A gait is a manner of limb movements made during locomotion. [1] Human gaits are the various ways in which humans can move, either naturally or as a result of specialized training. [2] Human gait is defined as bipedal forward propulsion of the center of gravity of the human body, in which there are sinuous movements of different segments of the body with little energy spent. Various gaits are characterized by differences in limb movement patterns, overall velocity, forces, kinetic and potential energy cycles, and changes in contact with the ground.
Human gaits are classified in various ways. Each gait can be generally categorized as either natural (one that humans use instinctively) or trained (a non-instinctive gait learned via training). Examples of the latter include hand walking and specialized gaits used in martial arts. [3] Gaits can also be categorized according to whether the person remains in continuous contact with the ground. [2]
One variable in gait is foot strike – which part of the foot connects with the ground first. [4]
Sprinting typically features a forefoot strike, but the heel does not usually contact the ground.
Some researchers classify foot strike by the initial center of pressure; this is mostly applicable to shod running (running while wearing shoes). [5] In this classification:
Foot strike varies between types of strides. It changes significantly and notably between walking and running, and between wearing shoes (shod) and not wearing shoes (barefoot).
Typically, barefoot walking features heel or mid-foot strikes, while barefoot running features mid-foot or forefoot strikes. Barefoot running rarely features heel strikes because the impact can be painful, the human heel pad not absorbing much of the force of impact. [4] By contrast, 75% of runners wearing modern running shoes use heel strikes; [6] running shoes are characterized by a padded sole, stiff soles and arch support, and slope down from a more-padded heel to a less-padded forefoot.
The cause of this change in gait in shoe running is unknown, but Lieberman noted that there is correlation between the foot-landing style and exposure to shoes. [6] In some individuals the gait pattern is largely unchanged (the leg and foot positions are identical in barefoot and shoes), but the wedge shape of the padding moves the point of impact back from the forefoot to the mid-foot. [5] In other cases it is believed that the padding of the heel softens the impact. This results in runners modifying their gait to move the point of contact further back in the foot. [6]
A 2012 study involving Harvard University runners found that those who "habitually rear-foot strike had approximately twice the rate of repetitive stress injuries than individuals who habitually forefoot strike." [7] This was the first study to investigate the link between foot strike and injury rates. However, earlier studies have shown that smaller collision forces were generated when running forefoot strike compared to rear-foot strike. This may protect the ankle joints and lower limbs from some of the impact-related injuries experienced by rear-foot strikers. [8]
In a 2017 article called "Foot Strike Pattern in Children During Shod-Unshod Running", over 700 children aged 6 to 16 were observed using multiple video recording devices in order to study their foot strike patterns and neutral support. Rear foot strike was most common, in both shod and unshod running, and in both boys and girls. There was a significant reduction in rear foot strike from shod to unshod: boys shod - 83.95% RFS, boys unshod - 62.65% RFS; girls shod - 87.85% RFS, girls unshod - 62.70% RFS. [9]
As of 2021 there was a very low level of evidence to suggest a relationship between foot strike pattern and runner injury. Studies used retrospective designs, low sample size and potentially inaccurate self-reporting. [10]
The central nervous system regulates gait in a highly ordered fashion through a combination of voluntary and automatic processes. The basic locomotor pattern is an automatic process that results from rhythmic reciprocal bursts of flexor and extensor activity. This rhythmic firing is the result of Central Pattern Generators (CPGs), [11] which operate regardless of whether a motion is voluntary or not. CPGs do not require sensory input to be sustained. However, studies have identified that gait patterns in deafferented or immobilized animals are more simplistic than in neurologically intact animals. (Deafferentation and immobilization are experimental preparations of animals to study neural control. Deafferentation involves transecting the dorsal roots of the spinal cord that innervate the animal's limbs, which impedes transmission of sensory information while keeping motor innervation of muscles intact. In contrast, immobilization involves injecting an acetylcholine inhibitor, which impedes the transmission of motor signals while sensory input is unaffected.) [12]
The complexity of gait arises from the need to adapt to expected and unexpected changes in the environment (e.g., changes in walking surface or obstacles). Visual, vestibular, proprioceptive, and tactile sensory information provides important feedback related to gait and permits the adjustment of a person's posture or foot placement depending on situational requirements. When approaching an obstacle, visual information about the size and location of the object is used to adapt the stepping pattern. These adjustments involve change in the trajectory of leg movement and the associated postural adjustments required to maintain their balance. Vestibular information provides information about position and movement of the head as the person moves through their environment. Proprioceptors in the joints and muscles provide information about joint position and changes in muscle length. Skin receptors, referred to as exteroceptors, provide additional tactile information about stimuli that a limb encounters. [12]
Gait in humans is difficult to study due to ethical concerns. Therefore, the majority of what is known about gait regulation in humans is ascertained from studies involving other animals or is demonstrated in humans using functional magnetic resonance imaging during the mental imagery of gait. [13] These studies have provided the field with several important discoveries.
There are three specific centers within the brain that regulate gait: [11] [13]
These centers are coordinated with the posture control systems within the cerebral hemispheres and the cerebellum. With each behavioral movement, the sensory systems responsible for posture control respond. [11] These signals act on the cerebral cortex, the cerebellum, and the brainstem. Many of these pathways are currently under investigation, but some aspects of this control are fairly well understood.
Sensory input from multiple areas of the cerebral cortex, such as the visual cortex, vestibular cortex, and the primary sensory cortex, is required for skilled locomotor tasks. This information is integrated and transmitted to the supplementary motor area (SMA) and premotor area of the cerebral cortex where motor programs are created for intentional limb movement and anticipatory postural adjustments. For example, the motor cortex uses visual information to increase the precision of stepping movements. When approaching an obstacle, an individual will make adjustments to their stepping pattern based on visual input regarding the size and location of the obstacle. [11] The primary motor cortex is responsible for the voluntary control for the contralateral leg while the SMA is linked to postural control.
The cerebellum plays a major role in motor coordination, regulating voluntary and involuntary processes. [14] [15] Regulation of gait by the cerebellum is referred to as “error/correction,” because the cerebellum responds to abnormalities in posture in order to coordinate proper movement. The cerebellum is thought to receive sensory information (e.g. visual, vestibular) about actual stepping patterns as they occur and compare them to the intended stepping pattern. When there is a discrepancy between these two signals, the cerebellum determines the appropriate correction and relays this information to the brainstem and motor cortex. Cerebellar output to the brainstem is thought to be specifically related to postural muscle tone while output to the motor cortex is related to cognitive and motor programming processes. [11] The cerebellum sends signals to the cerebral cortex and the brain stem in response to sensory signals received from the spinal cord. Efferent signals from these regions go to the spinal cord where motor neurons are activated to regulate gait. This information is used to regulate balance during stepping and integrates information about limb movement in space, as well as head position and movement. [12]
Spinal reflexes not only generate the rhythm of locomotion through CPGs but also ensure postural stability during gait. [16] There are multiple pathways within the spinal cord which play a role in regulating gait, including the role of reciprocal inhibition and stretch reflexes to produce alternating stepping patterns. A stretch reflex occurs when a muscle is stretched and then contracts protectively while opposing muscle groups relax. An example of this during gait occurs when the weight-bearing leg nears the end of the stance phase. At this point the hip extends and the hip flexors are elongated. Muscle spindles within the hip flexors detect this stretch and trigger muscle contraction of the hip flexors required for the initiation of the swing phase of gait. However, Golgi tendon organs in the extensor muscles also send signals related to the amount of weight being supported through the stance leg to ensure that limb flexion does not occur until the leg is adequately unweighted and the majority of weight has been transferred to the opposite leg. [12] Information from the spinal cord is transmitted for higher-order processing to supraspinal structures via spinothalamic, spinoreticular, and spinocerebellar tracts. [11]
The so-called natural gaits, in increasing order of speed, are the walk, jog, skip, run, and sprint. [2] [17] While other intermediate-speed gaits may occur naturally to some people, these five basic gaits occur naturally across almost all cultures. All natural gaits are designed to propel a person forward but can also be adapted for lateral movement. [2] As natural gaits all have the same purpose; they are mostly distinguished by when the leg muscles are used during the gait cycle.
Walking involves having at least one foot in contact with the ground at all times. There is also a period of time within the gait cycle where both feet are simultaneously in contact with the ground. [2] When a foot is lifted off the ground, that limb is in the "swing phase" of gait. When a foot is in contact with the ground, that limb is in the "stance phase" of gait. A mature walking pattern is characterized by the gait cycle being approximately 60% stance phase, 40% swing phase. [18] Initiation of gait is a voluntary process that involves a preparatory postural adjustment where the center of mass is moved forward and laterally prior to unweighting one leg. The center of mass is only within a person's base of support when both feet are in contact with the ground (known as double limb stance). When only one foot is in contact with the ground (single limb stance), the center of mass is in front of that foot and moving towards the leg that is in the swing phase. [11]
Skipping is a gait children display when they are about four to five years old. [2] While a jog is similar to a horse's trot, the skip is closer to the bipedal equivalent of a horse's canter. In order to investigate the gait strategies likely to be favored at low gravity, a study by Ackermann and Van Den Bogert ran a series of predictive, computational simulations of gait using a physiological model of the musculoskeletal system, without assuming any particular type of gait. They used a computationally efficient optimization strategy, allowing for multiple simulations. Their results reveal skipping as more efficient and less fatiguing than walking or running and suggest the existence of a walk-skip rather than a walk-run transition at low gravity. [17]
Time and distance parameters of gait patterns are dependent on a child's age. Different age leads to different step speed and timing. Arm swinging slows when the speed of walking is increased. The height of a child plays a significant role in stride distance and speed. The taller the child is the longer the stride will be and the further the step will be. Gait patterns are velocity and age dependent. For example, as age increases so does velocity. Meanwhile, as age increases, the cadence (rate at which someone walks that is measured in steps per minute) of the gait pattern decreases. Physical attributes such as height, weight, and even head circumference can also play a role in gait patterns in children. Environmental and emotional status also play a role in with speed, velocity, and gait patterns that a child uses. Besides, children of different genders will have different rates of gait development. Significant developmental changes in gait parameters such as stride time, swing time, and cadence occur in a child's gait two months after the onset of independent walking, possibly due to an increase in postural control at this point of development. [19]
By the age of three, most children have mastered the basic principles of walking, consistent with that of adults. Age is not the only deciding factor in gait development. Gender differences have been seen in young children as early as three years old. Girls tend to have a more stable gait than boys between the ages of 3–6 years old. Another difference includes the plantar contact area. Girls showed a smaller contact area in plantar loading patterns than boys in children with healthy feet. [19]
There are sex differences in human gait patterns: females tend to walk with smaller step width and more pelvic movement. [20] Gait analysis generally takes biological sex into consideration. [21] Sex differences in human gait can be explored using a demonstration created by the BioMotion Laboratory at York University in Toronto. [22]
Even though plantigrade locomotion usually distributes more weight toward the end of the limb than digitigrade locomotion, which increases energy expenditure in most systems, studies have shown that humans are economical walkers, but not economical runners, which is said to be consistent with evolutionary specialization for both economical walking and endurance running. [23]
For the same distance, walking with a natural heel-first gait burns roughly 70% less energy than running. Differences of this magnitude are unusual in mammals. [23] Kathyrn Knight of the Journal of Experimental Biology summarizes the findings of one study: "Landing heel first also allows us to transfer more energy from one step to the next to improve our efficiency, while placing the foot flat on the ground reduces the forces around the ankle (generated by the ground pushing against us), which our muscles have to counteract." [24] According to David Carrier of the University of Utah, who helped perform the study, "Given the great distances hunter-gatherers travel, it is not surprising that humans are economical walkers." [23]
A normal gait pattern depends on a range of biomechanical features, controlled by the nervous system for increased energy conservation and balance. [25] These biomechanical features of normal gait have been defined as key determinants of gait. It is therefore necessary for the refined neurological control and integration of these gait features for accuracy and precision with less energy expenditure. As a result, any abnormality of the neuro-musculo-skeletal system may lead to abnormality in gait and increased energy expenditure.
The six kinematics or determinants of gait, described below, were introduced by Saunders et al. in 1953, [26] and have been widely embraced with various refinements. [27] [28] [29] [30] [31] Recent studies have suggested that the first three determinants might contribute less to reducing the vertical displacement of the center of mass (COM).
These determinants of gait are known to ensure economical locomotion, [25] by the reduction in vertical center of mass (COM) excursion leading to reduction in metabolic energy. It is therefore suggested that the precise control of these determinants of gait [32] leads to increased energy conservation. These kinematic features of gait are integrated or coordinated in order to ensure a circular arc trajectory of the COM, as theory proposed as the 'compass gait (straight knee)'. The theory underlying the determinants run contrary to that of the 'inverted pendulum' theory with a static stance leg acting as a pendulum that prescribes an arc. [33] [34] [35] The six determinants of gaits and their effects on COM displacement and energy conservation are described below in chronological order:
Abnormal gait is a result of one or more of these tracts being disturbed. This can happen developmentally or as the result of neurodegeneration. [11] The most prominent example of gait irregularities due to developmental problems comes from studies of children on the autism spectrum. They have decreased muscle coordination, thus resulting in abnormalities in gait. [39] Some of this is associated with decreased muscle tone, also known as hypotonia, which is also common in ASD. The most prominent example of abnormal gait as a result of neurodegeneration is Parkinson's. [11]
Although these are the best understood examples of abnormal gait, there are other phenomena that are described in the medical field. [40]
Abnormal gait can also be a result of a stroke. However, by using treadmill therapy to activate the cerebellum, abnormalities in gait can be improved.
The author of the Deuterocanonical Book of Sirach observes that "a man's attire, and excessive laughter, and gait, shew what he is". [41] Biblical writer J. J. Collins suggests that this verse quotes a traditional maxim. [42]
The foot is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws and/or nails.
Running is a method of terrestrial locomotion by which humans and other animals move rapidly on foot. Running is a gait with an aerial phase in which all feet are above the ground. This is in contrast to walking, where one foot is always in contact with the ground, the legs are kept mostly straight, and the center of gravity vaults over the stance leg or legs in an inverted pendulum fashion. A feature of a running body from the viewpoint of spring-mass mechanics is that changes in kinetic and potential energy within a stride co-occur, with energy storage accomplished by springy tendons and passive muscle elasticity. The term "running" can refer to a variety of speeds ranging from jogging to sprinting.
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.
In terrestrial animals, plantigrade locomotion means walking with the toes and metatarsals flat on the ground. It is one of three forms of locomotion adopted by terrestrial mammals. The other options are digitigrade, walking on the toes with the heel and wrist permanently raised, and unguligrade, walking on the nail or nails of the toes with the heel/wrist and the digits permanently raised. The leg of a plantigrade mammal includes the bones of the upper leg (femur/humerus) and lower leg. The leg of a digitigrade mammal also includes the metatarsals/metacarpals, the bones that in a human compose the arch of the foot and the palm of the hand. The leg of an unguligrade mammal also includes the phalanges, the finger and toe bones.
Terrestrial locomotion has evolved as animals adapted from aquatic to terrestrial environments. Locomotion on land raises different problems than that in water, with reduced friction being replaced by the increased effects of gravity.
Barefoot running, also called "natural running", is the act of running without footwear. With the advent of modern footwear, running barefoot has become less common in most parts of the world but is still practiced in parts of Africa and Latin America. In some Western countries, barefoot running has grown in popularity due to perceived health benefits.
The evolution of human bipedalism, which began in primates approximately four million years ago, or as early as seven million years ago with Sahelanthropus, or approximately twelve million years ago with Danuvius guggenmosi, has led to morphological alterations to the human skeleton including changes to the arrangement, shape, and size of the bones of the foot, hip, knee, leg, and the vertebral column. These changes allowed for the upright gait to be overall more energy efficient in comparison to quadrupeds. The evolutionary factors that produced these changes have been the subject of several theories that correspond with environmental changes on a global scale.
Comparative foot morphology involves comparing the form of distal limb structures of a variety of terrestrial vertebrates. Understanding the role that the foot plays for each type of organism must take account of the differences in body type, foot shape, arrangement of structures, loading conditions and other variables. However, similarities also exist among the feet of many different terrestrial vertebrates. The paw of the dog, the hoof of the horse, the manus (forefoot) and pes (hindfoot) of the elephant, and the foot of the human all share some common features of structure, organization and function. Their foot structures function as the load-transmission platform which is essential to balance, standing and types of locomotion.
The endurance running hypothesis is a series of conjectures which presume humans evolved anatomical and physiological adaptations to run long distances and, more strongly, that "running is the only known behavior that would account for the different body plans in Homo as opposed to apes or australopithecines".
Orthotics is a medical specialty that focuses on the design and application of orthoses, sometimes known as braces, calipers, or splints. An orthosis is "an externally applied device used to influence the structural and functional characteristics of the neuromuscular and skeletal systems." Orthotists are medical professionals who specialize in designing orthotic devices such as braces or foot orthoses.
Locomotor effects of shoes are the way in which the physical characteristics or components of shoes influence the locomotion neuromechanics of a person. Depending on the characteristics of the shoes, the effects are various, ranging from alteration in balance and posture, muscle activity of different muscles as measured by electromyography (EMG), and the impact force. There are many different types of shoes that exist, such as running, walking, loafers, high heels, sandals, slippers, work boots, dress shoes, and many more. However, a typical shoe will be composed of an insole, midsole, outsole, and heels, if any. In an unshod condition, where one is without any shoes, the locomotor effects are primarily observed in the heel strike patterns and resulting impact forces generated on the ground.
Spinal locomotion results from intricate dynamic interactions between a central program in lower thoracolumbar spine and proprioceptive feedback from body in the absence of central control by brain as in complete spinal cord injury (SCI). Following SCI, the spinal circuitry below the lesion site does not become silent; rather, it continues to maintain active and functional neuronal properties, although in a modified manner.
Parkinsonian gait is the type of gait exhibited by patients with Parkinson's disease (PD). It is often described by people with Parkinson's as feeling like being stuck in place, when initiating a step or turning, and can increase the risk of falling. This disorder is caused by a deficiency of dopamine in the basal ganglia circuit leading to motor deficits. Gait is one of the most affected motor characteristics of this disorder although symptoms of Parkinson's disease are varied.
Terrestrial locomotion by means of a running gait can be accomplished on level surfaces. However, in most outdoor environments an individual will experience terrain undulations requiring uphill running. Similar conditions can be mimicked in a controlled environment on a treadmill also. Additionally, running on inclines is used by runners, both distance and sprinter, to improve cardiovascular conditioning and lower limb strength.
Limitations of animal running speed provides an overview of how various factors determine the maximum running speed. Some terrestrial animals are built for achieving extremely high speeds, such as the cheetah, pronghorn, race horse and greyhound, while humans can train to achieve high sprint speeds. There is no single determinant of maximum running speed: however, certain factors stand out against others and have been investigated in both animals and humans. These factors include: Muscle moment arms, foot morphology, muscle architecture, and muscle fiber type. Each factor contributes to the ground reaction force (GRF) and foot contact time of which the changes to increase maximal speed are not well understood across all species.
Arm swing in human bipedal walking is a natural motion wherein each arm swings with the motion of the opposing leg. Swinging arms in an opposing direction with respect to the lower limb reduces the angular momentum of the body, balancing the rotational motion produced during walking. Although such pendulum-like motion of arms is not essential for walking, recent studies point that arm swing improves the stability and energy efficiency in human locomotion. Those positive effects of arm swing have been utilized in sports, especially in racewalking and sprinting.
Neuromechanics of orthoses refers to how the human body interacts with orthoses. Millions of people in the U.S. suffer from stroke, multiple sclerosis, postpolio, spinal cord injuries, or various other ailments that benefit from the use of orthoses. Insofar as active orthoses and powered exoskeletons are concerned, the technology to build these devices is improving rapidly, but little research has been done on the human side of these human-machine interfaces.
A (bipedal) gait cycle is the time period or sequence of events or movements during locomotion in which one foot contacts the ground to when that same foot again contacts the ground, and involves propulsion of the centre of gravity in the direction of motion. A gait cycle usually involves co-operative movements of both the left and right legs and feet. A single gait cycle is also known as a stride.
The function of the lower limbs during walking is to support the whole-body against gravitational forces while generating movement patterns which progress the body forward. Walking is an activity that is primarily confined to the sagittal plane, which is also described as the plane of progression. During one gait cycle, there are two major phases: stance and swing. In a healthy individual walking at a normal walking speed, stance phase makes up approximately 60% of one gait cycle and swing makes up the remaining 40%. The lower limbs are only in contact with the ground during the stance phase, which is typically subdivided into 5 events: heel contact, foot flat, mid-stance, heel off, and toe off. The majority of stance phase (~40%) takes place in single-limb support where one limb is in contact with the ground and the contralateral limb is in swing phase. During this time interval, the lower limb must support constant changes in alignment of body weight while propelling forward. The hip, knee, and ankle joints move through cyclical kinematic patterns that are controlled by muscles which cross these joints. As postural changes occur, the body adapts by motor tuning an efficient muscular pattern that will accomplish the necessary kinematics required to walk.
Interlimb coordination is the coordination of the left and right limbs. It could be classified into two types of action: bimanual coordination and hands or feet coordination. Such coordination involves various parts of the nervous system and requires a sensory feedback mechanism for the neural control of the limbs. A model can be used to visualize the basic features, the control centre of locomotor movements, and the neural control of interlimb coordination. This coordination mechanism can be altered and adapted for better performance during locomotion in adults and for the development of motor skills in infants. The adaptive feature of interlimb coordination can also be applied to the treatment for CNS damage from stroke and the Parkinson's disease in the future.
The dictionary definition of gait at Wiktionary