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Skiadopoulos A, Knikou M. Tapping into the human spinal locomotor centres with transspinal stimulation. Sci Rep 2024; 14:5990. [PMID: 38472313 PMCID: PMC10933285 DOI: 10.1038/s41598-024-56579-0] [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: 12/28/2023] [Accepted: 03/08/2024] [Indexed: 03/14/2024] Open
Abstract
Human locomotion is controlled by spinal neuronal networks of similar properties, function, and organization to those described in animals. Transspinal stimulation affects the spinal locomotor networks and is used to improve standing and walking ability in paralyzed people. However, the function of locomotor centers during transspinal stimulation at different frequencies and intensities is not known. Here, we document the 3D joint kinematics and spatiotemporal gait characteristics during transspinal stimulation at 15, 30, and 50 Hz at sub-threshold and supra-threshold stimulation intensities. We document the temporal structure of gait patterns, dynamic stability of joint movements over stride-to-stride fluctuations, and limb coordination during walking at a self-selected speed in healthy subjects. We found that transspinal stimulation (1) affects the kinematics of the hip, knee, and ankle joints, (2) promotes a more stable coordination at the left ankle, (3) affects interlimb coordination of the thighs, and (4) intralimb coordination between thigh and foot, (5) promotes greater dynamic stability of the hips, (6) increases the persistence of fluctuations in step length variability, and lastly (7) affects mechanical walking stability. These results support that transspinal stimulation is an important neuromodulatory strategy that directly affects gait symmetry and dynamic stability. The conservation of main effects at different frequencies and intensities calls for systematic investigation of stimulation protocols for clinical applications.
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Affiliation(s)
- Andreas Skiadopoulos
- Klab4Recovery Research Program, The City University of New York, New York, USA
- Department of Physical Therapy, College of Staten Island, The City University of New York, Staten Island, NY, USA
| | - Maria Knikou
- Klab4Recovery Research Program, The City University of New York, New York, USA.
- Department of Physical Therapy, College of Staten Island, The City University of New York, Staten Island, NY, USA.
- PhD Program in Biology and Collaborative Neuroscience Program, Graduate Center of The City University of New York and College of Staten Island, New York, USA.
- Klab4Recovery Research Program, Neurosciences/Graduate Center of CUNY, DPT Department/College of Staten Island, 2800 Victory Blvd, 5N-207, New York, 10314, USA.
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Skiadopoulos A, Knikou M. Tapping Into the Human Spinal Locomotor Centres With Transspinal Stimulation. RESEARCH SQUARE 2024:rs.3.rs-3818499. [PMID: 38260677 PMCID: PMC10802712 DOI: 10.21203/rs.3.rs-3818499/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Human locomotion is controlled by spinal neuronal networks of similar properties, function, and organization to those described in animals. Transspinal stimulation affects the spinal locomotor networks and is used to improve standing and walking ability in paralyzed people. However, the function of locomotor centers during transspinal stimulation at different frequencies and intensities is not known. Here, we document the 3D joint kinematics and spatiotemporal gait characteristics during transspinal stimulation at 15, 30, and 50 Hz at sub-threshold and supra-threshold stimulation intensities. We document the temporal structure of gait patterns, dynamic stability of joint movements over stride-to-stride fluctuations, and limb coordination during walking at a self-selected speed in healthy subjects. We found that transspinal stimulation 1) affects the kinematics of the hip, knee, and ankle joints, 2) promotes a more stable coordination at the left ankle, 3) improves interlimb coordination of the thighs, 4) improves intralimb coordination between thigh and foot, 5) promotes greater dynamic stability of the hips, and lastly 6) affects the mechanical stability of the joints. These results support that transspinal stimulation is an important neuromodulatory strategy that directly affects gait symmetry and dynamic stability. The conservation of main effects at different frequencies and intensities calls for systematic investigation of stimulation protocols for clinical applications.
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Affiliation(s)
| | - Maria Knikou
- City University of New York and College of Staten Island
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Sheehan RC, Grabiner MD, Kaufman KR. Military training alters the fractal behavior of step width. J Biomech 2022; 145:111365. [PMID: 36335824 DOI: 10.1016/j.jbiomech.2022.111365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 09/12/2022] [Accepted: 10/27/2022] [Indexed: 11/05/2022]
Abstract
Non-linear analyses have been successfully applied to gait with evidence that fractal behavior of gait-related variables provide insights into function. Specifically, shifts in the fractal behavior of step width from pink toward white noise reflects a loss of complexity and diminished adaptive capacity and functionality. We previously reported an apparent difference in the fractal behavior of step width during treadmill walking between Service members with transtibial amputations and able-bodied civilian. We now combine recently collected data and data from two previous studies to further explore the relationship between lower limb injury, military service, and step width fractal behavior. Service member, regardless of the presence or type of injury, demonstrate step width fractal behavior walked in a way that the fractal behavior of their gait was significantly closer to white noise (-0.5 dB/Hz2) than uninjured civilians (-0.82 dB/Hz2). This data suggests that military training/service leads to a change in step width fractal behavior. Further studies are needed to explore what may cause this difference and any implications this may have on stability or performance.
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Affiliation(s)
- Riley C Sheehan
- Henry M. Jackson Foundation for the Advancement of Military Medicine Inc., Bethesda, MD, USA; Center for the Intrepid, Department of Rehabilitation Medicine, Brooke Army Medical Center, Fort Sam Houston, TX, USA; Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
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Camargo J, Molinaro D, Young A. Predicting biological joint moment during multiple ambulation tasks. J Biomech 2022; 134:111020. [DOI: 10.1016/j.jbiomech.2022.111020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 02/08/2022] [Accepted: 02/21/2022] [Indexed: 10/19/2022]
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Donlin MC, Pariser KM, Downer KE, Higginson JS. Adaptive treadmill walking encourages persistent propulsion. Gait Posture 2022; 93:246-251. [PMID: 35190317 PMCID: PMC8930561 DOI: 10.1016/j.gaitpost.2022.02.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 02/10/2022] [Accepted: 02/14/2022] [Indexed: 02/02/2023]
Abstract
BACKGROUND Adaptive treadmills allow real-time changes in walking speed by responding to changes in step length, propulsion, or position on the treadmill. The stride-to-stride variability, or persistence, of stride time during overground, fixed-speed, and adaptive treadmill walking has been studied, but persistence of propulsion during adaptive treadmill walking remains unknown. Because increased propulsion is often a goal of post-stroke rehabilitation, knowledge of the stride-to-stride variability may aid rehabilitation protocol design. RESEARCH QUESTION How do spatiotemporal and propulsive gait variables vary from stride to stride during adaptive treadmill walking, and how do they compare to fixed-speed treadmill walking? METHODS Eighteen young healthy subjects walked on an instrumented split-belt treadmill in the adaptive and fixed-speed modes for 10 minutes at their comfortable speed. Kinetic data was collected from the treadmill. Detrended fluctuation analysis was applied to the time series data. Shapiro-Wilk tests assessed normality and one-way repeated measures ANOVAs compared between adaptive, fixed-speed, and randomly shuffled conditions at a Bonferroni-corrected significance level of 0.0055. RESULTS Stride time, stride length, step length, and braking impulse were persistent (α > 0.5) in the adaptive and fixed-speed conditions. Adaptive and fixed-speed were different from each other. Stride speed was persistent in the adaptive condition and anti-persistent (α < 0.5) in the fixed-speed condition. Peak propulsive force, peak braking force, and propulsive impulse were persistent in the adaptive condition but not the fixed-speed condition (α ≈ 0.5). Net impulse was non-persistent in the adaptive and fixed-speed conditions. All variables were non-persistent in the shuffled condition. SIGNIFICANCE During adaptive treadmill walking, increases in propulsive force and impulse persist for multiple strides. Persistence was stronger on the adaptive treadmill, where increased propulsion translates into increased walking speed. For post-stroke gait rehabilitation where increasing propulsion and speed are goals, the stronger persistence of adaptive treadmill walking may be beneficial.
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Affiliation(s)
- Margo C. Donlin
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA,Corresponding author at: University of Delaware, 540 S. College Ave., STAR Health Sciences Complex, Rm. 201, Newark, DE, USA. (Margo Donlin)
| | - Kayla M. Pariser
- Department of Mechanical 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 Biomedical Engineering, University of Delaware, Newark, DE, USA,Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
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Theunissen K, Van Hooren B, Plasqui G, Meijer K. Self-paced and fixed speed treadmill walking yield similar energetics and biomechanics across different speeds. Gait Posture 2022; 92:2-7. [PMID: 34801952 DOI: 10.1016/j.gaitpost.2021.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 10/20/2021] [Accepted: 11/01/2021] [Indexed: 02/02/2023]
Abstract
BACKGROUND Treadmill assessments are often performed at a fixed speed. Feedback-controlled algorithms allow users to adjust the treadmill speed, hereby potentially better resembling natural self-paced locomotion. However, it is currently unknown whether the energetics and biomechanics of self-paced differ from fixed-paced treadmill walking. Such information is important for clinicians and researchers using self-paced locomotion for assessing gait. RESEARCH QUESTION To investigate whether energy cost and biomechanics are different between self-paced and matched-speed fixed-paced locomotion. METHODS 18 healthy participants (9 males/9 females, mean ± standard deviation age 24.8 ± 3.3 years, height 1.71 ± 0.81 m, weight 65.9 ± 8.1 kg) walked at four different self-paced speeds (comfortable, slow, very slow, fast) in randomized order on an instrumented treadmill while three-dimensional motion capture and gas exchange were measured continuously. The average walking speed during the last 2 min of the self-paced trials was used to match the speed in fixed-paced conditions. Linear mixed models were used to assess differences in mean values and within-subject variations between conditions (self-paced and fixed-paced) and speeds. Statistical Parametric Mapping was used to assess differences in kinematics of the lower limb between conditions. RESULTS Although self-paced walking consistently resulted in a 4-6% higher net cost of walking, there were no significant differences in the net cost of walking between conditions. Further, there were also no differences of clinical relevance in spatiotemporal outcomes and sagittal-plane lower-limb kinematics between the self-paced and fixed-paced conditions. Within-trial variability was also not significantly different between conditions. SIGNIFICANCE Self-paced and fixed-paced treadmill walking yield similar energetics and kinematics in healthy young individuals when mean values or linear measures of variation are of interest.
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Affiliation(s)
- Kyra Theunissen
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, The Netherlands; Rehabilitation Research Center, REVAL, Faculty of Rehabilitation Sciences, Hasselt University, Belgium; School of Care and Public Health Research Institute, Maastricht University Medical Centre, The Netherlands.
| | - Bas Van Hooren
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, The Netherlands
| | - Guy Plasqui
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, The Netherlands
| | - Kenneth Meijer
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, The Netherlands
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Castano CR, Huang HJ. Speed-related but not detrended gait variability increases with more sensitive self-paced treadmill controllers at multiple slopes. PLoS One 2021; 16:e0251229. [PMID: 33961654 PMCID: PMC8104374 DOI: 10.1371/journal.pone.0251229] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/22/2021] [Indexed: 11/19/2022] Open
Abstract
Self-paced treadmills are being used more frequently to study humans walking with their self-selected gaits on a range of slopes. There are multiple options to purchase a treadmill with a built-in controller, or implement a custom written self-paced controller, which raises questions about how self-paced controller affect treadmill speed and gait biomechanics on multiple slopes. This study investigated how different self-paced treadmill controller sensitivities affected gait parameters and variability on decline, level, and incline slopes. We hypothesized that increasing self-paced controller sensitivity would increase gait variability on each slope. We also hypothesized that detrended variability could help mitigate differences in variability that arise from differences in speed fluctuations created by the self-paced controllers. Ten young adults walked on a self-paced treadmill using three controller sensitivities (low, medium, and high) and fixed speeds at three slopes (decline, -10°; level, 0°; incline, +10°). Within each slope, average walking speeds and spatiotemporal gait parameters were similar regardless of self-paced controller sensitivity. With higher controller sensitivities on each slope, speed fluctuations, speed variance, and step length variance increased whereas step frequency variance and step width variance were unaffected. Detrended variance was not affected by controller sensitivity suggesting that detrending variability helps mitigate differences associated with treadmill speed fluctuations. Speed-trend step length variances, however, increased with more sensitive controllers. Further, detrended step length variances were similar for self-paced and fixed speed walking, whereas self-paced walking included substantial speed-trend step length variance not present in fixed speed walking. In addition, regardless of the self-paced controller, subjects walked fastest on the level slope with the longest steps, narrowest steps, and least variance. Overall, our findings suggest that separating gait variability into speed-trend and detrended variability could be beneficial for interpreting gait variability among multiple self-paced treadmill studies and when comparing self-paced walking with fixed speed walking.
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Affiliation(s)
- Cesar R. Castano
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida, United States of America
- * E-mail:
| | - Helen J. Huang
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida, United States of America
- Disability, Aging, and Technology Cluster, University of Central Florida, Orlando, Florida, United States of America
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Changes in Spatiotemporal Measures and Variability During User-Driven Treadmill, Fixed-Speed Treadmill, and Overground Walking in Young Adults: A Pilot Study. J Appl Biomech 2021; 37:277-281. [PMID: 33931571 DOI: 10.1123/jab.2020-0109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 12/21/2020] [Accepted: 01/27/2021] [Indexed: 11/18/2022]
Abstract
Walking is an integral indicator of human health commonly investigated while walking overground and with the use of a treadmill. Unlike fixed-speed treadmills, overground walking is dependent on the preferred walking speed under the individuals' control. Thus, user-driven treadmills may have the ability to better simulate the characteristics of overground walking. This pilot study is the first investigation to compare a user-driven treadmill, a fixed-speed treadmill, and overground walking to understand differences in variability and mean spatiotemporal measures across walking environments. Participants walked fastest overground compared to both fixed and user-driven treadmill conditions. However, gait cycle speed variability in the fixed-speed treadmill condition was significantly lower than the user-driven and overground conditions, with no significant differences present between overground and user-driven treadmill walking. The lack of differences in variability between the user-driven treadmill and overground walking may indicate that the user-driven treadmill can better simulate the variability of overground walking, potentially leading to more natural adaptation and motor control patterns of walking.
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Task specificity impacts dual-task interference in older adults. Aging Clin Exp Res 2021; 33:581-587. [PMID: 32377966 DOI: 10.1007/s40520-020-01575-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 04/18/2020] [Indexed: 10/24/2022]
Abstract
BACKGROUND Task prioritization is an important factor determines the magnitude and direction of dual-task interference in older adults. Greater dual-task cost during walking may lead to falling, sometimes causing lasting effects on mobility. AIMS We investigated dual-task interference for walking and cognitive performance. METHODS Twenty healthy, older adults (71 ± 5 years) completed three cognitive tasks: letter fluency, category fluency, and serial subtraction during seated and walking conditions on a self-paced treadmill for 3 min each, in addition to walking only condition. Walking speed, step length and width were measured during walking and each dual-task condition. RESULTS Comparing the percentage of correct answers in cognitive tasks across single and dual-task conditions, there was a main effect of cognitive task (p = 0.021), showing higher scores during letter fluency compared to serial subtraction (p = 0.011). Step width was significantly wider during dual-task letter fluency compared to walking alone (p = 0.003), category fluency (p = 0.001), and serial subtraction (p = 0.007). DISCUSSION During both fluency tasks, there was a cost for gait and cognition, with category showing a slightly higher cognitive cost compared to letter fluency. During letter fluency, to maintain cognitive performance, gait was sacrificed by increasing step width. During serial subtraction, there was a cost for gait, yet a benefit for cognitive performance. CONCLUSION Differential effect of cognitive task on dual-task performance is critical to be understood in designing future research or interventions to improve dual-task performance of most activities of daily living.
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Test-Retest Reliability and the Effects of Walking Speed on Stride Time Variability During Continuous, Overground Walking in Healthy Young Adults. J Appl Biomech 2020; 37:102-108. [PMID: 33361489 DOI: 10.1123/jab.2020-0138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 08/24/2020] [Accepted: 09/29/2020] [Indexed: 11/18/2022]
Abstract
Studies have investigated the reliability and effect of walking speed on stride time variability during walking trials performed on a treadmill. The objective of this study was to investigate the reliability of stride time variability and the effect of walking speed on stride time variability, during continuous, overground walking in healthy young adults. Participants completed: (1) 2 walking trials at their preferred walking speed on 1 day and another trial 2 to 4 days later and (2) 1 trial at their preferred walking speed, 1 trial approximately 20% to 25% faster than their preferred walking speed, and 1 trial approximately 20% to 25% slower than their preferred walking speed on a separate day. Data from a waist-mounted accelerometer were used to determine the consecutive stride times for each trial. The reliability of stride time variability outcomes was generally poor (intraclass correlations: .167-.487). Although some significant differences in stride time variability were found between the preferred walking speed, fast, and slow trials, individual between-trial differences were generally below the estimated minimum difference considered to be a real difference. The development of a protocol to improve the reliability of stride time variability outcomes during continuous, overground walking would be beneficial to improve their application in research and clinical settings.
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Wei W, Kaiming Y, Yu Z, Yuyang Q, Chenhui W. A comparison of variability and gait dynamics in spatiotemporal variables between different self-paced treadmill control modes. J Biomech 2020; 110:109979. [PMID: 32827775 DOI: 10.1016/j.jbiomech.2020.109979] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 01/18/2023]
Abstract
This study investigates the effects of treadmill control algorithms on spatiotemporal variables when walking on a self-paced (SP) treadmill. Ten healthy subjects walked at their preferred walking speed for 15 min under three different treadmill control modes. Stride time, stride length, and stride speed were measured using an inertial measurement unit. The mean, coefficient of variance, Poincaré descriptors, and gait dynamics were calculated for each parameter. The mean values of stride length and stride speed were significantly increased when the treadmill had a quick response speed to the user's walking behavior. The long-term variability of stride length and stride speed was significantly affected by the treadmill control algorithms. A reduced strength of long-range correlations of stride time and stride speed was found when walking on the SP treadmill with suppressed treadmill accelerations and small velocity variations. We suggest that the suppression of treadmill acceleration provides more adaptability and less constraint to the user during SP treadmill walking. Although further research is required, the present work provides a basis for interpreting the influence of treadmill control algorithms on human gait.
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Affiliation(s)
- Wang Wei
- Department of Mechanical Engineering, Tsinghua University, Beijing, China
| | - Yang Kaiming
- Department of Mechanical Engineering, Tsinghua University, Beijing, China.
| | - Zhu Yu
- Department of Mechanical Engineering, Tsinghua University, Beijing, China
| | - Qian Yuyang
- Department of Mechanical Engineering, Tsinghua University, Beijing, China
| | - Wan Chenhui
- Department of Mechanical Engineering, Tsinghua University, Beijing, China; School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, China
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Choi JS, Seo JW, Lee JS, Kim JG, Cho JH, Tack GR. Differences in reproducibility of gait variability and fractal dynamics according to walking duration. Technol Health Care 2020; 28:383-390. [PMID: 32364171 PMCID: PMC7369073 DOI: 10.3233/thc-209039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Gait variability and fractal dynamics may be affected by the walking duration. OBJECTIVE The purpose of this study is to examine the reproducibility of stride time while walking on a self-paced treadmill. METHODS Fifteen young and healthy subjects walked on the treadmill for 10 minutes. Three to eight minutes duration of the data were used to compare the trial-to-trial and day-to-day reproducibility of the average, variability, and fractal dynamics of stride time. RESULTS The results show that all variables had high trial-to-trial reproducibility. In the day-to-day results, the average walking speed and mean stride time showed reproducibility without regard for duration, but the variability and gait fractal dynamics showed differences in reproducibility according to duration. The variability and fractal dynamics showed better reproducibility in less than 5 minutes and over time, respectively. However, both variables generally showed improved reproducibility when average data from two to three rounds were used. CONCLUSION Based on the results of this study, it is proposed that variability should be examined using data of 5 min or less, and fractal dynamics should be examined using 5 min or more of repeated data when performing walking tests from a gait dynamics perspective.
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Affiliation(s)
- Jin-Seung Choi
- Department of Biomedical Engineering, Konkuk University, Korea.,BK21 Plus Research Institute of Biomedical Engineering, Konkuk University, Korea
| | - Jeong-Woo Seo
- Department of Biomedical Engineering, Konkuk University, Korea
| | - Jin-Soo Lee
- Department of Biomedical Engineering, Konkuk University, Korea
| | - Jung-Gil Kim
- Department of Biomedical Engineering, Konkuk University, Korea
| | - Jun-Hyeong Cho
- Department of Biomedical Engineering, Konkuk University, Korea
| | - Gye-Rae Tack
- Department of Biomedical Engineering, Konkuk University, Korea.,BK21 Plus Research Institute of Biomedical Engineering, Konkuk University, Korea
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FallahTafti F, Watson K, Boron JB, Myers SA, Schmid KK, Yentes JM. Strength of Plantar- and Dorsiflexors Mediates Step Regularity During a High Cognitive Load Situation in a Cross-sectional Cohort of Older and Younger Adults. J Geriatr Phys Ther 2019; 43:E45-E52. [PMID: 31851025 DOI: 10.1519/jpt.0000000000000254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND AND PURPOSE Completing simultaneous tasks while standing or walking (ie, a high cognitive load situation [HCLS]) is inevitable in daily activities and can lead to interference in task performances. Age-related physical and cognitive changes may confound performance variability during HCLS in older and younger adults. Identification of these confounding effects may reveal therapy targets to maintain optimal physical function later in life. The aim of this study was to investigate the effect of increasing the difficulty levels of an additional motor task and restricting visual information, on gait parameters in younger and older adults while considering the effect of cognitive and physical covariates. METHODS Fifteen healthy younger and 14 healthy older adults were asked to complete assessments of cognitive function, balance, and strength. They were then asked to walk on a self-paced treadmill with or without carrying a plastic tray. Opaqueness of the tray (vision) and the presence of water in glasses placed on the tray (increasing task difficulty) were varied. Mean, standard deviation, and regularity (sample entropy) of step width and length were compared across conditions and groups using repeated-measures analyses of variance with and without covariate analysis. Only significantly correlated covariates of cognition, balance, and strength were entered into each model. RESULTS AND DISCUSSION Older adults had greater step width irregularity compared with younger adults across all conditions when controlling for concentric plantar- and dorsiflexion strength. A decline in strength may likely alter neuromuscular control of gait, specifically control of step width, which has been associated with fall risk in older adults. Adjusting for the same covariates revealed increased regularity of step length, as visual feedback from the feet was restricted. Specifically, step length was more regular while carrying an opaque tray compared with not carrying a tray. Visual restriction was a contributing factor, which led to more predictable gait kinematics, indicating the role of sensory information to enhance the adaptability during walking under HCLS. CONCLUSION The knowledge of the regularity behavior of human movement can expand physical therapists' treatment approaches to promote further interactivity and coordination across body systems that model behavior of healthy young individuals. Targeting strength during therapy may provide additional benefits for gait performance under HCLS.
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Affiliation(s)
| | - Kristen Watson
- Department of Biomechanics, University of Nebraska at Omaha
| | | | - Sara A Myers
- Department of Biomechanics, University of Nebraska at Omaha
| | - Kendra K Schmid
- Department of Biostatistics, University of Nebraska Medical Center, Omaha
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Marmelat V, Duncan A, Meltz S. Effect of sampling frequency on fractal fluctuations during treadmill walking. PLoS One 2019; 14:e0218908. [PMID: 31697684 PMCID: PMC6837491 DOI: 10.1371/journal.pone.0218908] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 10/25/2019] [Indexed: 11/18/2022] Open
Abstract
The temporal dynamics of stride-to-stride fluctuations in steady-state walking reveal important information about locomotor control and can be quantified using so-called fractal analyses, notably the detrended fluctuation analysis (DFA). Gait dynamics are often collected during treadmill walking using 3-D motion capture to identify gait events from kinematic data. The sampling frequency of motion capture systems may impact the precision of event detection and consequently impact the quantification of stride-to-stride variability. This study aimed i) to determine if collecting multiple walking trials with different sampling frequency affects DFA values of spatiotemporal parameters during treadmill walking, and ii) to determine the reliability of DFA values across downsampled conditions. Seventeen healthy young adults walked on a treadmill while their gait dynamics was captured using different sampling frequency (60, 120 and 240 Hz) in each condition. We also compared data from the highest sampling frequency to downsampled versions of itself. We applied DFA to the following time series: step length, time and speed, and stride length, time and speed. Reliability between experimental conditions and between downsampled conditions were measured with 1) intraclass correlation estimates and their 95% confident intervals, calculated based on a single-measurement, absolute-agreement, two-way mixed-effects model (ICC 3,1), and 2) Bland-Altman bias and limits of agreement. Both analyses revealed a poor reliability of DFA results between conditions using different sampling frequencies, but a relatively good reliability between original and downsampled spatiotemporal variables. Collectively, our results suggest that using sampling frequencies of 120 Hz or 240 Hz provide similar results, but that using 60 Hz may alter DFA values. We recommend that gait kinematics should be collected at around 120 Hz, which provides a compromise between event detection accuracy and processing time.
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Affiliation(s)
- Vivien Marmelat
- Department of Biomechanics, University of Nebraska at Omaha, Omaha, Nebraska, United States of America
- * E-mail:
| | - Austin Duncan
- Department of Biomechanics, University of Nebraska at Omaha, Omaha, Nebraska, United States of America
| | - Shane Meltz
- Department of Biomechanics, University of Nebraska at Omaha, Omaha, Nebraska, United States of America
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