Preferred Pace Research Articles

P36: Relation between navicular mobility and multi-segment foot kinematics during walking

Individuals often carry items in one hand instead of both hands during activities of daily living. The combined effects of carrying asymmetric loads and stair negotiation may create even higher demands on the low back and lower extremity. The purpose of this study was to investigate the effect of symmetric and asymmetric loading conditions on L5/S1 and lower extremity moments during stair negotiation. Twenty-two college students performed stair ascent and stair descent on a three-step staircase (step height 18.5 cm, tread depth 29.5 cm) at preferred pace under five load conditions: no load, 10% body weight (BW) unilateral load, 20% BW unilateral load, 10% BW bilateral load, and 20% BW bilateral load. Video cameras and force platforms were used to collect kinematic and kinetic data. Inverse dynamics was used to calculate frontal plane moments for the L5/S1 and lower extremity. A 20% BW unilateral load resulted in significantly higher peak L5/S1 lateral bending, hip abduction, and external knee varus moments than nearly all other loading conditions during stair ascent and stair descent. Therefore, we suggest potential benefits when carrying symmetrical loads as compared to an asymmetric load in order to decrease the frontal joint moments, particularly at 20% BW load.

O71: Skeletal and anthropometric determinants of gait balance in asymptomatic adult subjects

Individuals often carry items in one hand instead of both hands during activities of daily living. The combined effects of carrying asymmetric loads and stair negotiation may create even higher demands on the low back and lower extremity. The purpose of this study was to investigate the effect of symmetric and asymmetric loading conditions on L5/S1 and lower extremity moments during stair negotiation. Twenty-two college students performed stair ascent and stair descent on a three-step staircase (step height 18.5 cm, tread depth 29.5 cm) at preferred pace under five load conditions: no load, 10% body weight (BW) unilateral load, 20% BW unilateral load, 10% BW bilateral load, and 20% BW bilateral load. Video cameras and force platforms were used to collect kinematic and kinetic data. Inverse dynamics was used to calculate frontal plane moments for the L5/S1 and lower extremity. A 20% BW unilateral load resulted in significantly higher peak L5/S1 lateral bending, hip abduction, and external knee varus moments than nearly all other loading conditions during stair ascent and stair descent. Therefore, we suggest potential benefits when carrying symmetrical loads as compared to an asymmetric load in order to decrease the frontal joint moments, particularly at 20% BW load.

The Ability of Sagittal Plane Kinematic Variables to Predict Loading in Different Populations of Runners

It is known that sagittal plane kinematics are able to predict loading in runners. This may be of use to clinicians who don’t have access to force measurement devices. However, running biomechanics differ between genders and age groups. Thus it may be that models used to predict loading in demographically distinct groups of runners need to be specific to age and gender. PURPOSE: To determine if kinematic predictors of kinetic variables during running apply across genders and age groups. METHODS: Sagittal plane kinematics and kinetics were assessed in young male (YM: n=13, age=23.1 ± 2.3 yrs, mass=77.0 ± 12.1 kg, height=1.79 ± 0.08 m, velocity=3.32 ± 0.48 m/s) and middle-aged female runners (MF: n=28, age=47.3 ± 7.0 yrs, mass=63.7 ± 7.8 kg, height=1.66 ± .07 m, velocity=2.55 ± 0.37 m/s) using a 5 camera motion analysis system (Qualysis, Goteborg, Sweden) running on an instrumented treadmill (Treadmetrix, Park City, Utah) at their preferred running pace. Kinematics (knee flexion at initial contact, foot angle at initial contact, step position, peak knee flexion and COM excursion) were the independent variables; kinetics (average vertical loading rate, braking impulse, knee power absorption and peak knee extension moment and peak vertical ground reaction force) were the dependent variables. Linear regression models were developed to predict loading in both groups (α=0.05). RESULTS: In both YM and MF, sagittal plane kinematics were useful in predicting peak knee moment (YM: R2=0.56, p=.002; MF: R2=0.47,p=.0002), knee power absorption (YM: R2=0.78, p=.0002; MF: R2=0.55, p<.0001), braking impulse (YM: R2=0.66, p=0.01; MF: R2=0.67, p<.0001), and peak vertical ground reaction force (YM: R2=0.31, p=0.03; MF: R2=0.23, p=0.02). Peak knee flexion appeared in the most models (peak knee moment, knee power absorption and braking impulse for both men and women), and thus may be the most useful single kinematic variable to assess loading across age groups and genders. In all models, greater knee flexion was associated with increased magnitude of loading. Average vertical loading rate could not be predicted using the chosen kinematics in either group. CONCLUSIONS: When equipment for kinetic assessment is not available, sagittal plane gait analysis may be a useful tool for clinicians to estimate loading in runners.

Carrying asymmetric loads during stair negotiation

Individuals often carry items in one hand instead of both hands during activities of daily living. The combined effects of carrying asymmetric loads and stair negotiation may create even higher demands on the low back and lower extremity. The purpose of this study was to investigate the effect of symmetric and asymmetric loading conditions on L5/S1 and lower extremity moments during stair negotiation. Twenty-two college students performed stair ascent and stair descent on a three-step staircase (step height 18.5cm, tread depth 29.5cm) at preferred pace under five load conditions: no load, 10% body weight (BW) unilateral load, 20% BW unilateral load, 10% BW bilateral load, and 20% BW bilateral load. Video cameras and force platforms were used to collect kinematic and kinetic data. Inverse dynamics was used to calculate frontal plane moments for the L5/S1 and lower extremity. A 20% BW unilateral load resulted in significantly higher peak L5/S1 lateral bending, hip abduction, and external knee varus moments than nearly all other loading conditions during stair ascent and stair descent. Therefore, we suggest potential benefits when carrying symmetrical loads as compared to an asymmetric load in order to decrease the frontal joint moments, particularly at 20% BW load.

Timing and magnitude of lumbar spine contribution to trunk forward bending and backward return in patients with acute low back pain

Alterations in the lumbo-pelvic coordination denote changes in neuromuscular control of trunk motion as well as load sharing between passive and active tissues in the lower back. Differences in timing and magnitude aspects of lumbo-pelvic coordination between patients with chronic low back pain (LBP) and asymptomatic individuals have been reported; yet, the literature on lumbo-pelvic coordination in patients with acute LBP is scant. A case-control study was conducted to explore the differences in timing and magnitude aspects of lumbo-pelvic coordination between females with (n=19) and without (n=19) acute LBP. Participants in each group completed one experimental session wherein they performed trunk forward bending and backward return at preferred and fast paces. The amount of lumbar contribution to trunk motion (as the magnitude aspect) as well as the mean absolute relative phase (MARP) and deviation phase (DP) between thoracic and pelvic rotations (as the timing aspect) of lumbo-pelvic coordination were calculated. The lumbar contribution to trunk motion in the 2nd and the 3rd quarters of both forward bending and backward return phases was significantly smaller in the patient than the control group. The MARP and the DP were smaller in the patient vs. the control group during entire motion. The reduced lumbar contribution to trunk motion as well as the more in-phase and less variable lumbo-pelvic coordination in patients with acute LBP compared to the asymptomatic controls is likely the result of a neuromuscular adaptation to reduce painful deformation and to protect injured lower back tissues.

Age-Related Differences in Locomotor Strategies During Adaptive Walking

ABSTRACTSimultaneous control of lower limb stepping movements and trunk motion is important for skilled walking; adapting gait to environmental constraints requires frequent alternations in stepping and trunk motion. These alterations provide a window into the locomotor strategies adopted by the walker. The authors examined gait strategies in young and healthy older adults when manipulating step width. Anteroposterior (AP) and mediolateral (ML) smoothness (quantified by harmonic ratios) and stepping consistency (quantified by gait variability) were analyzed during narrow and wide walking while controlling cadence to preferred pace. Results indicated older adults preserved ML smoothness at the expense of AP smoothness, shortened their steps, and exhibited reduced stepping consistency. The authors conclude that older adults prioritized ML control over forward progression during adaptive walking challenges.

Dynamic margin of stability during gait is altered in persons with multiple sclerosis

Persons with multiple sclerosis (PwMS) have high fall risk due to altered balance. To measure dynamic balance during walking, margin of stability (MoS) examines how the extrapolated center of mass moves relative to the base of support. This study investigates how MoS is affected in PwMS during walking at preferred, slow, and fast speeds, as well as the relationship between MoS and the Expanded Disability Severity Score (EDSS), fall history, and self-report balance confidence questionnaire. MoS was evaluated in PwMS without clinical gait impairment (MS1; n=20), PwMS with clinical gait impairment (MS2; n=20), and age-matched healthy controls (HC) (n=20), in the anterior/posterior (AP) and medial/lateral (ML) direction at heel strike and midstance. In the AP direction, MS2 had a higher MoS than HC (p<0.001) and MS1 (p<0.001) at heel strike and midstance. In the ML direction, MS2 had a higher MoS than HC (p<0.001) at heel strike only. At midstance, slow pace had a lower MoS than preferred pace (p<0.001) and fast pace (p=0.007). Compared to HC, PwMS walk slower which increases their AP MoS. In the ML direction, slow walking causes lower MoS at midstance, so PwMS increase their MoS by taking wider steps. AP MoS correlated with EDSS (p=0.008) and number of falls (p=0.001), and ML MoS correlated with number of falls (p=0.027). Walking slower, with shorter step length, and with wider step widths increases MoS for PwMS but may be a poor adaptive gait strategy since falls still occur.

Validity of a wearable accelerometer to quantify gait in spinocerebellar ataxia type 6

Biomarkers are required to track disease progression and measure the effectiveness of interventions for people with spinocerebellar ataxia type-6 (SCA6). Gait is a potential biomarker that is sensitive to SCA6 which can be measured using wearable technology, reducing the need for expensive specialist facilities. However, algorithms used to calculate gait using data from wearables have not been validated in SCA6. This study sought to examine the validity of a single wearable for deriving 14 spatio-temporal gait characteristics in SCA6 and control cohorts. Participants performed eight intermittent walks along a 7 m instrumented walkway at their preferred walking pace while also wearing a single accelerometer-based wearable on L5. Gait algorithms previously validated in neurological populations and controls were used to derive gait characteristics. We assessed the bias, agreement and sensitivity of gait characteristics derived using the instrumented walkway and the wearable. Mean gait characteristics showed good to excellent agreement for both groups, although gait variability and asymmetry showed poor agreement between the two systems. Agreement improved considerably in the SCA6 group when people who used walking sticks were excluded from the analysis, suggesting poorer agreement in people with more severe gait impairment. Despite poor agreement for some characteristics, gait measured using the wearable was generally more sensitive to group differences than the instrumented walkway. Our findings indicate mean gait characteristics can be accurately measured using an accelerometer-based wearable in people SCA6 with mild-to-moderately severe gait impairment yet further development of algorithms are required for people with more severe symptoms.

Lower Extremity Muscle Activation During Over Ground versus Treadmill Running

Introduction: Treadmills employ a movable belt that creates a backward force not normally present during running. Discrepancies exist in the literature regarding differences in joint kinematics, kinetics and muscle activation during overground running (O) and treadmill running (T). The authors sought to identify lower extremity muscle activation differences between O and T in heel-strike runners while running at their preferred speed. The backward motion of the treadmill was hypothesized to decrease hamstring activation, which would in turn require a new forward propulsion mechanism to exist. Methods: Ten recreational runners volunteered for the study. Active surface electrodes (were placed on the following muscles of the right lower extremity: Rectus femoris, Semitendinosus, Biceps femoris, Tibialis anterior, Soleus, Gastrocnemius, Gluteus maximus and Gluteus medius. Participants then underwent a five-minute jogging warm-up on a treadmill at their own preferred pace. Maximum voluntary isometric contractions (MVICs) were performed for each of the eight muscles in order to normalized the measurements. Muscle activation data were collected and analyzed for O and T with participants running at their preferred pace. Paired t-tests were performed to determine differences in muscle activation between O and T running for each of the eight muscles. The level of significance was set at 5%. Results and discussion: No significant differences were observed between O and T running for each of the eight muscles tested. Individual muscle activity was similar between O and T with the soleus exhibiting the highest activity and the rectus femoris demonstrating the lowest for both scenarios. Support for the hypothesis was not observed, as the average muscle activation patterns between the two running conditions were similar for each of the eight lower extremity muscles. These results are different from previous studies and may be due to the participants running at a self-selected speed or inability to analysis each phase of gait individually. Conclusion: Based solely on the average muscle activation of eight lower extremity muscles, the treadmill is an acceptable alternative to overground running in recreational runners.

Quantifying and Reducing Motion Artifacts in Wearable Seismocardiogram Measurements During Walking to Assess Left Ventricular Health.

Our objective is to provide a framework for extracting signals of interest from the wearable seismocardiogram (SCG) measured during walking at normal (subject's preferred pace) and moderately fast (1.34-1.45 m/s) speeds. We demonstrate, using empirical mode decomposition (EMD) and feature tracking algorithms, that the pre-ejection period (PEP) can be accurately estimated from a wearable patch that simultaneously measures electrocardiogram and sternal acceleration signals. We also provide a method to determine the minimum number of heartbeats required for an accurate estimate to be obtained for the PEP from the accelerometer signals during walking. The EMD-based denoising approach provides a statistically significant increase in the signal-to-noise ratio of wearable SCG signals and also improves estimation of PEP during walking. The algorithms described in this paper can be used to provide hemodynamic assessment from wearable SCG during walking. A major limitation in the use of the SCG, a measure of local chest vibrations caused by cardiac ejection of blood in the vasculature, is that a user must remain completely still for high-quality measurements. The motion can create artifacts and practically render the signal unreadable. Addressing this limitation could allow, for the first time, SCG measurements to be obtained reliably during movement-aside from increasing the coverage throughout the day of cardiovascular monitoring, analyzing SCG signals during movement would quantify the cardiovascular system's response to stress (exercise), and thus provide a more holistic assessment of overall health.

How can soundscapes affect the preferred walking pace?

In this paper we describe an experiment whose goal is to investigate the role of the footstep sounds and soundscapes to affect the pace of a person walking in place (mimicking the act of walking without leaving the current position). Subjects were exposed to different simulated footstep sounds and soundscapes, generated in realtime while walking in place. The results show that, indeed, participants adapted their walking pace to the presented sounds, and not only footstep sounds but also soundscapes affect the walking pace. We could observe as well that perceived ease of walking correlates with the perceived naturalness of ambient sounds.

Functional characteristics of left ventricular synchronization via right ventricular outflow-tract pacing detected by two-dimensional strain echocardiography

BackgroundRecently, due to the detrimental effects on the ventricular function associated with right ventricular apical (RVA) pacing, right ventricular septal (RVS) pacing has become the preferred pacing method. However, the term RVS pacing refers to both right ventricular outflow-tract (RVOT) and mid-septal (RVMS) pacing, leading to a misinterpretation of the results of clinical studies. The purpose of this study, therefore, was to elucidate the functional differences of RVA, RVOT, and RVMS pacing in patients with atrioventricular block. MethodsWe compared the QRS duration, global longitudinal strain (GLS), and left ventricular (LV) synchronization parameters at the three pacing sites in 47 patients. The peak systolic strain (PSS) time delay between the earliest and latest segments among the 18 LV segments and standard deviation (SD) of the time to the PSS were also calculated for the 18 LV segments at each pacing site using two-dimensional (2D) strain echocardiography. ResultsRVMS pacing was associated with a significantly shorter QRS duration compared with RVA and RVOT pacing (154.4±21.4 vs 186.5±19.9 and 171.1±21.5ms, P<0.001). In contrast, RVOT pacing revealed a greater GLS (−14.69±4.92 vs −13.12±4.76 and −13.51±4.81%, P<0.001), shorter PSS time delay between the earliest and latest segments (236.0±87.9 vs 271.3±102.9 and 281.9±126.6%, P=0.007), and shorter SD of the time to the PSS (70.8±23.8 vs 82.7±30.8 and 81.5±33.7ms, P=0.002) compared with RVA and RVMS pacing. ConclusionsThese results suggest that the functional characteristics of RVOT pacing may be a more optimal pacing site than RVMS, regardless of the pacing QRS duration, in patients with atrioventricular conduction disorders.

Metabolic Rate and Perceived Exertion of Walking in Older Adults With Idiopathic Chronic Fatigue.

Fatigue is a common complaint in older adults, often not associated with underlying medical conditions. The purpose of this study was to investigate metabolic rate (MR) of walking, walking performance, and perception-based exertion during walking in older adults with and without idiopathic chronic fatigue (ICF). 20 older adults (aged 70.8±4.9 years), reporting 2 SD above normative values of the Functional Assessment of Chronic Illness Therapy-Fatigue scale and without overt health conditions that explained their symptoms, were compared with 25 age-matched older adults (73.2±5.1 years) without fatigue symptoms. Participants walked 400 m at a rapid pace on a 20-m course. On a separate visit, oxygen consumption was measured during treadmill test at standard (40.2 m/min), preferred paces (40-83 m/min) and peak capacity. Ratings of perceived exertion (RPE) were measured at each treadmill stage and after each lap of the 400-m walk test. During the 400-m walk test, individuals with ICF showed lower overall walking speed and reported a steady increase in RPE with no change observed in non-fatigued group (1.63±1.72 vs 0.27±0.68, p < .01). Similar findings on RPE were noted on treadmill test. Gross MR, mass-specific MR, mass-specific net MR, and MR as a percent of peak oxygen consumption of walking were similar between groups during standard, preferred paces and peak capacity on treadmill. This study suggests that ICF in older adults is not related to elevated metabolic cost of walking. Higher RPE without concomitant decreases in performance indicate a potential disconnect between metabolic output and sensations during movement.

Changes in Sprint Kinetics and Kinematics Following Static or Dynamic Stretching

Pre-activity stretching is common practice among athletes, yet a lack of consensus exists as to which type of stretch should be performed. Various types of stretching have been utilized over time, though due to equivocal results in the literature, the criterion for choosing a stretch is often based on familiarity or tradition. PURPOSE: This study aimed to compare the effects of dynamic or static stretching on hip kinetics and kinematics during intermittent sprinting. Variables of interest included hip flexion torque production at baseline, post-stretch and post-sprint, hip angular velocity during the initial swing phase of gait, and sprint times throughout the repeated sprint protocol. METHODS: Participants included 10 male (age 25 ± 2.3 years) and 2 female (age 20 ± 1 years) experienced soccer players recruited from the Las Vegas community. Following written informed consent, participants were asked to report to the University of Nevada, Las Vegas Sports Injury Research Center twice. Each visit consisted of the following: 1) 5-minute treadmill warm up at a preferred pace, 2) baseline hip flexion torque measurements, 3) either a static or dynamic stretch, 4) post-stretch torque measurements, 5) a repeated sprint protocol, and 6) post-sprint torque measurements. Peak hip flexion torque values were analyzed in SPSS using a 2x3 repeated measures factorial ANOVA. Paired t-tests for average sprint time, difference between first and last sprint time, peak instantaneous velocity, and percent phase occurrence of peak velocity were computed with (α=0.05). RESULTS: No statistically significant differences were found for any variable among any level. CONCLUSIONS: A lack of statistical significance may be attributed to a low n and high variability among participants. Additionally, coupled with previous results in the literature, it may suggest that there is not a “one-size-fits-all” approach to pre-activity stretching.

Walking-Induced Fatigue Leads to Increased Falls Risk in Older Adults

BackgroundFor older adults, falls are a serious health problem, with more than 30% of people older than 65 suffering a fall at least once a year. One element often overlooked in the assessment of falls is whether a person's balance, walking ability, and overall falls risk is affected by performing activities of daily living such as walking. ObjectiveThis study assessed the immediate impact of incline walking at a moderate pace on falls risk, leg strength, reaction time, gait, and balance in 75 healthy adults from 30 to 79 years of age. Subjects were subdivided into 5 equal groups based on their age (group 1, 30–39 years; group 2, 40–49 years; group 3, 50–59 years; group 4, 60–69 years; group 5, 70–79 years). MethodsEach person's falls risk (using the Physiological Profile Assessment), simple reaction time, leg strength, walking ability, and standing balance were assessed before and after a period of incline walking on an automated treadmill. The walking task consisted of three 5-minute trials at a faster than preferred pace. Fatigue during walking was elicited by increasing the treadmill incline in increments of 2° (from level) every minute to a maximum of 8°. ResultsAs predicted, significant age-related differences were observed before the walking activity. In general, increasing age was associated with declines in gait speed, lower limb strength, slower reaction times, and increases in overall falls risk. Following the treadmill task, older adults exhibited increased sway (path length 60–69 years; 10.2 ± 0.7 to 12.1 ± 0.7 cm: 70–79 years; 12.8 ± 1.1 to 15.1 ± 0.8 cm), slower reaction times (70–79 years; 256 ± 6 to 287 ± 8 ms), and declines in lower limb strength (60–69 years; 36 ± 2 to 31 ± 1 kg: 70–79 years; 32.3 ± 2 to 27 ± 1 kg). However, a significant increase in overall falls risk (pre; 0.51 ± 0.17: post; 1.01 ± 0.18) was only seen in the oldest group (70–79 years). For all other persons (30–69 years), changes resulting from the treadmill-walking task did not lead to a significant increase in falls risk. ConclusionsAs most falls occur when an individual is moving and/or fatigued, assessing functional properties related to balance, gait, strength, and falls risk in older adults both at rest and following activity may provide additional insight.

Movement coordination during sit-to-stand in low back pain people

PurposeThe purpose of this study was to compare the inter-joint coordination during sit-to-stand (STD) and stand-to-sit (SIT) execution between healthy people and people with low back pain.MethodsFifteen healthy adults (age = 45.14 ± 5.18 years) and fifteen age-matched (age = 46.17 ± 8.26 years) people with chronic low back pain were selected voluntarily. They performed three repetitions of STD and SIT movement patterns in their preferred pace. Motion analysis system was used for measuring 3-dimensional (3D) angular displacement of hip, knee and ankle joints during execution of movement patterns. Decomposition indices were analysed and were compared between two groups through Hotelling T&lt;sup&gt;2&lt;/sup&gt; Multivariate Analysis of Variance (MANOVA) and follow-up Analysis of Variance (ANOVA)ResultsThe results showed that there is a significant difference (T&lt;sup&gt;2&lt;/sup&gt; = 18.32, F&lt;sub&gt;14, 5&lt;/sub&gt; = 8.33, &lt;i&gt;p&lt;/i&gt; &lt; 0.05) between the groups on decomposition indices. The ANOVA follow-up results showed that there are significant differences between two groups on decomposition indices of the whole pattern of STD (F&lt;sub&gt;1, 18&lt;/sub&gt; = 7.96, &lt;i&gt;p&lt;/i&gt; &lt; 0.05), whole pattern of SIT (F&lt;sub&gt;1, 18&lt;/sub&gt; = 5.37, &lt;i&gt;p&lt;/i&gt; &lt; 0.05), the first-half phase of STD (F&lt;sub&gt;1, 18&lt;/sub&gt; = 7.26, &lt;i&gt;p&lt;/i&gt; &lt; 0.05) and the first-half phase of SIT (F&lt;sub&gt;1, 18&lt;/sub&gt; = 6.33, &lt;i&gt;p&lt;/i&gt; &lt; 0.05).ConclusionsPeople with low back pain have dis-coordination in the function of different body parts, and results in pausing of one segment while the other segment moves independently. This knowledge may help in the development of rehabilitation strategies for movement in this population.

Reaction Time Is Slower When Walking at a Slow Pace in Young Adults

ABSTRACTLimited research has examined attentional requirements of walking at various speeds. Twenty young adults were asked to walk 10 m at their preferred pace, 30% faster or 30% slower while verbally responding “top” as fast as possible to random auditory stimuli. Slow walking demonstrated significantly longer reaction time (RT; 457 ± 91 ms) than preferred (423 ± 80 ms) and fast (396 ± 73 ms) walking speeds, F(2, 38) = 13.4, p < .001; η2p = .414. Walking at a preferred pace also led to longer RT than walking at a fast pace (p < .05). Slower RT during slow walking may be attributed to increased task complexity, energy requirements and equilibrium demands. Faster RTs during fast walking could be due to familiarity of the task, higher arousal levels, and similar task instructions compared to slower speeds.

AssistOn-Mobile: a series elastic holonomic mobile platform for upper extremity rehabilitation

SUMMARYWe present the design, control, and human–machine interface of a series elastic holonomic mobile platform,AssistOn-Mobile, aimed to administer therapeutic table-top exercises to patients who have suffered injuries that affect the function of their upper extremities. The proposed mobile platform is a low-cost, portable, easy-to-use rehabilitation device targeted for home use. In particular,AssistOn-Mobileconsists of a holonomic mobile platform with four actuated Mecanum wheels and a compliant, low-cost, multi-degrees-of-freedom series elastic element acting as its force sensing unit. Thanks to its series elastic actuation,AssistOn-Mobileis highly backdriveable and can provide assistance/resistance to patients, while performing omni-directional movements on plane.AssistOn-Mobilealso features Passive Velocity Field Control (PVFC) to deliver human-in-the-loop contour tracking rehabilitation exercises. PVFC allows patients to complete the contour-tracking tasks at their preferred pace, while providing the proper amount of assistance as determined by the therapists. PVFC not only minimizes the contour error but also does so by rendering the closed-loop system passive with respect to externally applied forces; hence, ensures the coupled stability of the human-robot system. We evaluate the feasibility and effectiveness ofAssistOn-Mobilewith PVFC for rehabilitation and present experimental data collected during human subject experiments under three case studies. In particular, we utilizeAssistOn-Mobilewith PVFC (a) to administer contour following tasks where the pace of the tasks is left to the control of the patients, so that the patients can assume a natural and comfortable speed for the tasks, (b) to limit compensatory movements of the patients by integrating a RGB-D sensor to the system to continually monitor the movements of the patients and to modulate the task speeds to provide online feedback to the patients, and (c) to integrate a Brain–Computer Interface such that the brain activity of the patients is mapped to the robot speed along the contour following tasks, rendering an assist-as-needed protocol for the patients with severe disabilities. The feasibility studies indicate thatAssistOn-Mobileholds promise in improving the accuracy and effectiveness of repetitive movement therapies, while also providing quantitative measures of patient progress.

Balance training with multi-task exercises improves fall-related self-efficacy, gait, balance performance and physical function in older adults with osteoporosis: a randomized controlled trial

Objective: To evaluate the effects of a balance training program including dual- and multi-task exercises on fall-related self-efficacy, fear of falling, gait and balance performance, and physical function in older adults with osteoporosis with an increased risk of falling and to evaluate whether additional physical activity would further improve the effects. Design: Randomized controlled trial, including three groups: two intervention groups (Training, or Training+Physical activity) and one Control group, with a 12-week follow-up. Setting: Stockholm County, Sweden. Participants: Ninety-six older adults, aged 66-87, with verified osteoporosis. Interventions: A specific and progressive balance training program including dual- and multi-task three times/week for 12 weeks, and physical activity for 30 minutes, three times/week. Main measures: Fall-related self-efficacy (Falls Efficacy Scale-International), fear of falling (single-item question – ‘In general, are you afraid of falling?’), gait speed with and without a cognitive dual-task at preferred pace and fast walking (GAITRite®), balance performance tests (one-leg stance, and modified figure of eight), and physical function (Late-Life Function and Disability Instrument). Results: Both intervention groups significantly improved their fall-related self-efficacy as compared to the controls (p ≤ 0.034, 4 points) and improved their balance performance. Significant differences over time and between groups in favour of the intervention groups were found for walking speed with a dual-task (p=0.003), at fast walking speed (p=0.008), and for advanced lower extremity physical function (p=0.034). Conclusions: This balance training program, including dual- and multi-task, improves fall-related self-efficacy, gait speed, balance performance, and physical function in older adults with osteoporosis.

Spontaneous Motor Tempo is the Easiest Pace to Act Upon for Both the Emergent and the Predictive Timing Modes

Spontaneous Motor Tempo is the Easiest Pace to Act Upon for Both the Emergent and the Predictive Timing Modes