Preferred walking speed

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The preferred walking speed is the speed at which humans or animals choose to walk. Many people tend to walk at about 1.4 metres per second (5.0 km/h; 3.1 mph; 4.6 ft/s). [1] [2] [3] Although many people are capable of walking at speeds upwards of 2.5 m/s (9.0 km/h; 5.6 mph; 8.2 ft/s), especially for short distances, they typically choose not to. [4] Individuals find slower or faster speeds uncomfortable.

Contents

Horses have also demonstrated normal, narrow distributions of preferred walking speed within a given gait, which suggests that the process of speed selection may follow similar patterns across species. [5] Preferred walking speed has important clinical applications as an indicator of mobility and independence. For example, elderly people or people suffering from osteoarthritis must walk more slowly. Improving (increasing) people's preferred walking speed is a significant clinical goal in these populations.

People have suggested mechanical, energetic, physiological and psychological factors as contributors to speed selection. Probably, individuals face a trade-off between the numerous costs associated with different walking speeds, and select a speed which minimizes these costs. For example, they may trade off time to destination, which is minimized at fast walking speeds, and metabolic rate, muscle force or joint stress. These are minimized at slower walking speeds. Broadly, increasing value of time, motivation, or metabolic efficiency may cause people to walk more quickly. Conversely, aging, joint pain, instability, incline, metabolic rate and visual decline cause people to walk more slowly.

Value of time

Commonly, individuals place some value on their time. Economic theory therefore predicts that value-of-time is a key factor influencing preferred walking speed.

Levine and Norenzayan (1999) measured preferred walking speeds of urban pedestrians in 31 countries and found that walking speed is positively correlated with the country's per capita GDP and purchasing power parity, as well as with a measure of individualism in the country's society. [3] It is plausible that affluence correlates with actual value considerations for time spent walking, and this may explain why people in affluent countries tend to walk more quickly.

This idea is broadly consistent with common intuition. Everyday situations often change the value of time. For example, when walking to catch a bus, the value of the one minute immediately before the bus has departed may be worth 30 minutes of time (the time saved not waiting for the next bus). Supporting this idea, Darley and Bateson show that individuals who are hurried under experimental conditions are less likely to stop in response to a distraction, and so they arrive at their destination sooner. [6]

Energetics

Energy minimization is widely considered a primary goal of the central nervous system. [7] The rate at which an organism expends metabolic energy while walking (gross metabolic rate) increases nonlinearly with increasing speed. However, they also require a continuous basal metabolic rate to maintain normal function. The energetic cost of walking itself is therefore best understood by subtracting basal metabolic rate from total metabolic rate, yielding Final metabolic rate. In human walking, net metabolic rate also increases nonlinearly with speed. These measures of walking energetics are based on how much oxygen people consume per unit time. Many locomotion tasks, however, require walking a fixed distance rather than for a set time. Dividing gross metabolic rate by walking speed results in gross cost of transport. For human walking, gross cost of transport is U-shaped. Similarly, dividing net metabolic rate by walking speed yields a U-shaped net cost of transport. These curves reflect the cost of moving a given distance at a given speed and may better reflect the energetic cost associated with walking.

Ralston (1958) showed that humans tend to walk at or near the speed that minimizes gross cost of transport. He showed that gross cost of transport is minimized at about 1.23 m/s (4.4 km/h; 2.8 mph), which corresponded to the preferred speed of his subjects. [8] Supporting this, Wickler et al. (2000) showed that the preferred speed of horses both uphill and on the level corresponds closely to the speed that minimizes their gross cost of transport. [9] Among other gait costs that human walkers choose to minimize, this observation has led many to suggest that people minimize cost and maximize efficiency during locomotion. [7] Because gross cost of transport includes velocity, gross cost of transport includes an inherent value of time. Subsequent research suggests that individuals may walk marginally faster than the speed that minimizes gross cost of transport under some experimental setups, although this may be due to how preferred walking speed was measured. [1]

In contrast, other researchers have suggested that gross cost of transport may not represent the metabolic cost of walking. People must continue to expend their basal metabolic rate regardless of whether they are walking, suggesting that the metabolic cost of walking should not include basal metabolic rate. Some researchers have therefore used net metabolic rate instead of gross metabolic rate to characterize the cost of locomotion. [10] Net cost of transport reaches a minimum at about 1.05 m/s (3.8 km/h; 2.3 mph). Healthy pedestrians walk faster than this in many situations.

Metabolic input rate may also directly limit preferred walking speed. Aging is associated with reduced aerobic capacity (reduced VO2 max). Malatesta et al. (2004) suggests that walking speed in elderly individuals is limited by aerobic capacity; elderly individuals are unable to walk faster because they cannot sustain that level of activity. [11] For example, 80-year-old individuals are walking at 60% of their VO2 max even when walking at speeds significantly slower than those observed in younger individuals.

Biomechanics

Biomechanical factors such as mechanical work, stability, and joint or muscle forces may also influence human walking speed. Walking faster requires additional external mechanical work per step. [12] Similarly, swinging the legs relative to the center of mass requires some internal mechanical work. As faster walking is accomplished with both longer and faster steps, internal mechanical work also increases with increasing walking speed. [13] Therefore, both internal and external mechanical work per step increases with increasing speed. Individuals may try to reduce either external or internal mechanical work by walking more slowly, or may select a speed at which mechanical energy recovery is at a maximum. [14]

Stability may be another factor influencing speed selection. Hunter et al. (2010) showed that individuals use energetically suboptimal gaits when walking downhill. He suggests that people may instead be choosing gait parameters that maximize stability while walking downhill. This suggests that under adverse conditions such as down hills, gait patterns may favor stability over speed. [15]

Individual joint and muscle biomechanics also directly affect walking speed. Norris showed that elderly individuals walked faster when their ankle extensors were augmented by an external pneumatic muscle. [16] Muscle force, specifically in the gastrocnemius and/or soleus, may limit walking speed in certain populations and lead to slower preferred speeds. Similarly, patients with ankle osteoarthritis walked faster after a complete ankle replacement than before. This suggests that reducing joint reaction forces or joint pain may factor into speed selection.

Visual flow

The rate at which the environment flows past the eyes seems to be a mechanism for regulating walking speed. In virtual environments, the gain in visual flow can be decoupled from a person's actual walking speed, much as one might experience when walking on a conveyor belt. There, the environment flows past an individual more quickly than their walking speed would predict (higher than normal visual gain). At higher than normal visual gains, individuals prefer to walk more slowly, while at lower than normal visual gains, individuals prefer to walk more quickly. [2] This behavior is consistent with returning the visually observed speed back toward the preferred speed and suggests that vision is used correctively to maintain walking speed at a value that is perceived to be optimal. Moreover, the dynamics of this visual influence on preferred walking speed are rapid—when visual gains are changed suddenly, individuals adjust their speed within a few seconds. [17] 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 directly senses metabolic rate and iteratively adapts gait to minimize it.

As exercise

With the wide availability of inexpensive pedometers, medical professionals recommend walking as an exercise for cardiac health and/or weight loss. The NIH gives the following guidelines:

Based on currently available evidence, we propose the following preliminary indices be used to classify pedometer-determined physical activity in healthy adults: (i). <5000 steps/day may be used as a 'sedentary lifestyle index'; (ii). 5000-7499 steps/day is typical of daily activity excluding sports/exercise and might be considered 'low active'; (iii). 7500-9999 likely includes some volitional activities (and/or elevated occupational activity demands) and might be considered 'somewhat active'; and (iv). >or=10000 steps/day indicates the point that should be used to classify individuals as 'active'. Individuals who take >12500 steps/day are likely to be classified as 'highly active'. [18]

The situation becomes slightly more complex when preferred walking speed is introduced. The faster the pace, the more calories burned if weight loss is a goal. Maximum heart rate for exercise (220 minus age), when compared to charts of "fat burning goals" support many of the references that give the average of 1.4 m/s (3.1 mph), as within this target range. Pedometers average 100 steps a minute in this range (depending on individual stride), or one and a half to two hours to reach a daily total of 10,000 or more steps (100 minutes at 100 steps per minute would be 10,000 steps). [19]

In urban design

The typical walking speed of 1.4 metres per second (5.0 km/h; 3.1 mph; 4.6 ft/s) is recommended by design guides including the Design Manual for Roads and Bridges. Transport for London recommend 1.33 metres per second (4.8 km/h; 3.0 mph; 4.4 ft/s) in the PTAL methodology.

See also

Related Research Articles

Bipedalism Terrestrial locomotion using two limbs

Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped, meaning 'two feet'. Types of bipedal movement include walking, running, and hopping.

Walking Gait of locomotion among legged animals

Walking is one of the main gaits of terrestrial locomotion among legged animals. Walking is typically slower than running and other gaits. Walking is defined by an 'inverted pendulum' gait in which the body vaults over the stiff limb or limbs with each step. This applies regardless of the usable number of limbs—even arthropods, with six, eight, or more limbs, walk.

Gait

Gait is the pattern of movement of the limbs of animals, including humans, during locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on speed, terrain, the need to maneuver, and energetic efficiency. Different animal species may use different gaits due to differences in anatomy that prevent use of certain gaits, or simply due to evolved innate preferences as a result of habitat differences. While various gaits are given specific names, the complexity of biological systems and interacting with the environment make these distinctions "fuzzy" at best. Gaits are typically classified according to footfall patterns, but recent studies often prefer definitions based on mechanics. The term typically does not refer to limb-based propulsion through fluid mediums such as water or air, but rather to propulsion across a solid substrate by generating reactive forces against it.

Horse gait Ways of movement of equines

Horses can use various gaits during locomotion across solid ground, either naturally or as a result of specialized training by humans.

Pedometer Device, usually portable and electronic or electromechanical, that counts each step a person takes by detecting the motion of the persons hands or hips

A pedometer is a device, usually portable and electronic or electromechanical, that counts each step a person takes by detecting the motion of the person's hands or hips. Because the distance of each person's step varies, an informal calibration, performed by the user, is required if presentation of the distance covered in a unit of length is desired, though there are now pedometers that use electronics and software to automatically determine how a person's step varies. Distance traveled can be measured directly by a GPS receiver.

Gait (human) a pattern of limb movements made during locomotion.

A gait is a pattern of limb movements made during locomotion. Human gaits are the various ways in which a human can move, either naturally or as a result of specialized training. Human gait is defined as bipedal, biphasic forward propulsion of the center of gravity of the human body, in which there are alternate sinuous movements of different segments of the body with least expenditure of energy. Different gait patterns are characterized by differences in limb-movement patterns, overall velocity, forces, kinetic and potential energy cycles, and changes in the contact with the ground.

Passive dynamics refers to the dynamical behavior of actuators, robots, or organisms when not drawing energy from a supply. Depending on the application, considering or altering the passive dynamics of a powered system can have drastic effects on performance, particularly energy economy, stability, and task bandwidth. Devices using no power source are considered "passive", and their behavior is fully described by their passive dynamics.

Ambling gait

An ambling gait or amble is any of several four-beat intermediate horse gaits, all of which are faster than a walk but usually slower than a canter and always slower than a gallop. Horses that amble are sometimes referred to as "gaited", particularly in the United States. Ambling gaits are smoother for a rider than either the two-beat trot or pace and most can be sustained for relatively long periods, making them particularly desirable for trail riding and other tasks where a rider must spend long periods in the saddle. Historically, horses able to amble were highly desired for riding long distances on poor roads. Once roads improved and carriage travel became popular, their use declined in Europe but continued in popularity in the Americas, particularly in areas where plantation agriculture was practiced and the inspection of fields and crops necessitated long daily rides.

Gross motor skill

Gross motor skills are the abilities usually acquired during childhood as part of a child's motor learning. By the time they reach two years of age, almost all children are able to stand up, walk and run, walk up stairs, etc. These skills are built upon, improved and better controlled throughout early childhood, and continue in refinement throughout most of the individual's years of development into adulthood. These gross movements come from large muscle groups and whole body movement. These skills develop in a head-to-toe order. The children will typically learn head control, trunk stability, and then standing up and walking. It is shown that children exposed to outdoor play time activities will develop better gross motor skills.

A facultative biped is an animal that is capable of walking or running on two legs (bipedal), as a response to exceptional circumstances (facultative), while normally walking or running on four limbs or more. In contrast, obligate bipedalism is where walking or running on two legs is the primary method of locomotion. Facultative bipedalism has been observed in several families of lizards and multiple species of primates, including sifakas, capuchin monkeys, baboons, gibbons, gorillas, bonobos and chimpanzeess. Different facultatively bipedal species employ different types of bipedalism corresponding to the varying reasons they have for engaging in facultative bipedalism. In primates, bipedalism is often associated with food gathering and transport. In lizards, it has been debated whether bipedal locomotion is an advantage for speed and energy conservation or whether it is governed solely by the mechanics of the acceleration and lizard's center of mass. Facultative bipedalism is often divided into high-speed (lizards) and low-speed (gibbons), but some species cannot be easily categorized into one of these two. Facultative bipedalism has also been observed in cockroaches and some desert rodents.

The endurance running hypothesis is the hypothesis that the evolution of certain human characteristics can be explained as adaptations to long-distance running. The hypothesis suggests that endurance running played an important role for early hominins in obtaining food. Researchers have proposed that endurance running began as an adaptation for scavenging and later for persistence hunting.

Normal aging movement control in humans is about the changes in the muscles, motor neurons, nerves, sensory functions, gait, fatigue, visual and manual responses, in men and women as they get older but who do not have neurological, muscular or neuromuscular disorder. With aging, neuromuscular movements are impaired, though with training or practice, some aspects may be prevented.

Running energetics is the study of the energy cost of running. It is clear in the vast majority of species that as running speed increases the energetic cost of running increases. It also has long been known that between and within species variability exists in the energy cost of running a given speed. This variability has led to the study of biomechanical or physiological factors that may be predictive of the energy cost to run both between and within species.

Human locomotion is considered to take two primary forms: walking and running. In contrast, many quadrupeds have three distinct forms of locomotion: walk, trot, and gallop. Walking is a form of locomotion defined by a double support phase when both feet are on the ground at the same time. Running is a form of locomotion that does not have this double support phase.

Obesity and walking describes how the locomotion of walking differs between an obese individual and a non-obese individual. The prevalence of obesity is becoming a worldwide problem, with the American population leading the way. In 2007-2008, prevalence rates for obesity among adult American men were approximately 32% and over 35% amongst adult American women. According to the Johns Hopkins Bloomberg School of Public Health, 66% of the American population is either overweight or obese and this number is predicted to increase to 75% by 2015. Obesity is linked to health problems such as decreased insulin sensitivity and diabetes, cardiovascular disease, cancer, sleep apnea, and joint pain such as osteoarthritis. It is thought that a major factor of obesity is that obese individuals are in a positive energy balance, meaning that they are consuming more calories than they are expending. Humans expend energy through their basal metabolic rate, the thermic effect of food, non-exercise activity thermogenesis (NEAT), and exercise. While many treatments for obesity are presented to the public, exercise in the form of walking is an easy, relatively safe activity that has the potential to move a person towards a negative energy balance and if done for a long enough time may reduce weight.

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The energy cost of transport quantifies the energy efficiency of transporting an animal or vehicle from one place to another. As a dimensionless quantity, it allows for the comparison of dissimilar animals or modes of transportation. It has a wide range of applications, from comparing human gaits to observing the change in efficiency of trains over time.

Effect of gait parameters on energetic cost

The effect of gait parameters on energetic cost is a relationship that describes how changes in step length, cadence, step width, and step variability influence the mechanical work and metabolic cost involved in gait. The source of this relationship stems from the deviation of these gait parameters from metabolically optimal values, with the deviations due to environmental, pathological, and other factors.

Locomotion in space

Locomotion in space includes any variety of actions or methods used to move one's body through an environment with microgravity conditions. Locomotion in these conditions is different from locomotion in Earth's gravity. There are many factors that contribute to these differences, and they are crucial when researching long-term survival of humans in space.

Gait deviations Medical condition

Gait deviations are nominally referred to as any variation of standard human gait, typically manifesting as a coping mechanism in response to an anatomical impairment. Lower-limb amputees are unable to maintain the characteristic walking patterns of an able-bodied individual due to the removal of some portion of the impaired leg. Without the anatomical structure and neuromechanical control of the removed leg segment, amputees must use alternative compensatory strategies to walk efficiently. Prosthetic limbs provide support to the user and more advanced models attempt to mimic the function of the missing anatomy, including biomechanically controlled ankle and knee joints. However, amputees still display quantifiable differences in many measures of ambulation when compared to able-bodied individuals. Several common observations are whole-body movements, slower and wider steps, shorter strides, and increased sway.

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  19. Charts of walking speed ranges for weight loss or health