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Background: Gait slowing is a common feature of Parkinson’s disease (PD). Many therapies aim to improve gait speed in persons with PD, but goals are often imprecise. How fast should each patient walk? And how do persons with PD benefit from walking faster? There is an important need to understand how walking speed affects fundamental aspects of gait—including energy cost and stability—that could guide individualized therapy decisions in persons with PD. Objective: We investigated how changes in walking speed affected energy cost and spatiotemporal gait parameters in persons with PD. We compared these effects between dopaminergic medication states and to those observed in age-matched control participants. Methods: Twelve persons with PD and twelve control participants performed treadmill walking trials spanning at least five different speeds (seven speeds were desired, but not all participants could walk at the fastest speeds). Persons with PD participated in two walking sessions on separate days (once while optimally medicated, once after 12-hour withdrawal from dopaminergic medication). We measured kinematic and metabolic data across all trials. Results: Persons with PD significantly reduced energy cost by walking faster than their preferred speeds. This held true across medication conditions and was not observed in control participants. The patient-specific walking speeds that reduced energy cost did not significantly affect gait variability metrics (used as proxies for gait stability). Conclusion: The gait slowing that occurs with PD results in energetically suboptimal walking. Rehabilitation strategies that target patient-specific increases in walking speed could result in a less effortful gait.

Wearable inertial measurement units (IMUs) are used in gait analysis due to their discrete wearable attachment and long data recording possibilities within indoor and outdoor environments. Previously, lower back and shin/shank-based IMU algorithms detecting initial and final contact events (ICs-FCs) were developed and validated on a limited number of healthy young adults (YA), reporting that both IMU wear locations are suitable to use during indoor and outdoor gait analysis. However, the impact of age (e.g., older adults, OA), pathology (e.g., Parkinson′s Disease, PD) and/or environment (e.g., indoor vs. outdoor) on algorithm accuracy have not been fully investigated. Here, we examined IMU gait data from 128 participants (72-YA, 20-OA, and 36-PD) to thoroughly investigate the suitability of ICs-FCs detection algorithms (1 × lower back and 1 × shin/shank-based) for quantifying temporal gait characteristics depending on IMU wear location and walking environment. The level of agreement between algorithms was investigated for different cohorts and walking environments. Although mean temporal characteristics from both algorithms were significantly correlated for all groups and environments, subtle but characteristically nuanced differences were observed between cohorts and environments. The lowest absolute agreement level was observed in PD (ICC2,1 = 0.979, 0.806, 0.730, 0.980) whereas highest in YA (ICC2,1 = 0.987, 0.936, 0.909, 0.989) for mean stride, stance, swing, and step times, respectively. Absolute agreement during treadmill walking (ICC2,1 = 0.975, 0.914, 0.684, 0.945), indoor walking (ICC2,1 = 0.987, 0.936, 0.909, 0.989) and outdoor walking (ICC2,1 = 0.998, 0.940, 0.856, 0.998) was found for mean stride, stance, swing, and step times, respectively. Findings of this study suggest that agreements between algorithms are sensitive to the target cohort and environment. Therefore, researchers/clinicians should be cautious while interpreting temporal parameters that are extracted from inertial sensors-based algorithms especially for those with a neurological condition.

Modern smartphones such as the iPhone contain an integrated accelerometer, which can be used to measure body movement and estimate the volume and intensity of physical activity. Objectives: The primary objective was to assess the validity of the iPhone to measure step count and energy expenditure during laboratory-based physical activities. A further objective was to compare free-living estimates of physical activity between the iPhone and the ActiGraph GT3X+ accelerometer. Methods: Twenty healthy adults wore the iPhone 5S and GT3X+ in a waist-mounted pouch during bouts of treadmill walking, jogging, and other physical activities in the laboratory. Step counts were manually counted, and energy expenditure was measured using indirect calorimetry. During two weeks of free-living, participants (n = 17) continuously wore a GT3X+ attached to their waist and were provided with an iPhone 5S to use as they would their own phone. Results: During treadmill walking, iPhone (703 ± 97 steps) and GT3X+ (675 ± 133 steps) provided accurate measurements of step count compared with the criterion method (700 ± 98 steps). Compared with indirect calorimetry (8 ± 3 kcal·min−1), the iPhone (5 ± 1 kcal·min−1) underestimated energy expenditure with poor agreement. During free-living, the iPhone (7,990 ± 4,673 steps·day−1) recorded a significantly lower (p −1). Conclusions: The iPhone accurately estimated step count during controlled laboratory walking but recorded a significantly lower volume of physical activity compared with the GT3X+ during free-living.

Background A specific walking speed minimizing the U-shaped relationship between energy cost of transport per unit distance (CoT) and speed is called economical speed (ES). To investigate the effects of reduced body weight on the ES, we installed a body weight support (BWS) apparatus with a spring-like characteristics. We also examined whether the 'calculated' ES was equivalent to the 'preferred' walking speed (PWS) with 30% BWS. Methods We measured oxygen uptake and carbon dioxide output to calculate CoT values at seven treadmill walking speeds (0.67–2.00 m s− 1) in 40 healthy young males under normal walking (NW) and BWS. The PWS was determined under both conditions on a different day. Results A spring-like behavior of our BWS apparatus reduced the CoT values at 1.56, 1.78, and 2.00 m s− 1. The ES with BWS (1.61 ± 0.11 m s− 1) was faster than NW condition (1.39 ± 0.06 m s− 1). A Bland-Altman analysis indicated that there were no systematic biases between ES and PWS in both conditions. Conclusions The use of BWS apparatus with a spring-like behavior reduced the CoT values at faster walking speeds, resulting in the faster ES with 30% BWS compared to NW. Since the ES was equivalent to the PWS in both conditions, the PWS could be mainly determined by the metabolic minimization in healthy young males. This result also derives that the PWS can be a substitutable index of the individual ES in these populations.

Summary Several mouse in vivo neuronal recording techniques require head fixation. Head-fixed treadmill walking can be used to design tasks that enable the study of neural activity in the context of behavior. Here, we provide a detailed protocol for constructing a treadmill with tactile spatial cues, training mice on a rewarded behavioral task, and analyzing behavioral data. We discuss common problems and solutions we have developed to optimize training. Finally, we demonstrate how to test spatial memory performance using this task., Graphical abstract, Highlights • Protocol for a rewarded head-fixed treadmill task for mice • Assembly of treadmill and overview of a surgical procedure • Training of mice on head-fixed, rewarded spatial memory tasks • Analysis of reward search by spatial analysis of lick behavior along a treadmill, Several mouse in vivo neuronal recording techniques require head fixation. Head-fixed treadmill walking can be used to design tasks that enable the study of neural activity in the context of behavior. Here, we provide a detailed protocol for constructing a treadmill with tactile spatial cues, training mice on a rewarded behavioral task, and analyzing behavioral data. We discuss common problems and solutions we have developed to optimize training. Finally, we demonstrate how to test spatial memory performance using this task.

Stability during walking is considered a crucial aspect of assessing gait ability. The current study aimed to assess walking stability by applying principal component analysis (PCA) to decompose three-dimensional (3D) whole-body kinematic data of 104 healthy young adults (21.9 ± 3.5 years, 54 females) derived from a depth-sensing camera into a set of movement components/synergies called “principal movements” (PMs), forming together to achieve the task goal. The effect of sex as the focus area was tested on three PCA-based variables computed for each PM: the relative explained variance (rVAR) as a measure of the composition of movement structures; the largest Lyapunov exponent (LyE) as a measure of variability; and the number of zero-crossings (N) as a measure of the tightness of neuromuscular control. The results show that the sex effects appear in the specific PMs. Specifically, in PM1, resembling the swing-phase movement, females have greater LyE (p = 0.013) and N (p = 0.017) values than males. Moreover, in PM3, representing the mid-stance-phase movement, females have smaller rVAR (p = 0.020) but greater N (p = 0.008) values than males. These empirical findings suggest that the inherent sex differences in walking stability should be considered in assessing and training locomotion.

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.

Bioimpedance measurements collected during dynamic activities have alterations compared to static conditions as a result of contraction and relaxation of skeletal muscle. Understanding these effects will be an important consideration for studies collecting this type of data during free-living. In this preliminary trial, 128 kHz knee tissue resistance was collected during 5 walking activities (e.g. treadmill walking and stair climbing) of increasing intensity from a single participant. Mean and maximum resistances were observed to increase with increasing activity, with 1.14 Ω (+1.80%) and 2.03 Ω (+6.48%) mean increases for the highest intensity treadmill walking (compared to the lowest) for the two localized tissue sites, respectively.

A self-paced treadmill automatically adjusts speed in real-time to match the user’s walking speed, presumably leading to a more nature gait than fixed-speed treadmill. However, previous study has proven that the acceleration applied to the subjects would influence the gait stability. In order to have insights on to which extent will the accelerations affect gait stability, simulation analysis based on conceptual model has been done in the current study. This paper utilized a non-inertial frame based spring-loaded inverted pendulum model to analysis the condition of stability during continuous self-paced treadmill walking. Simulations were done for 100 continuous self-paced treadmill walking at the normal walking speed. And 10ms impulse accelerations of different magnitudes with the range of (−1g, 1g) were applied at different gait events such as toe-off, foot-flat and heel-strike. The simulation results showed that the magnitude of the accelerations had significantly influence on continuous self-paced treadmill walking and directional-dependency was also found. However, no significantly difference was found when applying the impulse acceleration at different gait events.

BackgroundMobility and cognitive impairments in Parkinson’s disease (PD) often coexist and are prognostic of adverse health events. Consequently, assessment and training that simultaneously address both gait function and cognition are important to consider in rehabilitation and promotion of healthy aging. For this purpose, a computer game-based rehabilitation treadmill platform (GRP) was developed for dual-task (DT) assessment and training.ObjectiveThe first objective was to establish the test-retest reliability of the GRP assessment protocol for DT gait, visuomotor and executive cognitive function in PD patients. The second objective was to examine the effect of task condition [single task (ST) vs. DT] and disease severity (stage 2 vs. stage 3) on gait, visuomotor and cognitive function.MethodsThirty individuals aged 55 to 70 years, diagnosed with PD; 15 each at Hoehn and Yahr scale stage 2 (PD-2) and 3 (PD-3) performed a series of computerized visuomotor and cognitive game tasks while sitting (ST) and during treadmill walking (DT). A treadmill instrumented with a pressure mat was used to record center of foot pressure and compute the average and coefficient of variation (COV) of step time, step length, and drift during 1-min, speed-controlled intervals. Visuomotor and cognitive game performance measures were quantified using custom software. Testing was conducted on two occasions, 1 week apart.ResultsWith few exceptions, the assessment protocol showed moderate to high intraclass correlation coefficient (ICC) values under both ST and DT conditions for the spatio-temporal gait measures (average and COV), as well as the visuomotor tracking and cognitive game performance measures. A significant decline in gait, visuomotor, and cognitive game performance measures was observed during DT compared to ST conditions, and in the PD-3 compared to PD-2 groups.ConclusionThe high to moderate ICC values along with the lack of systematic errors in the measures indicate that this tool has the ability to repeatedly record reliable DT interference (DTI) effects over time. The use of interactive digital media provides a flexible method to produce and evaluate DTI for a wide range of executive cognitive activities. This also proves to be a sensitive tool for tracking disease progression.Clinical Trial Registrationwww.ClinicalTrials.gov, identifier NCT03232996.

Biomarkers that can identify age-related decline in walking function have potential to promote healthier aging by triggering timely interventions that can mitigate or reverse impairments. Recent evidence suggests that changes in neuromuscular control precede changes in walking function; however, it is unclear which measures are best suited for identifying age-related changes. In this study, non-negative matrix factorization of electromyography data collected during treadmill walking was used to calculate two measures of the complexity of muscle co-activations during walking for 36 adults: (1) the number of muscle synergies and (2) the dynamic motor control index. Study participants were grouped into young (18–35 years old), young-old (65–74 years old), and old–old (75+ years old) subsets. We found that the dynamic motor control index [χ2(2) = 9.41, p = 0.009], and not the number of muscle synergies [χ2(2) = 5.42, p = 0.067], differentiates between age groups [χ2(4) = 10.62, p = 0.031, Nagelkerke R2 = 0.297]. Moreover, an impairment threshold set at a dynamic motor control index of 90 (i.e., one standard deviation below the young adults) was able to differentiate between age groups [χ2(2) = 9.351, p = 0.009]. The dynamic motor control index identifies age-related differences in neuromuscular complexity not measured by the number of muscle synergies and may have clinical utility as a marker of neuromotor impairment.

Background The assessment of stability recovery performance following perturbations contributes to the determination of fall resisting skills. This study investigated the association between stability recovery performances in two perturbation tasks (lean-and-release versus tripping). Methods Healthy adults (12 young: 24 ± 3 years; 21 middle-aged: 53 ± 5 years; 11 old: 72 ± 5 years) were suddenly released from a forward-inclined position attempting to recover stability with a single step. In a second task, all participants experienced a mechanically induced trip during treadmill walking. To assess dynamic stability performance, the antero-posterior margin of stability (MoS), the base of support (BoS), and the rate of increase in BoS were determined at each foot touchdown (TD) for both tasks. Results Only weak to moderate correlations in dynamic stability performance parameters were found between the two tasks (0.568 > r > 0.305, 0.001 p p = 0.003; g = 1.151), lower BoS at TD (p = 0.019; g = 0.888) and lower rate of increase in BoS until TD (p = 0.002; g = 1.212) after release. Despite these profound subgroup differences in the lean-and-release task, no differences between multiple- and single-steppers were observed in the stability recovery performance during tripping. Conclusion The results provide evidence that the ability to effectively control dynamic stability following a sudden balance disturbance in adults across a wide age range is limited in its generalisation for different perturbation tasks.

When in a new situation, the nervous system may benefit from adapting its control policy. In determining whether or not to initiate this adaptation, the nervous system may rely on some features of the new situation. Here we tested whether one such feature is salient cost savings. We changed cost saliency by manipulating the gradient of participants’ energetic cost landscape during walking. We hypothesized that steeper gradients would cause participants to spontaneously adapt their step frequency to lower costs. To manipulate the gradient, a mechatronic system applied controlled fore-aft forces to the waist of participants as a function of their step frequency as they walked on a treadmill. These forces increased the energetic cost of walking at high step frequencies and reduced it at low step frequencies. We successfully created three cost landscapes of increasing gradients, where the natural variability in participants’ step frequency provided cost changes of 3.6% (shallow), 7.2% (intermediate) and 10.2% (steep). Participants did not spontaneously initiate adaptation in response to any of the gradients. Using metronome-guided walking— a previously established protocol for eliciting initiation of adaptation—participants next experienced a step frequency with a lower cost. Participants then adapted by −1.41±0.81 (p=0.007) normalized units away from their originally preferred step frequency obtaining cost savings of 4.80±3.12%. That participants would adapt under some conditions, but not in response to steeper cost gradients, suggests that the nervous system does not solely rely on the gradient of energetic cost to initiate adaptation in novel situations.

This study aimed to investigate the walking economy and possible factors influencing self-selected walking speed (SSWS) in patients with fibrotic interstitial lung disease (ILD) compared to controls. In this study, 10 patients with ILD (mean age: 63.8 ± 9.2 years, forced expiratory volume in the first second: 56 ± 7% of predicted) and 10 healthy controls underwent resting pulmonary function tests, cardiopulmonary exercise, and submaximal treadmill walking tests at different speeds. The walking economy was assessed by calculating the cost-of-transport (CoT). Dynamic stability was assessed by stride-to-stride fluctuations using video recordings. Patients with ILD showed reduced peak oxygen uptake with a tachypneic breathing pattern and significant oxygen desaturation during exercise. The CoT did not differ between the groups (p = 0.680), but dyspnea and SpO2 were higher and lower, respectively, in patients with ILD at the same relative speeds. SSWS was reduced in ILD patients (2.6 ± 0.9 vs. 4.2 ± 0.4 km h−1p = 0.001) and did not correspond to the energetically optimal walking speed. Dynamic stability was significantly lower in patients with ILD than in healthy controls, mainly at lower speeds. Patients with ILD presented a similar cost of transport compared to healthy controls; however, they chose lower SSWS despite higher walking energy expenditure. Although walking stability and dyspnea were negatively affected, these factors were not associated with the slower walking speed chosen by individuals with ILD.

Diabetic foot ulcers (DFU) cause approximately 100,000 amputations every year in the US. Current preventive methods provide suboptimal prevention as several reports indicated that amputation rates are on the rise or have not decreased. Our group has previously developed temperature regulating insoles (TRI) that maintain plantar temperatures at 28°C, as previous research demonstrated that cooler tissue is resistant to ulceration. Our purpose in this study was to explore whether blood perfusion is affected by the cooling effect, via quantifying tissue oxygen saturation (StO2). Twelve subjects were recruited after providing informed consent. Inclusion criterion included being able to walk w/o assistance and not having active DFU. All subjects wore the instrumented shoes, with TRI only in the right shoe. Subjects completed two bouts of 5-minute walking on treadmill at self-selected speeds. Plantar temperatures and StO2 images were collected before and after treadmill walking with hyperspectral (Kent Imaging, CA) and thermal (FLIR® Systems, Inc, USA) cameras. Results indicated that while temperature regulation was on target in the forefoot and heel areas around 28°C (~4°C reduction compared to control side) the average difference in StO2 was only 3.0% (standard deviation of difference=2.8%, p=0.22). This suggests that cooling of the diabetic foot to prevent DFU does not necessarily lead to impaired blood perfusion. Disclosure A. Ersen: None. R. T. Myers: None. K. M. Raspovic: Consultant; Self; Orthofix Medical Inc. M. Ramos-roman: None. T. Lalli: None. Y. Salem: None. G. B. Hirschman: Board Member; Self; Vivonics Inc., Stock/Shareholder; Self; Vivonics Inc. M. Yavuz: None. Funding National Institutes of Health (R43DK109858, UL1TR001105)

Muscle synergies reflect the presence of a common neural input to multiple muscles. Steering small sets of synergies is commonly believed to simplify the control of complex motor tasks like walking and running. When these locomotor patterns emerge, it is likely that synergies emerge as well. We hence hypothesized that in children learning to run the number of accompanying synergies increases and that some of the synergies’ activities display a temporal shift related to a reduced stance phase as observed in adults. We investigated the development of locomotion in 23 children aged 2–9 years of age and compared them with seven young adults. Muscle activity of 15 bilateral leg, trunk, and arm muscles, ground reaction forces, and kinematics were recorded during comfortable treadmill walking and running, followed by a muscle synergy analysis. We found that toddlers (2–3.5 years) and preschoolers (3.5–6.5 years) utilize a “walk-run strategy” when learning to run: they managed the fastest speeds on the treadmill by combining double support (DS) and flight phases (FPs). In particular the activity duration of the medial gastrocnemius muscle was weakly correlated with age. The number of synergies across groups and conditions needed to cover sufficient data variation ranged between four and eight. The number of synergies tended to be smaller in toddlers than it did in preschoolers and school-age children but the adults had the lowest number for both conditions. Against our expectations, the age groups did not differ significantly in the timing or duration of synergies. We believe that the increase in the number of muscle synergies in older children relates to motor learning and exploration. The ability to run with a FP is clearly associated with an increase in the number of muscle synergies.

Background and purpose Individuals with Rett syndrome suffer from severely impaired cognitive and motor performance. Current movement-related therapeutic programs often include traditional physical therapy activities and assisted treadmill walking routines for those individuals who are ambulatory. However, there are no quantitative reports of kinematic gait parameters obtained during treadmill walking. The purpose of this research was to characterize the kinematic patterns of the lower limbs during treadmill walking as speed was slowly increased. Methods Seventeen independently ambulatory females diagnosed with a methyl-CpG-binding protein 2 gene mutation walked on a motorized treadmill while joint kinematics were obtained by a camera-based motion capture system and analysis software. Results Stride times progressively decreased as treadmill speeds increased. There were significant main effects of speed on sagittal knee and hip ranges of motion and hip velocity. There were large joint asymmetries and variance values relative to other ambulatory patient populations, although variance values decreased as walking speed increased. Conclusions The results indicate that individuals with Rett syndrome can adapt their kinematic gait patterns in response to increasing treadmill speed, but only within a narrow range of speeds. We suggest that treadmill training for ambulatory individuals with Rett syndrome may promote improved walking kinematics and possibly provide overall health benefits.Implications for rehabilitationWalking is an activity that can counter the negative impacts of the sedentary lifestyle of many individuals with disabilities, including those individuals with Rett syndrome.Documentation of the lower limb kinematic patterns displayed during walking by ambulatory females with Rett syndrome can be used by clinicians to evaluate their patients' gait performance in response to therapeutic and pharmacological interventions designed to promote walking.The ability to adapt to increases in treadmill speed suggests that a training program of treadmill walking may be effective in promoting improved gait performance in individuals with Rett syndrome.

Postural instability and muscle fatigue are from elementary causes of deteriorations in children with cerebral palsy (CP). The aim of this study was to investigate the immediate effect of maximal treadmill walking on muscle fatigue and postural stability in children with hemiplegic CP. Thirty (17 boys and 13 girls) children with hemiplegic CP of both sexes, aged from 5 to 11years, participatedin this study. Muscle fatigue and postural stability were assessed for every child by using isokinetic dynamometer and pediatric reaching test, respectively, before and after maximal treadmill walking at two separated sessions. The results showed that there were no significant differences in fatigue index (P=0.33 and 0.1), peak torque of quadriceps and hamstring muscles (P=0.52 and 0.14), and anterior and lateral reaching tests of postural stability (P=0.46 and 0.63) before and after maximal treadmill walking. Maximal treadmill walking does not cause muscle fatigue or postural instability in children with hemiplegic CP.

Background Adaptation to split-belt treadmill walking differs between individual stroke survivors. Many discussions only address spatiotemporal parameters that are related to movement, and the changes in interlimb spatiotemporal parameters as a consequence of adaptation are poorly understood. Objectives To investigate symmetry of the center of pressure (CoP) position relative to the center of mass (CoM), and ascertain whether this can be used to identify differences in adaptation of interlimb spatiotemporal parameters among stroke survivors during split-belt walking. Methods Twenty-two chronic post-stroke patients and nine elderly controls walked in tied- then split-belt (2:1 ratio of fast:slow) conditions. Spatiotemporal parameters were compared within groups to assess symmetry of the CoM-CoP angle at foot contact. Results Asymmetry of the CoM-CoP angle was associated with asymmetry of spatiotemporal parameters. Re-establishment of symmetry of CoM-CoP angle was reflected in re-established symmetry of spatiotemporal parameters in post-stroke and control participants. Conclusions Post-stroke patients who re-establish symmetry of the COM-COP angle are able to adapt their walking for split-belt perturbation. This suggests that predictively symmetric foot placements on the fast and slow sides are necessary for adaptation in walking. Symmetrical foot placement is achieved by interlimb coordination and may contribute to dynamic stability.

Knowledge of efficacious dosing respective to exercise type and pain condition is extremely limited in the literature. This study aimed to determine the impact of dose of moderate intensity treadmill walking on experimentally-induced pain in healthy human participants. Forty females were divided into 4 groups: control (no exercise), low dose exercise (3×/wk), moderate dose exercise (5×/wk) or high dose exercise (10×/wk). Over a 7-day period, subjects performed treadmill walking during assigned exercise days. Both qualitative and quantitative measures of pain were measured at baseline, during the trial, and 24 hrs post-final intervention session via sensitivity thresholds to painful thermal and painful pressure stimulation. Significant effects of treatment were found post-intervention for constant pressure pain intensity (p = 0.0016) and pain unpleasantness ratings (p = 0.0014). Post-hoc tests revealed significant differences between control and moderate and control and high dose groups for constant pressure pain intensity (p = 0.0015), (p = 0.0094), respectively and constant pressure pain unpleasantness (p = 0.0040), (p = 0.0040), respectively. Moderate and high dose groups had the greatest reductions in ratings of pain, suggesting that our lowest dose of exercise was not sufficient to reduce pain and that the moderate dose of exercise may be a sufficient starting dose for exercise-based adjuvant pain therapy.

Background : There is lack of studies on the effects of the bag-carrying style on the shoulder muscles and body alignment in adults with rounded shoulder posture (RSP). Objective: The purpose of this study was to investigate the effects of various bag-carrying styles on muscle tone, muscle stiffness and spinal alignment in 20 adults with RSP as they were walking on a treadmill. Design : Crossover Study Design. Methods: A subject performed treadmill walking for 15 minutes at a speed of 4 ㎞/ｈ while carrying three different types of bags: a backpack, a cross bag, and a shoulder bag. Results : The results showed that the main effect of timing was observed in the muscle tone for all the variables and in muscle stiffness only for the upper and lower trapezius muscles. As for the main effect of timing, the muscle tone of the upper trapezius and the pectoralis major significantly increased in all conditions, while the muscle tone of the lower trapezius significantly decreased in all conditions. The muscle stiffness of the upper trapezius significantly increased in all conditions, while the muscle stiffness of the lower trapezius significantly decreased in all conditions. As for the spinal alignment, the dimple distance data values significantly decreased for the cross-bag style. Conclusions : This study demonstrated that walking with a heavy bag, regardless of the bag-carrying style, increased muscle stiffness around the shoulders in adults with rounded shoulder posture, and walking with a crossbag also induced changes in spinal alignment.

Treadmills used for gait training in clinical rehabilitation and experimental settings are commonly fitted with handrails to assist or support persons in locomotor tasks. However, the effects of balance support through handrail holding on locomotor learning are unknown. Locomotor learning can be studied on split-belt treadmills, where participants walk on two parallel belts with asymmetric left and right belt speeds, to which they adapt their stepping pattern within a few minutes. The aim of this study was to determine how handrail holding affects the walking pattern during split-belt adaptation and after-effects in able-bodied persons. Fifty healthy young participants in five experimental groups were instructed to hold handrails, swing arms freely throughout the experiment or hold handrails during adaptation and swing arms freely during after-effects. Step length asymmetry and double support asymmetry were measured to assess the spatiotemporal walking pattern. The results showed that holding handrails during split-belt adaptation reduces magnitude of initial perturbation of step length asymmetry and reduces after-effects in step length asymmetry upon return to symmetric belt speeds. The findings of this study imply that balance support during gait training reduces locomotor learning, which should be considered in daily clinical gait practice and future research on locomotor learning.

Lowering locomotion's metabolic cost Walking and running require different gaits, with each type of motion putting a greater bias on different muscles and joints. Kim et al. developed a soft, fully portable, lightweight exosuit that is able to reduce the metabolic rate for both running and walking by assisting each motion via the hip extension (see the Perspective by Pons). A waist belt holds most of the mass, thus reducing the cost of carrying the suit. By tracking the motion of the user, the suit is able to switch modes between the two types of motion automatically. Science , this issue p. 668 ; see also p. 636

The purpose of this study was to determine whether applying repetitive constraint forces to the non-paretic leg during walking would induce motor learning of enhanced use of the paretic leg in individuals post-stroke. Sixteen individuals post chronic (>6months) stroke were recruited in this study. Each subject was tested in two conditions, i.e., applying a constraint force to the non-paretic leg during treadmill walking and treadmill walking only. For the constraint condition, subjects walked on a treadmill with no force for 1 minute (baseline), with force for 7 minutes (adaptation), and then without force for 1 minute (post-adaptation). For the treadmill only condition, a similar protocol was used but no force was applied. EMGs from muscles of the paretic leg and ankle kinematic data were recorded. Spatial-temporal gait parameters during overground walking pre and post treadmill walking were also collected. Integrated EMGs of ankle plantarflexors and hip extensors during stance phase significantly increased during the early adaptation period, and partially retained (15–21% increase) during the post-adaptation period for the constraint force condition, which were significantly greater than that for the treadmill only (3–5%) condition. The symmetry of step length during overground walking significantly improved (p = 0.04) after treadmill walking with the constraint condition, but had no significant change after treadmill walking only. Repetitively applying constraint force to the non-paretic leg during treadmill walking may lead to a motor learning of enhanced use of the paretic leg in individuals post-stroke, which may transfer to overground walking.

An innovative model describing the evolution of the spatiotemporal variables of unrestricted overground human walking is developed in this paper. The proposed model is an alternative to the contemporary related ones that are generally based on treadmill walking data. Modelling is split into two stages. A statistical model reproducing the intra-pedestrian variability of the step speed is firstly inferred and calibrated from experimental overground data. Another model, which was previously developed by the authors to reproduce the intra-pedestrian variability of the step interval of treadmill walking, is afterwards modified and combined with the former to reproduce the variability of the step interval of overground walking. The modification consists in updating the model parameters in each step as a function of its speed. An extensive campaign of Monte Carlo simulations of single-pedestrian loading on simple-supported low-frequency footbridges was carried out. The campaign included a variety of footbridge configurations and both the treadmill and overground models. Results are condensed in the form of characteristic response spectra. Comparison of results reveals that within a certain range of footbridge frequencies, which depends on the footbridge length, the treadmill model slightly overestimates the response. Outside this range, the response is underestimated up to around 24%. The limits of this range are finally formulated as linear functions of the footbridge length and some practical recommendations to obtain the characteristic response are established.

Background Walking balance in older adults is disproportionately susceptible to lateral instability provoked by optical flow perturbations. The prolonged exposure to these perturbations could promote reactive balance control and increased balance confidence in older adults, but this scientific premise has yet to be investigated. This proof of concept study was designed to investigate the propensity for time-dependent tuning of walking balance control and the presence of aftereffects in older adults following a single session of optical flow perturbation training. Methods Thirteen older adults participated in a randomized, crossover design performed on different days that included 10 min of treadmill walking with (experimental session) and without (control session) optical flow perturbations. We used electromyographic recordings of leg muscle activity and 3D motion capture to quantify foot placement kinematics, lateral margin of stability, and antagonist coactivation during normal walking (baseline), early (min 1) and late (min 10) responses to perturbations, and aftereffects immediately following perturbation cessation (post). Results At their onset, perturbations elicited 17% wider and 7% shorter steps, higher step width and length variability (+171% and +132%, respectively), larger and more variable margins of stability (MoS), and roughly twice the antagonist leg muscle coactivation (p-values

Tietjen, AMJ and Devereux, GR. Physical demands of exergaming in healthy young adults. J Strength Cond Res 33(7): 1978-1986, 2019-The efficacy of whole-body exergaming (WBE) in healthy young adults remains largely unknown. This study aimed to: (a) compare the physical demands of WBE in healthy adults with traditional exercise; (b) determine whether the physical demands of WBE were reproducible. Twenty-five healthy adults (age: 22.9 ± 6.4 years; height: 1.7 ± 0.1 m; mass: 69.1 ± 12.2 kg) completed two 10-minute experimental conditions (WBE on the Xbox Kinect and treadmill walking) in a randomized cross-over design study. Whole-body exergaming produced a significant increase in the peak heart rate (138 ± 23 b·min), oxygen consumption (40 ± 13 ml·kg·min), metabolic equivalents (METs) (11 ± 4) compared with treadmill walking (115 ± 18 b·min, 25 ± 5 ml·kg·min, 7 ± 2 MET) and a modest increase in the mean heart rate (111 ± 19 b·min vs. 104 ± 15 b·min). Whole-body exergaming produced significantly greater vertical (381 ± 118 vs. 127 ± 14 % body mass [%BM]), anterior (70 ± 22 vs. 27 ± 4 %BW), and medial (56 ± 21 vs. 7 ± 2 %BW) ground reaction forces. No difference was present in mean oxygen consumption and MET. The reproducibility of WBE was assessed in a subgroup of 11 participants (age: 24.2 ± 6.7 years; height: 1.8 ± 0.1 m; mass: 75.3 ± 10.0 kg), who completed 2 additional 10-minute WBE sessions. No difference was observed between all outcome measures. These findings indicate that WBE can reliably replicate, or surpass, the physical demands of treadmill walking and may serve as an effective addition to a health-focused exercise program.

Background: Yoga is a popular alternative to walking, but the tempo at which asanas must be performed to elicit comparable metabolic and cardiorespiratory demands is unknown. Therefore, the authors aim to compare the metabolic demands of moderate-intensity walking to Surya Namaskar yoga performed at varying tempos. Methods: Inactive obese adults with limited prior yoga experience (n = 10) completed 10 minutes of treadmill walking at a self-selected pace (rating of perceived exertion = 12–13) and three, 10-minute bouts of yoga at a low (6 s/pose; LSUN), medium (4 s/pose; MSUN), and high (3 s/pose; HSUN) tempo with 10-minutes rest between exercise bouts. Results: Mean metabolic equivalents observed in MSUN (3.64 [0.607]), HSUN (4.22 [0.459]), and treadmill (5.29 [1.147]) were greater than 3.0 (P ≤ .01), but not LSUN (3.28 [0.529], P = .13). Treadmill elicited greater caloric and kilocaloric expenditure (1.36 [0.23] L·min−1; 64 [11] kcal) than LSUN (0.87 [0.24] L·min−1; 39 [11] kcal) and MSUN (1.00 [0.29] L·min−1; 45 [13] kcal) (P ≤ .01). Absolute between yoga tempos were not different, but relative was higher in HSUN (14.89 [1.74] mL·min−1·kg) versus LSUN (11.39 [1.83] mL·min−1·kg) (P = .02). Conclusions: Yoga can meet (LSUN) or exceed (MSUN and HSUN) moderate-intensity exercise recommendations. For unfit or obese populations, varying tempos of yoga practice may serve as a lower-impact option for beginning an exercise program.

Falls to the side are associated with significant morbidity, including increased risk of hip and radius fracture. Although step width variability, as measured by standard deviation, has been hypothesized to be associated with falls to the side, there is little supporting evidence. The extent to which such a relationship could be reliably established, however, is dependent on the accuracy with which step width, and thus step width variability, is measured. It has been reported that 400 consecutive steps are required to accurately estimate step width of young adults during treadmill walking. The degree to which this requirement generalizes to other populations has not been determined. Here, a secondary analysis of step width time series data from 19 middle-age women during treadmill walking revealed that 400 steps were insufficient to accurately estimate step width or step width variability for the majority of the women sampled. Patterns observed in the data suggest the potential influence of confounding factors including acclimatization to the task and fatigue during the protocol. The results suggest that the minimum number of steps previously reported as necessary to accurately assess step width and step width variability of young adults during treadmill walking is not valid for middle-age women. Furthermore, the results point to the potential value of reproducing and/or extending the original experiment that established 400 consecutive steps as necessary to accurately estimate step kinematics among young adults.

The aims of this study were to estimate the walking cadence required to elicit a VO2reserve (VO2R) of 40% and determine if fitness status moderates the relationship between walking cadence and %VO2R. Twenty participants (10 male, mean(s) age 32(10) years; VO2max 45(10) mL·kg-1·min-1) completed resting and maximal oxygen consumption tests prior to 7 x 5-min bouts of treadmill walking at increasing speed while wearing an Apple Watch and measuring oxygen consumption continuously. The 7 x 5-min exercise bouts were performed at speeds between 3 and 6 km·h-1 with 5-min seated rest following each bout. Walking cadence measured at each treadmill speed was recorded using the Apple Watch "Activity" app. Using Bayesian regression, we predict that participants need a walking cadence of 138 to 140 steps·min-1 to achieve a VO2R of 40%. However, these values are moderated by fitness status such that those with lower fitness can achieve 40% VO2R at a slower walking cadence. The results suggest that those with moderate fitness need to walk at ~40% higher than the currently recommended walking cadence (100 steps·min-1) to elicit moderate-intensity physical activity. However, walking cadence required to achieve moderate-intensity physical activity is moderated by fitness status.

PURPOSE To determine the efficacy residing for 2 d at various altitudes while sedentary (S) or active (A; ~90 min hiking 2 d) on exercise performance at 4300 m. METHODS Sea-level (SL) resident men (n = 45) and women (n = 21) (mean ± SD; 23 ± 5 yr; 173 ± 9 cm; 73 ± 12 kg; V˙O2peak = 49 ± 7 mL·kg·min) were randomly assigned to a residence group and, S or A within each group: 2500 m (n = 11S, 8A), 3000 m (n = 6S, 12A), 3500 m (n = 6S, 8A), or 4300 m (n = 7S, 8A). Exercise assessments occurred at SL and 4300 m after 2-d residence and consisted of 20 min of steady-state (SS) treadmill walking (45% ± 3% SL V˙O2peak) and a 5-mile, self-paced running time trial (TT). Arterial oxygen saturation (SpO2) and HR were recorded throughout exercise. Resting SpO2 was recorded at SL, at 4 and 46 h of residence, and at 4300 m before exercise assessment. To determine if 2-d altitude residence improved 4300 m TT performance, results were compared with estimated performances using a validated prediction model. RESULTS For all groups, resting SpO2 was reduced (P < 0.01) after 4 h of residence relative to SL inversely to the elevation and did not improve after 46 h. Resting SpO2 (~83%) did not differ among groups at 4300 m. Although SL and 4300 m SS exercise SpO2 (97% ± 2% to 74% ± 4%), HR (123 ± 10 bpm to 140 ± 12 bpm) and TT duration (51 ± 9 to 73 ± 16 min) were different (P < 0.01), responses at 4300 m were similar among all groups, as was actual and predicted 4300 m TT performances (74 ± 12 min). CONCLUSIONS Residing for 2 d at 2500 to 4300 m, with or without daily activity, did not improve resting SpO2, SS exercise responses, or TT performance at 4300 m.

The objectives of this study were to evaluate the effects of community-based walking training (CWT) on the walking ability and fall-related self-efficacy of chronic stroke patients and compare the effects of CWT to the conventional walking programs in stroke patients. Previous studies focused on walking speed, walking endurance, and balance. However, no studies have examined the changes in fall-related self-efficacy after CWT. In order to achieve purpose of this study, 45 chronic stroke patients, who were hospitalized at National Rehabilitation Center, were randomly divided into the CWT group (CWTG, n=15), the treadmill walking training group (TWTG, n=15), and the control group (CG, n=15). The treatment was conducted 3 times per week (30 min each) for 4 weeks. CWT was carried out by gradually increasing the difficulty level in various environments outside the hospital room. The results revealed that the CWTG was more effective in enhancing the walking ability and fall-related self-efficacy than the TWTG and the CG. These findings demonstrated that the CWTG increased the walking ability and fall-related self-efficacy of chronic stroke patients. Therefore, we suggest that adding CWT to standard rehabilitation might be an effective method for improving walking ability and fall-related self-efficacy in chronic stroke patients.

Guteal muscle activation during walkway and treadmill walking was compared by means of Surface EMG (SEMG). Healthy older adults (50–75 years, n = 54; 29 females, 25 males) walked on a walkway (WW) at their self-selected slow, normal, and fast walking speeds and on a treadmill (TM) at 2, 3, 4, 5, and 6 km/h. Subject-individual, best-matched speed pairs were constituted and named SLOW, NORMAL, and FAST. Hip muscle activation was measured on both sides at mid-distance between the greater trochanter and the iliac crest by applying eight equally-spaced bipolar SEMG channels from ventral to dorsal (P1–P8). Grand averaged amplitude curves and mean amplitudes over the complete stride were analyzed to compare WW and TM walking. TM walking evoked significantly elevated mean amplitude levels, particularly at the ventral positions P1 to P4, which were disproportionately increased at SLOW. In grand averaged curves, corresponding significant amplitude differences between WW and TM were observed during load acceptance (SLOW; NORMAL), mid-stance (all speeds), and late swing phase (SLOW), with the number of significant differences decreasing for all electrode positions from SLOW to FAST. Compared to WW walking, TM walking may thus require systematically elevated effort of gluteal muscles, in particular at slow walking speed.

Background Increasing walking speed and including bilateral external ankle load have been shown to improve aspects of the gait pattern of children with Down syndrome (DS). However, it is unknown if speed and ankle load improves the cycle-to-cycle variability in a similar way. Research question How do changes of walking speed and external ankle load impact spatiotemporal variability during treadmill walking in children with and without DS? Methods Thirteen children with DS (aged 7–10 years) and thirteen age- and sex-matched typically developing (TD) children participated in this study. Subjects completed two bouts of 60-second treadmill walking at two different speeds (slow and fast) and two load conditions (no load and ankle load equaling to 2% bodyweight at each side). Kinematic data was captured using a Vicon motion capture system. Mean and coefficient of variance of spatiotemporal gait variables were calculated and compared between children with and without DS. Results and significance Across all conditions, the DS group took shorter and wider steps than the TD group, but walked with a similar swing percentage, double support percentage, and foot rotation angle. Further, the DS group demonstrated greater variability of all spatiotemporal parameters, except for step width and foot rotation angle. Our results indicated that children with DS can modulate their spatiotemporal gait pattern accordingly like their TD peers when walking faster on a treadmill and/or with an external ankle load. Smaller step width variability in the DS group suggests that mediolateral stability may be prioritized during treadmill walking to safely navigate the treadmill and complete walking tasks. Similar temporal parameters but distinct spatial parameters in the DS group suggest that they may have developed similar rhythmic control but are confined by their spatial movement limitations.

The purpose of this study was to assess relationships between plasma sodium concentration ([Na+]) and bone mineral content (BMC) after an acute sodium load plus treadmill walking and then quantify the amount of sodium the dual energy X-ray absorptiometry (DXA) scan could detect. The primary study was a single-blind randomized control crossover trial under two conditions: ingestion of six flour tablets (placebo trial) or six 1-g NaCl tablets (salt intervention trial). The tablets were ingested after baseline blood and urine collection followed immediately by the DXA scan. After 60 min of rest, a 45-min treadmill walk was conducted. Immediately postexercise, blood and urine were collected and the DXA scan was repeated. Main outcomes included changes (∆: post minus pre) in plasma [Na+] and BMC. Additionally, six 1-g NaCl tablets were superimposed over a DXA spine phantom for separate quantification of sodium as BMC. Fourteen subjects completed the primary study. Two-way repeated measures ANOVA tests revealed significant interaction ( F = 13.06; P = 0.0007), condition ( F = 21.88; P < 0.001), and time ( F = 6.51; P = 0.014) effects in plasma [Na+]. A significant condition ( F = 6.46; P = 0.014) effect was also noted in urine [Na+]. Total body BMC∆ was negatively correlated with plasma [Na+]∆ ( r = −0.43; P = 0.02) and urine [Na+]∆ ( r = −0.47; P = 0.01). Total body BMC∆ in the salt intervention trial [−5.5 (27) g] closely approximated the amount of NaCl ingested and subsequently absorbed into the bloodstream. The DXA scan quantified 67% of NaCl tablets as BMC in spine phantom analyses. Total body BMC∆ was negatively related to plasma and urine [Na+]∆ after treadmill walking. Reductions in total body BMC closely approximated the amount of NaCl ingested (~6 g). The DXA scan quantified NaCl as BMC.

IN BRIEF A large number of adults with type 2 diabetes experience comorbidities that discourage physical activity and hinder regular participation in land-based exercise programs. An aquatic exercise program is an innovative exercise modality that incorporates combined aerobic and resistance exercise. The purpose of this study was to determine if an underwater treadmill walking program featuring gradual and progressive increases in walking speed and duration has a positive effect on glycemic control, metabolic health, cardiovascular function, body composition, and leg strength in middle-aged adults with type 2 diabetes.

The purpose of this study was to investigate the effect of somatotype on the VO2max and hormone (adrenaline and noradrenaline) during treadmill walking. Forty healthy men participated and were randomized to four groups: Male 1 (M1) group, Male 2 (M2) group, Male 3 (M3) group, and Male 4 (M4) group. M4 group is the largest body type, and M1 group is the smaller the body type. Participants walked at a speed of 3.5 km/h for five minutes at an incline angle of 0°, 5°, and 10° in the treadmill. Maximum oxygen consumption and hormone (adrenaline and noradrenaline) were measured. In the results, VO2max has significantly increased according to the degree of the treadmill inclination, and M4 group (larger body type) consumed more oxygen than the M1 group (smaller body type). In the hormone, there was a significant increase in adrenaline concentration after walking in all groups, and there was a significant difference in M1-M4, M2-M4 and M3-M4. The noradrenaline concentration significantly increased after treadmill gait in all groups, and there was no significant difference in noradrenaline between groups. This study suggests that the larger body type consumes more oxygen during walking, and treadmill walking contributes to an increase in the concentration of adrenaline and noradrenaline.

Background: Vestibular deficit is common following concussion and may affect gait. The purpose of this study was to investigate differences in head and pelvic center of mass (COM) movement during gait in military tactical athletes with and without concussion-related central vestibular impairment.Material and Methods: 24 patients with post-concussion vestibular impairment (20 males, 4 females; age: 31.7 ± 7.9 years; BMI: 27.3 ± 3.3) and 24 matched controls (20 males, 4 females; age: 31.8 ± 6.4 years; BMI: 27.2 ± 2.6) were included in the analyses. Three-dimensional head and pelvic displacement and velocities were collected at a 1.0 m/s standardized treadmill walking speed and assessed using Statistical Parametric Mapping t-tests. Maximum differences (dmax) between groups were reported for all significant kinematic findings.Results: The Vestibular group demonstrated significantly diminished anteroposterior head excursions (dmax = 2.3 cm, p = 0.02) and slower anteroposterior (dmax = 0.37 m/s, p = 0.01), mediolateral (dmax = 0.47 m/s, p = 0.02) and vertical (dmax = 0.26 m/s, p < 0.001) velocities during terminal stance into pre-swing phases compared to the Control group. Vertical pelvic excursion was significantly increased in midstance (dmax = 2.4 cm, p = 0.03) and mediolaterally during pre- to initial-swing phases (dmax = 7.5 cm, p < 0.001) in the Vestibular group. In addition, pelvic velocities of the Vestibular group were higher mediolaterally during midstance (dmax = 0.19 m/s, p = 0.02) and vertically during post-initial contact (dmax = 0.14 m/s, p < 0.001) and pre-swing (dmax = 0.16 m/s, p < 0.001) compared to the Control group.Significance: The Vestibular group demonstrated a more constrained head movement strategy during gait compared with Controls, a finding that is likely attributed to a neurological impairment of visual-vestibular-somatosensory integration.

BACKGROUND The purpose of this study was to determine if body weight supported treadmill training (BWSTT) decreased metabolic and cardiovascular demand in older (50-74 years) healthy adults while walking a self-selected speeds. The results of this study could impact clinician application to exercise therapy. METHODS Twenty subjects (50% female, 58.3+7.3 yr) completed 3, 5-minute treadmill walking trials at a self-selected pace, with 0%, 15%, and 30% body weight support (BWS). Blood pressure (BP), heart rate (HR), and oxygen uptake (VO2) were measured at rest, and during walking trials. Mean data from minutes 3-5 were analyzed for difference by repeated measures ANOVA and Bonferroni post-hoc testing. RESULTS At rest, HR was 70.8+8.2 bpm and BP was 126.8+12.2 / 84.3+8.6 mmHg. Mean walking speed was 67.1 m/min. Tested parameters during exercise trials were significantly (p

BackgroundLong-range persistent correlations in stride time (ST) and length (SL) are the fundamental traits of treadmill gait. Our recent work showed that the ST and SL time series’ statistical properties originated from the superposition of large-scale trends and small-scale fluctuations (residuals). Trends served as the control manifolds about which ST and SL fluctuated. The scaling exponents of the residuals were slightly smaller than 0.5.Research questionDo random changes in treadmill belt speed affect the trend properties and scaling exponents of ST/SL residuals?MethodsWe used Multivariate Adaptive Regression Splines (MARS) to determine gait trends during a walk on a treadmill whose belt speed was perturbed by a strong random noise. Then, we calculated the scaling exponents of MARS residuals with the madogram estimator.ResultsExcept for the ST at the lowest treadmill speed v = 0.8 m/s, the normalized trend duration was at least three times greater than that for the unperturbed walk. The Cauchy distribution scale parameter, which served as a measure of the width of SL and ST trend slope distributions, was at v = 1.2 m/s, almost 50% and 25% smaller than the unperturbed values. The differences were even greater at v = 1.6 m/s: 73% and 83%. For all speeds, the ST and SL MARS residuals were strongly anti-persistent. At v = 1.2 m/s, the corresponding scaling exponents were equal to 0.37±0.10 and 0.25±0.09. Apart from ST at v = 0.8 m/s, the ST/SL scaling indices were close to 0.5.SignificancePersistence of gait parameters is closely related to the properties of their trends. Longer trends with a gentle slope and strong anti-persistence of ST/SL residuals are the manifestations or tight control required during the perturbed treadmill walk.

Introduction Step counts represent a straight-forward method of measuring physical activity in adults with Parkinson's disease (PD). The present study examined the absolute and relative accuracy and precision of a wrist-worn research-grade accelerometer (i.e., ActiGraph GT3X+) for measuring step counts during over-ground and treadmill walking in adults with PD and controls without PD. Methods Participants (PD: n = 29; controls: n = 31) wore two ActiGraph GT3X + accelerometers, one on each wrist, and completed an over-ground walking bout followed by a treadmill walking bout at the same speed. Step counts were measured manually using a hand-held tally counter. Accuracy and precision were based on absolute and relative metrics. Results The ActiGraph GT3X + underestimated step counts in both participants with PD (4.7–11% error) and controls without PD (8.8–17% error), with a greater discrepancy in controls. The ActiGraph GT3X + provided more accurate and precise estimates of step counts when placed on the more affected wrist and non-dominant wrist for participants with PD and controls, respectively, and was more accurate and precise during over-ground walking compared with treadmill walking for both groups. Conclusions Our results suggest that placement of the device (i.e., dominant vs. non-dominant), type of activity (i.e., over-ground vs. treadmill walking), and presence of clinical conditions may impact the accuracy and precision of data when using the research-grade ActiGraph GT3X + accelerometer for measuring step counts.