loader brace), followed by changing the vertical magnitude of the ground reaction force (e.g. cane use).

CLINICAL RELEVANCE

Defining the major determinants of the knee adduction moment may help guide clinicians in choosing conservative interventions to reduce it in conditions such as medial tibiofemoral osteoarthritis.

Influence of body weight unloading and support surface during walking of children with cerebral palsy

Introduction Partial body weight support (BWS) systems have been employed for gait training of children with cerebral palsy (CP). Therefore, it would be important to analyze if the type of walking surface and the amount of body weight unloading over lower limbs change the way these children walk. Objectives Investigate the influence of walking surface and amount of body weight unloading on the spatial temporal characteristics during walking of children with CP. Materials and methods Seven children with spastic CP between four and eight years old and GMFCS (Gross Motor Function Classification System) between I and IV, were videotaped walking with 0%, 15% and 30% of BWS on both dynamic (treadmill) and static (ground level) surfaces. Walking spatial temporal variables were calculated. Results Children walked with similar velocity in all experimental conditions. While stance duration decreased as the percentage of BWS increased, no differences were found for stance and swing periods and cadence. Children walked with longer steps and strides and with faster strides on static surface compared to dynamic surface. Conclusion Children with CP presenting different levels of motor impairment presented some alterations in the spatial temporal walking parameters as they walked with body unloading. However, such alterations might be due mainly to the type of walking surface than the percentage of body weight unloading on lower limbs.

Pivoting neuromuscular control and proprioception in females and males

PURPOSE

Noncontact ACL injuries occur most commonly in pivoting sports and are much more frequent in females than in males. However, information on sex differences in proprioceptive acuity under weight-bearing and leg neuromuscular control in pivoting is scarce. The objective of this study was to investigate sex differences in pivoting neuromuscular control during strenuous stepping tasks and proprioceptive acuity under weight-bearing.

METHODS

21 male and 22 female subjects were recruited to evaluate pivoting proprioceptive acuity under weight-bearing, and pivoting neuromuscular control (in terms of leg pivoting instability, stiffness, maximum internal and external pivoting angles, and entropy of time-to-peak EMG in lower limb muscles) during strenuous stepping tasks performed on a novel offaxis elliptical trainer.

RESULTS

Compared to males, females had significantly lower proprioceptive acuity under weight-bearing in both internal and external pivoting directions, higher pivoting instability, larger maximum internal pivoting angle, lower leg pivoting stiffness, and higher entropy of time-to-peak EMG in the gastrocnemius muscles during strenuous stepping tasks with internal and external pivoting perturbations.

CONCLUSIONS

Results of this study may help us better understand factors contributing to ACL injuries in females and males, develop training strategies to improve pivoting neuromuscular control and proprioceptive acuity, and potentially reduce ACL and lower-limb musculoskeletal injuries.

Evidence against an ecological explanation of the jitter advantage for vection

Visual-vestibular conflicts have been traditionally used to explain both perceptions of self-motion and experiences of motion sickness. However, sensory conflict theories have been challenged by findings that adding simulated viewpoint jitter to inducing displays enhances (rather than reduces or destroys) visual illusions of self-motion experienced by stationary observers. One possible explanation of this jitter advantage for vection is that jittering optic flows are more ecological than smooth displays. Despite the intuitive appeal of this idea, it has proven difficult to test. Here we compared subjective experiences generated by jittering and smooth radial flows when observers were exposed to either visual-only or multisensory self-motion stimulations. The display jitter (if present) was generated in real-time by updating the virtual computer-graphics camera position to match the observer’s tracked head motions when treadmill walking or walking in place, or was a playback of these head motions when standing still. As expected, the (more naturalistic) treadmill walking and the (less naturalistic) walking in place were found to generate very different physical head jitters. However, contrary to the ecological account of the phenomenon, playbacks of treadmill walking and walking in place display jitter both enhanced visually induced illusions of self-motion to a similar degree (compared to smooth displays).

EMG and kinematic responses to unexpected slips after slip training in virtual reality

The objective of the study was to design a virtual reality (VR) training to induce perturbation in older adults similar to a slip and examine the effect of the training on kinematic and muscular responses in older adults. Twenty-four older adults were involved in a laboratory study and randomly assigned to two groups (VR training and control). Both groups went through three sessions including baseline slip, training, and transfer of training on slippery surface. The training group experienced 12 simulated slips using a visual perturbation induced by tilting a VR scene while walking on the treadmill and the control group completed normal walking during the training session. Kinematic, kinetic, and electromyography data were collected during all the sessions. Results demonstrated the proactive adjustments such as increased trunk flexion at heel contact after training. Reactive adjustments included reduced time to peak activations of knee flexors, reduced knee coactivation, reduced time to trunk flexion, and reduced trunk angular velocity after training. In conclusion, the study findings indicate that the VR training was able to generate a perturbation in older adults that evoked recovery reactions and such motor skill can be transferred to the actual slip trials.

Overground versus self-paced treadmill walking in a virtual environment in children with cerebral palsy

Treadmill walking offers several advantages for clinical gait analysis and gait training, but may affect gait parameters. We compared walking on a self-paced treadmill in a virtual environment (TM+) with overground walking in a conventional gait lab (CGL), and with natural walking (NW) outside a lab environment on a GaitRite measurement mat, for 11 typically developing (TD) children and 9 children with cerebral palsy (CP). Spatiotemporal parameters and subjective scores on similarity to normal walking were compared between all three conditions, while kinematic parameters and Gait and Motion Analysis Profile Scores (GPS and MAP) were compared between CGL and TM+. Subjects walked slower and with shorter strides in both lab conditions compared to NW. Stride width was 3-4 cm wider in TM+ than in CGL and NW. Mean kinematic curves showed a few differences between CGL and TM+: on the treadmill children with CP walked with on average 2° more pelvic tilt, 7° more knee flexion at initial contact, and more deviating knee and ankle kinematics as indicated by the MAP scores. These differences may in part be due to increased fatigue in TM+ as a result of longer continuous walking time. Our results indicate that differences between self-paced treadmill walking in a VR and walking in a conventional gait lab are generally small, but need to be taken into account when performing gait analysis on a treadmill.

Kinematics of turning during walking over ground and on a rotating treadmill

Background

After neurological injury, gait rehabilitation typically focuses on task oriented training with many repetitions of a particular movement. Modern rehabilitation devices, including treadmills, augment gait rehabilitation. However, they typically provide gait training only in the forward direction of walking, hence the mechanisms associated with changing direction during turning are not practiced. A regular treadmill extended with the addition of rotation around the vertical axis is a simple device that may enable the practice of turning during walking. The objective of this study was to investigate to what extent pelvis and torso rotations in the transversal plane, as well as stride lengths while walking on the proposed rotating treadmill, resemble those in over ground turning.

Methods

Ten neurologically and orthopedically intact subjects participated in the study. We recorded pelvis and torso rotations in the transversal plane and the stride lengths during over ground turning and while walking on a rotating treadmill in four experimental conditions of turning. The similarity between pelvis and torso rotations in over ground turning and pair-matching walking on the rotating treadmill was assessed using intra-class correlation coefficient (ICC - two-way mixed single measure model). Finally, left and right stride lengths in over ground turning as well as while walking on the rotating treadmill were compared using a paired t-test for each experimental condition.

Results

An agreement analysis showed average ICC ranging between 0.9405 and 0.9806 for pelvis and torso rotation trajectories respectively, across all experimental conditions and directions of turning. The results of the paired t-tests comparing left and right stride lengths showed that the stride of the outer leg was longer than the stride of the inner leg during over ground turning as well as when walking on the rotating treadmill. In all experimental conditions these differences were statistically significant.

Conclusions

In this study we found that pelvis rotation and torso rotation are similar when turning over ground as compared to walking on a rotating treadmill. Additionally, in both modes of turning, we found that the stride length of the outer leg is significantly longer than the stride length of the inner leg.

Electronic supplementary material

The online version of this article (doi:10.1186/1743-0003-11-127) contains supplementary material, which is available to authorized users.

Development of vision based multiview gait recognition system with MMUGait database

This paper describes the acquisition setup and development of a new gait database, MMUGait. This database consists of 82 subjects walking under normal condition and 19 subjects walking with 11 covariate factors, which were captured under two views. This paper also proposes a multiview model-based gait recognition system with joint detection approach that performs well under different walking trajectories and covariate factors, which include self-occluded or external occluded silhouettes. In the proposed system, the process begins by enhancing the human silhouette to remove the artifacts. Next, the width and height of the body are obtained. Subsequently, the joint angular trajectories are determined once the body joints are automatically detected. Lastly, crotch height and step-size of the walking subject are determined. The extracted features are smoothened by Gaussian filter to eliminate the effect of outliers. The extracted features are normalized with linear scaling, which is followed by feature selection prior to the classification process. The classification experiments carried out on MMUGait database were benchmarked against the SOTON Small DB from University of Southampton. Results showed correct classification rate above 90% for all the databases. The proposed approach is found to outperform other approaches on SOTON Small DB in most cases.

Gait parameters and muscle activation patterns at 3, 6 and 12 months after total hip arthroplasty

Gait analysis was performed on 20 patients with unilateral hip prosthesis (3, 6 and 12 months post-operatively) and 20 controls to investigate their gait characteristics and muscle activation patterns. One year after the intervention, patients still walked with a higher percentage of "atypical" cycles, a prolonged heel contact, a shortened flat foot contact, a reduced hip dynamic range of motion and abnormal timing in the muscle activation patterns of tibialis anterior, gastrocnemius lateralis, biceps femoris and gluteus medius, with respect to the control group. Although the gait velocity and the knee range of motion improved from 3 to 6 months post-surgery, the above mentioned parameters did not improve from 6 to 12 months. THA patients failed to obtain normal gait one year after surgery.

Three-dimensional kinematic comparison of treadmill and overground running

The treadmill is an attractive device for the investigation of human locomotion, yet the extent to which lower limb kinematics differ from overground running remains a controversial topic. This study aimed to provide an extensive three-dimensional kinematic comparison of the lower extremities during overground and treadmill running. Twelve participants ran at 4.0 m/s (+/- 5%) in both treadmill and overground conditions. Angular kinematic parameters of the lower extremities during the stance phase were collected at 250 Hz using an eight-camera motion analysis system. Hip, knee, and ankle joint kinematics were quantified in the sagittal, coronal, and transverse planes, and contrasted using paired t-tests. Of the analysed parameters hip flexion at footstrike and ankle excursion to peak angle were found to be significantly reduced during treadmill running by 12 degrees (p = 0.001) and 6.6 degrees (p = 0.010), respectively. Treadmill running was found to be associated with significantly greater peak ankle eversion (by 6.3 degrees, p = 0.006). It was concluded that the mechanics of treadmill running cannot be generalized to overground running.

Electromyographic patterns of tibialis posterior and related muscles when walking at different speeds

The effect of walking speed on superficial lower limb muscles, such as tibialis anterior and triceps surae, is well established. However, there are no published data available for tibialis posterior - a muscle that plays an important role in controlling foot motion. The purpose of this study was to characterise the electromyographic timing and amplitude of selected lower limb muscles across five walking speeds. Thirty young adults were instructed to walk barefoot while electromyographic activity was recorded from tibialis posterior and peroneus longus via intramuscular electrodes, and medial gastrocnemius and tibialis anterior via surface electrodes. At faster walking speeds, peak electromyographic amplitude increased systematically during the contact and midstance/propulsion phases. Changes in the time of peak amplitude were also observed for tibialis posterior, tibialis anterior and peroneus longus activity; however, these were muscle and phase specific. During contact phase, peak electromyographic amplitude for tibialis posterior and peroneus longus was similar across very slow to slow walking speeds. During midstance/propulsion phase, peak electromyographic amplitude for tibialis posterior and medial gastrocnemius was similar across very slow to slow walking speeds. These findings may reflect a relatively higher than expected demand for peroneus longus and tibialis posterior to assist with medio-lateral foot stability at very slow speeds. Similarly, peak amplitude of medial gastrocnemius was also relatively unchanged at the very slow speed, presumably to compensate for the reduced forward momentum. The data presented in this study may serve as a reference for comparing similarly matched participants with foot deformity and/or pathological gait.

Methodological aspects of EEG and body dynamics measurements during motion

EEG involves the recording, analysis, and interpretation of voltages recorded on the human scalp which originate from brain gray matter. EEG is one of the most popular methods of studying and understanding the processes that underlie behavior. This is so, because EEG is relatively cheap, easy to wear, light weight and has high temporal resolution. In terms of behavior, this encompasses actions, such as movements that are performed in response to the environment. However, there are methodological difficulties which can occur when recording EEG during movement such as movement artifacts. Thus, most studies about the human brain have examined activations during static conditions. This article attempts to compile and describe relevant methodological solutions that emerged in order to measure body and brain dynamics during motion. These descriptions cover suggestions on how to avoid and reduce motion artifacts, hardware, software and techniques for synchronously recording EEG, EMG, kinematics, kinetics, and eye movements during motion. Additionally, we present various recording systems, EEG electrodes, caps and methods for determinating real/custom electrode positions. In the end we will conclude that it is possible to record and analyze synchronized brain and body dynamics related to movement or exercise tasks.

Real-time knee adduction moment feedback training using an elliptical trainer

The external knee adduction moment (EKAM) is associated with knee osteoarthritis (OA) in many aspects including presence, progression, and severity of knee OA. Despite of its importance, there is a lack of EKAM estimation methods that can provide patients with knee OA real-time EKAM biofeedback for training and clinical evaluations without using a motion analysis laboratory. A practical real-time EKAM estimation method, which utilizes kinematics measured by a simple six degree-of-freedom goniometer and kinetics measured by a multi-axis force sensor underneath the foot, was developed to provide real-time feedback of the EKAM to the patients during stepping on an elliptical trainer, which can potentially be used to control and alter the EKAM. High reliability (ICC(2,1): 0.9580) of the real-time EKAM estimation method was verified through stepping trials of seven subjects without musculoskeletal disorders. Combined with advantages of elliptical trainers including functional weight-bearing stepping and mitigation of impulsive forces, the real-time EKAM estimation method is expected to help patients with knee OA better control frontal plane knee loading and reduce knee OA development and progression.

Effects of adding a virtual reality environment to different modes of treadmill walking

Differences in gait between overground and treadmill walking are suggested to result from imposed treadmill speed and lack of visual flow. To counteract this effect, feedback-controlled treadmills that allow the subject to control the belt speed along with an immersive virtual reality (VR) have recently been developed. We studied the effect of adding a VR during both fixed speed (FS) and self-paced (SP) treadmill walking. Nineteen subjects walked on a dual-belt instrumented treadmill with a simple endless road projected on a 180° circular screen. A main effect of VR was found for hip flexion offset, peak hip extension, peak knee extension moment, knee flexion moment gain and ankle power during push off. A consistent interaction effect between VR and treadmill mode was found for 12 out of 30 parameters, although the differences were small and did not exceed 50% of the within subject stride variance. At FS, the VR seemed to slightly improve the walking pattern towards overground walking, with for example a 6.5mm increase in stride length. At SP, gait became slightly more cautious by adding a VR, with a 9.1mm decrease in stride length. Irrespective of treadmill mode, subjects rated walking with the VR as more similar to overground walking. In the context of clinical gait analysis, the effects of VR are too small to be relevant and are outweighed by the gains of adding a VR, such as a more stimulating experience and possibility of augmenting it by real-time feedback.

Neuromuscular constraints on muscle coordination during overground walking in persons with chronic incomplete spinal cord injury

OBJECTIVE

Incomplete spinal cord injury (iSCI) disrupts motor control and limits the ability to coordinate muscles for overground walking. Inappropriate muscle activity has been proposed as a source of clinically observed walking deficits after iSCI. We hypothesized that persons with iSCI exhibit lower locomotor complexity compared to able-body (AB) controls as reflected by fewer motor modules, as well as, altered module composition and activation.

METHODS

Eight persons with iSCI and eight age-matched AB controls walked overground at prescribed cadences. Electromyograms of fourteen single leg muscles were recorded. Non-negative matrix factorization was used to identify the composition and activation of motor modules, which represent groups of consistently co-activated muscles that accounted for 90% of variability in muscle activity.

RESULTS

Motor module number, composition, and activation were significantly altered in persons with iSCI as compared to AB controls during overground walking at self-selected cadences. However, there was no significant difference in module number between persons with iSCI and AB controls when cadence and assistive device were matched.

CONCLUSIONS

Muscle coordination during overground walking is impaired after chronic iSCI.

SIGNIFICANCE

Our results are indicative of neuromuscular constraints on muscle coordination after iSCI. Altered muscle coordination contributes to person-specific gait deficits during overground walking.

Speed-dependent reference joint trajectory generation for robotic gait support

For the control of actuated orthoses, or gait rehabilitation robotics, kinematic reference trajectories are often required. These trajectories, consisting of joint angles, angular velocities and accelerations, are highly dependent on walking-speed. We present and evaluate a novel method to reconstruct body-height and speed-dependent joint trajectories. First, we collected gait kinematics in fifteen healthy (middle) aged subjects (47-68), at a wide range of walking-speeds (0.5-5 kph). For each joint trajectory multiple key-events were selected (among which its extremes). Second, we derived regression-models that predict the timing, angle, angular velocity and acceleration for each key-event, based on walking-speed and the subject׳s body-height. Finally, quintic splines were fitted between the predicted key-events to reconstruct a full gait cycle. Regression-models were obtained for hip ab-/adduction, hip flexion/extension, knee flexion/extension and ankle plantar-/dorsiflexion. Results showed that the majority of the key-events were dependent on walking-speed, both in terms of timing and amplitude, whereas the body-height had less effect. The reconstructed trajectories matched the measured trajectories very well, in terms of angle, angular velocity and acceleration. For the angles the RMSE between the reconstructed and measured trajectories was 2.6°. The mean correlation coefficient between the reconstructed and measured angular trajectories was 0.91. The method and the data presented in this paper can be used to generate speed-dependent gait patterns. These patterns can be used for the control of several robotic gait applications. Alternatively they can assist the assessment of pathological gait, where they can serve as a reference for "normal" gait.

How gravity and muscle action control mediolateral center of mass excursion during slow walking: a simulation study

Maintaining mediolateral (ML) balance is very important to prevent falling during walking, especially at very slow speeds. The effect of walking speed on support and propulsion of the center of mass (COM) has been focus of previous studies. However, the influence of speed on ML COM control and the associated coupling with sagittal plane control remains unclear. Simulations of walking at very slow and normal speeds were generated for twelve healthy subjects. Our results show that gluteus medius (GMED) contributions to ML stability decrease, while its contributions to sagittal plane accelerations increase during very slow compared to normal walking. Simultaneously the destabilizing influence of gravity increases in ML direction at a very slow walking speed. This emphasizes the need for a tight balance between gravity and gluteus medius action to ensure ML stability. When walking speed increases, GMED has a unique role in controlling ML acceleration and therefore stabilizing ML COM excursion. Contributions of other muscles decrease in all directions during very slow speed. Increased contributions of these muscles are therefore required to provide for both stability and propulsion when walking speed increases.

Does visual feedback during walking result in similar improvements in trunk control for young and older healthy adults?

BACKGROUND

Most current applications of visual feedback to improve postural control are limited to a fixed base of support and produce mixed results regarding improved postural control and transfer to functional tasks. Currently there are few options available to provide visual feedback regarding trunk motion while walking. We have developed a low cost platform to provide visual feedback of trunk motion during walking. Here we investigated whether augmented visual position feedback would reduce trunk movement variability in both young and older healthy adults.

METHODS

The subjects who participated were 10 young and 10 older adults. Subjects walked on a treadmill under conditions of visual position feedback and no feedback. The visual feedback consisted of anterior-posterior (AP) and medial-lateral (ML) position of the subject's trunk during treadmill walking. Fourier transforms of the AP and ML trunk kinematics were used to calculate power spectral densities which were integrated as frequency bins "below the gait cycle" and "gait cycle and above" for analysis purposes.

RESULTS

Visual feedback reduced movement power at very low frequencies for lumbar and neck translation but not trunk angle in both age groups. At very low frequencies of body movement, older adults had equivalent levels of movement variability with feedback as young adults without feedback. Lower variability was specific to translational (not angular) trunk movement. Visual feedback did not affect any of the measured lower extremity gait pattern characteristics of either group, suggesting that changes were not invoked by a different gait pattern.

CONCLUSIONS

Reduced translational variability while walking on the treadmill reflects more precise control maintaining a central position on the treadmill. Such feedback may provide an important technique to augment rehabilitation to minimize body translation while walking. Individuals with poor balance during walking may benefit from this type of training to enhance path consistency during over-ground locomotion.

Development of an elliptical trainer with real-time knee adduction moment feedback

The external knee adduction moment (EKAM) is associated with knee osteoarthritis (OA) in many aspects including its presence, progression, and severity. Despite of its importance, there is a lack of EKAM estimation methods that can provide patients with knee OA a real-time EKAM biofeedback during training and be used for routine clinical evaluations outside motion analysis laboratories. Thus, a practical real-time EKAM estimation method, which utilizes kinematic variables from a simple 6-DOF goniometer, was developed to provide patients with knee OA a real-time feedback of their EKAM during stepping on elliptical trainers (ETs) to reduce the damaging EKAM. Feasibility of the proposed method was verified on seven healthy subjects. Combined with advantages of ETs (e.g., functional weight-bearing stepping, mitigation of delivery of impulsive forces), the real-time EKAM estimation method is expected to benefit patients with knee OA.

Treadmill walking speed and survival prediction in men with cardiovascular disease: a 10-year follow-up study

OBJECTIVE

To determine whether the walking speed maintained during a 1 km treadmill test at moderate intensity predicts survival in patients with cardiovascular disease.

DESIGN

Population-based prospective study.

SETTING

Outpatient secondary prevention programme in Ferrara, Italy.

PARTICIPANTS

1255 male stable cardiac patients, aged 25-85 years at baseline.

MAIN OUTCOME MEASURES

Walking speed maintained during a 1 km treadmill test, measured at baseline and mortality over a median follow-up of 8.2 years.

RESULTS

Among 1255 patients, 141 died, for an average annual mortality of 1.4%. Of the variables considered, the strongest predictor of all-cause mortality was walking speed (95% CI 0.45 to 0.75, p<0.0001). Based on the average speed maintained during the test, participants were subdivided into quartiles and mortality risk adjusted for confounders was calculated. Compared to the slowest quartile (average walking speed 3.4 km/h), the relative mortality risk decreased for the second, third and fourth quartiles (average walking speed 5.5 km/h), with HRs of 0.73 (95% CI 0.46 to 1.18); 0.54 (95% CI 0.31 to 0.95) and 0.20 (95% CI 0.07 to 0.56), respectively (p for trend <0.0001). Receiver operating curve analysis showed an area under the curve of 0.71 (p<0.0001) and the highest Youden index (0.35) for a walking speed of 4.0 km/h.

CONCLUSIONS

The average speed maintained during a 1 km treadmill walking test is inversely related to survival in patients with cardiovascular disease and is a simple and useful tool for stratifying risk in patients undergoing secondary prevention and cardiac rehabilitation programmes.

Gender differences in offaxis neuromuscular control during stepping under a slippery condition

PURPOSE

Females are at greater risks of musculoskeletal injuries than are males, which may be related to decreased neuromuscular control in axial and/or frontal planes, offaxis neuromuscular control. The objective of this study was to investigate gender differences in offaxis neuromuscular control during stepping under a slippery condition.

METHODS

Forty-three healthy subjects (21 males and 22 females) performed different stepping tasks under a slippery condition, namely, free pivoting task (FPT) to control axial plane pivoting, free sliding task (FST) to control frontal plane sliding, and free pivoting and sliding task (FPST) to control axial pivoting, and frontal sliding on a custom-made offaxis elliptical trainer.

RESULTS

Compared to males, females showed significantly higher pivoting instability, higher max internal and external pivoting angles, higher mean max medial and lateral sliding distance, and higher entropy of time to peak EMG in the medial and lateral gastrocnemius muscles during the FPST and higher entropy of time to peak EMG in the lateral gastrocnemius muscle during the FPT and FST.

CONCLUSIONS

The findings may help us understand potential injury risk factors associated with gender differences, and provide a basis for developing targeted neuromuscular training to improve offaxis neuromuscular control, and reduce musculoskeletal injuries associated with excessive offaxis loadings.

Referent body weight values in over ground walking, over ground jogging, treadmill jogging, and elliptical exercise

OBJECTIVES

I. To evaluate average percentage body weight (APBW) values and weight-bearing distribution percentages (WBDP) between four common sports activities in a referent adult population. II. To suggest clinical implications.

DESIGN

Original research study.

SETTING

Lerner Sports Center, Hebrew University, Mount Scopus, Jerusalem, Israel.

PARTICIPANTS

Seventy-five asymptomatic volunteers, mean age=33.5 (19-72) years SD=15.1, mean weight (kg)=70.7 (43-113) SD=14.1.

INTERVENTIONS

Four tests were conducted: 1. Overground walking (OGW) over a 20 m distance, 2. Overground jogging (OGJ) over a 20 m distance, 3. Treadmill jogging (TJ) at a constant speed of 8.5 km/h for a 15-second interval and 4. Elliptical exercise (EE) for a 20 second period at a resistance and incline level of 10, and a steady pace within the range of 70-95 steps/min.

MAIN OUTCOME MEASURE

The Smartstep™ weight-bearing gait analysis system.

RESULTS

The APBW value on the entire foot in OGW was 112% (SD=15.57), in OGJ, 201% (SD=31.24, in TJ, 175% (SD=25.48) and in EE, 73% (SD=13.8). Regarding WBDP, the swing phase in OGJ and TJ was significantly longer than the stance phase (p<0.05). OGW resulted in significantly less swing phase compared to OGJ and TJ (p<0.05).

CONCLUSIONS

EE significantly reduces weight-bearing as compared to other common functional and sporting activities. These findings may assist the rehabilitation team when considering returning individuals back to early activity following certain bony or soft tissue pathologies or lower-limb surgical procedures. This information is also useful from a repetitive loading standpoint (to prevent overuse injury) or for exercise recommendations for those at greater risk for exacerbating chronic joint pathology.

Mass affects lower extremity muscle activity patterns in children's gait

Overweight children demonstrate biomechanical differences during gait; however it is not known if these differences occur within active or passive tissue. The purpose of this study was to examine differences in lower extremity muscle activation patterns of children with different body mass during three walking speeds. Twenty children (8-12 years) were recruited and classified as overweight (OW), normal-weight (NW), or underweight (UW). Electromyography was recorded for vastus lateralis, semitendinosus, gastrocnemius, and tibialis anterior while participants walked on a treadmill at slow (SP), self-selected (SSP), and fast (FP) speeds. Differences in group and walking speed were analyzed for duration of muscle activation (presented as a percentage of stride, stance, or swing phases). Compared to OW, UW experienced greater duration of vastus lateralis and tibialis anterior activation during the swing phase. OW had greater duration of gastrocnemius activation during stride than UW. Increased walking speed resulted in greater duration of vastus lateralis activation for all groups. NW also exhibited greater duration of tibialis anterior activation at faster walking speeds. During FP, OW had greater duration of gastrocnemius activity during stance, but lower duration during swing. These findings are consistent with the idea that children with greater mass adopt a more passive gait strategy during swing to maximize energy recovery. Increased duration of gastrocnemius activity during stance also provides greater stability and stronger propulsion, which corroborates previous research. These findings help to understand the neuromuscular mechanisms associated with previous biomechanical findings in children's gait.

Self-paced versus fixed speed treadmill walking

Instrumented treadmills are increasingly used in gait research, although the imposed walking speed is suggested to affect gait performance. A feedback-controlled treadmill that allows subjects to walk at their preferred speed, i.e. functioning in a self-paced (SP) mode, might be an attractive alternative, but could disturb gait through accelerations of the belt. We compared SP with fixed speed (FS) treadmill walking, and also considered various feedback modes. Nineteen healthy subjects walked on a dual-belt instrumented treadmill. Spatio-temporal, kinematic and kinetic gait parameters were derived from both the average stride patterns and stride-to-stride variability. For 15 out of 70 parameters significant differences were found between SP and FS. These differences were smaller than 1cm, 1°, 0.2 Nm and 0.2 W/kg for respectively stride length and width, joint kinematics, moments and powers. Since this is well within the normal stride variability, these differences were not considered to be clinically relevant, indicating that SP walking is not notably affected by belt accelerations. The long-term components of walking speed variability increased during SP walking (43%, p<0.01), suggesting that SP allows for more natural stride variability. Differences between SP feedback modes were predominantly found in the timescales of walking speed variability, while the gait pattern was similar between modes. Overall, the lack of clinically significant differences in gait pattern suggests that SP walking is a suitable alternative to fixed speed treadmill walking in gait analysis.

Self in motion: sensorimotor and cognitive mechanisms in gait agency

Acting in our environment and experiencing ourselves as conscious agents are fundamental aspects of human selfhood. While large advances have been made with respect to understanding human sensorimotor control from an engineering approach, knowledge about its interaction with cognition and the conscious experience of movement (agency) is still sparse, especially for locomotion. We investigated these relationships by using life-size visual feedback of participants' ongoing locomotion, thereby extending agency research previously limited to goal-directed upper limb movements to continuous movements of the entire body. By introducing temporal delays and cognitive loading we were able to demonstrate distinct effects of bottom-up visuomotor conflicts as well as top-down cognitive loading on the conscious experience of locomotion (gait agency) and gait movements. While gait agency depended on the spatial and temporal congruency of the avatar feedback, gait movements were solely driven by its temporal characteristics as participants nonconsciously attempted to synchronize their gait with their avatar's gait. Furthermore, gait synchronization was suppressed by cognitive loading across all tested delays, whereas gait agency was only affected for selective temporal delays that depended on the participant's step cycle. Extending data from upper limb agency and auditory gait agency, our results are compatible with effector-independent and supramodal control of agency; they show that both mechanisms are dissociated from automated sensorimotor control and that cognitive loading further enhances this dissociation.

Agreement between temporal and spatial gait parameters from an instrumented walkway and treadmill system at matched walking speed

BACKGROUND

Commercially available instrumented treadmill systems that provide continuous measures of temporospatial gait parameters have recently become available for clinical gait analysis. This study evaluated the level of agreement between temporospatial gait parameters derived from a new instrumented treadmill, which incorporated a capacitance-based pressure array, with those measured by a conventional instrumented walkway (criterion standard).

METHODS

Temporospatial gait parameters were estimated from 39 healthy adults while walking over an instrumented walkway (GAITRite(®)) and instrumented treadmill system (Zebris) at matched speed. Differences in temporospatial parameters derived from the two systems were evaluated using repeated measures ANOVA models. Pearson-product-moment correlations were used to investigate relationships between variables measured by each system. Agreement was assessed by calculating the bias and 95% limits of agreement.

RESULTS

All temporospatial parameters measured via the instrumented walkway were significantly different from those obtained from the instrumented treadmill (P<.01). Temporospatial parameters derived from the two systems were highly correlated (r, 0.79-0.95). The 95% limits of agreement for temporal parameters were typically less than ±2% of gait cycle duration. However, 95% limits of agreement for spatial measures were as much as ±5cm.

CONCLUSIONS

Differences in temporospatial parameters between systems were small but statistically significant and of similar magnitude to changes reported between shod and unshod gait in healthy young adults. Temporospatial parameters derived from an instrumented treadmill, therefore, are not representative of those obtained from an instrumented walkway and should not be interpreted with reference to literature on overground walking.