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Spatiotemporal metrics such as step frequency have been associated with running injuries in some studies. Wearables can measure these metrics and provide real-time feedback in-field, but are often not validated. This study assessed the validity of commercially available wireless instrumented insoles (ARION) for quantifying spatiotemporal metrics during level running at different speeds (2.78-5.0 m s -1 ,) and slopes (3° and 6° up/downhill) to an instrumented treadmill. Mean raw, percentage and absolute percentage error, and limits of agreement (LoA) were calculated. Agreement was statistically quantified using four thresholds: excellent, <5%; good, <10%; acceptable, <15%; and poor, >15% error. Excellent agreement (<5% error) was achieved for stride time across all conditions, and for step frequency across all but one condition with good agreement. Contact time and swing time generally showed at least good agreement. The mean difference across all conditions was -0.95% for contact time, 0.11% for stride time, 0.6% for swing time, -0.11% for step frequency, and -0.09% when averaged across all outcomes and conditions. The accuracy at an individual level was generally good to excellent, being <10% for all but two conditions, with these conditions being <15%. Additional experiments among four runners showed that step length could also be measured with an accuracy of 1.76% across different speeds with an updated version of the insoles. These findings suggests that the ARION wearable may not only be useful for large-scale in-field studies investigating group differences, but also to quantify spatiotemporal metrics with generally good to excellent accuracy for individual runners., (© 2023 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

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., Competing Interests: The authors declare there are no competing interests., (©2022 Senden et al.)

Background: Falls risk is elevated in chronic obstructive pulmonary disease (COPD). However, there is a lack of evidence regarding the contributing factors. Here, we examined the feasibility of, and initial responses to, large walking perturbations in COPD, as well as the adaptation potential of people with COPD to repeated walking perturbations that might indicate potential for perturbation-based balance training in COPD., Methods: 12 participants with COPD undergoing inpatient pulmonary rehabilitation and 12 age-gender-matched healthy control participants walked on an instrumented treadmill and experienced repeated treadmill-belt acceleration perturbations (leading to a forward balance loss). Three-dimensional motion capture was used to quantify the stability of participants body position during perturbed walking. Feasibility, stability following the initial perturbations and adaptation to repeated perturbations were assessed., Findings: Using perturbations in this manner was feasible in this population (no harness assists and participants completed the minimum number of perturbations). No clear, specific deficit in reactive walking stability in COPD was found (no significant effects of participant group on stability or recovery step outcomes). There were mixed results for the adaptability outcomes which overall indicated some adaptability to repeated perturbations, but not to the same extent as the healthy control participants., Interpretation: Treadmill-based perturbations during walking are feasible in COPD. COPD does not appear to result in significant deficits in stability following sudden perturbations and patients do demonstrate some adaptability to repeated perturbations. Perturbation-based balance training may be considered for fall prevention in research and practice in people with COPD., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: One factor related to disability in people with spinal deformity is decreased postural control and increased risk of falling. However, little is known about the effect of osteoporotic vertebral compression fractures (OVCFs) and their recovery on gait and stability. Walking characteristics of older adults with and without vertebral fractures have not yet been compared., Aims: The purpose of the current study was to examine the spatiotemporal gait parameters and their variability in patients with an OVCF and healthy participants during treadmill walking at baseline and after 6 months of recovery., Methods: Twelve female patients suffering a symptomatic OVCF were compared to 11 matched controls. Gait analysis was performed with a dual-belt instrumented treadmill with a 180° projection screen providing a virtual environment (computer-assisted rehabilitation environment). Results of patients with an OVCF and healthy participants were compared. Furthermore, spatiotemporal gait parameters were assessed over 6 months following the fracture., Results: Patients suffering from an OVCF appeared to walk with significantly shorter, faster and wider strides compared to their healthy counterparts. Although stride time and length improved over time, the majority of the parameters analysed remained unchanged after 6 months of conservative treatment., Discussion: Since patients do not fully recover to their previous level of mobility after 6 months of conservative treatment for OVCF, it appears of high clinical importance to add balance and gait training to the treatment algorithm of OVCFs., Conclusions: Patients suffering from an OVCF walk with shorter, faster and wider strides compared to their healthy counterparts adopt a less stable body configuration in the anterior direction, potentially increasing their risk of forward falls if perturbed. Although stride time and stride length improve over time even reaching healthy levels again, patients significantly deviate from normal gait patterns (e.g. in stability and step width) after 6 months of conservative treatment.

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.

Ankle fractures are among the most common lower limb fractures. Associations between postoperative radiographic results and clinical outcome have been found, but less is known about the relevant ankle biomechanics. This study analyzed ankle kinematics, radiographic findings, and patient-reported outcome measures (PROM) in patients treated for ankle fractures. The hypothesis was that patients after ankle fracture surgery had less flexion/extension in the ankle compared to healthy subjects and that fracture severity had significant influence on kinematics and patient satisfaction. Thirty-three patients (n = 33 feet) operated for ankle fractures were recruited. Ankle kinematics were analyzed using the Oxford Foot model, and results were compared with an age-matched healthy control group (11 patients, 20 feet). In addition, patients were divided by fracture (severity) classification and kinematic results were correlated with PROM and radiographic findings. Patients treated for ankle fracture showed lower walking speed (p < 0.001) when asked to walk in preferred normal speed. When compared at equal speed, significantly less range of motion (ROM) between the hindfoot and tibia in the sagittal plane (flexion/extension) during loading and push-off phases (p = 0.003 and p < 0.001) was found in patients after ankle fractures compared to healthy subjects. Lowest ROM and poorest PROM results were found for patients with trimalleolar ankle fractures. There was a significant correlation between ROM (flexion/extension) during the push-off phase and SF-36 physical functioning (r 2  = 0.403, p = 0.027) and SF-36 general health (r 2  = 0.473, p = 0.008). Fracture severity was significantly correlated with flexion/extension ROM in the ankle during both loading and push-off phases (r 2  = -0.382, p = 0.005, and r 2  = -0.568, p < 0.001) and was also significantly correlated with PROM. This study found that patients with ankle fractures had significantly altered ankle kinematics compared to healthy subjects. The poorest results were found among patients with trimalleolar fractures. Weak to strong significant correlations were found between fracture severity, ankle kinematics, and PROM. © 2019 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:1658-1666, 2019., (© 2019 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society.)

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.

Background: The effects of age and speed on foot and ankle kinematics in gait studies using foot models are not fully understood, whereas this can have significant influence. We analyzed these variables with the 4-segment Oxford foot model., Methods: Twenty-one healthy subjects (aged 20-65 years) were recruited for gait analysis. The effect of speed on foot and ankle kinematics was assessed by comparing results during slow walking and fast walking. To assess the effect of age, a group of 13 healthy young adults (aged 20-24 years) were compared with a group of 8 older adults (aged 53-65 years). Also, the interaction between age and speed was analyzed., Results: Regarding speed, there was a significant difference between forefoot/hindfoot motion in the sagittal plane (flexion/extension) during both loading- and push-off phase (P = .004, P < .001). Between hindfoot/tibia, there was a significant difference for all parameters except for motion in the sagittal plane (flexion/extension) during push-off phase (P = .5). Age did not significantly influence kinematics. There was no interaction between age and speed., Conclusion: Our analysis found that speed significantly influenced the kinematic outcome parameters. This was more pronounced in the ankle joint. In contrast, no significant differences were found between younger and older healthy subjects.

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., Competing Interests: The authors have declared that no competing interests exist.

Background: Calcaneal fractures are associated with substantial morbidity and socioeconomic impact, frequently leading to limited functional outcome and high economic costs. The Oxford foot model (OFM) has been reported as a valid addition to the biomechanical examination of the foot. The aim of our study was to analyze the gait of patients after operative repair of a calcaneal fracture in relation to functional outcome and radiographic findings., Methods: Thirteen patients with a calcaneal fracture underwent gait analysis with OFM at a minimum of six months after open surgery. Intersegmental range of motion was measured during gait. Results were compared with those of healthy subjects and those of patients who had undergone subtalar arthrodesis. Patient-reported questionnaires and radiographic images were also evaluated., Results: The range of motion between the hindfoot and the tibia in the push-off phase in the transverse plane was significantly correlated with the clinical outcome as reported by patients based on the Foot and Ankle Disability Index (FADI) (r(2) = 0.51; p < 0.001) and the Short Form (SF)-36 physical component summary score (r(2) = 0.52; p < 0.001). We found a significant correlation between the step-off in the subtalar joint as measured on postoperative computed tomography (CT) and range of motion (r(2) = -0.74; p = 0.004). The step-off was also correlated with the patient-reported outcome questionnaire FADI (r(2) = -0.76; p = 0.003) and the SF-36 physical component summary score (r(2) = -0.78; p = 0.002)., Conclusions: This study demonstrated that the subtalar joint range of motion of patients after a calcaneal fracture was related both to the quality of the reduction of the subtalar joint as evaluated on postoperative CT scans and patient-reported functional outcome., (Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.)

Increased forefoot loading in diabetic polyneuropathy plays an important role in the development of plantar foot ulcers and can originate from alterations in muscle strength, joint moments and gait pattern. The current study evaluated whether strength training can improve lower extremity joint moments and spatiotemporal gait characteristics in patients with diabetic polyneuropathy. An intervention group receiving strength training during 24 weeks and a control group receiving no intervention. Measurements were performed in both groups at t=0, t=12, t=24 and t=52 weeks at an individually preferred and standardized imposed gait velocity. The strength training did not affect the maximal amplitude of hip, knee and ankle joint moments, but did result in an increase in stance phase duration, stride time and stride length of approximately 5%, during the imposed gait velocity. In addition, both groups increased their preferred gait velocity over one year. Future longitudinal studies should further explore the possible effects of strength training on spatiotemporal gait characteristics. The current study provides valuable information on changes in gait velocities and the progressive lower extremity problems in patients with polyneuropathy.

The aim of this study was to identify the cascade of effects leading from alterations in force generation around the ankle joint to increased plantar pressures under the forefoot. Gait analysis including plantar pressure measurement was performed at an individually preferred and a standardized, imposed gait velocity in diabetic subjects with polyneuropathy (n=94), without polyneuropathy (n=39) and healthy elderly (n=19). The plantar flexion moment at 40% of the stance phase was negatively correlated with the displacement rate of center of pressure (r=-.749, p<.001 at the imposed, and r=-.693, p<.001 at the preferred gait velocity). Displacement rate of center of pressure was strongly correlated with forefoot loading (r=-.837, p<.001 at the imposed, and r=-.731, p<.001 at the preferred gait velocity). People with a relatively high plantar flexion moment at 40% of the stance phase, have a faster forward transfer of center of pressure and consequently higher loading of the forefoot. This indicates that interventions aimed at increasing the control of the roll-off of the foot may contribute to a better plantar pressure distribution., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: To date, detailed analyses of walking patterns using accelerometers during the 6-min walk test (6MWT) have not been performed in patients with chronic obstructive pulmonary disease (COPD). Therefore, it remains unclear whether and to what extent COPD patients have an altered walking pattern during the 6MWT compared to healthy elderly subjects., Methodology/principal Findings: 79 COPD patients and 24 healthy elderly subjects performed the 6MWT wearing an accelerometer attached to the trunk. The accelerometer features (walking intensity, cadence, and walking variability) and subject characteristics were assessed and compared between groups. Moreover, associations were sought with 6-min walk distance (6MWD) using multiple ordinary least squares (OLS) regression models. COPD patients walked with a significantly lower walking intensity, lower cadence and increased walking variability compared to healthy subjects. Walking intensity and height were the only two significant determinants of 6MWD in healthy subjects, explaining 85% of the variance in 6MWD. In COPD patients also age, cadence, walking variability measures and their interactions were included were significant determinants of 6MWD (total variance in 6MWD explained: 88%)., Conclusions/significance: COPD patients have an altered walking pattern during 6MWT compared to healthy subjects. These differences in walking pattern partially explain the lower 6MWD in patients with COPD.

Purpose: Joint moments have been acknowledged as key factors in understanding gait abnormalities. Gait velocity is further known to affect joint moments and foot pressures. Keeping gait velocity constant is thus a strategy to cancel out the influence of different preferred gait speed between groups. But even if gait velocity is controlled, individuals can choose different stride length-stride frequency combinations to cope with an imposed gait velocity., Scope: To understand the influence of stride frequency-stride length on joint moments and plantar pressures., Methods: Twenty healthy young adults had to cross an 8m walkway with a walking speed of 1.3ms(-1). The wooden walkway was equipped with a force and a pressure platform. While walking speed was kept constant each participant walked with five different imposed stride lengths (SL): preferred (SL0); with a decrease of 10% (SL-10); with a decrease of 20% (SL-20); with an increase of 10% (SL+10) and with an increase of 20% (SF+20)., Results: Ankle and knee joint moments significantly decreased with a decrease in SL. A significant (p<.05) lower peak pressure was achieved with a decreased SL under the heel, toes and midfoot., Discussion/conclusion: The results showed that a change in stride lengths alters both, joint moments and foot pressures with clinically interesting indications. Redistribution of joint moments in the elderly for example might rather result from decreased SL than from age., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: People with diabetes or diabetic polyneuropathy often experience limitations in mobility and gait. These limitations are believed to be related to disturbed muscle function and sensory information. In previous studies on diabetic gait, results were confounded by a lower, preferred walking speed in people with diabetes or diabetic polyneuropathy. This study aimed to identify gait-velocity independent effects of diabetes and diabetic polyneuropathy on lower extremity kinematics and muscle activation patterns., Methods: Eight people with diabetic polyneuropathy, 10 diabetic controls without polyneuropathy and ten healthy, age-matched controls walked at their preferred velocity and a standard velocity of 1.4 ms(-1). Muscle activation patterns of gluteus maximus, biceps femoris, rectus femoris, vastus medialis, gastrocnemius medialis, soleus, and tibialis anterior, and spatiotemporal and joint angles characteristics were analysed., Findings: Independent of walking speed, muscle activation differed between groups. In diabetic polyneuropathy participants activation of ankle-joint dorsal flexors was prolonged by 5-10% of the stride cycle. Activity of monoarticular knee-joint extensors lasted about 10% longer in both diabetic groups compared to healthy elderly. Initiation of muscle activity did not differ between groups. If gait velocity was controlled, spatiotemporal characteristics were similar between groups., Interpretation: The study showed that independent of the preferred lower gait velocity, people with diabetes or diabetic polyneuropathy adjust the timing of muscle activity. Contrarily, the concurrent changes in spatiotemporal characteristics occurred to be the result of changed velocity only. The delayed cessation of muscle activity suggested a reduced rate of force development underlying the adjusted timing of muscle activation., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

Background: Patients with diabetic polyneuropathy (DPN) are often confronted with ulceration of foot soles. Increased plantar pressure under the forefoot has been identified as a major risk factor for ulceration. This study sets out to test the hypothesis that changes in gait characteristics induced by DPN related muscle weakness are the origin of the elevated plantar pressures., Methods: Three groups of subjects participated: people diagnosed with diabetes without polyneuropathy (DC), people diagnosed with diabetic polyneuropathy (DPN) and healthy, age-matched controls (HC). In all subjects isometric strength of plantar and dorsal flexors was assessed. Moreover, joint moments at ankle, knee and hip joints were determined while walking barefoot at a velocity of 1.4 m/s. Simultaneously plantar pressure patterns were measured., Results: Compared to HC-subjects, DPN-participants walked with a significantly increased internal plantar flexor moment at the first half of the stance phase. Also in DPN-subjects the maximal braking and propelling force applied to the floor was decreased. Moreover, in DPN-subjects the ratio of forefoot-to-rear foot plantar pressures was increased. Body-mass normalized strength of dorsal flexors showed a trend to be reduced in people with diabetes, both DC and DPN, compared to HC-subjects. Plantar flexors tended to be less weak in DC compared to HC and in DPN relative to DC., Conclusion: The results of this study suggest that adverse plantar pressure patterns are associated with redistribution of joint moments, and a consequent reduced capacity to control forward velocity at heel strike.

Previous studies showed age-related redistribution of joint torques from ankle joint plantar flexion to hip joint extension in gait. In the present study it was hypothesized that running can prevent the occurrence of this joint torque redistribution. Four groups of subjects participated in this study (young and elderly both physically active and inactive). All subjects walked at a comfortable, preferred velocity and at an imposed velocity of 1.5m/s. Kinematics of lower limb segments and ground reaction forces were assessed. Inverse dynamics method was applied to determine torques around ankle, knee and hip joints. A redistribution of joint torques from plantar flexion to hip joint extension was found to occur in both active and inactive elderly. However, the active elderly had a larger increase of the hip extension torque. By this they are able to maintain the support torque at the level of young subjects. Inactive elderly displayed reduced support torques. It is concluded that the age-related redistribution of joint torques is an important phenomenon. Frequent running does not prevent this shift. Active elderly increase this redistribution to compensate for muscle function reduction.