Fast visual prediction and slow optimization of preferred walking speed

2012 ◽  
Vol 107 (9) ◽  
pp. 2549-2559 ◽  
Author(s):  
Shawn M. O'Connor ◽  
J. Maxwell Donelan
Keyword(s):  
Nervous System ◽  
Healthy Subjects ◽  
Walking Speed ◽  
Prior Experience ◽  
Sensory Information ◽  
Energetic Cost ◽  
The Subject ◽  
Walking Speeds ◽  
Visual Speed ◽  
Direction Opposite

People prefer walking speeds that minimize energetic cost. This may be accomplished by directly sensing metabolic rate and adapting gait to minimize it, but only slowly due to the compounded effects of sensing delays and iterative convergence. Visual and other sensory information is available more rapidly and could help predict which gait changes reduce energetic cost, but only approximately because it relies on prior experience and an indirect means to achieve economy. We used virtual reality to manipulate visually presented speed while 10 healthy subjects freely walked on a self-paced treadmill to test whether the nervous system beneficially combines these two mechanisms. Rather than manipulating the speed of visual flow directly, we coupled it to the walking speed selected by the subject and then manipulated the ratio between these two speeds. We then quantified the dynamics of walking speed adjustments in response to perturbations of the visual speed. For step changes in visual speed, subjects responded with rapid speed adjustments (lasting <2 s) and in a direction opposite to the perturbation and consistent with returning the visually presented speed toward their preferred walking speed, when visual speed was suddenly twice (one-half) the walking speed, subjects decreased (increased) their speed. Subjects did not maintain the new speed but instead gradually returned toward the speed preferred before the perturbation (lasting >300 s). The timing and direction of these responses strongly indicate that a rapid predictive process informed by visual feedback helps select preferred speed, perhaps to complement a slower optimization process that seeks to minimize energetic cost.

scholarly journals Bilateral vestibulopathy and age: experimental considerations for testing dynamic visual acuity on a treadmill

2020 ◽  
Vol 267 (S1) ◽  
pp. 265-272
Author(s):  
D. Starkov ◽  
M. Snelders ◽  
F. Lucieer ◽  
A. M. L. Janssen ◽  
M. Pleshkov ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Healthy Subjects ◽  
Walking Speed ◽  
Static Condition ◽  
Drop Out ◽  
Dynamic Visual Acuity ◽  
Bilateral Vestibulopathy ◽  
Drop Out Rate ◽  
Visual Acuity Loss ◽  
Walking Speeds

Abstract Introduction Bilateral vestibulopathy (BVP) can affect visual acuity in dynamic conditions, like walking. This can be assessed by testing Dynamic Visual Acuity (DVA) on a treadmill at different walking speeds. Apart from BVP, age itself might influence DVA and the ability to complete the test. The objective of this study was to investigate whether DVA tested while walking, and the drop-out rate (the inability to complete all walking speeds of the test) are significantly influenced by age in BVP-patients and healthy subjects. Methods Forty-four BVP-patients (20 male, mean age 59 years) and 63 healthy subjects (27 male, mean age 46 years) performed the DVA test on a treadmill at 0 (static condition), 2, 4 and 6 km/h (dynamic conditions). The dynamic visual acuity loss was calculated as the difference between visual acuity in the static condition and visual acuity in each walking condition. The dependency of the drop-out rate and dynamic visual acuity loss on BVP and age was investigated at all walking speeds, as well as the dependency of dynamic visual acuity loss on speed. Results Age and BVP significantly increased the drop-out rate (p ≤ 0.038). A significantly higher dynamic visual acuity loss was found at all speeds in BVP-patients compared to healthy subjects (p < 0.001). Age showed no effect on dynamic visual acuity loss in both groups. In BVP-patients, increasing walking speeds resulted in higher dynamic visual acuity loss (p ≤ 0.036). Conclusion DVA tested while walking on a treadmill, is one of the few “close to reality” functional outcome measures of vestibular function in the vertical plane. It is able to demonstrate significant loss of DVA in bilateral vestibulopathy patients. However, since bilateral vestibulopathy and age significantly increase the drop-out rate at faster walking speeds, it is recommended to use age-matched controls. Furthermore, it could be considered to use an individual “preferred” walking speed and to limit maximum walking speed in older subjects when testing DVA on a treadmill.

Walking Speed at Self-Selected Exercise Pace Is Lower but Energy Cost Higher in Older Versus Younger Women

2009 ◽  
Vol 6 (3) ◽  
pp. 327-332 ◽  
Author(s):  
Lynnette M. Jones ◽  
Debra L. Waters ◽  
Michael Legge
Keyword(s):  
Older Women ◽  
Energy Cost ◽  
Walking Speed ◽  
Metabolic Cost ◽  
Energetic Cost ◽  
Energy Costs ◽  
Energy Equivalent ◽  
Younger Women ◽  
Exercise Modality ◽  
Walking Speeds

Background:Walking is usually undertaken at a speed that coincides with the lowest metabolic cost. Aging however, alters the speed–cost relationship, as preferred walking speeds decrease and energy costs increase. It is unclear to what extent this relationship is affected when older women undertake walking as an exercise modality. The aim of this study was to compare the energetic cost of walking at a self-selected exercise pace for 30 min in older and younger women.Methods:The energetic cost of walking was assessed using the energy equivalent of oxygen consumption measured in 18 young (25 to 49 y) and 20 older (50 to 79 y) women who were asked to walk at their “normal” exercise pace on a motorized treadmill for 30 min.Results:The mass-specific net cost of walking (Cw) was 15% higher and self-selected walking speed was 23% lower in the older women than in the younger group. When speed was held constant, the Cw was 0.30 (J · .kg−1 · m−1) higher in the older women.Conclusions:Preferred exercise pace incurs a higher metabolic cost in older women and needs be taken into consideration when recommending walking as an exercise modality.

scholarly journals Influence of walking speed on locomotor time production

2013 ◽  
Author(s):  
Fabrice MEGROT ◽  
Carole MEGROT
Keyword(s):  
Healthy Subjects ◽  
Walking Speed ◽  
The Other ◽  
Temporal Perception ◽  
Time Production ◽  
Fast Walking ◽  
Slow Walking ◽  
Perception Of Time ◽  
Walking Speeds

The aim of the present study was to determine whether or not walking speed affects temporal perception. It was hypothesized that fast walking would reduce the perceived length of time while slow walking increase production estimates. 16 healthy subjects were included. After a first « calibration » phase allowing the determination of different walking speeds, the subjects were instructed to demonstrate periods of time or « target times » of 3s and 7s, by a walking movement. Then, subjects were asked to simulate walking by raising one foot after the other without advancing. Finally, a third condition, Motionless, involved producing the target times while standing without movement. The results of this study suggest that movement does influence the perception of time, causing an overestimation of time. In agreement with the results of Denner et al. (1963) the subjects produced times which were longer than the target times.

scholarly journals The Relationship Between Walking Speed and the Energetic Cost of Walking in Persons With Multiple Sclerosis and Healthy Controls: A Systematic Review

2021 ◽  
pp. 154596832110050
Author(s):  
Kyra Theunissen ◽  
Guy Plasqui ◽  
Annelies Boonen ◽  
Bente Brauwers ◽  
Annick Timmermans ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Healthy Subjects ◽  
Walking Speed ◽  
Included Study ◽  
Treadmill Walking ◽  
Energetic Cost ◽  
Overground Walking ◽  
Blood Institute ◽  
National Heart Lung ◽  
The Relationship

Background Persons with multiple sclerosis (pwMS) experience walking impairments, characterized by decreased walking speeds. In healthy subjects, the self-selected walking speed is the energetically most optimal. In pwMS, the energetically most optimal walking speed remains underexposed. Therefore, this review aimed to determine the relationship between walking speed and energetic cost of walking (Cw) in pwMS, compared with healthy subjects, thereby assessing the walking speed with the lowest energetic cost. As it is unclear whether the Cw in pwMS differs between overground and treadmill walking, as reported in healthy subjects, a second review aim was to compare both conditions. Method PubMed and Web of Science were systematically searched. Studies assessing pwMS, reporting walking speed (converted to meters per second), and reporting oxygen consumption were included. Study quality was assessed with a modified National Heart, Lung and Blood Institute checklist. The relationship between Cw and walking speed was calculated with a second-order polynomial function and compared between groups and conditions. Results Twenty-nine studies were included (n = 1535 pwMS) of which 8 included healthy subjects (n = 179 healthy subjects). PwMS showed a similar energetically most optimal walking speed of 1.44 m/s with a Cw of 0.16, compared with 0.14 mL O2/kg/m in healthy subjects. The most optimal walking speed in treadmill was 1.48 m/s, compared with 1.28 m/s in overground walking with a similar Cw. Conclusion Overall, the Cw is elevated in pwMS but with a similar energetically most optimal walking speed, compared with healthy subjects. Treadmill walking showed a similar most optimal Cw but a higher speed, compared with overground walking.

scholarly journals Is natural variability in gait sufficient to initiate spontaneous energy optimization in human walking?

2019 ◽  
Vol 121 (5) ◽  
pp. 1848-1855 ◽  
Author(s):  
Jeremy D. Wong ◽  
Jessica C. Selinger ◽  
J. Maxwell Donelan
Keyword(s):  
Nervous System ◽  
Energy Optimization ◽  
Natural Variability ◽  
Gait Variability ◽  
Treadmill Walking ◽  
Energetic Cost ◽  
Overground Walking ◽  
Step Frequency ◽  
Time Periods ◽  
Walking Speeds

In new walking contexts, the nervous system can adapt preferred gaits to minimize energetic cost. During treadmill walking, this optimization is not usually spontaneous but instead requires experience with the new energetic cost landscape. Experimenters can provide subjects with the needed experience by prescribing new gaits or instructing them to explore new gaits. Yet in familiar walking contexts, people naturally prefer energetically optimal gaits: the nervous system can optimize cost without an experimenter’s guidance. Here we test the hypothesis that the natural gait variability of overground walking provides the nervous system with sufficient experience with new cost landscapes to initiate spontaneous minimization of energetic cost. We had subjects walk over paths of varying terrain while wearing knee exoskeletons that penalized walking as a function of step frequency. The exoskeletons created cost landscapes with minima that were, on average, 8% lower than the energetic cost at the initially preferred gaits and achieved at walking speeds and step frequencies that were 4% lower than the initially preferred values. We found that our overground walking trials amplified gait variability by 3.7-fold compared with treadmill walking, resulting in subjects gaining greater experience with new cost landscapes, including frequent experience with gaits at the new energetic minima. However, after 20 min and 2.0 km of walking in the new cost landscapes, we observed no consistent optimization of gait, suggesting that natural gait variability during overground walking is not always sufficient to initiate energetic optimization over the time periods and distances tested in this study. NEW & NOTEWORTHY While the nervous system can continuously optimize gait to minimize energetic cost, what initiates this optimization process during every day walking is unknown. Here we tested the hypothesis that the nervous system leverages the natural variability in gait experienced during overground walking to converge on new energetically optimal gaits created using exoskeletons. Contrary to our hypothesis, we found that participants did not adapt toward optimal gaits: natural variability is not always sufficient to initiate spontaneous energy optimization.

Effects of Hyperoxia on Lung Utrastructure

1970 ◽  
Vol 28 ◽  
pp. 26-27
Author(s):  
Gladys Harrison
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Light Microscopy ◽  
Oxygen Effects ◽  
Age Dependent ◽  
The Central Nervous System ◽  
The Subject ◽  
Space Age ◽  
Alveolar Septa ◽  
Extensive Damage

With the advent of the space age and the need to determine the requirements for a space cabin atmosphere, oxygen effects came into increased importance, even though these effects have been the subject of continuous research for many years. In fact, Priestly initiated oxygen research when in 1775 he published his results of isolating oxygen and described the effects of breathing it on himself and two mice, the only creatures to have had the “privilege” of breathing this “pure air”.Early studies had demonstrated the central nervous system effects at pressures above one atmosphere. Light microscopy revealed extensive damage to the lungs at one atmosphere. These changes which included perivascular and peribronchial edema, focal hemorrhage, rupture of the alveolar septa, and widespread edema, resulted in death of the animal in less than one week. The severity of the symptoms differed between species and was age dependent, with young animals being more resistant.

Neuromuscular Control of Movement

2018 ◽  
Keyword(s):  
Nervous System ◽  
Sensory Information ◽  
Neuromuscular Control ◽  
Complex Environments ◽  
Locomotor Rhythm ◽  
Motor Responses ◽  
Reflex Pathways ◽  
Local Reflex ◽  
Local Circuits ◽  
And Control

The control of movement is essential for animals traversing complex environments and operating across a range of speeds and gaits. We consider how animals process sensory information and initiate motor responses, primarily focusing on simple motor responses that involve local reflex pathways of feedback and control, rather than the more complex, longer-term responses that require the broader integration of higher centers within the nervous system. We explore how local circuits facilitate decentralized coordination of locomotor rhythm and examine the fundamentals of sensory receptors located in the muscles, tendons, joints, and at the animal’s body surface. These sensors monitor the animal’s physical environment and the action of its muscles. The sensory information is then carried back to the animal’s nervous system by afferent neurons, providing feedback that is integrated at the level of the spinal cord of vertebrates and sensory-motor ganglia of invertebrates.

scholarly journals Myofascial Release of the Hamstrings Improves Physical Performance—A Study of Young Adults

Healthcare ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 674
Author(s):  
Keisuke Itotani ◽  
Kanta Kawahata ◽  
Wakana Takashima ◽  
Wakana Mita ◽  
Hitomi Minematsu ◽  
...  
Keyword(s):  
Young Adults ◽  
Physical Performance ◽  
Walking Speed ◽  
Quadriceps Muscle ◽  
Lower Limbs ◽  
Joint Movement ◽  
Myofascial Release ◽  
Functional Reach Test ◽  
Hamstring Flexibility ◽  
Walking Speeds

Physical performance is mainly assessed in terms of gait speed, chair rise capacity, and balance skills, and assessments are often carried out on the lower limbs. Such physical performance is largely influenced by the strength of the quadriceps and hamstrings muscles. Flexibility of the hamstrings is important because quadriceps muscle activity influences the hip flexion angle. Therefore, hamstring flexibility is essential to improve physical performance. In this study, Myofascial Release (MFR) was applied to the hamstrings to evaluate its effects. MFR on the hamstrings was performed on 17 young adults. Physical function and physical performance were measured before, immediately after, and 5 days after the MFR intervention: finger floor distance (FFD), range of motion (ROM) of the straight leg raising test (SLR), standing long jump (SLJ), squat jump (SJ), functional reach test (FRT), comfortable walking speeds (C-walking speed), and maximum walking speeds (M-walking speed). The results of the analysis show a significant increase in FFD (−2.6 ± 8.9 vs. 0.4 ± 9.4 vs. 2.4 ± 8.9, p < 0.01), SLJ (185.6 ± 44.5 vs. 185.0 ± 41.8 vs. 196.6 ± 40.1, p < 0.01), and M-walking speed (2.9 ± 0.6 vs. 3.0 ± 0.6 vs. 3.3 ± 0.6, p < 0.01). This study has shown that MFR for hamstrings not only improves flexibility but also increases M-walking speed and physical performance of the SLJ. As MFR is safe and does not involve joint movement, it may be useful for maintaining and improving performance and flexibility during inactivity and for stretching before exercise.

scholarly journals SMARTIES Project: The Survey of Needs for Municipalities and Trainers for Smart Cities

Challenges ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 13
Author(s):  
George Xydis ◽  
Luca Pagliaricci ◽  
Živilė Paužaitė ◽  
Vygintas Grinis ◽  
Gyula Sallai ◽  
...  
Keyword(s):  
Public Sector ◽  
Smart Cities ◽  
Prior Experience ◽  
Environmental Awareness ◽  
General Concept ◽  
Decision Makers ◽  
The Public ◽  
Low Level ◽  
The Subject

In an aim to contribute to already existing knowledge upon the subject of smart cities and the public sector’s wider knowledge in Europe, this study investigates the perception by the municipalities and the wider public sector, responsible for implementing smart solutions in the environment. The understanding of the concept of smart cities/villages by municipalities is on a low level due to the fact that the problem is too wide, not well described, solutions even wider, accompanied by the lack of experts able to offer comprehensive solutions to municipalities. The study presents factors according to the current municipalities’ knowledge (environmental awareness, knowledge and prior experience) and the existing market, of whether these factors can be said that affect the acceptance of smart cities. The public is already aware of the smart cities as a general concept, however, the study sheds light upon the established knowledge that the decision makers have in five countries, Hungary, Slovakia, Italy, Lithuania, and Denmark.

scholarly journals The emerging role of mechanical and topographical factors in the development and treatment of nervous system disorders: dark and light sides of the force

2021 ◽  
Author(s):  
Natalia Bryniarska-Kubiak ◽  
Andrzej Kubiak ◽  
Małgorzata Lekka ◽  
Agnieszka Basta-Kaim
Keyword(s):  
Nervous System ◽  
Physical Factors ◽  
Nervous System Diseases ◽  
Therapeutic Approaches ◽  
System Disease ◽  
New Therapeutic Approaches ◽  
The Subject ◽  
Topographical Factors ◽  
New Treatment

AbstractNervous system diseases are the subject of intensive research due to their association with high mortality rates and their potential to cause irreversible disability. Most studies focus on targeting the biological factors related to disease pathogenesis, e.g. use of recombinant activator of plasminogen in the treatment of stroke. Nevertheless, multiple diseases such as Parkinson’s disease and Alzheimer’s disease still lack successful treatment. Recently, evidence has indicated that physical factors such as the mechanical properties of cells and tissue and topography play a crucial role in homeostasis as well as disease progression. This review aims to depict these factors’ roles in the progression of nervous system diseases and consequently discusses the possibility of new therapeutic approaches. The literature is reviewed to provide a deeper understanding of the roles played by physical factors in nervous system disease development to aid in the design of promising new treatment approaches. Graphic abstract

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