Slowing down to preserve balance in the presence of optical flow perturbations |
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| Affiliation: | 1. Applied Biomechanics Lab, Joint Dept. of BME, UNC Chapel Hill and NC State University, USA;2. Dept. of Chemical and Biomedical Engineering, West Virginia University, USA;3. Division of Physical Therapy, Department of Allied Health Sciences, UNC Chapel Hill, USA;1. Dipartimento di Scienze Biomediche per la Salute, Università degli Studi di Milano, Milano, Italy;2. Dipartimento di Meccanica, Politecnico di Milano, Milano, Italy;3. Exercise Physiology and Physical Assessment Laboratory, Serra Gaúcha University Center, Caxias do Sul, Brazil;4. Integrated Colleges of Taquara (FACCAT), Taquara, Brazil;1. School of Arts, Sciences and Humanities, Universidade de São Paulo, EACH-USP, São Paulo, SP, Brazil;2. Biomedical Engineering Laboratory and Neuroscience Program, Universidade de São Paulo, EPUSP, PTC, São Paulo, SP, Brazil;3. Neural Engineering Research Laboratory, Center for Biomedical Engineering, University of Campinas, Brazil;4. Department of Electronics and Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Brazil;1. Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai, China;2. Gait and Motion Analysis Center, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China;1. Department of Biomechanics and Sport Injuries, Faculty of Physical Education, Kharazmi University, Tehran, Iran;2. Department of Sports Injury and Corrective Exercise, Faculty of Physical education, Allameh Tabataba’i University, Tehran, Iran;1. Ziauddin University, 128/2 14th Street off Khayaban e Muhafiz Phase 6 Defence Housing Authority Karachi, Pakistan;2. Shaheed Mohtarma Benazir Bhutto Medical College Liyari, Parsa citi, Garden East, Karachi, Pakistan;3. Dow University of Health Sciences, Bridge View Apartment, Frere Town, Clifton Block 8, Karachi 75600, Pakistan;1. Department of Neurology, Balance Disorders Laboratory, Oregon Health & Science University, Portland, USA;2. National Center for Rehabilitative Auditory Research (NCRAR), VA Portland Health Care System, Portland, USA;3. Biostatistics & Design Program, Oregon Health & Science University, Portland, USA;4. Department of Dietetics, Human Nutrition and Sport, School of Sport and Exercise Science, La Trobe University, Melbourne, Australia |
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| Abstract: | BackgroundThe use of sensory and mechanical perturbations applied during walking has grown in popularity due to their ability to elicit instability relevant to falls. However, the vast majority of perturbation studies on walking balance are performed on a treadmill at a fixed speed.Research questionThe aim of this study was to quantify the effects of mediolateral optical flow perturbations on walking speed and balance outcomes in young adults walking with fixed-speed and self-paced treadmill controllers.MethodsFifteen healthy young adults (8 female, age: 23.1 ± 4.6 yrs) completed four five-minute randomized walking trials in a speed-matched virtual reality hallway. In two of the trials, we added continuous mediolateral optical flow perturbations to the virtual hallway. Trials with and without optical flow perturbations were performed with either a fixed-speed or self-paced treadmill controller. We measured walking speed, balance outcomes (step width, margin of stability, local dynamic instability) and gait variability (step width variability and margin of stability variability).ResultsWe found significant increases in step width (+20%, p = 0.004) and local dynamic instability (+11%, p = 0.008) of participants while responding to optical flow perturbations at a fixed treadmill speed. We found no significant differences in these outcome measures when perturbations were applied on a self-paced treadmill. Instead, participants walked 5.7% slower between the self-paced treadmill controller conditions when responding to optical flow perturbations (1.48 ± 0.13 m/s vs. 1.57 ± 0.16 m/s, p = 0.005).SignificanceOur findings suggest that during walking, when presented with a balance challenge, an individual will instinctively reduce their walking speed in order to better preserve stability. However, comparisons to prior literature suggest that this response may depend on environmental and/or perturbation context. Cumulatively, our results point to opportunities for leveraging self-paced treadmill controllers as a more ecologically-relevant option in balance research with potential clinical applications in diagnostics and rehabilitation. |
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| Keywords: | Stability Walking Gait Speed |
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