Optimization of energy and time predicts dynamic speeds for human walking
Humans make a number of choices when they walk, such as how fast and for how long. The preferred steady walking speed seems chosen to minimize energy expenditure per distance traveled. But the speed of actual walking bouts is not only steady, but rather a time-varying trajectory, which can also be m...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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eLife Sciences Publications Ltd
2023-02-01
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| Series: | eLife |
| Subjects: | |
| Online Access: | https://elifesciences.org/articles/81939 |
| _version_ | 1797866228312702976 |
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| author | Rebecca Elizabeth Carlisle Arthur D Kuo |
| author_facet | Rebecca Elizabeth Carlisle Arthur D Kuo |
| author_sort | Rebecca Elizabeth Carlisle |
| collection | DOAJ |
| description | Humans make a number of choices when they walk, such as how fast and for how long. The preferred steady walking speed seems chosen to minimize energy expenditure per distance traveled. But the speed of actual walking bouts is not only steady, but rather a time-varying trajectory, which can also be modulated by task urgency or an individual’s movement vigor. Here we show that speed trajectories and durations of human walking bouts are explained better by an objective to minimize Energy and Time, meaning the total work or energy to reach destination, plus a cost proportional to bout duration. Applied to a computational model of walking dynamics, this objective predicts dynamic speed vs. time trajectories with inverted U shapes. Model and human experiment (N=10) show that shorter bouts are unsteady and dominated by the time and effort of accelerating, and longer ones are steadier and faster and dominated by steady-state time and effort. Individual-dependent vigor may be characterized by the energy one is willing to spend to save a unit of time, which explains why some may walk faster than others, but everyone may have similar-shaped trajectories due to similar walking dynamics. Tradeoffs between energy and time costs can predict transient, steady, and vigor-related aspects of walking. |
| first_indexed | 2024-04-09T23:21:41Z |
| format | Article |
| id | doaj.art-56d9aff8f3e54d5abe458d49356dc903 |
| institution | Directory Open Access Journal |
| issn | 2050-084X |
| language | English |
| last_indexed | 2024-04-09T23:21:41Z |
| publishDate | 2023-02-01 |
| publisher | eLife Sciences Publications Ltd |
| record_format | Article |
| series | eLife |
| spelling | doaj.art-56d9aff8f3e54d5abe458d49356dc9032023-03-21T16:37:42ZengeLife Sciences Publications LtdeLife2050-084X2023-02-011210.7554/eLife.81939Optimization of energy and time predicts dynamic speeds for human walkingRebecca Elizabeth Carlisle0Arthur D Kuo1https://orcid.org/0000-0001-5233-9709Biomedical Engineering Program, University of Calgary, Calgary, CanadaBiomedical Engineering Program, University of Calgary, Calgary, Canada; Faculty of Kinesiology, University of Calgary, Calgary, CanadaHumans make a number of choices when they walk, such as how fast and for how long. The preferred steady walking speed seems chosen to minimize energy expenditure per distance traveled. But the speed of actual walking bouts is not only steady, but rather a time-varying trajectory, which can also be modulated by task urgency or an individual’s movement vigor. Here we show that speed trajectories and durations of human walking bouts are explained better by an objective to minimize Energy and Time, meaning the total work or energy to reach destination, plus a cost proportional to bout duration. Applied to a computational model of walking dynamics, this objective predicts dynamic speed vs. time trajectories with inverted U shapes. Model and human experiment (N=10) show that shorter bouts are unsteady and dominated by the time and effort of accelerating, and longer ones are steadier and faster and dominated by steady-state time and effort. Individual-dependent vigor may be characterized by the energy one is willing to spend to save a unit of time, which explains why some may walk faster than others, but everyone may have similar-shaped trajectories due to similar walking dynamics. Tradeoffs between energy and time costs can predict transient, steady, and vigor-related aspects of walking.https://elifesciences.org/articles/81939biomechanicshuman physiologymetabolic costlocomotionneural controloptimal control |
| spellingShingle | Rebecca Elizabeth Carlisle Arthur D Kuo Optimization of energy and time predicts dynamic speeds for human walking eLife biomechanics human physiology metabolic cost locomotion neural control optimal control |
| title | Optimization of energy and time predicts dynamic speeds for human walking |
| title_full | Optimization of energy and time predicts dynamic speeds for human walking |
| title_fullStr | Optimization of energy and time predicts dynamic speeds for human walking |
| title_full_unstemmed | Optimization of energy and time predicts dynamic speeds for human walking |
| title_short | Optimization of energy and time predicts dynamic speeds for human walking |
| title_sort | optimization of energy and time predicts dynamic speeds for human walking |
| topic | biomechanics human physiology metabolic cost locomotion neural control optimal control |
| url | https://elifesciences.org/articles/81939 |
| work_keys_str_mv | AT rebeccaelizabethcarlisle optimizationofenergyandtimepredictsdynamicspeedsforhumanwalking AT arthurdkuo optimizationofenergyandtimepredictsdynamicspeedsforhumanwalking |