Walking Direction Research Articles

Pre- and unplanned walking turns in Parkinson’s disease – Effects of dopaminergic medication

Although dopaminergic medication improves functional mobility in individuals with Parkinson’s disease (PD), its effects on walking turns are uncertain. Our goals was to determine whether dopaminergic medication improves preplanned and unplanned walking turns in individuals with PD, compared to healthy controls. Nineteen older adults with mild-to-moderate PD and 17 healthy controls performed one of the following three tasks, presented randomly: walking straight, or walking and turning 180° to the right or left. The walking direction was visually cued before starting to walk (preplanned) or after (unplanned, i.e., 0.6m before reaching the turning point). Subjects with PD were assessed off dopaminergic medication (OFF) and on dopaminergic medication (ON) medication. Turning strategy (step and spin turns), turning performance (turning distance and body rotation) and walking pattern were analyzed for three turning steps. Irrespective of medication state and turning condition, step and spin turns followed a nearly 50:50 distribution. After intake of dopaminergic medication, subjects with PD increased their turning distance but not the amount of body rotation or their walking pattern. Compared to controls, turning impairments in subjects with PD remained while ON medication and problems regulating step width were the most prominent features of their walking pattern. Specifically, subjects with PD turned with narrower cross-over steps, i.e. when the external foot crossed over the line of progression of the internal leg. We conclude that turning impairments remained even after dopaminergic medication and problems modulating step width appears to be a critical feature for turning in PD.

Analysis of Balance during Functional Walking in Stroke Survivors.

BackgroundAn important objective of rehabilitation care is to regain adequate balance function to safely ambulate in community. However, in rehabilitation practice, it remains unclear if a stroke survivor functionally recovers by restitution or by learning to compensate for the lack of restoration of body function. Aim of this study is to propose and evaluate methods for the objective evaluation of balance during functional walking in stroke survivors.MethodsStroke survivors performed twice a Timed “Up & Go” (TUG) test. Ground reaction forces and position changes of both feet were measured using instrumented shoes and used to estimate the position of the center of mass (CoM). Balance control and efficiency metrics were defined to evaluate functional walking under variable conditions. Metrics were corrected based on the instantaneous velocity direction of CoM. Intra- and inter-participant variations for different phases of the TUG test were examined. Metrics were related to the Berg balance scale (BBS).ResultsParticipants with higher BBS scores show a more efficient walking pattern. Their walking velocity and walking direction is less variable and they are more frequently unstable when walking in a straight line or when turning. Furthermore, the less affected participants are able to move their CoM more towards their affected side.DiscussionWe developed and demonstrated a method to assess walking balance of stroke survivors. System design and evaluation methods allow balance evaluation during functional walking in daily life. Some presented metrics show correlations with BBS scores. Clear inter- and intra-patient variations in metric values are present that cannot be explained by BBS scores, which supports the additional value of the presented system. Presented methods may be used for objective evaluation of restitution and compensation of walking balance and have a potential application in individual evidence-based therapy.

Design of adaptive biometric gait recognition algorithm with free walking directions

Gait is one of well-identified biometrics that has been broadly applied for human identification at a distance based on their motion style. However, the current gait recognition might have difficulties due to changing the viewing angles anduncertainty associated with gait signature extraction. This study deals with the design of an intelligent gait recognition system that tackles the problems mentioned above. This system is based on spatial-domain energy deviation image as a gait signature by adopting clustering technique to estimate the gait period in the gait sequence with arbitrary walking directions. To further improve the performance of the proposed system, interval type-2 fuzzy K-nearest neighbor classifier is used to diminish the effect of uncertainty formed by variations in gait signature extraction. Interval type-2 fuzzy set is involved in extending themembership values of each gait signature by using several initial K in order to handle and manage uncertainty that exists in choosing the initial value K. The proposed method realises the reduction in the dimensions of the gait feature and over-fitting. The comprehensive analyses reveal that the proposed algorithm can significantly enhance the multiple view gait recognition performance when being matched to the similar methods in the literature.

Control Strategy for Modifiable Bipedal Walking on Unknown Uneven Terrain

Previous walking pattern generation methods could generate walking patterns that allow only straight walking on flat and uneven terrain. They were unable to generate modifiable walking patterns whereby the sagittal and lateral step lengths and walking direction can be changed at every footstep. This paper proposes a novel walking pattern generation method to realize modifiable walking of humanoid robots on unknown uneven terrain. The proposed method employs a walking pattern generator based on the 3-D linear inverted pendulum model (LIPM), which enables a humanoid robot to vary its walking patterns at every footstep. A control strategy for walking on unknown uneven terrain is proposed. Virtual spring-damper (VSD) models are used to compensate for the disturbances that occur between the robot and the terrain when the robot walks on uneven terrain with unknown height. In addition, methods for generating the foot and vertical center of mass (COM) of the 3-D LIPM trajectories are developed to realize stable walking on unknown uneven terrain. The proposed method is implemented on a small-sized humanoid robot platform, DARwIn-OP and its effectiveness is demonstrated experimentally.

Performance of real-world functional vision tasks by blind subjects improves after implantation with the Argus® II retinal prosthesis system.

BackgroundThe main objective of this study was to test Argus II subjects on three real‐world functional vision tasks.DesignThe study was designed to be randomized and prospective. Testing was conducted in a hospital/research laboratory setting at the various participating centres.ParticipantsTwenty eight Argus II subjects, all profoundly blind, participated in this study.MethodsSubjects were tested on the three real‐world functional vision tasks: Sock Sorting, Sidewalk Tracking and Walking Direction Discrimination taskMain Outcome MeasuresFor the Sock Sorting task, percentage correct was computed based on how accurately subjects sorted the piles on a cloth‐covered table and on a bare table. In the Sidewalk Tracking task, an ‘out of bounds’ count was recorded, signifying how often the subject veered away from the test course. During the Walking Direction Discrimination task, subjects were tested on the number of times they correctly identified the direction of testers walking across their field of view.ResultsThe mean percentage correct OFF versus ON for the Sock Sorting task was found to be significantly different for both testing conditions (t‐test, P < 0.01). On the Sidewalk Tracking task, subjects performed significantly better with the system ON than they did with the system OFF (t‐test, P < 0.05). Eighteen (18) of 27 subjects (67%) performed above chance with the system ON, and 6 (22%) did so with system OFF on the Walking Direction Discrimination task.ConclusionsArgus II subjects performed better on all three tasks with their systems ON than they did with their systems OFF.

Correction of hip internal rotation in walking cerebral palsy adolescent using a soft tissue procedure an alternative to femoral rotation osteotomy

Hip internal rotation (HIR) during gait is one of the main functional disorders related to cerebral palsy (CP) in children. Most of the procedures proposed rotational osteotomy of the femur (FRO), (and/or tibia). However, multilevel surgery (SEMLS) including bone procedure, implicates more difficult and longer rehabilitation. When bone deformity is moderate, the authors hypothesized that FRO could be avoided. They developed a soft tissues procedure to improve HIR. The aim of the study was assessment of the procedure. In walking CP the authors selected patients presented with femoral anteversion less than 40° who were proposed for soft tissue procedure alone. Patients were previously tested with botulinum toxin injection of the hamstring muscles. The soft tissue procedure was: lengthening of semimembranosus, transfer of semitendinosus associated with tenotomy of the gracilis and gluteus minimus muscles. All the patients with pre and postoperative full data (clinical, kinematics and kinetics) were included. Data (i.e. foot intoeing, dynamic hip internal rotation in stance phase, hip rotation moment) were collected. Follow-up was at least one year after SEMLS. We collected 20 selected patients with 24 lower limbs studied. Rotation of the pelvis did not differ significantly ( P = 0.21). Hip rotation in stance phase (50%), presented significant improvement from 16.5° intoeing to 0.5° external rotation ( P < 0.0001). Feet angulation related to walking direction was significantly improved, from 13° intoeing to 0.5° external rotation ( P < 0.0001). HIR is a frequent gait disorder in CP. The etiology of the HIR seems to be related to muscles contractures and spasticity. Recently, soft tissue procedures were reported of interest in HIR. The soft tissue procedures presented improved significantly HIR making pointless FRO. Rehabilitation should be making easier. Relevance: the authors improve significantly the HIR using a soft tissues procedure and advocated reducing indication for FRO in internal rotation of lower limbs in order to make easier rehabilitation after SEMLS.

Constraint-based hierarchical motion analysis for biological movements

Movements of the human body are comprised of multiple motion components organized in a hierarchical manner. For example, the motion of a foot joint is nested within a moving leg, which is nested within a moving body. It remains unknown how humans discover the hierarchical structure representing bodily movements, and what fundamental constraints underlie the formation of motion structure. A non-parametric Bayesian model was developed to infer the hierarchical motion structures that can generate observed visual input. Many different hierarchical motion structures would be consistent with observed bodily movements, but three types of constraints sufficed to resolve ambiguity: a generic prior on object parsing (favoring simpler hierarchical structures), a generic prior on spatially smooth motion within a component (resulting from rigid movements of individual parts), and a body-specific constraint (certain joints move in coordination based on body structure). This generative model can account for a range of findings in the literature on biological motion perception, including better recognition performance for an upright than an inverted point-light walker, above-chance performance in discriminating walking direction for a spatially-scrambled and phase-scrambled walker (Troje & Westhoff, 2006, Exp. 2), the special contribution of foot movements in discriminating walking direction (Troje & Westhoff, 2006, Exp. 3), the variation in recognition accuracy across different action categories (Dittrich, 1993). The model also reveals how body structure interacts with the organization of motion components to form efficient action representations. When the body constraint was included in the formation of hierarchical structure, the representation space of actions was altered to cluster similar action types, but enlarge the distances of different actions. This finding suggests that the body constraint plays an important role in organizing motion information into a hierarchical structure, thereby increasing the representational power of an action space. Meeting abstract presented at VSS 2016

Smartphone Inertial Sensor-Based Indoor Localization and Tracking With iBeacon Corrections

The Global Positioning System (GPS) can be readily used for outdoor localization, but GPS signals are degraded in indoor environments. How to develop a robust and accurate indoor localization system is an emergent task. In this paper, we propose a smartphone inertial sensor-based indoor localization and tracking system with occasional iBeacon corrections. Some important issues in a smartphone-based pedestrian dead reckoning (PDR) approach, i.e., step detection, walking direction estimation, and initial point estimation, are studied. One problem of the PDR approach is the drift with walking distance. We apply a recent technology, iBeacon, to occasionally calibrate the drift of the PDR approach. By analyzing iBeacon measurements, we define an efficient calibration range where an extended Kalman filter is utilized. The proposed localization and tracking system can be implemented in resource-limited smartphones. To evaluate the performance of the proposed approach, real experiments under two different environments have been conducted. The experimental results demonstrated the effectiveness of the proposed approach. We also tested the localization accuracy with respect to the number of iBeacons.

Action Congruency Influences Crowding When Discriminating Biological Motion Direction.

Identification and discrimination of peripheral stimuli are often difficult when a few stimuli adjacent to the target are present (crowding). Our previous study showed that crowding occurs for walking direction discrimination of a biological motion stimulus. In the present study, we attempted to examine whether action congruency between the target and flankers would influence the crowding effect on biological motion stimuli. Each biological motion stimulus comprised one action (e.g., walking, throwing wastepaper, etc.) and was rotated in one of five directions around the vertical axis. In Experiment 1, observers discriminated between the directions of the target stimulus actions, which were surrounded by two flankers in the peripheral visual field. The crowding effect was stronger when the flankers performed the same action as the target and the directions differed. The congruency of action type enhanced the crowding effect in the direction-discrimination task. In Experiment 2, observers discriminated between action types of target stimuli. The crowding effect for the action-discrimination task was not modulated by the congruency of action direction. Thus, identical actions induced a larger crowding effect for action-direction discrimination, but congruent directions did not influence crowding for action-type discrimination. These results suggest that the processes involved in direction discrimination of biological motion are partially distinct from action discrimination processes.

Backward-walking biological motion orients attention to moving away instead of moving toward.

Walking direction is an important attribute of biological motion because it carries key information, such as the specific intention of the walker. Although it is known that spatial attention is guided by walking direction, it remains unclear whether this attentional shift is reflexive (i.e., constantly shifts to the walking direction) or not. A richer interpretation of this effect is that attention is guided to seek the information that is necessary to understand the motion. To investigate this issue, we examined how backward-walking biological motion orients attention because the intention of walking backward is usually to avoid something that walking forward would encounter. The results showed that attention was oriented to the walking-away direction of biological motion instead of the walking-toward direction (Experiment 1), and this effect was not due to the gaze direction of biological motion (Experiment 2). Our findings suggest that the attentional shift triggered by walking direction is not reflexive, thus providing support for the rich interpretation of these attentional effects.

Gait Planning of Omnidirectional Walk on Inclined Ground for Biped Robots

When a biped robot moves about in a physical environment, it may encounter inclined ground. Biped walking on inclined ground still remains challenging for biped robots. Previous studies have discussed biped walking on inclined ground along specific directions. However, omnidirectional walk on inclined ground has rarely been investigated. In this paper, we propose a gait pattern generation method for omnidirectional biped walking on inclined ground. First, a model that describes the motion of biped walking on inclined ground uniformly with two angle parameters is proposed. A mathematical relationship between motions in the sagittal and coronal planes of the biped robot are presented. Then, based on nonorthogonal motion decoupling, a method that generates gait patterns for omnidirectional walking with a double support phase for biped robots is proposed. The trajectories of each foot are designated by the walking speed, step length, and walking direction. The motion trajectory of the center of mass (CoM) of the robot is planned using a linear inverted pendulum model in the sagittal and coronal planes. The motion of CoM in the sagittal and coronal planes is constrained in parallel to the gradient vector of the inclined ground and the horizontal plane, respectively. Finally, the effectiveness of the proposed gait planning method for biped walking on is validated by simulations and experiments with an actual biped robot.

Macroscopic modeling of pedestrian flow based on a second-order predictive dynamic model

This work presents a second-order predictive dynamic model for pedestrian flow to investigate movement patterns and non-equilibrium phenomena in pedestrian traffic. This model is described as a system of nonlinear hyperbolic conservation laws with relaxation under the hypothesis that a group of pedestrians are regarded as a continuous anisotropic medium. The desired or preferred walking direction of pedestrians is assumed to minimize the total actual walking cost based on predictive traffic conditions, which satisfies the predictive dynamic user-equilibrium assignment. To solve this model, a cell-centered finite volume method for hyperbolic conservation laws coupled with a self-adaptive method of successive averages for an arisen discrete fixed point problem is adopted. The proposed model and algorithm are validated by comparing the results carried out by the model with experimental observations under non-congested conditions. Numerical examples are designed to investigate macroscopic features and path-choice behaviors of pedestrian flow. Numerical results indicate that the proposed model is able to reproduce some complex nonlinear phenomena in pedestrian traffic, such as the formation of congestions and stop-and-go waves.

PEDESTRIAN DETECTION BY LASER SCANNING AND DEPTH IMAGERY

Pedestrian flow is much less regulated and controlled compared to vehicle traffic. Estimating flow parameters would support many safety, security or commercial applications. Current paper discusses a method that enables acquiring information on pedestrian movements without disturbing and changing their motion. Profile laser scanner and depth camera have been applied to capture the geometry of the moving people as time series. Procedures have been developed to derive complex flow parameters, such as count, volume, walking direction and velocity from laser scanned point clouds. Since no images are captured from the faces of pedestrians, no privacy issues raised. The paper includes accuracy analysis of the estimated parameters based on video footage as reference. Due to the dense point clouds, detailed geometry analysis has been conducted to obtain the height and shoulder width of pedestrians and to detect whether luggage has been carried or not. The derived parameters support safety (e.g. detecting critical pedestrian density in mass events), security (e.g. detecting prohibited baggage in endangered areas) and commercial applications (e.g. counting pedestrians at all entrances/exits of a shopping mall).

PEDESTRIAN DETECTION BY LASER SCANNING AND DEPTH IMAGERY

Abstract. Pedestrian flow is much less regulated and controlled compared to vehicle traffic. Estimating flow parameters would support many safety, security or commercial applications. Current paper discusses a method that enables acquiring information on pedestrian movements without disturbing and changing their motion. Profile laser scanner and depth camera have been applied to capture the geometry of the moving people as time series. Procedures have been developed to derive complex flow parameters, such as count, volume, walking direction and velocity from laser scanned point clouds. Since no images are captured from the faces of pedestrians, no privacy issues raised. The paper includes accuracy analysis of the estimated parameters based on video footage as reference. Due to the dense point clouds, detailed geometry analysis has been conducted to obtain the height and shoulder width of pedestrians and to detect whether luggage has been carried or not. The derived parameters support safety (e.g. detecting critical pedestrian density in mass events), security (e.g. detecting prohibited baggage in endangered areas) and commercial applications (e.g. counting pedestrians at all entrances/exits of a shopping mall).

Generative rules of Drosophila locomotor behavior as a candidate homology across phyla.

The discovery of shared behavioral processes across phyla is a significant step in the establishment of a comparative study of behavior. We use immobility as an origin and reference for the measurement of fly locomotor behavior; speed, walking direction and trunk orientation as the degrees of freedom shaping this behavior; and cocaine as the parameter inducing progressive transitions in and out of immobility. We characterize and quantify the generative rules that shape Drosophila locomotor behavior, bringing about a gradual buildup of kinematic degrees of freedom during the transition from immobility to normal behavior, and the opposite narrowing down into immobility. Transitions into immobility unfold via sequential enhancement and then elimination of translation, curvature and finally rotation. Transitions out of immobility unfold by progressive addition of these degrees of freedom in the opposite order. The same generative rules have been found in vertebrate locomotor behavior in several contexts (pharmacological manipulations, ontogeny, social interactions) involving transitions in-and-out of immobility. Recent claims for deep homology between arthropod central complex and vertebrate basal ganglia provide an opportunity to examine whether the rules we report also share common descent. Our approach prompts the discovery of behavioral homologies, contributing to the elusive problem of behavioral evolution.

VELOCITY-BASED EGRESS MODEL FOR THE ANALYSIS OF EVACUATION PROCESS ON PASSENGER SHIPS

This study presents a velocity-based egress model, which takes into account different aspects of human behavior in an emergency situation, for the evacuation analysis on passenger ships. It was supposed that the egress model consists of three behaviors: individual, crowd, and emergency behavior. The individual behavior was represented by the body shape, walking speed, walking direction, and rotation of each passenger. The basic walking direction of each passenger was obtained as a solution to the shortest distance route to a destination using a visibility graph. The crowd behavior of the passengers was composed of two components: one is a flock behavior, a form of collective behavior of a large number of interacting passengers with a common group objective, and the other is a leader- following behavior, which causes one or more passengers to follow another moving passenger who is designated as the leader. The emergency behavior of the passengers was represented by a counterflow-avoiding behavior to avoid collision with other passengers walking in the opposite direction. Eleven basic tests and 2 examples specified in International Maritime Organization Maritime Safety Committee/Circulation 1238 were conducted, and it was confirmed that all the requirements of such tests had been met.

Ambulatory assessment of walking balance after stroke using instrumented shoes.

BackgroundFor optimal guidance of walking rehabilitation therapy of stroke patients in an in-home setting, a small and easy to use wearable system is needed. In this paper we present a new shoe-integrated system that quantifies walking balance during activities of daily living and is not restricted to a lab environment. Quantitative parameters were related to clinically assessed level of balance in order to assess the additional information they provide.MethodsData of 13 participants who suffered a stroke were recorded while walking 10 meter trials and wearing special instrumented shoes. The data from 3D force and torque sensors, 3D inertial sensors and ultrasound transducers were fused to estimate 3D (relative) position, velocity, orientation and ground reaction force of each foot. From these estimates, center of mass and base of support were derived together with a dynamic stability margin, which is the (velocity) extrapolated center of mass with respect to the front-line of the base of support in walking direction. Additionally, for each participant step lengths and stance times for both sides as well as asymmetries of these parameters were derived.ResultsUsing the proposed shoe-integrated system, a complete reconstruction of the kinematics and kinetics of both feet during walking can be made. Dynamic stability margin and step length symmetry were not significantly correlated with Berg Balance Scale (BBS) score, but participants with a BBS score below 45 showed a small-positive dynamic stability margin and more asymmetrical step lengths. More affected participants, having a lower BBS score, have a lower walking speed, make smaller steps, longer stance times and have more asymmetrical stance times.ConclusionsThe proposed shoe-integrated system and data analysis methods can be used to quantify daily-life walking performance and walking balance, in an ambulatory setting without the use of a lab restricted system. The presented system provides additional insight about the balance mechanism, via parameters describing walking patterns of an individual subject. This information can be used for patient specific and objective evaluation of walking balance and a better guidance of therapies during the rehabilitation.Trial registrationThe study protocol is a subset of a larger protocol and registered in the Netherlands Trial Registry, number NTR3636.

Acute and Long-Term Effects of Multidirectional Treadmill Training on Gait and Balance in Parkinson Disease

BackgroundTreadmill training has been shown to be a promising rehabilitation strategy for improving gait and balance in persons with Parkinson disease (PD). Most studies have involved only forward walking as an intervention. The effects of multidirectional treadmill (forward, backward, and left and right sideways) on gait and balance have not been reported. ObjectiveTo investigate the acute and long-term effects of multidirectional treadmill training (MDTT) on gait and balance in persons with PD, and to determine the optimal training duration. DesignSingle group, repeated-measures design. SettingResearch laboratory in a hospital. ParticipantsTen persons with PD (mean age 65.9 ± 7.4 years; average disease duration 3.90 ± 2.18 years). InterventionsMDTT was used. Participants walked forward, backward, and left and right sideways for 5-7 minutes in each direction at their fastest tolerated speed. The training was 3 days per week continuously for 8 weeks. Main Outcome MeasurementsGait speed, cadence, and stride length of forward, backward and sideways walks; time and number of steps to turn 360°; and the timed 5-step test and Timed Up-and-Go (TUG) test were performed after the first session of MDTT and every 2 weeks. Effect size of MDTT on each gait and balance variable was measured every 2 weeks for 8 weeks to determine the optimal training duration. Gait and balance variables after the first session of MDTT were compared to the baseline values (pre-MDTT) to study the acute effect of MDTT. ResultsStride length of forward, backward, and sideways walks improved immediately after 1 session of MDTT (P = .031, .012, and .001, respectively). The number of steps to turn and the timed 5-step test score decreased after the first session (P = .016, and .010, respectively). Six weeks of training was found to yield the largest mean effect size of all gait and balance variables. At 6 weeks of MDTT, gait speed of all walking directions (P = .001-.031), stride length of backward (P < .005) and sideways (P = .001) walks, cadence of sideways walk (P = .036), number of steps to turn (P = .014), and timed 5-step test (P = .033) improved from pre-MDTT measures. ConclusionsMDTT immediately improved gait and balance in persons with PD. Six weeks of MDTT might be the optimal training duration to improve gait and balance in the long term. Level of EvidenceIV

Dynamic Simulation of Modifiable Walking Pattern Generation to Handle Infeasible Navigational Commands for Humanoid Robots

The modifiable walking pattern generation (MWPG) algorithm can handle dynamic walking commands by changing the walking period, step length, and direction independently. When an infeasible command is given, the algorithm changes the command to a feasible one. After the feasibility of the navigational command is checked, it is translated into the desired center of mass (CM) state. To achieve the desired CM state, a reference CM trajectory is generated using predefined zero moment point (ZMP) functions. Based on the proposed algorithm, various complex walking patterns were generated, including backward and sideways walking. The effectiveness of the patterns was verified in dynamic simulations using the Webots simulator.

Functional Relevance of Relative Maintenance of Maximal Eccentric Quadriceps Torque in Healthy Old Adults

Background: Old referenced to young adults show a relative maintenance of maximal eccentric (RELM) compared to concentric muscle torque: ∼76 and ∼59%, respectively. However, it is unknown if RELM affords functional benefits in old adults. Objective: We examined if there is specificity between the two types of peak quadriceps torque (i.e., concentric and eccentric) and timed gait performance measured during level, ramp, and stair walking and if gait performance was higher in old adults with high versus low RELM. Methods: We measured peak concentric and eccentric quadriceps torque at 60 and 120°/s and timed gait at habitual and safe-fast speeds in healthy young (age 22.7 years, n = 24) and old (age 70.0 years, n = 21) adults. Results: Comparable to previous studies, RELM was 21%, but instead of the anticipated specificity, we found that concentric compared with eccentric torque was more strongly associated with gait performance than eccentric torque, independently of walking direction and age (R² = 0.16: eccentric vs. descending gaits; R² = 0.17: eccentric vs. ascending gaits; R² = 0.45: concentric vs. descending gaits; R² = 0.56: concentric vs. ascending gaits, n = 45, all p < 0.01). Furthermore, old adults (n = 10) with ∼30% greater than normal levels of RELM (n = 11) ambulated at similar velocities measured on level and inclined surfaces. Conclusion: Normal and 30% above normal levels of RELM do not seem to increase or predict healthy old adults' gait performance on level and inclined surfaces. Future work should examine if RELM is associated with a heightened performance in other measures of neuromuscular function, such as gait biomechanics, muscle activation, as well as rate and control of voluntary force development in old adults with high or low mobility.