scholarly journals Associations Between Foot Placement Asymmetries and Metabolic Cost of Transport in Hemiparetic Gait

2016 ◽  
Vol 31 (2) ◽  
pp. 168-177 ◽  
Author(s):  
James M. Finley ◽  
Amy J. Bastian
Keyword(s):  
Walking Speed ◽  
Metabolic Cost ◽  
Positive Association ◽  
Stroke Survivor ◽  
Gas Analysis ◽  
Stroke Survivors ◽  
Cost Of Transport ◽  
Foot Placement ◽  
Hemiparetic Gait ◽  
All Speeds

Stroke survivors often have a slow, asymmetric walking pattern. They also walk with a higher metabolic cost than healthy, age-matched controls. It is often assumed that spatial-temporal asymmetries contribute to the increased metabolic cost of walking poststroke. However, elucidating this relationship is made challenging because of the interdependence between spatial-temporal asymmetries, walking speed, and metabolic cost. Here, we address these potential confounds by measuring speed-dependent changes in metabolic cost and implementing a recently developed approach to dissociate spatial versus temporal contributions to asymmetry in a sample of stroke survivors. We used expired gas analysis to compute the metabolic cost of transport (CoT) for each participant at 4 different walking speeds: self-selected speed, 80% and 120% of their self-selected speed, and their fastest comfortable speed. We also computed CoT for a sample of age- and gender-matched control participants who walked at the same speeds as their matched stroke survivor. Kinematic data were used to compute the magnitude of a number of variables characterizing spatial-temporal asymmetries. Across all speeds, stroke survivors had a higher CoT than controls. We also found that our sample of stroke survivors did not choose a self-selected speed that minimized CoT, contrary to typical observations in healthy controls. Multiple regression analyses revealed negative associations between speed and CoT and a positive association between asymmetries in foot placement relative to the trunk and CoT. These findings suggest that interventions designed to increase self-selected walking speed and reduce foot-placement asymmetries may be ideal for improving walking economy poststroke.

scholarly journals Impact of elastic ankle exoskeleton stiffness on neuromechanics and energetics of human walking across multiple speeds

2020 ◽  
Author(s):  
Richard W. Nuckols ◽  
Gregory S. Sawicki
Keyword(s):  
Muscle Activation ◽  
Walking Speed ◽  
Metabolic Cost ◽  
Weighted Sum ◽  
Joint Mechanics ◽  
Metabolic Demand ◽  
Muscle Dynamics ◽  
Activation Rate ◽  
Ankle Exoskeleton ◽  
All Speeds

Abstract Background: Elastic ankle exoskeletons with intermediate stiffness springs in parallel with the human plantarflexors can reduce the metabolic cost of walking by ~7% at 1.25 m s -1 . In a move toward ‘real-world’ application, we examined whether the unpowered approach has metabolic benefit across a range of walking speeds, and if so, whether the optimal exoskeleton stiffness was speed dependent. We hypothesized that, for any walking speed, there would be an optimal ankle exoskeleton stiffness - not too compliant and not too stiff - that minimizes the user’s metabolic cost. In addition, we expected the optimal stiffness to increase with walking speed. Methods: Eleven participants walked on a level treadmill at 1.25, 1.50, and 1.75 m s -1 while we used a state-of-the-art exoskeleton emulator to apply bilateral ankle exoskeleton assistance at five controlled rotational stiffnesses (k exo = 0, 50, 100, 150, 250 Nm rad -1 ). We measured metabolic cost, lower limb joint mechanics, and EMG of muscles crossing the ankle, knee, and hip. Results: Metabolic cost was significantly reduced at the lowest exoskeleton stiffness (50 Nm rad -1 ) for assisted walking at both 1.25 (4.2%; p = 0.0162) and 1.75 m s -1 (4.7%; p = 0.0045). At these speeds, the metabolically optimal exoskeleton stiffness provided peak assistive torques of ~0.20 Nm kg -1 that resulted in reduced biological ankle moment of ~12% and reduced soleus muscle activity of ~10%. We found no stiffness that could reduce the metabolic cost of walking at 1.5 m s -1 . Across all speeds, the non-weighted sum of soleus and tibialis anterior activation rate explained the change in metabolic rate due to exoskeleton assistance ( p < .05; R 2 > 0.56). Conclusions: Elastic ankle exoskeletons with low rotational stiffness reduce users’ metabolic cost of walking at slow and fast but not intermediate walking speed. The relationship between the non-weighted sum of soleus and tibialis activation rate and metabolic cost (R 2 > 0.56) indicates that muscle activation may drive metabolic demand. Future work using simulations and ultrasound imaging will get ‘under the skin’ and examine the interaction between exoskeleton stiffness and plantarflexor muscle dynamics to better inform stiffness selection in human-machine systems.

scholarly journals Quantifying Cause-Effect Relations Between Walking Speed, Propulsive Force, and Metabolic Cost

2021 ◽  
Author(s):  
Richard Pimentel ◽  
Jordan N Feldman ◽  
Michael D Lewek ◽  
Jason R Franz
Keyword(s):  
Young Adults ◽  
Health Status ◽  
Time Course ◽  
Walking Speed ◽  
Metabolic Cost ◽  
Propulsive Force ◽  
Metabolic Power ◽  
Cost Of Transport ◽  
Walking Speeds ◽  
Variance Explained

Walking speed is a useful surrogate for health status across the population. Walking speed appears to be governed in part by propulsive force (FP) generated during push-off and simultaneously optimized to minimize metabolic cost. However, no study to our knowledge has established empirical cause-effect relations between FP, walking speed, and metabolic cost, even in young adults. To overcome the potential linkage between these factors, we used a self-paced treadmill controller and real-time biofeedback to independently prescribe walking speed or FP across a range of condition intensities. Walking with larger and smaller FP led to instinctively faster and slower walking speeds, respectively, with about 80% of variance explained between those outcomes. We also found that comparable changes in either FP or walking speed elicited predictable and relatively uniform changes in metabolic cost, each explaining about ~53% of the variance in net metabolic power and ~15% of the variance in cost of transport, respectively. These findings build confidence that interventions designed to increase FP will translate to improved walking speed. Repeating this protocol in other populations may identify additional cause-effect relations that could inform the time course of gait decline due to age and disease.

scholarly journals A novel Movement Amplification environment reveals effects of controlling lateral centre of mass motion on gait stability and metabolic cost

2020 ◽  
Vol 7 (1) ◽  
pp. 190889
Author(s):  
Mengnan/Mary Wu ◽  
Geoffrey L. Brown ◽  
Jane L. Woodward ◽  
Sjoerd M. Bruijn ◽  
Keith E. Gordon
Keyword(s):  
Metabolic Cost ◽  
Mass Motion ◽  
Step Width ◽  
Centre Of Mass ◽  
Cost Of Transport ◽  
Gait Patterns ◽  
Gait Stability ◽  
Foot Placement ◽  
Base Of Support ◽  
Healthy Participants

During human walking, the centre of mass (COM) laterally oscillates, regularly transitioning its position above the two alternating support limbs. To maintain upright forward-directed walking, lateral COM excursion should remain within the base of support, on average. As necessary, humans can modify COM motion through various methods, including foot placement. How the nervous system controls these oscillations and the costs associated with control are not fully understood. To examine how lateral COM motions are controlled, healthy participants walked in a ‘Movement Amplification’ force field that increased lateral COM momentum in a manner dependent on the participant's own motion (forces were applied to the pelvis proportional to and in the same direction as lateral COM velocity). We hypothesized that metabolic cost to control lateral COM motion would increase with the gain of the field. In the Movement Amplification field, participants were significantly less stable than during baseline walking. Stability significantly decreased as the field gain increased. Participants also modified gait patterns, including increasing step width, which increased the metabolic cost of transport as the field gain increased. These results support previous research suggesting that humans modulate foot placement to control lateral COM motion, incurring a metabolic cost.

Energetics of Load Carriage by Bamboo Carrying Poles

2019 ◽  
Author(s):  
Yuning Xu ◽  
Lianxin Yang ◽  
Ken Chen ◽  
Jiwen Zhang ◽  
Chenglong Fu
Keyword(s):  
Walking Speed ◽  
Load Capacity ◽  
Metabolic Cost ◽  
Load Carriage ◽  
Transport Cost ◽  
Co2 Production ◽  
Long Distance ◽  
Heavy Load ◽  
Cost Of Transport ◽  
Heavy Loads

Abstract Unlike western conventions of rigid body attachments (e.g. backpack), carriers in Asia prefer to use bamboo poles, an ancient, ingenious, elastically-suspended equipment, especially when carrying heavy loads. As an elastically-suspended equipment, bamboo pole might have some potential benefits including reducing peak shoulder forces as well as saving metabolic transport cost, but certain skills should be needed for loading. Experienced carriers routinely carry loads exceeding their own body mass (Mb) for a long distance, while novices might hurt themselves. However, no skillful bamboo pole carriers’ performance or loading with heavy load has not been reported as far as we know. We set out to determine the loads capability and distances carried by skillful carriers, measure their metabolic cost for carrying the loads, and observe whether their natural walking speed changed as a function of load. In this paper, we compared the skillful carriers’ energy expenditure on carrying loads in both normal bamboo pole on shoulder and typical backpacks with hip support. Both carrying postures were normal, just as what subjects used in their daily life. The O2 consumption and CO2 production were measured in 13 subjects while standing or walking with loads. All subjects were asked to carry loads ranging from 0 kg to their load capacity in two loading type, while walking on a 1-meter wide nearly circular level track at their preferred speed. These speeds were record by cameras placed beside the track. Experimental results show that bamboo pole perform better under heavy load: 1. Loading by bamboo pole helped carriers to load 16% body weight heavier than by backpack on average. 2. With the load increasing, the walking speed loading by backpack would decrease from 1.3m/s (0kg) to 1.1m/s (load capacity), however loading by bamboo pole would slightly increase. 3. The rate of energy consumptions both increase with load increasing. Bamboo pole require more metabolic consumption than backpack with same load. 4. Since natural walking speed by bamboo pole faster than by backpack, the cost of transport by bamboo pole would be more economic than by backpack while the load is 50kg or more.

scholarly journals Role of caregiver factors in outpatient medical follow-up post-stroke: observational study in Singapore

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Shilpa Tyagi ◽  
Gerald Choon-Huat Koh ◽  
Nan Luo ◽  
Kelvin Bryan Tan ◽  
Helen Hoenig ◽  
...  
Keyword(s):  
Observational Study ◽  
Management Strategies ◽  
Stroke Survivor ◽  
Stroke Survivors ◽  
Post Stroke ◽  
Memory Problems ◽  
Healthcare Needs ◽  
Stroke Study

Abstract Background Outpatient medical follow-up post-stroke is not only crucial for secondary prevention but is also associated with a reduced risk of rehospitalization. However, being voluntary and non-urgent, it is potentially determined by both healthcare needs and the socio-demographic context of stroke survivor-caregiver dyads. Therefore, we aimed to examine the role of caregiver factors in outpatient medical follow-up (primary care (PC) and specialist outpatient care (SOC)) post-stroke. Method Stroke survivors and caregivers from the Singapore Stroke Study, a prospective, yearlong, observational study, contributed to the study sample. Participants were interviewed 3-monthly for data collection. Counts of PC and SOC visits were extracted from the National Claims Database. Poisson modelling was used to explore the association of caregiver (and patient) factors with PC/SOC visits over 0–3 months (early) and 4–12 months (late) post-stroke. Results For the current analysis, 256 stroke survivors and caregivers were included. While caregiver-reported memory problems of a stroke survivor (IRR: 0.954; 95% CI: 0.919, 0.990) and caregiver burden (IRR: 0.976; 95% CI: 0.959, 0.993) were significantly associated with lower early post-stroke PC visits, co-residing caregiver (IRR: 1.576; 95% CI: 1.040, 2.389) and negative care management strategies (IRR: 1.033; 95% CI: 1.005, 1.061) were significantly associated with higher late post-stroke SOC visits. Conclusion We demonstrated that the association of caregiver factors with outpatient medical follow-up varied by the type of service (i.e., PC versus SOC) and temporally. Our results support family-centred care provision by family physicians viewing caregivers not only as facilitators of care in the community but also as active members of the care team and as clients requiring care and regular assessments.

scholarly journals Gait Parameter Adjustments for Walking on a Treadmill at Preferred, Slower, and Faster Speeds in Older Adults with Down Syndrome

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Beth A. Smith ◽  
Masayoshi Kubo ◽  
Beverly D. Ulrich
Keyword(s):  
Older Adults ◽  
Down Syndrome ◽  
Stride Frequency ◽  
Gait Patterns ◽  
Gait Stability ◽  
Foot Placement ◽  
Gait Parameters ◽  
Younger Age ◽  
All Speeds ◽  
Walking Speeds

The combined effects of ligamentous laxity, hypotonia, and decrements associated with aging lead to stability-enhancing foot placement adaptations during routine overground walking at a younger age in adults with Down syndrome (DS) compared to their peers with typical development (TD). Our purpose here was to examine real-time adaptations in older adults with DS by testing their responses to walking on a treadmill at their preferred speed and at speeds slower and faster than preferred. We found that older adults with DS were able to adapt their gait to slower and faster than preferred treadmill speeds; however, they maintained their stability-enhancing foot placements at all speeds compared to their peers with TD. All adults adapted their gait patterns similarly in response to faster and slower than preferred treadmill-walking speeds. They increased stride frequency and stride length, maintained step width, and decreased percent stance as treadmill speed increased. Older adults with DS, however, adjusted their stride frequencies significantly less than their peers with TD. Our results show that older adults with DS have the capacity to adapt their gait parameters in response to different walking speeds while also supporting the need for intervention to increase gait stability.

scholarly journals COPING STRATEGIES BY STROKE CAREGIVERS: EVIDENCE FROM A QUALITATIVE STUDY IN SARAWAK, MALAYSIA

2020 ◽  
Vol 20 (1) ◽  
pp. 48-54
Author(s):  
Md Mizanur Rahman ◽  
Zabidah binti Putit ◽  
Norliza binti Suut ◽  
Mohamad Taha Arif ◽  
Asri bin Said ◽  
...  
Keyword(s):  
Qualitative Study ◽  
Coping Strategies ◽  
Qualitative Data ◽  
Service Providers ◽  
Stroke Survivor ◽  
Stroke Survivors ◽  
Rehabilitation Centre ◽  
Emotion Suppression ◽  
Self Blame ◽  
Community Rehabilitation

Caring for stroke survivors is inevitably a burden to caregivers. It is not uncommon for stroke survivors who are discharged from the hospital and found themselves at home without any help and care from the supposed caregivers. However, in instances where there are available and willing caregivers, a sudden and unpredictable task of caring for stroke survivors require the stroke caregivers to apply their coping strategies due to the demanding nature of looking after a survivor. This study aimed to determine coping strategies undertaken by stroke caregivers in caring for stroke survivors. This was an exploratory qualitative study and data was collected from the caregivers of stroke survivor using a semi-structured guided questionnaire. A total of 18 caregivers were included in the study. The data were collected from November 2015 until June 2016 at a selected community rehabilitation centre in Kuching, Sarawak. The qualitative data analysis revealed that the coping strategies undertaken by stroke caregivers include change of role in life, self-motivation, sharing with other people, crying, trying to forget things that happen, hoping survivors will get better, emotion suppression and self-blame. The study highlighted the experiences by the caregivers for caring for stroke patients and focused on the coping strategies undertaken by the caregivers. Better ununderstanding of these experiences does help the service providers to provide better support and resources for caregivers in caring for stroke survivors.

scholarly journals Factors affecting metabolic cost of transport during a multi-stage running race

2013 ◽  
Vol 217 (5) ◽  
pp. 787-795 ◽  
Author(s):  
S. Lazzer ◽  
P. Taboga ◽  
D. Salvadego ◽  
E. Rejc ◽  
B. Simunic ◽  
...  
Keyword(s):  
Metabolic Cost ◽  
Cost Of Transport ◽  
Factors Affecting ◽  
Multi Stage

Reduced prosthetic stiffness lowers the metabolic cost of running for athletes with bilateral transtibial amputations

2017 ◽  
Vol 122 (4) ◽  
pp. 976-984 ◽  
Author(s):  
Owen N. Beck ◽  
Paolo Taboga ◽  
Alena M. Grabowski
Keyword(s):  
Lower Limb ◽  
Metabolic Cost ◽  
Ground Reaction Forces ◽  
Metabolic Rates ◽  
Distance Running ◽  
Cost Of Transport ◽  
Leg Stiffness ◽  
Metabolic Costs ◽  
In Series ◽  
Reaction Forces

Inspired by the springlike action of biological legs, running-specific prostheses are designed to enable athletes with lower-limb amputations to run. However, manufacturer’s recommendations for prosthetic stiffness and height may not optimize running performance. Therefore, we investigated the effects of using different prosthetic configurations on the metabolic cost and biomechanics of running. Five athletes with bilateral transtibial amputations each performed 15 trials on a force-measuring treadmill at 2.5 or 3.0 m/s. Athletes ran using each of 3 different prosthetic models (Freedom Innovations Catapult FX6, Össur Flex-Run, and Ottobock 1E90 Sprinter) with 5 combinations of stiffness categories (manufacturer’s recommended and ± 1) and heights (International Paralympic Committee’s maximum competition height and ± 2 cm) while we measured metabolic rates and ground reaction forces. Overall, prosthetic stiffness [fixed effect (β) = 0.036; P = 0.008] but not height ( P ≥ 0.089) affected the net metabolic cost of transport; less stiff prostheses reduced metabolic cost. While controlling for prosthetic stiffness (in kilonewtons per meter), using the Flex-Run (β = −0.139; P = 0.044) and 1E90 Sprinter prostheses (β = −0.176; P = 0.009) reduced net metabolic costs by 4.3–4.9% compared with using the Catapult prostheses. The metabolic cost of running improved when athletes used prosthetic configurations that decreased peak horizontal braking ground reaction forces (β = 2.786; P = 0.001), stride frequencies (β = 0.911; P < 0.001), and leg stiffness values (β = 0.053; P = 0.009). Remarkably, athletes did not maintain overall leg stiffness across prosthetic stiffness conditions. Rather, the in-series prosthetic stiffness governed overall leg stiffness. The metabolic cost of running in athletes with bilateral transtibial amputations is influenced by prosthetic model and stiffness but not height. NEW & NOTEWORTHY We measured the metabolic rates and biomechanics of five athletes with bilateral transtibial amputations while running with different prosthetic configurations. The metabolic cost of running for these athletes is minimized by using an optimal prosthetic model and reducing prosthetic stiffness. The metabolic cost of running was independent of prosthetic height, suggesting that longer legs are not advantageous for distance running. Moreover, the in-series prosthetic stiffness governs the leg stiffness of athletes with bilateral leg amputations.

scholarly journals Contributions of metabolic and temporal costs to human gait selection

2018 ◽  
Vol 15 (143) ◽  
pp. 20180197 ◽  
Author(s):  
Erik M. Summerside ◽  
Rodger Kram ◽  
Alaa A. Ahmed
Keyword(s):  
Movement Time ◽  
Metabolic Cost ◽  
Metabolic Energy ◽  
Human Gait ◽  
Cost Of Transport ◽  
Relative Value ◽  
Weighted Combination

Humans naturally select several parameters within a gait that correspond with minimizing metabolic cost. Much less is understood about the role of metabolic cost in selecting between gaits. Here, we asked participants to decide between walking or running out and back to different gait specific markers. The distance of the walking marker was adjusted after each decision to identify relative distances where individuals switched gait preferences. We found that neither minimizing solely metabolic energy nor minimizing solely movement time could predict how the group decided between gaits. Of our twenty participants, six behaved in a way that tended towards minimizing metabolic energy, while eight favoured strategies that tended more towards minimizing movement time. The remaining six participants could not be explained by minimizing a single cost. We provide evidence that humans consider not just a single movement cost, but instead a weighted combination of these conflicting costs with their relative contributions varying across participants. Individuals who placed a higher relative value on time ran faster than individuals who placed a higher relative value on metabolic energy. Sensitivity to temporal costs also explained variability in an individual's preferred velocity as a function of increasing running distance. Interestingly, these differences in velocity both within and across participants were absent in walking, possibly due to a steeper metabolic cost of transport curve. We conclude that metabolic cost plays an essential, but not exclusive role in gait decisions.

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