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

The impact of ankle-foot orthotics on selective motor control during gait in children and adolescents with cerebral palsy

BACKGROUND

Children with cerebral palsy (CP) often exhibit altered selective motor control during gait (SMCg). Ankle-foot-orthoses (AFOs) are used in this population to improve gait, by reducing the degrees of freedom at the ankle joint. However, the specific impact of AFOs on SMCg and whether this effect is more related to gait deviations or motor development remains unclear.

RESEARCH QUESTION

Do AFOs impact SMCg, and is the change related to joint kinematics or age?

METHODS

Gait analysis data from 53 children and adolescents with spastic CP, walking both barefoot and with AFOs, were included. Electromyography data from six lower-limb muscles, and lower limb joint kinematics were analyzed for both walking conditions. SMCg was quantified by the total variance in electromyography activity accounted for by one synergy (tVAF1), where an increase in tVAF1 indicates a decrease in SMCg. Kinematic gait deviation was assessed using the Gait-Profile-Score (GPS) and sagittal plane ankle Gait-Variable-Score (ankle-GVS). All analyses were performed for the more clinically involved leg only.

RESULTS

Walking with AFOs resulted in a mean increase in tVAF1 of 0.02±0.07 (p=0.015) and a median increase in ankle-GVS of 3.4º (p>0.001). No significant changes were observed in GPS, and no correlation was found between the changes in tVAF1 and ankle-GVS. A significant positive moderate correlation was found between the change in tVAF1 and age, even with ankle-GVS as a covariate (r=0.45; p>0.001).

SIGNIFICANCE

Walking with an AFO resulted in a small decrease in SMCg, with large inter-participant variability. Younger participants showed a greater decrease in SMCg, which may indicate greater neuromuscular plasticity in early developmental stages.

Alterations in stride-to-stride fluctuations in patients with chronic obstructive pulmonary disease during a self-paced treadmill 6-minute walk test

Evaluating variability and stability using measures for nonlinear dynamics may provide additional insight into the structure of the locomotor system, reflecting the neuromuscular system's organization of gait. This is in particular of interest when this system is affected by a respiratory disease and it's extrapulmonary manifestations. This study assessed stride-to-stride fluctuations and gait stability in patients with chronic obstructive pulmonary disease (COPD) during a self-paced, treadmill 6-minute walk test (6MWT) and its association with clinical outcomes. In this cross-sectional study, eighty patients with COPD (age 62±7y; forced expiratory volume in first second 56±19%predicted) and 39 healthy older adults (62±7y) were analyzed. Gait parameters including stride-to-stride fluctuations (coefficient of variation (CoV), predictability (sample entropy) and stability (Local Divergence Exponent (LDE)) were calculated over spatiotemporal parameters and center of mass velocity. Independent t-test, Mann-Whitney U test and ANCOVA analyses were conducted. Correlations were calculated between gait parameters, functional mobility using Timed Up and Go Test, and quadriceps muscle strength using dynamometry. Patients walked slower than healthy older adults. After correction for Speed, patients demonstrated increased CoV in stride length (F(1,116) = 5.658, p = 0.019), and increased stride length predictability (F(1,116) = 3.959, p = 0.049). Moderate correlations were found between mediolateral center of mass velocity LDE and normalized maximum peak torque (ρ = -0.549). This study showed that patients with COPD demonstrate alterations in stride length fluctuations even when adjusted for walking speed, highlighting the potential of nonlinear measures to detect alterations in gait function in patients with COPD. Association with clinical outcomes were moderate to weak, indicating that these clinical test are less discriminative for gait alterations.

Gait patterns during overground and virtual omnidirectional treadmill walking

BACKGROUND

Omnidirectional treadmills (ODTs) offer a promising solution to the virtual reality (VR) locomotion problem, which describes the mismatch between visual and somatosensory information and contributes to VR sickness. However, little is known about how walking on ODTs impacts the biomechanics of gait. This project aimed to compare overground and ODT walking and turning in healthy young adults.

METHODS

Fifteen young adults completed forward walk, 180° turn, and 360° turn tasks under three conditions: (1) overground, (2) on the Infinadeck ODT in a virtual environment without a handrail, and (3) on the ODT with a handrail. Kinematic data for all walking trials were gathered using 3D optical motion capture.

RESULTS

Overall, gait speed was slower during ODT walking than overground. When controlling for gait speed, ODT walking resulted in shorter steps and greater variability in step length. There were no significant differences in other spatiotemporal metrics between ODT and overground walking. Turning on the ODT required more steps and slower rotational speeds than overground turns. The addition of the stability handrail to the ODT resulted in decreased gait variability relative to the ODT gait without the handrail.

CONCLUSION

Walking on an ODT resembles natural gait patterns apart from slower gait speed and shorter step length. Slower walking and shorter step length are likely due to the novelty of physically navigating a virtual environment which may result in a more conservative approach to gait. Future work will evaluate how older adults and those with neurological disease respond to ODT walking.

Recreational cycling provides greater satisfaction and flow in an immersive virtual environment than in real life

BACKGROUND

As the state of satisfaction and flow involved in the physical activity (PA) determines future training commitment, it is undoubtedly very important to study the factors influencing the attractiveness of PA. One of such factors is the usage of virtual reality (VR) technology which creates opportunities for its users to practice various forms of PA in a altered way. It is interesting whether PA practiced in a virtual environment can offer higher levels of satisfaction and flow comparing with PA practiced in the real world. Positive answer to this question support the statement that the use of such technology could contribute to the future commitment in PA. Therefore, in order to find out whether PA in VR can be an attractive alternative towards the PA in a real world, the research should be undertaken to verify if the state of satisfaction and flow involved in the practising certain PA in the VR environment could be higher comparing to the levels of pleasure and flow connected with the same PA carried out in the real world.

OBJECTIVE

The main objective of the study was to assess the level of satisfaction and flow experienced by healthy adults during various cycling conditions: real life (RL), non-immersive and immersive virtual reality (nIVR and IVR). Additionally, questionnaires for assessing satisfaction with PA and flow in RL and VR were also validated in terms of their measurement reliability. The correlation of the results obtained during tests using both measurement tools was also assessed.

METHODS

Forty students were studied, including 20 women (age 22.35 ± 2.32 years) and 20 men (age 22.95 ± 2.19 years). The Physical Activity Enjoyment Scale (PACES) was used to evaluate the enjoyment of cycling. Flow state was assessed using The Flow State Scale (FSS).

RESULTS

Based on Friedman's analysis of variance regarding the results obtained for all the respondents, it can be concluded that the conditions of cycling significantly affect their level of satisfaction (χ2 = 85.61(40;3); p < 0.001) and flow (χ2 = 40.52(40;3); p < 0.001). The research participants rated cycling the highest in IVR. Based on the calculated Cronbach's alpha coefficients, high measurement reliability of the questionnaires used in nIVR (PACES, α = 0.94; FFS-2, α = 0.86) and IVR (PACES, α = 0.89; FFS-2, α = 0.91). There was also a significant positive moderate correlation between PA satisfaction and user flow.

CONCLUSIONS

The research is the first attempt to directly compare the sense of satisfaction and flow when practicing cycling in RL and in nIVR and IVR. The greater attractiveness and higher level of flow during PA in IVR compared to a similar traditional form of PA in RL, found on the basis of the conducted research, should prompt reflection by both those involved in planning and promoting PA, as well as the creators of active video games (AVGs). Due to the great attractiveness of PA in IVR and the constant, dynamic development of immersive information technologies, virtual training may, in the near future, become not only an important supplement to conventional forms of exercise, but perhaps even an alternative solution.

Consequences of Virtual Reality Experience on Biomechanical Gait Parameters in Children with Cerebral Palsy: A Scoping Review

Virtual reality (VR), coupled with motion tracking, can investigate walking in a controlled setting while applying various walking challenges. The purpose of this review was to summarize the evidence on consequences of VR on biomechanical gait parameters in children with cerebral palsy. MEDLINE, Embase and Web of Science were searched. Among 7.574 studies, screened by two independent reviewers, seven studies were included, analyzing treadmill (n = 6) or overground walking (n = 1) under VR. Most frequently reported were the spatiotemporal parameters walking speed, stride length, step width, stance phase, and the kinematic parameters range of knee flexion and peak ankle dorsiflexion. However, methodological approaches and reporting of the results were inconsistent among studies. This review reveals that VR can complement information gained from clinical gait analysis. However, this is still an emerging field of research and there is limited knowledge on the effect of VR on gait parameters, notably during overground walking.

A longitudinal analysis of selective motor control during gait in individuals with cerebral palsy and the relation to gait deviations

OBJECTIVE

To investigate longitudinal changes in selective motor control during gait (SMCg) in individuals with cerebral palsy (CP), and to assess if they are related to changes in gait deviations.

METHOD

Twenty-three children/adolescents with spastic CP (mean ± SD age = 9.0±2.5 years) and two 3D gait assessments (separated by 590±202 days) with no interim surgical intervention, were included. SMCg was assessed using muscle synergy analysis to determine the dynamic motor control index (walk-DMC). Gait deviation was assessed using the Gait profile score (GPS) and Gait variable scores (GVS).

RESULTS

There were no mean changes in walk-DMC score, GPS or GVS between assessments. However, changes in walk-DMC scores in the more involved leg related to changes in hip flexion-extension and hip internal-external GVS (rp = -0.56; p = 0.017 and rp = 0.65; p = 0.004, respectively).

CONCLUSIONS

On average, there were no significant longitudinal changes in SMCg. However, there was considerable variability between individuals, which may relate to changes in hip joint kinematics. This suggests that a combination of neural capacity and biomechanical factors influence lower limb muscle co-activation in individuals with CP, with a potential important role for the hip muscles. These findings highlight the importance of taking an individualized approach when evaluating SMCg in individuals with CP.

Virtual reality-based interventions for the rehabilitation of vestibular and balance impairments post-concussion: a scoping review

BACKGROUND

Concussions and mild traumatic brain injuries are the most common causes of physical and cognitive disability worldwide. Concussion can result in post-injury vestibular and balance impairments that can present up to five years post initial concussion event, ultimately affecting many daily and functional activities. While current clinical treatment aims to reduce symptoms, the developing use of technology in everyday life has seen the emergence of virtual reality. Current literature has failed to identify substantial evidence regarding the use of virtual reality in rehabilitation. The primary aim of this scoping review is to identify, synthesise, and assess the quality of studies reporting on the effectiveness of virtual reality for the rehabilitation of vestibular and balance impairments post-concussion. Additionally, this review aims to summarise the volume of scientific literature and identify the knowledge gaps in current research pertaining to this topic.

METHODS

A scoping review of six databases (PubMed, Embase, CINAHL, ProQuest, SportDiscus, Scopus) and a grey literature (Google Scholar) was conducted using three key concepts (virtual reality, vestibular symptoms, and post-concussion). Data was charted from studies and outcomes were categorised into one of three categories: (1) balance; (2) gait; or (3) functional outcome measures. Critical appraisal of each study was conducted using the Joanna Briggs Institute checklists. A critical appraisal of each outcome measure was also completed utilising a modified GRADE appraisal tool to summarise the quality of evidence. Effectiveness was assessed using calculations of change in performance and change per exposure time.

RESULTS

Three randomised controlled trials, three quasi-experimental studies, three case studies, and one retrospective cohort study were ultimately included, using a thorough eligibility criteria. All studies were inclusive of different virtual reality interventions. The ten studies had a 10-year range and identified 19 different outcome measures.

CONCLUSION

The findings from this review suggests that virtual reality is an effective tool for the rehabilitation of vestibular and balance impairments post-concussion. Current literature shows sufficient but low level of evidence, and more research is necessary to develop a quantitative standard and to better understand appropriate dosage of virtual reality intervention.

Handheld Weights as an Effective and Comfortable Way To Increase Exercise Intensity of Physical Activity in Virtual Reality: Empirical Study

BACKGROUND

In recent years, there has been a growing interest in active virtual reality games (AVRGs) that provide entertainment and encourage more physical activity (PA). Since playing AVRGs involves primarily arm movements, the intensity of this form of PA may not be sufficient for health benefits. Therefore, it is worth looking for virtual entertainment solutions that are comfortable for users and at the same time increase physical exercise.

OBJECTIVE

The main objective of this study was to evaluate the effect of external loading of the arms in the form of handheld weights (HHWs) on exercise intensity in users playing a popular AVRG. The results obtained in the study were compared with the PA recommendations for health. The study also assessed the perceptions of the users about the attractiveness and usefulness of this type of exercise and discomfort caused by additional load on the arms.

METHODS

The study covered 17 young adults aged 18 to 25 years playing an AVRG (Beat Saber) with no arm load and with HHWs (0.5 kg). A PlayStation 4 PRO console (Sony) with accessories including a head-mounted display and controllers was used in the study. PA intensity was evaluated using a heart rate monitor based on the percentage of maximal heart rate (% HRmax). The usability, attractiveness, and comfort perceived during exercise by users were evaluated using a survey questionnaire.

RESULTS

The measurements showed that the mean % HRmax in participants playing Beat Saber without HHWs was significantly lower (P<.001; Cohen d=1.07) than that observed when playing with HHWs. It should be emphasized that with no additional load, the intensity of PA was low (mean 63.7% HRmax, SD 9.3% HRmax), while with the upper limb load, it increased to a moderate level (mean 67.1% HRmax, SD 10.3% HRmax), which is recommended for health benefits. The survey conducted in the study showed that HHWs (0.5 kg) attached to the wrists did not disturb Beat Saber players.

CONCLUSIONS

Since PA in most of the modern AVRGs primarily involves upper limb movements, the use of HHW seems to be a simple and effective way to increase exercise intensity, especially because, as reported by the study participants, such a procedure does not cause discomfort while using the application.

Influence of the number of muscles and strides on selective motor control during gait in individuals with cerebral palsy

OBJECTIVE

To evaluate the influence of the number of muscles and strides on estimating motor control accuracy during treadmill-gait, in individuals with cerebral palsy (CP).

METHODS

Bilateral lower limb electromyography data were extracted for 44 children/adolescents with CP. The number of synergy solutions required to explain 90 % of the variance (tVAF-threshold) and the total variance accounted for by one synergy (tVAF₁) were calculated for a different number of strides (between 5 and 50) and muscles both unilaterally (four to seven) and bilaterally (eight to 14). The kappa and intraclass correlation coefficients were used to assess similarities in tVAF-threshold and tVAF₁ between the different number of strides and muscle sets.

RESULTS

In both analyses, the number of muscles influenced the tVAF-threshold. Additionally, using <30 strides led to only substantial-moderate agreement with 50 strides (k < 0.80). In both analyses, the mean tVAF₁ values demonstrated high-agreement between the different number of muscles (intraclass-correlations = 0.88-0.93) and strides (intraclass-correlations = 0.96-0.99); In the group level, it may result in an error of ≤2.3 %. However, in the individual level, using different number of muscles or <40 strides may result in an error of ≥6 %.

CONCLUSION

Differing numbers of muscles and strides did not influence the group mean tVAF₁ value, but it influenced the tVAF-threshold value. In addition, using different number of muscles or strides can lead to a large measurement error in the individual tVAF₁ value.

Biomechanical differences between self-paced and fixed-speed treadmill walking in persons after stroke

BACKGROUND

Using self-paced treadmills for gait analysis requires less space compared to overground gait labs while a more natural walking pattern could be preserved compared to fixed-speed treadmill walking. Although self-paced treadmills have been used in stroke related intervention studies, studies comparing self-paced to fixed-speed treadmill walking in this population are scarce.

METHODS

Twenty-five persons after stroke (10 males/15 females; 53 ± 12.05 years; 40.72 ± 42.94 months post stroke) walked on a treadmill in a virtual environment (GRAIL, Motek) in two conditions (self-paced and fixed-speed). After familiarization, all participants completed two trials (3 min) at comfortable walking velocity in randomized order. A paired-sample t-test or Wilcoxon Signed Rank test was used to calculate differences between both conditions for spatiotemporal parameters. Statistical Parametric mapping was conducted using the t-tests (SPM(t)), to statistically compare the kinematic and kinetic curves.

RESULTS

The self-selected walking velocity on the treadmill was higher in the self-paced condition compared to the fixed-speed condition (p < 0.001). However, most variability and symmetry measures were similar in both conditions. Only the standard deviation of the step length at the paretic side was significant higher (p = 0.007) and step length symmetry was significantly better (p = 0.032) in the self-paced condition. Detected kinematic and kinetic differences were small (< 3°, < 0.1 Nm/kg) and stride to stride variability was comparable in both conditions.

CONCLUSION

Based on the results of the current study, self-paced walking can be used as an equivalent to fixed-speed treadmill walking in persons after stroke. Accordingly, this justifies the use of this more functional mode in clinical gait assessment and rehabilitation trials.

Comparison of sagittal plane gait characteristics between the overground and treadmill approach for gait analysis in typically developing children

Background

Instrumented treadmills have become more mainstream in clinical assessment of gait disorders in children, and are increasingly being applied as an alternative to overground gait analysis. Both approaches differ in multiple elements of set-up (e.g., overground versus treadmill, Pug-in Gait versus Human Body Model-II), workflow (e.g., limited amount of steps versus many successive steps) and post-processing of data (e.g., different filter techniques). These individual elements have shown to affect gait. Since the approaches are used in parallel in clinical practice, insight into the compound effect of the multiple different elements on gait is essential. This study investigates whether the outcomes of two approaches for 3D gait analysis are interchangeable in typically developing children.

Methods

Spatiotemporal parameters, sagittal joint angles and moments, and ground reaction forces were measured in typically developing children aged 3-17 years using the overground (overground walking, conventional lab environment, Plug-In Gait) and treadmill (treadmill walking in virtual environment, Human Body Model-II) approach. Spatiotemporal and coefficient of variation parameters, and peak values in kinematics and kinetics of both approaches were compared using repeated measures tests. Kinematic and kinetic waveforms from both approaches were compared using statistical parametric mapping (SPM). Differences were quantified by mean differences and root mean square differences.

Results

Children walked slower, with lower stride and stance time and shorter and wider steps with the treadmill approach than with the overground approach. Mean differences ranged from 0.02 s for stride time to 3.3 cm for step width. The patterns of sagittal kinematic and kinetic waveforms were equivalent for both approaches, but significant differences were found in amplitude. Overall, the peak joint angles were larger during the treadmill approach, showing mean differences ranging from 0.84° (pelvic tilt) to 6.42° (peak knee flexion during swing). Mean difference in peak moments ranged from 0.02 Nm/kg (peak knee extension moment) to 0.32 Nm/kg (peak hip extension moment), showing overall decreased joint moments with the treadmill approach. Normalised ground reaction forces showed mean differences ranging from 0.001 to 0.024.

Conclusion

The overground and treadmill approach to 3D gait analysis yield different sagittal gait characteristics. The systematic differences can be due to important changes in the neuromechanics of gait and to methodological choices used in both approaches, such as the biomechanical model or the walkway versus treadmill. The overview of small differences presented in this study is essential to correctly interpret the results and needs to be taken into account when data is interchanged between approaches. Together with the research/clinical question and the context of the child, the insight gained can be used to determine the best approach.

Overground Walking in a Fully Immersive Virtual Reality: A Comprehensive Study on the Effects on Full-Body Walking Biomechanics

Virtual reality (VR) is an emerging technology offering tremendous opportunities to aid gait rehabilitation. To this date, real walking with users immersed in virtual environments with head-mounted displays (HMDs) is either possible with treadmills or room-scale (overground) VR setups. Especially for the latter, there is a growing interest in applications for interactive gait training as they could allow for more self-paced and natural walking. This study investigated if walking in an overground VR environment has relevant effects on 3D gait biomechanics. A convenience sample of 21 healthy individuals underwent standard 3D gait analysis during four randomly assigned walking conditions: the real laboratory (RLab), a virtual laboratory resembling the real world (VRLab), a small version of the VRlab (VRLab-), and a version which is twice as long as the VRlab (VRLab+). To immerse the participants in the virtual environment we used a VR-HMD, which was operated wireless and calibrated in a way that the virtual labs would match the real-world. Walking speed and a single measure of gait kinematic variability (GaitSD) served as primary outcomes next to standard spatio-temporal parameters, their coefficients of variant (CV%), kinematics, and kinetics. Briefly described, participants demonstrated a slower walking pattern (-0.09 ± 0.06 m/s) and small accompanying kinematic and kinetic changes. Participants also showed a markedly increased gait variability in lower extremity gait kinematics and spatio-temporal parameters. No differences were found between walking in VRLab+ vs. VRLab-. Most of the kinematic and kinetic differences were too small to be regarded as relevant, but increased kinematic variability (+57%) along with increased percent double support time (+4%), and increased step width variability (+38%) indicate gait adaptions toward a more conservative or cautious gait due to instability induced by the VR environment. We suggest considering these effects in the design of VR-based overground training devices. Our study lays the foundation for upcoming developments in the field of VR-assisted gait rehabilitation as it describes how VR in overground walking scenarios impacts our gait pattern. This information is of high relevance when one wants to develop purposeful rehabilitation tools.

Dual-task treadmill walking at self-paced versus fixed speeds

BACKGROUND

Investigating cognitive-motor interference on the treadmill allows for better examination of motor adaptation to the dual-task challenges through the information of continuous strides. However, one of the major critiques for conducting dual-task investigation on a treadmill is the use of a constant, fixed walking speed, constraining the natural fluctuations of the speed of human walking, which could be addressed by using the self-paced feature of a feedback-controlled treadmill.

RESEARCH QUESTION

Do people use different adaptation and task prioritization strategies during the dual-task treadmill walking at self-paced versus fixed speeds?

METHODS

Eighteen healthy younger participants walked on an instrumented treadmill (1) under two speed conditions: self-paced and fixed-speed, and (2) with and without each of the four different cognitive tasks. Dynamic margins of stability (MOS), step spatiotemporal measures, kinematic variability, and local dynamic stability were computed for each trial.

RESULTS

Participants had significantly more local instability during self-paced than fixed-speed treadmill walking. The often-reported response of reducing stride time variability during dual-task, fixed-speed walking was not observed during dual-task, self-paced walking. In addition, there were significantly greater dual-task interference effects on stride time variability and local dynamic stability as well as the Paced Auditory Serial Addition Test performance during self-paced walking. Reduced variability in the lower-extremity joint angles, trunk motion and position, and MOS measures were observed both in dual-task, self-paced and fixed-speed walking.

SIGNIFICANCE

Healthy younger adults had different task prioritization and greater dual-task effects on gait stability and cognitive performance during self-paced versus fixed-speed walking. However, similar adaptation strategies, in terms of gait adjustments, were used for the two walking conditions. The results suggest that self-paced treadmill walking is more challenging than the fixed-speed walking and can serve as a better alternative to the overground walking than the fixed-speed walking for the dual-task investigation.

Developing a BIM-Based MUVR Treadmill System for Architectural Design Review and Collaboration

Virtual reality (VR) is quickly becoming the medium of choice for various architecture, engineering, and construction applications, such as design visualization, construction planning, and safety training. In particular, this technology offers an immersive experience to enhance the way architects review their design with team members. Traditionally, VR has used a desktop PC or workstation setup inside a room, yielding the risk of two users bump into each other while using multiuser VR (MUVR) applications. MUVR offers shared experiences that disrupt the conventional single-user VR setup, where multiple users can communicate and interact in the same virtual space, providing more realistic scenarios for architects in the design stage. However, this shared virtual environment introduces challenges regarding limited human locomotion and interactions, due to physical constraints of normal room spaces. This study thus presented a system framework that integrates MUVR applications into omnidirectional treadmills. The treadmills allow users an immersive walking experience in the simulated environment, without space constraints or hurt potentialities. A prototype was set up and tested in several scenarios by practitioners and students. The validated MUVR treadmill system aims to promote high-level immersion in architectural design review and collaboration.

Validity Analysis of WalkerViewTM Instrumented Treadmill for Measuring Spatiotemporal and Kinematic Gait Parameters

The detection of gait abnormalities is essential for professionals involved in the rehabilitation of walking disorders. Instrumented treadmills are spreading as an alternative to overground gait analysis. To date, the use of these instruments for recording kinematic gait parameters is still limited in clinical practice due to the lack of validation studies. This study aims to investigate the performance of a multi-sensor instrumented treadmill (i.e., WalkerView^TM, WV) for performing gait analysis. Seventeen participants performed a single gait test on the WV at three different speeds (i.e., 3 km/h, 5 km/h, and 6.6 km/h). In each trial, spatiotemporal and kinematic parameters were recorded simultaneously by the WV and by a motion capture system used as the reference. Intraclass correlation coefficient (ICC) of spatiotemporal parameters showed fair to excellent agreement at the three walking speeds for steps time, cadence, and step length (range 0.502–0.996); weaker levels of agreement were found for stance and swing time at all the tested walking speeds. Bland–Altman analysis of spatiotemporal parameters showed a mean of difference (MOD) maximum value of 0.04 s for swing/stance time and WV underestimation of 2.16 cm for step length. As for kinematic variables, ICC showed fair to excellent agreement (ICC > 0.5) for total range of motion (ROM) of hip at 3 km/h (range 0.579–0.735); weaker levels of ICC were found at 5 km/h and 6.6 km/h (range 0.219–0.447). ICC values of total knee ROM showed poor levels of agreement at all the tested walking speeds. Bland–Altman analysis of hip ROM revealed a higher MOD value at higher speeds up to 3.91°; the MOD values of the knee ROM were always higher than 7.67° with a 60° mean value of ROM. We demonstrated that the WV is a valid tool for analyzing the spatiotemporal parameters of walking and assessing the hip’s total ROM. Knee total ROM and all kinematic peak values should be carefully evaluated, having shown lower levels of agreement.

The Role of Binocular Vision in Avoiding Virtual Obstacles While Walking

Advances in Virtual Reality technology have enabled physical walking in virtual environments. While most Virtual Reality systems render stereoscopic images to users, the implication of binocular viewing with respect to the performance of human walking in virtual environments remains largely unknown. In the present study, we conducted two walking experiments in virtual environments using a linear treadmill and a novel projected display known as the Wide Immersive Stereo Environment (WISE) to study the role of binocular viewing in virtual locomotion. The first experiment investigated the walking performance of people stepping over obstacles while the second experiment focused on a scenario on stepping over gaps. Both experiments were conducted under both stereoscopic viewing and non-stereoscopic viewing conditions. By analysing the gait parameters, we found that binocular viewing helped people to make more accurate movements to step over obstacles and gaps in virtual locomotion.

Effect of a Virtual Reality-Enhanced Exercise and Education Intervention on Patient Engagement and Learning in Cardiac Rehabilitation: Randomized Controlled Trial

BACKGROUND

Cardiac rehabilitation (CR) is clinically proven to reduce morbidity and mortality; however, many eligible patients do not enroll in treatment. Furthermore, many enrolled patients do not complete their full course of treatment. This is greatly influenced by socioeconomic factors but is also because of patients' lack of understanding of the importance of their care and a lack of motivation to maintain attendance.

OBJECTIVE

This study aims to explore the potential benefits of virtual reality (VR) walking trails within CR treatment, specifically with regard to patient knowledge retention, satisfaction with treatment, and the overall attendance of treatment sessions.

METHODS

New CR patients were enrolled and randomized on a rolling basis to either the control group or intervention group. Intervention patients completed their time on the treadmill with VR walking trails, which included audio-recorded education, whereas control patients completed the standard of care therapy. Both groups were assisted by nursing staff for all treatment sessions. Primary outcomes were determined by assessing 6-minute walk test improvement. In addition, secondary outcomes of patients' cardiac knowledge and satisfaction were assessed via a computer-based questionnaire; patient adherence to the recommended number of sessions was also monitored. Cardiac knowledge assessment included a prerehabilitation education quiz, and the same quiz was repeated at patients' final visit and again at the 2-month follow-up. The satisfaction questionnaire was completed at the final visit.

RESULTS

Between January 2018 and May 2019, 72 patients were enrolled-41 in the intervention group and 31 in the control group. On the basis of the results of the prerehabilitation and postrehabilitation 6-minute walk test, no significant differences were observed between the intervention and control groups (P=.64). No statistical differences were observed between groups in terms of education (P=.86) or satisfaction (P=.32) at any time point. The control group had statistically more favorable rates of attendance, as determined by the risk group comparison (P=.02) and the comparison of the rates for completing the minimum number of sessions (P=.046), but no correlation was observed between the study group and reasons for ending treatment.

CONCLUSIONS

Although no improvements were seen in the VR intervention group over the control group, it is worth noting that limitations in the study design may have influenced these outcomes, not the medium itself. Furthermore, the qualitative information suggests that patients may have indeed enjoyed their experience with VR, even though quantitative satisfaction data did not capture this. Further considerations for how and when VR should be applied to CR are suggested in this paper.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03945201; https://clinicaltrials.gov/ct2/show/NCT03945201.

Is Motorized Treadmill Running Biomechanically Comparable to Overground Running? A Systematic Review and Meta-Analysis of Cross-Over Studies

BACKGROUND

Treadmills are often used in research, clinical practice, and training. Biomechanical investigations comparing treadmill and overground running report inconsistent findings.

OBJECTIVE

This study aimed at comparing biomechanical outcomes between motorized treadmill and overground running.

METHODS

Four databases were searched until June 2019. Crossover design studies comparing lower limb biomechanics during non-inclined, non-cushioned, quasi-constant-velocity motorized treadmill running with overground running in healthy humans (18-65 years) and written in English were included. Meta-analyses and meta-regressions were performed where possible.

RESULTS

33 studies (n = 494 participants) were included. Most outcomes did not differ between running conditions. However, during treadmill running, sagittal foot-ground angle at footstrike (mean difference (MD) - 9.8° [95% confidence interval: - 13.1 to - 6.6]; low GRADE evidence), knee flexion range of motion from footstrike to peak during stance (MD 6.3° [4.5 to 8.2]; low), vertical displacement center of mass/pelvis (MD - 1.5 cm [- 2.7 to - 0.8]; low), and peak propulsive force (MD - 0.04 body weights [- 0.06 to - 0.02]; very low) were lower, while contact time (MD 5.0 ms [0.5 to 9.5]; low), knee flexion at footstrike (MD - 2.3° [- 3.6 to - 1.1]; low), and ankle sagittal plane internal joint moment (MD - 0.4 Nm/kg [- 0.7 to - 0.2]; low) were longer/higher, when pooled across overground surfaces. Conflicting findings were reported for amplitude of muscle activity.

CONCLUSIONS

Spatiotemporal, kinematic, kinetic, muscle activity, and muscle-tendon outcome measures are largely comparable between motorized treadmill and overground running. Considerations should, however, particularly be given to sagittal plane kinematic differences at footstrike when extrapolating treadmill running biomechanics to overground running. Protocol registration CRD42018083906 (PROSPERO International Prospective Register of Systematic Reviews).

Performance in complex life situations: effects of age, cognition, and walking speed in virtual versus real life environments

Background

Virtual reality (VR) enables objective and accurate measurement of behavior in ecologically valid and safe environments, while controlling the delivery of stimuli and maintaining standardized measurement protocols. Despite this potential, studies that compare virtual and real-world performance of complex daily activities are scarce. This study aimed to compare cognitive strategies and gait characteristics of young and older healthy adults as they engaged in a complex task while navigating in a real shopping mall and a high-fidelity virtual replica of the mall.

Methods

Seventeen older adults (mean (SD) age = 71.2 (5.6) years, 64% males) and 17 young adults (26.7 (3.7) years, 35% males) participated. In two separate sessions they performed the Multiple Errands Test (MET) in a real-world mall or the Virtual MET (VMET) in the virtual environment. The real-world environment was a small shopping area and the virtual environment was created within the CAREN™ (Computer Assisted Rehabilitation Environment) Integrated Reality System. The performance of the task was assessed using motor and physiological measures (gait parameters and heart rate), MET or VMET time and score, and navigation efficiency (cognitive performance and strategy). Between (age groups) and within (environment) differences were analyzed with ANOVA repeated measures.

Results

There were no significant age effects for any of the gait parameters but there were significant environment effects such that both age groups walked faster (F_(1,32) = 154.96, p < 0.0001) with higher step lengths (F_(1,32) = 86.36, p < 0.0001), had lower spatial and temporal gait variability (F_(1,32) = 95.71–36.06, p < 0.0001) and lower heart rate (F_(1,32) = 13.40, p < 0.01) in the real-world. There were significant age effects for MET/VMET scores (F_(1,32) = 19.77, p < 0.0001) and total time (F_(1,32) = 11.74, p < 0.05) indicating better performance of the younger group, and a significant environment effect for navigation efficiency (F_(1,32) = 7.6, p < 0.01) that was more efficient in the virtual environment.

Conclusions

This comprehensive, ecological approach in the measurement of performance during tasks reminiscent of complex life situations showed the strengths of using virtual environments in assessing cognitive aspects and limitations of assessing motor aspects of performance. Difficulties by older adults were apparent mainly in the cognitive aspects indicating a need to evaluate them during complex task performance.

Lower limb kinematic, kinetic and spatial-temporal gait data for healthy adults using a self-paced treadmill

Through gait analysis, gait phases can be identified, the kinematic and kinetic parameters of human gait events can be determined, and quantitative evaluation can be undertaken. This data article is the first to report a comprehensive data set on a large cohort of healthy participants. Individual strides were determined from vertical force data and all kinematics and kinetic data separated into strides. Local minima and maxima were determined respectively for each anatomical region and the mean calculated for twenty of the 25 strides. When twenty strides were not available the mean of ten strides was used. Stride data were time normalised so one stride was represented by 100%. In addition to the local maxima and minima, the kinematic- and kinetic-time curves were explored and used to determine the mean kinematic-time and kinetic-time curves across all trials and participants (∼1800 gait cycles) to provide mean±sd kinematic- and kinetic-time curves for each of the anatomical regions.

Kinematic Gait Adjustments to Virtual Environments on Different Surface Conditions: Do Treadmill and Over-Ground Walking Exhibit Different Adaptations to Passive Virtual Immersion?

BACKGROUND

The aim of this study was to examine the kinematic gait adjustments performed in response to passive and photorealistic virtual reality environment (VRE) demands during over-ground and treadmill walking conditions and determine whether the surface presentation order affects the gait adjustments in response to different VREs.

METHODS

Twenty young participants divided into two groups performed two virtual reality (VR) walking protocols which included two different VREs (snowy and crowded conditions). Group A performed the VR over-ground protocol (four natural walking (NW), seven VR snowy, and seven VR crowded trials) followed by the VR treadmill protocol (four NW, one VR snowy, and one VR crowded trials); Group B performed the VR treadmill protocol (four NW, seven VR snowy, and seven VR crowded trials) followed by the VR over-ground protocol (four NW, one VR snowy, and one VR crowded trials). Center of mass (COM) excursion angles and mediolateral (ML) COM excursions were analyzed and used as outcome measures.

RESULTS

Group A showed higher COM excursion angles and ML-COM excursion on over-ground VR trials compared to NW trials (p < 0.05), while Group B only showed kinematic changes for the crowded VRE compared to NW trials during the treadmill walking protocol (p < 0.05). Post over-ground exposure, Group A showed greater COM excursion angle and ML-COM excursions on VR trials compared to NW trials during the treadmill walking protocol (p < 0.05). Post treadmill exposure, Group B only showed higher COM excursion angles for the snowy VRE compared to NW trials during the over-ground walking protocol (p < 0.01).

CONCLUSION

Results showed that higher kinematic gait adjustments in response to VRE demands were observed during over-ground walking. Additionally, higher sensorimotor responses to VRE demands were observed when the VR protocol was first performed on the over-ground surface and followed by the treadmill walking condition (Group A) compared to the opposite (Group B).

An Evaluation of Symmetries in Ground Reaction Forces during Self-Paced Single- and Dual-Task Treadmill Walking in the Able-Bodied Men

Gait is a complex autonomous activity that has long been viewed as a symmetrical locomotion, even when it adapts to secondary concurrent attention-demanding tasks. This study aimed to evaluate the symmetry of the three ground reaction forces (GRFs) in able-bodied individuals during self-paced treadmill walking with and without concurrent cognitive demands. Twenty-five male participants (age: 34.00 ± 4.44 years) completed two gait assessment sessions, each of whom were familiarized with the walking trials during their first session. Both sessions involved six-minute self-paced treadmill walking under three conditions: single-task walking and walking while concurrently responding to auditory 1-back and 2-back memory tasks. The symmetry of the GRFs was estimated using a nonlinear approach. Changes in the symmetry and walking speed across conditions in both sessions were assessed using inferential statistics. Results demonstrated that the three GRFs deviated from perfect symmetry by ≥10%. Engaging working memory during walking significantly reduced the symmetry of the vertical GRF (p = 0.003), and its detrimental effects on walking speed were significantly reduced in the second session with respect to the first session (p < 0.05). The findings indicate imperfect gait symmetry in able-bodied individuals, suggesting that common perceptions of gait symmetry should be reconsidered to reflect its objective importance in clinical settings.

Characterization of speed adaptation while walking on an omnidirectional treadmill

BACKGROUND

Conventional treadmills are widely used for gait retraining in rehabilitation setting. Their usefulness for training more complex locomotor tasks, however, remains limited given that they do not allow changing the speed nor the direction of walking which are essential walking adaptations for efficient and safe community ambulation. These drawbacks can be addressed by using a self-pace omnidirectional treadmill, as those recently developed by the gaming industry, which allows speed changes and locomotor movements in any direction. The extent to which these treadmills yield a walking pattern that is similar to overground walking, however, is yet to be determined.

METHODS

The objective of this study was to compare spatiotemporal parameters, body kinematics and lower limb muscle activation of healthy young individuals walking at different speeds (slow, comfortable, fast) on a low-cost non-motorized omnidirectional treadmill with and without virtual reality (VR) vs. overground.

RESULTS

Results obtained from 12 young healthy individuals (18-29 years) showed that participants achieved slower speed on the treadmill compared to overground. On the treadmill, faster walking speeds were achieved by a mere increase in cadence, as opposed to a combined increase in cadence and step length when walking overground. At matched speed, enhanced stance phase knee flexion, reduced late stance ankle plantarflexion, as well as enhanced activation amplitudes of hip extensors in late stance and hip extensors in early swing were observed. The addition of VR to treadmill walking had little or no effect of walking outcomes. Collectively, results show that the omnidirectional treadmill yields a different walking pattern and lead to different adaptations to speed compared to overground walking. We suggest that these alterations are mainly driven by the reduced shear forces between the weight bearing foot and supporting surface and a perceived threat to balance on the omnidirectional treadmill.

CONCLUSION

Since such treadmills are likely to be used for prolonged periods of time by gamers or patients undergoing physical rehabilitation, further research should aim at determining the impact of repeated exposure on gait biomechanics and lower limb musculoskeletal integrity.

Can Physical Activity in Immersive Virtual Reality Be Attractive and Have Sufficient Intensity to Meet Health Recommendations for Obese Children? A Pilot Study

Immersive virtual reality (IVR) is a technology that blurs the line between the physical world and a digital environment. Using appropriate pointing devices, it is possible to engage in physical activity (PA). The main aim of the study was to assess the attractiveness and intensity of physical exercise while playing active video games (AVGs) in IVR on an omnidirectional treadmill by obese children and to present the results compared to health recommendations (PA). It was also assessed whether the AVGs storyline can effectively motivate the participants to undertake locomotor activity by increasing the intensity of their effort (moving in a limited space vs. having to follow a set route). Eleven children aged 8 to 12 years with diagnosed obesity participated in the experiment. The attractiveness of PA was assessed with a questionnaire, while the intensity of exercise was estimated on the basis of heart rate. The answers show that AVGs are attractive and more enjoyable for the respondents than conventional video games. All participants declared their willingness to practice this form of PA. The intensity of PA of obese children during two games was high but during the game where the player was supposed to follow a set route, it was significantly higher (83.3 ± 9.2% HRmax) than during the game whose storyline assumed moving in a limited space (77.4 ± 9.8% HRmax). Due to the high intensity of PA while playing the AVGs studied, it can be assumed that obese children can benefit for their health if the games are used on a regular basis. However, further research is needed to verify this thesis.

Reliability of gait parameters in male and female healthy adults during self-paced treadmill-based walking

Background/aims

The purpose of this study was to examine the intra-rater reliability of the Gait Real-time Analysis Interactive Laboratory system during self-paced mode, in repeated gait analysis of healthy individuals.

Methods

A total of 10 healthy men (age: 35.4 ± 13.3 years; body mass index: 25.2 ± 4.3) and 10 healthy women (age: 41.1 ± 16.4 years; body mass index: 24.5 ± 2.6) were split into two groups according to sex. They walked on a split-belt, self-paced treadmill. Each participant completed two gait assessments separated by an average of 7 ± 3 days. Key gait kinematic, kinetic and spatial-temporal parameters were analysed. The interclass correlation coefficient, standard error of measurement and minimum detectable change were calculated to evaluate the reliability of these gait parameters.

Results

There was a high repeatability of spatial temporal and excellent repeatability of kinematic and kinetic parameters in both groups.

Conclusions

The findings suggest that the Gait Real-time Analysis Interactive Laboratory system in self-paced mode is a good instrument to evaluate gait parameters for women as well as men.

Time-course of running treadmill adaptation in novice treadmill runners

Studies on running biomechanics and energetics are usually conducted on a treadmill. To ensure that locomotion on a treadmill is comparable to locomotion overground, participants need to be expert in the use of the device. This study aimed to identify the number and duration of sessions needed to obtain stable measurements for spatiotemporal and metabolic parameters in unexperienced treadmill runners. Fourteen male recreational runners performed three 15-min treadmill running trials in different days at a submaximal speed. Spatiotemporal and metabolic parameters were registered at minutes: 5, 10, 15 and their within-trial and between-trial changes were analysed using a two-way repeated measures ANOVA and Bonferroni post-hoc test. Within-trial differences were found in step frequency (decreased over time), Step Length and Contact Time (increased), reaching stability at different time points. Ventilator parameters increased, reaching stability after 5-10 min, while heart rate increased progressively over time. The only between-trial differences were an increase in step length and a decrease in step frequency at min 1, between trials 1 and 3. In conclusion, at least three running trials of 15 min are required to familiarize with the device. The last 5 min of the third trial can be regarded as stable measurements.

The impact of motor task and environmental constraints on gait patterns during treadmill walking in a fully immersive virtual environment

BACKGROUND

Virtual environments (VE) are increasingly used in rehabilitation settings for gait training, and positive effects are reported. However, little is known about how walking under environmental constraints and solving motor tasks in fully immersive VEs impact gait patterns.

RESEARCH QUESTION

How are gait patterns in healthy adults impacted by walking under environmental constraints and solving motor tasks on a treadmill, in a fully immersive VE?

METHODS

29 healthy adults (age: 28.9±4.8 yrs) were included. Basic gait parameters (step length, cadence, walk ratio) and gait variability in the anteroposterior, mediolateral and vertical directions were measured using an inertial sensor attached to the lower back. A familiarisation treadmill walk >2 min was performed, followed by 200 m familiarisation walk in the VE with no task or environmental constraints The participants were then exposed to height, two grabbing tasks, a balancing task and narrow-path walking. Gait patterns were captured for 15-25 seconds during each of the conditions. The Simulator Sickness Questionnaire was completed before and after the session.

RESULTS

Gait regularity decreased when solving all the motor tasks, and under all the environmental constraints, except when being familiarised to height exposure, where regularity returned to pre-exposure levels. Step length and walk ratio decreased, and cadence increased during height exposure and while performing the grabbing tasks and the balancing task. The different tasks and environments appeared to have specific impact on gait patterns. There was no increase in simulator sickness symptoms.

SIGNIFICANCE

Gait patterns were impacted by solving motor tasks, and by environmental constraints, in healthy young adults, suggesting increased need for balance control. We suggest that VE-training on a treadmill holds potential for improving gait and balance control.

Setting, Age, and Intensity Influence Responses to Exercise in Young Endurance Runners

We investigated the effects of exercise setting (indoor treadmill vs. outdoor trail), age (17 middle school, 18 high school, and 13 college participants), and level of exertion (Borg Ratings of Perceived Exertion of 10, 12, and 16 on a 22-point scale) on young male endurance runners’ heart rate (HR), running speed, attentive focus, and affect. Three-way analyses of variance revealed that on the outdoor trail (vs. indoor treadmill), HR and speed were higher ( p < .001) and attentive focus was more dissociative ( p = .047). There were significant Age × Setting interactions for HR ( p = .047), speed ( p = .023), and attentive focus ( p = .002), with older participants exhibiting a greater increase in speed and HR and a greater shift toward dissociative focus on the outdoor trail. Three-way analyses of variance also yielded significant Age × Time interactions on components of the Physical Activity Affect Scale in that younger participants exhibited larger declines in positive affect ( p = .003) and tranquility ( p < .001) and larger increases in fatigue ( p < .001) as a result of the running session. Our data suggest that either runners develop more positive responses to exercise as they mature or those young runners who experience running more negatively tend to drop out of running so that the remaining older participants continuing to run are those who experience exercise positively.

High day-to-day repeatability of lower extremity muscle activation patterns and joint biomechanics of dual-belt treadmill gait: A reliability study in healthy young adults

PURPOSE

The reliability of lower extremity muscle activation patterns has not been clearly studied in a dual-belt instrumented treadmill environment. The primary study objective was to quantify the day-to-day reliability of quadriceps, hamstrings, gastrocnemius and gluteus medius activation patterns in healthy young adult gait. Secondarily, the reliability of spatiotemporal, and knee/hip motion and moment-based gait outcomes was assessed.

SCOPE

20 young adults were recruited and tested on two separate days. Using standardized procedures, participants were prepared for surface electromyography and lower extremity motion capture. All individuals walked on a dual-belt instrumented treadmill while muscle activation, segment motions and ground reaction forces were recorded. Sagittal plane motion and net external sagittal and frontal plane moments were calculated. Discrete biomechanical and muscle activation measures were calculated, and non-negative matrix factorization extracted amplitude and temporal muscle activation features. Intraclass Correlation Coefficients, Standard Error of Measurement and Minimum Detectable Change were calculated.

CONCLUSIONS

High to excellent Intraclass correlation coefficients were found between visits for most primary and secondary outcomes. The absolute and relative reliability, including Minimum Detectable Change values, provided in this study support the use of dual-belt instrumented treadmill walking as an acceptable medium to collect biomechanical and lower extremity EMG outcomes for future studies.

An update on pulmonary rehabilitation techniques for patients with chronic obstructive pulmonary disease

Introduction: Pulmonary rehabilitation (PR) is one of the core components in the management of patients with chronic obstructive pulmonary disease (COPD). In order to achieve the maximal level of independence, autonomy, and functioning of the patient, targeted therapies and interventions based on the identification of physical, emotional and social traits need to be provided by a dedicated, interdisciplinary PR team.Areas covered: The review discusses cardiopulmonary exercise testing in the selection of different modes of training modalities. Neuromuscular electrical stimulation as well as gait assessment and training are discussed as well as add-on therapies as oxygen, noninvasive ventilator support or endoscopic lung volume reduction in selected patients. The potentials of pulsed inhaled nitric oxide in patients with underlying pulmonary hypertension is explored as well as nutritional support. The impact of sleep quality on outcomes of PR is reviewed.Expert opinion: Individualized, comprehensive intervention based on thorough assessment of physical, emotional, and social traits in COPD patients forms a continuous challenge for health-care professionals and PR organizations in order to dynamically implement and adapt these strategies based on dynamic, more optimal understanding of underlying pathophysiological mechanisms.

The walking speed-dependency of gait variability in bilateral vestibulopathy and its association with clinical tests of vestibular function

Understanding balance and gait deficits in vestibulopathy may help improve clinical care and our knowledge of the vestibular contributions to balance. Here, we examined walking speed effects on gait variability in healthy adults and in adults with bilateral vestibulopathy (BVP). Forty-four people with BVP, 12 healthy young adults and 12 healthy older adults walked at 0.4 m/s to 1.6 m/s in 0.2 m/s increments on a dual belt, instrumented treadmill. Using motion capture and kinematic data, the means and coefficients of variation for step length, time, width and double support time were calculated. The BVP group also completed a video head impulse test and examinations of ocular and cervical vestibular evoked myogenic potentials and dynamic visual acuity. Walking speed significantly affected all gait parameters. Step length variability at slower speeds and step width variability at faster speeds were the most distinguishing parameters between the healthy participants and people with BVP, and among people with BVP with different locomotor capacities. Step width variability, specifically, indicated an apparent persistent importance of vestibular function at increasing speeds. Gait variability was not associated with the clinical vestibular tests. Our results indicate that gait variability at multiple walking speeds has potential as an assessment tool for vestibular interventions.

The Treadport: Natural Gait on a Treadmill

OBJECTIVE

To evaluate the differences between walking on an advanced robotic locomotion interface called the Treadport and walking overground with healthy subjects.

BACKGROUND

Previous studies have compared treadmill-based and overground walking in terms of gait parameters. The Treadport's unique features including self-selected speed capability, large belt, kinesthetic force feedback, and virtual reality environment distinguish it from other locomotion interfaces and could provide a natural walking experience for the users.

METHOD

Young, healthy subjects (N = 17) walked 10 meters 10 times each for both overground and the Treadport environments. Comparison between walking conditions used spatiotemporal and kinematic parameters. In addition, electromyographic data was collected for five of the 17 subjects to compare muscle activity between the two conditions.

RESULTS

Gait on the Treadport was found to have no significant differences (p > .05) with overground walking in terms of hip and knee joint angles, cadence and stride length and stride speed, and muscle activation of the four muscle groups measured. Differences (p < .05) were observed in ankle dorsiflexion which was reduced by 2.47 ± 0.01 degrees on the Treadport.

CONCLUSION

Walking overground and on the Treadport is highly correlated and not significantly different in 13 of 14 parameters.

APPLICATION

This study suggests that the Treadport creates an environment for natural walking experience, where natural gait of users is almost preserved, with great potential to be useful for other applications, such as gait rehabilitation of individuals with walking impairments.

Optic flow improves step width and length in older adults while performing dual task

BACKGROUND

Dual-task paradigms are used to investigate gait and cognitive declines in older adults (OA). Optic-flow is a virtual reality environment where the scene flows past the subject while walking on a treadmill, mimicking real-life locomotion.

AIMS

To investigate cost of environment (no optic-flow v. optic-flow) while completing single- and dual-task walking and dual-task costs (DTC; single- v. dual-task) in optic-flow and no optic-flow environments.

METHODS

Twenty OA and seven younger adults (YA) walked on a self-paced treadmill in 3-min segments per task and both environments. Five task conditions included: no task, semantic fluency (category), phonemic fluency (letters), word reading, and serial-subtraction.

RESULTS

OAs had a benefit of optic-flow compared to no optic-flow for step width (p = 0.015) and step length (p = 0.045) during letters compared to the YA. During letters, OA experienced improvement in step width DTC; whereas YA had a decrement in step width DTC from no optic-flow to optic-flow (p = 0.038). During serial-subtraction, OA had less step width DTC when compared to YA in both environments (p = 0.02).

DISCUSSION

During letters, step width and step length improved in OA while walking in optic-flow. Also, step width DTC differed between the two groups. Sensory information from optic-flow appears to benefit OA. Letters relies more on verbal ability and word knowledge, which are preserved in aging. However, YA use a complex speech style during dual tasking, searching for complex words and an increased speed of speech.

CONCLUSIONS

OA can benefit from optic-flow by improving spatial gait parameters, specifically, step width, during dual-task walking.

Gait adaptations during overground walking and multidirectional oscillations of the visual field in a virtual reality headset

BACKGROUND

Virtual reality (VR) has been used to study locomotor adaptability during balance-demanding tasks by exploring how humans react and adapt to the virtual environment (VE) and discordant sensorimotor stimulations. Previous research primarily focused on treadmill walking and little is known regarding the propensity for gait adaptations during overground walking and over time.

RESEARCH QUESTION

To what extent healthy young adults modify and adapt gait during overground walking in a VE and with continuous multidirectional perturbations of the visual field while wearing a VR headset?

METHODS

Twelve healthy young adults walked for 6 min on an instrumented walkway in four different conditions: RE, VE, and VE with antero-posterior (AP) and medio-lateral (ML) pseudo-random oscillations of the visual field. For each condition, stride length (SL), stride width (SW), stride time (ST) and their variability (SLV, SWV, and STV) were calculated using one-minute walking intervals. A 2-way repeated-measures ANOVA was performed to determine the main and interaction effects of the walking conditions and time.

RESULTS

Participants took shorter SL and showed higher SWV while walking in the VE. Perturbations of the visual field resulted in reduced SL, larger SW, and higher stride variability (i.e., SLV, SWV, and STV). The response was anisotropic, such that effects were more pronounced during the ML compared to AP perturbations. Over time, participants adapted to the VE and the visual perturbations by increasing SL and reducing SW, SLV, STV, and ST (only during VE and ML conditions). SWV did not adapt over time.

SIGNIFICANCE

The paper provided first evidence for visuomotor adaptations during unperturbed overground walking and during visual perturbations while wearing a VR headset. It represents an initial investigation that may help the development of new VR methods for early detection and remediation of gait deficits in more ecological conditions.

Biomechanical and neurocognitive performance outcomes of walking with transtibial limb loss while challenged by a concurrent task

Individuals who have sustained loss of a lower limb may require adaptations in sensorimotor and control systems to effectively utilize a prosthesis, and the interaction of these systems during walking is not clearly understood for this patient population. The aim of this study was to concurrently evaluate temporospatial gait mechanics and cortical dynamics in a population with and without unilateral transtibial limb loss (TT). Utilizing motion capture and electroencephalography, these outcomes were simultaneously collected while participants with and without TT completed a concurrent task of varying difficulty (low- and high-demand) while seated and walking. All participants demonstrated a wider base of support and more stable gait pattern when walking and completing the high-demand concurrent task. The cortical dynamics were similarly modulated by the task demand for both groups, to include a decrease in the novelty-P3 component and increase in the frontal theta/parietal alpha ratio power when completing the high-demand task, although specific differences were also observed. These findings confirm and extend prior efforts indicating that dual-task walking can negatively affect walking mechanics and/or neurocognitive performance. However, there may be limited additional cognitive and/or biomechanical impact of utilizing a prosthesis in a stable, protected environment in TT who have acclimated to ambulating with a prosthesis. These results highlight the need for future work to evaluate interactions between these cognitive-motor control systems for individuals with more proximal levels of lower limb loss, and in more challenging (ecologically valid) environments.

Circumvention of Pedestrians While Walking in Virtual and Physical Environments

Virtual environments (VEs) are increasingly used in the context of scientific inquiries and rehabilitation for tasks that are otherwise difficult to control or perform safely in physical environments (PEs), such as avoiding other pedestrians during locomotion. The usefulness of VEs, however, remains constrained by the extent to which they can elicit natural responses. The objectives of the study were to examine circumvention strategies in response to pedestrians approaching from different directions in the VE versus PE and to determine the effects of repeated practice on the circumvention strategies. Twelve participants were assessed over five blocks of eight trials that consisted of walking toward a target while circumventing pedestrians approaching from different directions (0°, ± 30° right or left or none) in the VE and the PE. Similar onset distances of circumvention strategy and preferred side of circumvention were observed between the two environments. Participants, however, maintained enlarged minimum distances from the interferer (13%) and walked slower (11.5%) in the VE. Repeated practice resulted in walking speed increments of 7.4% over the entire session that were similar in the VE versus PE. While the changes observed in VE may reflect the use of more cautious circumvention strategies, the similarities in strategies between the two environments and the advantages of VEs (e.g., controlled exposure, reproduction of ecologically valid conditions, and safety) suggest that virtual reality is a valuable tool to study visually guided locomotor tasks, such as pedestrian circumvention, and shows great potential for assessment and intervention in physical rehabilitation.

Full Band Spectra Analysis of Gait Acceleration Signals for Peripheral Arterial Disease Patients

Peripheral arterial disease (PAD) is an artherosclerotic occlusive disorder of distal arteries, which can give rise to the intermittent claudication (IC) phenomenon, i.e., limb pain and necessity to stop. PAD patients with IC have altered their gait, increasing the fall risk. Several gait analysis works have studied acceleration signals (from sensors) to characterize the gait. One common technique is spectral analysis. However, this approach mainly uses dominant frequency (f_d ) to characterize gait patterns, and in a narrow spectral band, disregarding the full spectra information. We propose to use a full band spectral analysis (up to 15 Hz) and the fundamental frequency (f₀) in order to completely characterize gait for both control subjects and PAD patients. Acceleration gait signals were recorded using an acquisition equipment consisting of four wireless sensor nodes located at ankle and hip height on both sides. Subjects had to walk, free-fashion, up to 10 min. The analysis of the periodicity of the gait acceleration signals, showed that f₀ is statistically higher (p < 0.05) in control subjects (0.9743 ± 0.0716) than in PAD patients (0.8748 ± 0.0438). Moreover, the spectral envelope showed that, in controls, the power spectral density distribution is higher than in PAD patients, and that the power concentration is hither around the f_d . In conclusion, full spectra analysis allowed to better characterize gait in PAD patients than classical spectral analysis. It allowed to better discriminate PAD patients and control subjects, and it also showed promising results to assess severity of PAD.

How many strides are required for a reliable estimation of temporal gait parameters? Implementation of a new algorithm on the phase coordination index

Background

The Phase coordination index (PCI), a temporal gait measure that quantifies consistency and accuracy in generating the anti-phased left-right stepping pattern, assesses bilateral coordination of gait in various cohorts (e.g., Parkinson's disease, post stroke). As PCI is based on mean values calculated across a series of gait cycles, individuals are required to perform lengthy walking trials, prolonging gait assessments which cause discomfort to some of them. This study introduces an algorithm to identify the required number of strides to obtain a reliable, characteristic PCI value.

Methods

Simulated data sets, as well as physiological data (obtained from healthy elderly and young persons, from over ground and treadmill trials) were used in this research. A series of N-1 PCI values was calculated for i = 2,3,4…N gait cycles for each participant. There is a value i = k, representing certain number of cycles, for which no significant change in PCI occurs as additional cycles are added, termed point of stabilization (POS). The algorithm presented here uses a 2-stage iterative process to determine POS. Stage 1 searches for the gross location of the interval of PCI values containing the POS. In stage 2, the algorithm performs a high-resolution recursive, iterative process within this interval to find the exact point. The criterion for defining stability within a window of PCI values is a coefficient of variation (CV) of ≤ 5%.

Results

Our recursive, iterative algorithm indicates that ~23 strides on average should be captured to attain a characteristic PCI.

Conclusions

Gait trials with at least 23 strides on average should suffice to obtain a reliable estimation of PCI in healthy young adults. While this methodology may be considered generic, future studies should obtain POS values based on additional cohorts (e.g., disabled participants, fixed walking speeds).

An Immersive Virtual Reality Platform to Enhance Walking Ability of Children with Acquired Brain Injuries

Background: Acquired brain injury (ABI) may result in lifelong impairment of physical, cognitive, and psychosocial functions. Several rehabilitative treatments are often needed to support walking recovery, thus participants’ engagement becomes a crucial aspect, especially when patients are children. In the last few years, traditional physiotherapy (PT) has been flanked by innovative technologies for rehabilitation in the fields of robotics and Virtual Reality (VR). Preliminary results have shown interesting perspectives in the use of a VR system, the GRAIL (Gait Real-time Analysis Interactive Lab), in improving walking abilities in a small group of children with ABI, although further insights are needed about its use as rehabilitative tool in the pediatric population.

Objectives: To evaluate the efficacy of a rehabilitation treatment on a GRAIL system for the improvement of walking abilities, in a group of children suffering from ABI.

Methods: 12 children with ABI (study group – SG; mean age = 12.1 ± 3.8 years old) underwent a 10-session treatment with the GRAIL, an instrumented multi-sensor platform based on immersive VR for gait training and rehabilitation in engaging VR environments. Before (T0) and at the end of the treatment (T1), the participants were assessed by means of functional scales (Gross Motor Function Measure (GMFM), Functional Assessment Questionnaire (FAQ), 6-Minute Walk Test (6minWT) and the 3D-Gait Analysis, over ground (OGA) and on GRAIL (GGA).

Results: All the participants completed the rehabilitative treatment. The functional evaluations showed an improvement in Gross Motor abilities (GMFM-88, p = 0.008), especially in standing (GMFM-D, p = 0.007) and walking (GMFM-E, p = 0.005), an increase of the endurance (6minWT, p = 0.002), and enhanced autonomy in daily life activities (FAQ, p = 0.025). OGA identified a significant decrease of the Gillette Gait Index for the impaired side and a general increase of symmetry. GGA showed improvements in spatiotemporal parameters and joints range of motion that moved towards normality and symmetry recovery.

Conclusions: A 10-session treatment with GRAIL on children with ABI led to improvements in their walking abilities and enhanced their engagement during the training. This is desirable when long life impairments are faced and children’s motor functions have to be regained and it supports the leading role that VR might have in the rehabilitation field.

Spatiotemporal gait characteristics in patients with COPD during the Gait Real-time Analysis Interactive Lab-based 6-minute walk test

Background and aim

Overground gait assessment is limited by the analysis of multiple strides or both spatiotemporal gait characteristics, while fixed speed treadmill walking restricts natural gait speed variations. The Gait Real-time Analysis Interactive Lab (GRAIL)-based 6-minute walk test (6MWT) enables 3D motion analysis and self-paced treadmill walking, and could provide insight in gait alterations in patients with chronic obstructive pulmonary disease (COPD). The aim of this study is to compare spatiotemporal gait characteristics between patients with COPD and healthy elderly during the GRAIL-based 6MWT.

Materials and methods

Eighty COPD patients (60% male; 62±7 years; FEV₁:56±19% predicted) and 38 healthy elderly (63% male; 62±6 years; FEV₁:119±17% predicted) performed two GRAIL-based 6MWTs. Mean differences and coefficient of variation of spatiotemporal gait characteristics were calculated using the trial with the largest walk distance. Sub-analyses were conducted to account for walking speed differences between groups, and muscle strength and COPD severity within the patient group.

Results

COPD patients showed increased temporal gait characteristics, decreased stride and step lengths, and increased gait variability compared to healthy elderly (p<0.01). Stride length variability remained increased in COPD after correction for walking speed (MD:0.98%, CI:0.36–1.61, p = 0.003). Reduced quadriceps strength did not translate into altered gait characteristics, while COPD severity is associated with stride time (left MD:-0.02s, CI:-0.04–0.01, p = 0.003; right MD:-0.02s, CI:-0.04–0.01, p = 0.003).

Discussion

COPD patients performed the GRAIL-based 6MWT differently compared to healthy elderly. Further research should use other variability measures to investigate gait characteristics in COPD, to assess subtle alterations in gait and to enable development of rehabilitation strategies to improve gait, and possibly balance and fall risk in COPD. Other lower limb muscle groups should be considered when investigating gait alterations in COPD.

Conclusion

COPD patients have different gait characteristics compared to healthy elderly. Independent of walking speed, COPD patients demonstrate increased stride length variability during the GRAIL-based 6MWT compared to healthy elderly.

Intra-rater repeatability of gait parameters in healthy adults during self-paced treadmill-based virtual reality walking

Self-paced treadmill walking is becoming increasingly popular for the gait assessment and re-education, in both research and clinical settings. Its day-to-day repeatability is yet to be established. This study scrutinised the test-retest repeatability of key gait parameters, obtained from the Gait Real-time Analysis Interactive Lab (GRAIL) system. Twenty-three male able-bodied adults (age: 34.56 ± 5.12 years) completed two separate gait assessments on the GRAIL system, separated by 5 ± 3 days. Key gait kinematic, kinetic, and spatial-temporal parameters were analysed. The Intraclass-Correlation Coefficients (ICC), Standard Error Measurement (SEM), Minimum Detectable Change (MDC), and the 95% limits of agreements were calculated to evaluate the repeatability of these gait parameters. Day-to-day agreements were excellent (ICCs > 0.87) for spatial-temporal parameters with low MDC and SEM values, <0.153 and <0.055, respectively. The repeatability was higher for joint kinetic than kinematic parameters, as reflected in small values of SEM (<0.13 Nm/kg and <3.4°) and MDC (<0.335 Nm/kg and <9.44°). The obtained values of all parameters fell within the 95% limits of agreement. Our findings demonstrate the repeatability of the GRAIL system available in our laboratory. The SEM and MDC values can be used to assist researchers and clinicians to distinguish 'real' changes in gait performance over time.

Fractal fluctuations in spatiotemporal variables when walking on a self-paced treadmill

This study investigated the fractal dynamic properties of stride time (ST), stride length (SL) and stride speed (SS) during walking on a self-paced treadmill (STM) in which the belt speed is automatically controlled by the walking speed. Twelve healthy young subjects participated in the study. The subjects walked at their preferred walking speed under four conditions: STM, STM with a metronome (STM+met), fixed-speed (conventional) treadmill (FTM), and FTM with a metronome (FTM+met). To compare the fractal dynamics between conditions, the mean, variability, and fractal dynamics of ST, SL, and SS were compared. Moreover, the relationship among the variables was examined under each walking condition using three types of surrogates. The mean values of all variables did not differ between the two treadmills, and the variability of all variables was generally larger for STM than for FTM. The use of a metronome resulted in a decrease in variability in ST and SS for all conditions. The fractal dynamic characteristics of SS were maintained with STM, in contrast to FTM, and only the fractal dynamic characteristics of ST disappeared when using a metronome. In addition, the fractal dynamic patterns of the cross-correlated surrogate results were identical to those of all variables for the two treadmills. In terms of the fractal dynamic properties, STM walking was generally closer to overground walking than FTM walking. Although further research is needed, the present results will be useful in research on gait fractal dynamics and rehabilitation.

The effect of uphill and downhill walking on gait parameters: A self-paced treadmill study

It has been shown that gait parameters vary systematically with the slope of the surface when walking uphill (UH) or downhill (DH) (Andriacchi et al., 1977; Crowe et al., 1996; Kawamura et al., 1991; Kirtley et al., 1985; McIntosh et al., 2006; Sun et al., 1996). However, gait trials performed on inclined surfaces have been subject to certain technical limitations including using fixed speed treadmills (TMs) or, alternatively, sampling only a few gait cycles on inclined ramps. Further, prior work has not analyzed upper body kinematics. This study aims to investigate effects of slope on gait parameters using a self-paced TM (SPTM) which facilitates more natural walking, including measuring upper body kinematics and gait coordination parameters. Gait of 11 young healthy participants was sampled during walking in steady state speed. Measurements were made at slopes of +10°, 0° and -10°. Force plates and a motion capture system were used to reconstruct twenty spatiotemporal gait parameters. For validation, previously described parameters were compared with the literature, and novel parameters measuring upper body kinematics and bilateral gait coordination were also analyzed. Results showed that most lower and upper body gait parameters were affected by walking slope angle. Specifically, UH walking had a higher impact on gait kinematics than DH walking. However, gait coordination parameters were not affected by walking slope, suggesting that gait asymmetry, left-right coordination and gait variability are robust characteristics of walking. The findings of the study are discussed in reference to a potential combined effect of slope and gait speed. Follow-up studies are needed to explore the relative effects of each of these factors.

Speed-Interactive Treadmill Training Using Smartphone-Based Motion Tracking Technology Improves Gait in Stroke Patients

This study was conducted to investigate the effects of speed-interactive treadmill training (SITT) using smartphone-based motion tracking technology on gait in stroke patients. Thirty-four chronic stroke patients were randomly divided into a SITT group (n = 18) and a standard treadmill training (control) group (n = 16). The SITT group underwent smartphone-based SSIT while the control group underwent standard treadmill training. Both groups performed the training for 35 min per session, 3 times per week, for 6 weeks. Both groups used nonmotorized treadmills so that patients could control the speed. Evaluation was conducted during the week before and after the training. The OptoGait system measured gait spatiotemporal parameters. Both groups showed significant improvement in the temporal and spatial gait parameters (p < .05). In the SITT group, compared to the control group, the two-way analysis of variance with repeated measures showed an improvement in the temporal and spatial gait parameters after the intervention period (p < .05). This study confirmed that SITT improved the gait function of stroke patients. Based on this result, the authors propose that SITT, by improving gait, can be used as an effective training method to improve patients' functional activities in the clinic.

Reproducibility and Validity of the 6-Minute Walk Test Using the Gait Real-Time Analysis Interactive Lab in Patients with COPD and Healthy Elderly

BACKGROUND

The 6-minute walk test (6MWT) in a regular hallway is commonly used to assess functional exercise capacity in patients with chronic obstructive pulmonary disease (COPD). However, treadmill walking might provide additional advantages over overground walking, especially if virtual reality and self-paced treadmill walking are combined. Therefore, this study aimed to assess the reproducibility and validity of the 6MWT using the Gait Real-time Analysis Interactive Lab (GRAIL) in patients with COPD and healthy elderly.

METHODOLOGY/RESULTS

Sixty-one patients with COPD and 48 healthy elderly performed two 6MWTs on the GRAIL. Patients performed two overground 6MWTs and healthy elderly performed one overground test. Differences between consecutive 6MWTs and the test conditions (GRAIL vs. overground) were analysed. Patients walked further in the second overground test (24.8 m, 95% CI 15.2-34.4 m, p<0.001) and in the second GRAIL test (26.8 m, 95% CI 13.9-39.6 m). Healthy elderly improved their second GRAIL test (49.6 m, 95% CI 37.0-62.3 m). The GRAIL 6MWT was reproducible (intra-class coefficients = 0.65-0.80). The best GRAIL 6-minute walk distance (6MWD) in patients was shorter than the best overground 6MWD (-27.3 ± 49.1 m, p<0.001). Healthy elderly walked further on the GRAIL than in the overground condition (23.6 ± 41.4 m, p<0.001). Validity of the GRAIL 6MWT was assessed and intra-class coefficient values ranging from 0.74-0.77 were found.

CONCLUSION

The GRAIL is a promising system to assess the 6MWD in patients with COPD and healthy elderly. The GRAIL 6MWD seems to be more comparable to the 6MWDs assessed overground than previous studies on treadmills have reported. Furthermore, good construct validity and reproducibility were established in assessing the 6MWD using the GRAIL in patients with COPD and healthy elderly.

Gait rehabilitation with a high tech platform based on virtual reality conveys improvements in walking ability of children suffering from acquired brain injury

The Gait Real-time Analysis Interactive Lab (GRAIL) is an instrumented multi-sensor platform based on immersive virtual reality for gait training and rehabilitation. Few studies have been included GRAIL to evaluate gait patterns in normal and disabled people and to improve gait in adults, while at our knowledge no evidence on its use for the rehabilitation of children is available. In this study, 4 children suffering from acquired brain injury (ABI) underwent a 5 session treatment with GRAIL, to improve walking and balance ability in engaging VR environments. The first and the last sessions were partially dedicated to gait evaluation. Results are promising: improvements were recorded at the ankle level, selectively at the affected side, and at the pelvic level, while small changes were measured at the hip and knee joints, which were already comparable to healthy subjects. All these changes also conveyed advances in the symmetry of the walking pattern. In the next future, a longer intervention will be proposed and more children will be enrolled to strongly prove the effectiveness of GRAIL in the rehabilitation of children with ABI.

Self-paced versus fixed speed walking and the effect of virtual reality in children with cerebral palsy

While feedback-controlled treadmills with a virtual reality could potentially offer advantages for clinical gait analysis and training, the effect of self-paced walking and the virtual environment on the gait pattern of children and different patient groups remains unknown. This study examined the effect of self-paced (SP) versus fixed speed (FS) walking and of walking with and without a virtual reality (VR) in 11 typically developing (TD) children and nine children with cerebral palsy (CP). We found that subjects walked in SP mode with twice as much between-stride walking speed variability (p<0.01), fluctuating over multiple strides. There was no main effect of SP on kinematics or kinetics, but small interaction effects between SP and group (TD versus CP) were found for five out of 33 parameters. This suggests that children with CP might need more time to familiarize to SP walking, however, these differences were generally too small to be clinically relevant. The VR environment did not affect the kinematic or kinetic parameters, but walking with VR was rated as more similar to overground walking by both groups (p=0.02). The results of this study indicate that both SP and FS walking, with and without VR, can be used interchangeably for treadmill-based clinical gait analysis in children with and without CP.

Kinetic comparison of walking on a treadmill versus over ground in children with cerebral palsy

Kinetic outcomes are an essential part of clinical gait analysis, and can be collected for many consecutive strides using instrumented treadmills. However, the validity of treadmill kinetic outcomes has not been demonstrated for children with cerebral palsy (CP). In this study we compared ground reaction forces (GRF), center of pressure, and hip, knee and ankle moments, powers and work, between overground (OG) and self-paced treadmill (TM) walking for 11 typically developing (TD) children and 9 children with spastic CP. Considerable differences were found in several outcome parameters. In TM, subjects demonstrated lower ankle power generation and more absorption, and increased hip moments and work. This shift from ankle to hip strategy was likely due to a more backward positioning of the hip and a slightly more forward trunk lean. In mediolateral direction, GRF and hip and knee joint moments were increased in TM due to wider step width. These findings indicate that kinetic data collected on a TM cannot be readily compared with OG data in TD children and children with CP, and that treadmill-specific normative data sets should be used when performing kinetic gait analysis on a treadmill.

Stroke Rehabilitation Using Virtual Environments

This review covers the rationale, mechanisms, and availability of commercially available virtual environment-based interventions for stroke rehabilitation. It describes interventions for motor, speech, cognitive, and sensory dysfunction. Also discussed are the important features and mechanisms that allow virtual environments to facilitate motor relearning. A common challenge is the inability to translate success in small trials to efficacy in larger populations. The heterogeneity of stroke pathophysiology has been blamed, and experts advocate for the study of multimodal approaches. Therefore, this article also introduces a framework to help define new therapy combinations that may be necessary to address stroke heterogeneity.