The independent effects of speed and propulsive force on joint power generation in walking |
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| Institution: | 1. Department of Orthopaedic Surgery, Duke University, Durham, NC, USA;2. Michael W. Krzyzewski Human Performance Lab, Duke University Medical Center DUMC 102916, Durham, NC 27710, USA;3. Department of Evolutionary Anthropology, Duke University, DUMC 2914, Durham, NC 27710, USA;1. Department of Mechanical Engineering, University of Delaware, Newark, DE, USA;2. Department of Engineering, Hofstra University, Hempstead, NY, USA;3. Biomechanics and Movement Science Interdisciplinary Program, University of Delaware, Newark, DE, USA;4. Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE, USA;5. Department of Biomedical Engineering, University of Delaware, Newark, DE, USA;1. Ottawa Hospital Research Institute, 505 Smyth Road, Ottawa, ON, K1H8M2, Canada;2. University of Ottawa, Department of Human Kinetics, Canada;3. University of Ottawa, Faculty of Medicine, 451 Smyth Rd, Ottawa, ON, K1H8M5, Canada;1. Department of Health and Human Development, Western Washington University, Bellingham, WA 98225, United States;2. Department of Kinesiology, Iowa State University, Ames, IA 50011, United States;1. KU Leuven, Dept of Rehabilitation Sciences, Musculoskeletal Rehabilitation Research Group, Leuven, 3000, Belgium;2. KU Leuven, Foot and Ankle Research Unit, Lubbeek, 3212, Belgium;3. UZ Leuven, Clinical Motion Analysis Laboratory, CERM, Lubbeek, 3212, Belgium;4. Institut D’Enseignement Supérieur Parnasse Deux-Alice, Division of Podiatry, Bruxelles, 1000, Belgium;5. Artevelde University College, Dept of Podiatry, Ghent, 9000, Belgium |
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| Abstract: | Walking speed is modulated using propulsive forces (FP) during push-off and both preferred speed and FP decrease with aging. However, even prior to walking slower, reduced FP may be accompanied by potentially unfavorable changes in joint power generation. For example, compared to young adults, older adults exhibit a redistribution of mechanical power generation from the propulsive plantarflexor muscles to more proximal muscles acting across the knee and hip. Here, we used visual biofeedback based on real-time FP measurements to decouple and investigate the interaction between joint-level coordination, whole-body FP, and walking speed. 12 healthy young subjects walked on a dual-belt instrumented treadmill at a range of speeds (0.9–1.3 m/s). We immediately calculated the average FP from each speed. Subjects then walked at 1.3 m/s while completing a series of biofeedback trials with instructions to match their instantaneous FP to their averaged FP from slower speeds. Walking slower decreased FP and total positive joint work with little effect on relative joint-level contributions. Conversely, subjects walked at a constant speed with reduced FP, not by reducing total positive joint work, but by redistributing the mechanical demands of each step from the plantarflexor muscles during push-off to more proximal leg muscles during single support. Interestingly, these naturally emergent joint- and limb-level biomechanical changes, in the absence of neuromuscular constraints, resemble those due to aging. Our findings provide important reference data to understand the presumably complex interactions between joint power generation, whole-body FP, and walking speed in our aging population. |
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| Keywords: | Plantarflexor Push-off Aging Gait Biofeedback |
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