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Downer KE, Pariser KM, Donlin MC, Higginson JS. How Important is Position in Adaptive Treadmill Control? J Biomech Eng 2024; 146:011006. [PMID: 37851541 PMCID: PMC10680982 DOI: 10.1115/1.4063823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 10/10/2023] [Accepted: 10/13/2023] [Indexed: 10/20/2023]
Abstract
To more closely mimic overground walking, researchers are developing adaptive treadmills (ATMs) that update belt speed in real-time based on user gait mechanics. Many existing ATM control schemes are solely based on position on the belt and do not respond to changes in gait mechanics, like propulsive forces, that result in increased overground walking speed. To target natural causal mechanisms to alter speed, we developed an ATM controller that adjusts speed via changes in position, step length, and propulsion. Gains on each input dictate the impact of the corresponding parameter on belt speed. The study objective was to determine the effect of modifying the position gain on self-selected walking speed, measures of propulsion, and step length. Twenty-two participants walked at their self-selected speed with four ATM controllers, each with a unique position gain. Walking speed, anterior and posterior ground reaction force peaks and impulses, net impulse, and step length were compared between conditions. Smaller position gains promoted more equivalent anterior and posterior impulses, resulting in a net impulse closer to zero (p = 0.0043), a characteristic of healthy gait. Walking speed, anterior and posterior ground reaction force peaks and impulses, and step length did not change between conditions (all p > 0.05). These results suggest that reducing the importance of position in the ATM controller may promote more balanced anterior and posterior impulses, possibly improving the efficacy of the ATM for gait rehabilitation by emphasizing changes in gait mechanics instead of position to naturally adjust speed.
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Affiliation(s)
- Kaitlyn E. Downer
- Department of Mechanical Engineering, University of Delaware, 540 S. College Avenue, STAR Health Sciences Complex, Rm 201, Newark, DE 19713; Department of Mechanical and Aerospace Engineering, University of Florida, 1929 Stadium Dr, Nuclear Sciences Building, Rm 209, Gainesville, FL 32611
| | - Kayla M. Pariser
- Department of Mechanical Engineering, University of Delaware, 540 S. College Avenue, STAR Health Sciences Complex, Rm 201, Newark, DE 19713
| | - Margo C. Donlin
- Department of Biomedical Engineering, University of Delaware, 540 S. College Avenue, STAR Health Sciences Complex, Rm 201, Newark, DE 19713
| | - Jill S. Higginson
- Department of Mechanical Engineering, University of Delaware, 540 S. College Avenue, STAR Health Sciences Complex, Rm 201, Newark, DE 19713; Department of Biomedical Engineering, University of Delaware, 540 S. College Avenue, STAR Health Sciences Complex, Rm 201, Newark, DE 19713
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Castano CR, Lee LD, Huang HJ. Speeding up: Discrete mediolateral perturbations increased self-paced walking speed in young and older adults. Gait Posture 2023; 102:198-204. [PMID: 37043989 DOI: 10.1016/j.gaitpost.2023.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 02/16/2023] [Accepted: 04/03/2023] [Indexed: 04/14/2023]
Abstract
BACKGROUND In uncertain environments and with increasing age, humans often walk, slower while taking shorter, quicker, and wider steps, reflective of a cautious gait., Understanding when humans opt to use a cautious gait and the differences in gait, strategies used as people age could be examined with perturbations on a self-paced, treadmill that allows participants to adjust their walking speed. Adding varying degrees, of unpredictability, an inherent element of real-world walking, could also improve, understanding of when specific gait strategies are used RESEARCH QUESTION: We investigated how healthy young and older adults adjust their, gait strategies when responding to perturbations of varying unpredictability. We, hypothesized that more unpredictable perturbations would produce more cautious gait, strategies and be more pronounced in older adults than young adults METHODS: Ten young and ten older adults walked on a self-paced treadmill with, discrete mediolateral treadmill shift perturbations. We changed the shift magnitude, and/or the timing of the perturbations during the gait cycle to vary perturbation, unpredictability. We analyzed walking speed and step kinematics from treadmill and, motion capture data RESULTS: Surprisingly, participants walked faster, not slower, for the conditions with, perturbations. Even more surprising, older adults walked faster overall than young, adults. As expected, participants took faster and wider steps for the most unpredictable, perturbation but also took longer steps, which was not expected. Step kinematic, variability and average step width also increased as perturbation unpredictability, increased, suggesting that the more unpredictable conditions demanded greater, balance control. Additionally, older adults had greater step kinematic variability, highlighted further using detrended step length variability, compared to young adults SIGNIFICANCE: Overall, these findings provide new insights about gait strategies and, suggest that perturbations such as discrete mediolateral treadmill shifts can potentially, be designed to encourage participants to walk faster, if it is beneficial.
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Affiliation(s)
- Cesar R Castano
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL, United States.
| | - Lindsey D Lee
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL, United States
| | - Helen J Huang
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL, United States; Disability, Aging, and Technology Cluster, University of Central Florida, Orlando, FL, United States; BiionixTM (Bionic Materials, Implants & Interfaces) Cluster, University of Central Florida, Orlando, FL, United States
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Xie H, Liang H, Chien JH. Different types of plantar vibration affect gait characteristics differently while walking on different inclines. PeerJ 2023; 11:e14619. [PMID: 36643634 PMCID: PMC9835691 DOI: 10.7717/peerj.14619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 12/01/2022] [Indexed: 01/11/2023] Open
Abstract
Background Plantar vibration has been widely used to strengthen the sensation of the somatosensory system, further enhancing balance during walking on a level surface in patients with stroke. However, previous studies with plantar vibration only involved the level surface, which neglected the importance of inclined/declined walking in daily life. Thus, combining the plantar vibration and inclined/declined walking might answer a critical research question: whether different types of plantar vibration had different effects on gait characteristics during walking on different inclines. Methods Eighteen healthy young adults were recruited. Fifteen walking conditions were assigned randomly to these healthy adults (no, sub-, and supra-threshold plantar vibration × five different inclines: +15%, +8%, 0%, -8%, -15% grade). A motion capture system with eight cameras captured 12 retro-reflective markers and measured the stride time, stride length, step width, and respective variabilities. Results A significant interaction between vibration and inclination was observed in the stride time (p < 0.0001) and step width (p = 0.015). Post hoc comparisons found that supra-threshold vibration significantly decreased the stride time (-8%: p < 0.001; -15%: p < 0.001) while the sub-threshold vibration significantly increased the step width (-8%: p = 0.036) in comparison with no plantar vibration. Conclusions When walking downhill, any perceivable (supra-threshold) vibration on the plantar area decreased the stride time. Also, the increase in step width was observed by non-perceivable (sub-threshold) plantar vibration while walking uphill. These observations were crucial as follows: (1) applying sub-threshold plantar vibrations during uphill walking could increase the base of support, and (2) for those who may need challenges in locomotor training, applying supra-threshold vibration during downhill walking could reach this specific training goal.
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Affiliation(s)
- Haoyu Xie
- Department of Health & Rehabilitation Science, University of Nebraska Medical Center, Omaha, NE, United States
| | - Haolan Liang
- Department of Health & Rehabilitation Science, University of Nebraska Medical Center, Omaha, NE, United States
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Pimentel RE, Feldman JN, Lewek MD, Franz JR. Quantifying mechanical and metabolic interdependence between speed and propulsive force during walking. Front Sports Act Living 2022; 4:942498. [PMID: 36157906 PMCID: PMC9500214 DOI: 10.3389/fspor.2022.942498] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 08/02/2022] [Indexed: 11/13/2022] Open
Abstract
Walking speed is a useful surrogate for health status across the population. Walking speed appears to be governed in part by interlimb coordination between propulsive (FP) and braking (FB) forces generated during step-to-step transitions and is simultaneously optimized to minimize metabolic cost. Of those forces, FP generated during push-off has received significantly more attention as a contributor to walking performance. Our goal was to first establish empirical relations between FP and walking speed and then to quantify their effects on metabolic cost in young adults. To specifically address any link between FP and walking speed, 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 ~80% of variance in walking speed explained by FP. We also found that comparable changes in either FP or walking speed elicited predictable and relatively uniform changes in metabolic cost, together explaining ~53% of the variance in net metabolic power and ~14% of the variance in cost of transport. These results provide empirical data in support of an interdependent relation between FP and walking speed, building confidence that interventions designed to increase FP will translate to improved walking speed. Repeating this protocol in other populations may identify other relations that could inform the time course of gait decline due to age and disease.
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Affiliation(s)
- Richard E. Pimentel
- Applied Biomechanics Laboratory, Joint Department of BME, UNC, and NCSU, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- Human Movement Science Laboratory, Division of Physical Therapy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Jordan N. Feldman
- Applied Biomechanics Laboratory, Joint Department of BME, UNC, and NCSU, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- Human Movement Science Laboratory, Division of Physical Therapy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Michael D. Lewek
- Human Movement Science Laboratory, Division of Physical Therapy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Jason R. Franz
- Applied Biomechanics Laboratory, Joint Department of BME, UNC, and NCSU, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- Human Movement Science Laboratory, Division of Physical Therapy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- *Correspondence: Jason R. Franz
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Franks PW, Bryan GM, Reyes R, O'Donovan MP, Gregorczyk KN, Collins SH. The Effects of Incline Level on Optimized Lower-Limb Exoskeleton Assistance: a Case Series. IEEE Trans Neural Syst Rehabil Eng 2022; 30:2494-2505. [PMID: 35930513 DOI: 10.1109/tnsre.2022.3196665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
For exoskeletons to be successful in real-world settings, they will need to be effective across a variety of terrains, including on inclines. While some single-joint exoskeletons have assisted incline walking, recent successes in level-ground assistance suggest that greater improvements may be possible by optimizing assistance of the whole leg. To understand how exoskeleton assistance should change with incline, we used human-in-the-loop optimization to find whole-leg exoskeleton assistance torques that minimized metabolic cost on a range of grades. We optimized assistance for three able-bodied, expert participants on 5 degree, 10 degree, and 15 degree inclines using a hip-knee-ankle exoskeleton emulator. For all assisted conditions, the cost of transport was reduced by at least 50% relative to walking in the device with no assistance, which is a large improvement to walking comparable to the benefits of whole-leg assistance on level-ground (N = 3). Optimized extension torque magnitudes and exoskeleton power increased with incline. Hip extension, knee extension and ankle plantarflexion often grew as large as allowed by comfort-based limits. Applied powers on steep inclines were double the powers applied during level-ground walking, indicating that greater exoskeleton power may be optimal in scenarios where biological powers and costs are higher. Future exoskeleton devices could deliver large improvements in walking performance across a range of inclines if they have sufficient torque and power capabilities.
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Pariser KM, Donlin MC, Downer KE, Higginson JS. Adaptive treadmill control can be manipulated to increase propulsive impulse while maintaining walking speed. J Biomech 2022; 133:110971. [PMID: 35121382 PMCID: PMC8891055 DOI: 10.1016/j.jbiomech.2022.110971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 01/20/2022] [Accepted: 01/21/2022] [Indexed: 11/18/2022]
Abstract
Adaptive treadmills (ATM) designed to promote increased propulsion may be an effective tool for gait training since propulsion is often impaired post-stroke. Our lab developed a novel ATM controller that adjusts belt speed via real-time changes in step length, propulsive impulse, and position. This study modified the relative importance of propulsion to step length in the controller to determine the effect of increased propulsive feedback gain on measures of propulsion and walking speed. Twenty-two participants completed five trials at their self-selected speed, each with a unique ATM controller. Walking speed, peak AGRF and PGRF, and AGRF, PGRF, and net impulse were compared between the modifications using one-way repeated measures ANOVAs at a significance level of 0.05. Participants chose similar walking speeds across all conditions (all p > 0.2730). There were no significant differences in peak AGRF (p = 0.1956) or PGRF (p = 0.5159) between conditions. AGRF impulse significantly increased as the gain on the propulsive impulse term was increased relative to the gain on step length (p < 0.0001) while PGRF and net impulse were similar across all conditions (p = 0.5487). Increasing the propulsive impulse gain essentially alters the treadmill environment by providing a controlled amount of resistance to increases in propulsive forces. Our findings demonstrate that the ATM can be modified to promote increased propulsive impulse while maintaining a consistent walking speed. Since increasing propulsion is a common goal of post-stroke gait training, these ATM modifications may improve the efficacy of the ATM for gait rehabilitation.
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Affiliation(s)
- Kayla M Pariser
- Department of Mechanical Engineering, University of Delaware, Newark, DE, USA.
| | - Margo C Donlin
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
| | - Kaitlyn E Downer
- Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Jill S Higginson
- Department of Mechanical Engineering, University of Delaware, Newark, DE, USA; Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
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