Ultrasonic motion analysis system--measurement of temporal and spatial gait parameters

The duration of stance and swing phase and step and stride length are important parameters in human gait. In this technical note a low-cost ultrasonic motion analysis system is described that is capable of measuring these temporal and spatial parameters while subjects walk on the floor. By using the propagation delay of sound when transmitted in air, this system is able to record the position of the subjects' feet. A small ultrasonic receiver is attached to both shoes of the subject while a transmitter is placed stationary on the floor. Four healthy subjects were used to test the device. Subtracting positions of the foot with zero velocity yielded step and stride length. The duration of stance and swing phase was calculated from heel-strike and toe-off. Comparison with data obtained from foot contact switches showed that applying two relative thresholds to the speed graph of the foot could reliably generate heel-strike and toe-off. Although the device is tested on healthy subjects in this study, it promises to be extremely valuable in examining pathological gait. When gait is asymmetrical, walking speed is not constant or when patients do not completely lift their feet, most existing devices will fail to correctly assess the proper gait parameters. Our device does not have this shortcoming and it will accurately demonstrate asymmetries and variations in the patient's gait. As an example, the recording of a left hemiplegic patient is presented in the discussion.     

Gait characteristics of two macaques, with emphasis on relationships with speed

The gait of a juvenile rhesus monkey as he walked, ran, underwent a run-gallop transition, and galloped on a motor-driven treadmill is described. Additionally, gait data for an adult animal during walking are also presented. Footfall sequences, stride durations, and absolute and relative swing and stance durations for all four limbs are reported, and, where possible, correlated with speed. Furthermore, support patterns and delays between footfalls are presented as a function of speed. The analysis revealed many similarities with previous studies on both primates and other species, but additionally demonstrated that the fore- and hindlimbs may not relate to speed in an identical manner and that galloping is initiated asymmetrically by a single diagonal couplet. The implications of these results in terms of understanding the neural mechanisms by which quadrupeds increase speed are discussed.     

The walking gaits of some species of Pecora

A method is presented for defining the walking gaits of quadrupeds from films so that they can be compared in closely related species. Differences in walking patterns of 18 pecoran species belonging to four families are discussed with respect to anatomy and environment. Variation in the walk patterns of members within a species are assessed. They are found to vary often with the speed at which the walk is executed, with the terrain, with the presence of heavy horns or antlers and with age. The time taken for one walking stride increases with the increase in length of the legs, but the legs swing forward more rapidly than they would if they acted passively like cylindrical pendulums.     

Kinematic parameters of terrestrial locomotion in cursorial (ratites), swimming (ducks), and striding birds (quail and guinea fowl).

The importance of size, functional features and morphological features in adaptation for walking in birds were studied. The time and space kinematic parameters of locomotion were compared in two running birds, the ratites (rhea, kiwi, Paleognatiforms), in two swimming birds, (ducks) and two striding birds, (quail and Guinea fowl). The results showed that in the two phases, stance and swing, the time and space parameters worked in opposite ways: the duration of the swing was constant, but its length increased with speed. In contrast, the duration of the stance was correlated to speed, while its length was not (except in ducks). In all the birds, a higher speed was achieved by a decrease of the stance duration, and an increase of the swing length. The kinematic parameters were not used in the same way in all species: There is a size effect and large birds increase their speed mainly by increasing the frequency of their movements and the small species increase mainly their amplitude. Nevertheless, it is not the main factor and morphology, such as swimming adaptation features of the ducks, and behaviour, are important because they modify the mechanical constraints and influence the kinematics parameters.     

Pedestrian locomotion energetics and gait characteristics of a diving bird, the great cormorant, Phalacrocorax carbo

Great cormorants Phalacrocorax carbo are foot propelled diving birds that seem poorly suited to locomotion on land. They have relatively short legs, which are presumably adapted for the generation of high forces during the power stroke of aquatic locomotion, and walk with a pronounced "clumsy waddle". We hypothesise (1) that the speed, independent minimum cost of locomotion (C min, ml O2 m(-1)) will be high for cormorants during treadmill exercise, and (2) that cormorants will have a relatively limited speed range in comparison to more cursorial birds. We measured the rate of oxygen consumption (V02) of cormorants during pedestrian locomotion on a treadmill, and filmed them to determine duty factor (the fraction of stride period that the foot is in contact with the ground), foot contact time (tc), stride frequency (f), swing phase duration and stride length. C min was 2.1-fold higher than that predicted by their body mass and phylogenetic position, but was not significantly different from the C min of runners (Galliformes and Struthioniformes). The extrapolated gamma-intercept of the relationship between V02 and speed was 1.9-fold higher than that predicted by allometry. Again, cormorants were not significantly different from runners. Contrary to our hypothesis, we therefore conclude that cormorants do not have high pedestrian transport costs. Cormorants were observed to use a grounded gait with two double support phases at all speeds measured, and showed an apparent gait transition between 0.17 and 0.25 m s(-1). This transition occurs at a Froude number between 0.016 and 0.037, which is lower than the value of approximately 0.5 observed for many other species. However, despite the use of a limited speed range, and a gait transition at relatively low speed, we conclude that the pedestrian locomotion of these foot propelled diving birds is otherwise generally similar to that of cursorial birds at comparable relative velocities.     

A biomechanical study of balance recovery during the fall forward

The study deals with the biomechanics of balance recovery of human subjects in a falling forward situation. Eight subjects took part in the experiment. The subject, held in the initial leaning forward position, was released without his knowledge. The instruction was to recover the induced disequilibrium by walking. The biomechanical analysis shows two phases in the balance recovery. The first phase—preparation phase—is characterized by three events at fixed timing whatever the initial inclination. (i) Dynamic reaction time, showing no significant inter-individual variation (mean VALUE = 90.8 ms). (ii) Braking of the forward fall, between 184 ms and 237.2 ms, depending on the subject. (iii) Beginning of the swing phase—i.e. toe-off instant—between 235.9 ms and 328.3 ms, depending on the subject. The second phase—gait execution phase—is characterized by the duration of the swing phase, the duration of the stance phase, the stride length and execution speed. The durations diminish whereas the stride length and the execution speed increase with respect to the initial inclination. For the same execution speed, the stride length is shorter than in normal walking.

It has been concluded that balance recovery following an induced fall forward begins with an invariable preparation process which is followed by an adaptable recovery one.     

The locomotion of the camel (Camelus dromedarius)

The feet and gaits of many camels Camelus dromedarius were studied and filmed in Mauritania, Africa. The camel has a digitigrade stance, large feet to support the animal in soft sand, and soles of flexible pads that step readily onto small stones where necessary. The walking stride is long and slow, with the body supported for much of each stride on the two right or two left legs. The pattern of supporting legs was significantly different in slow compared to fast walking camels, and in young compared to adult camels and compared to adults pulling water at the wells. There was no difference in pattern in one individual's walk, when it was either loaded or unloaded. The angles that the leg bones made with each other and with the horizon are depicted for the walk and the pace. The camel is the only animal which paces often and never trots. The pace is an unstable gait only suitable for flat terrain such as that in deserts. It may have evolved from the pace-like walk which is by far the dominant gait in this animal, which spends most of each day walking from plant to plant browsing or grazing. The pace is not used by all camelids, as one author has claimed. The pace and the gallop were only used by the camels at wells, when the animals were chased from the water by men.     

A feedback-controlled treadmill (treadmill-on-demand) and the spontaneous speed of walking and running in humans.

A novel apparatus, composed by a controllable treadmill, a computer, and an ultrasonic range finder, is here proposed to help investigation of many aspects of spontaneous locomotion. The acceleration or deceleration of the subject, detected by the sensor and processed by the computer, is used to accelerate or decelerate the treadmill in real time. The system has been used to assess, in eight subjects, the self-selected speed of walking and running, the maximum "reasonable" speed of walking, and the minimum reasonable speed of running at different gradients (from level up to +25%). This evidenced the speed range at which humans neither walk nor run, from 7.2 +/- 0.6 to 8.4 +/- 1.1 km/h for level locomotion, slightly narrowing at steeper slopes. These data confirm previous results, obtained indirectly from stride frequency recordings. The self-selected speed of walking decreases with increasing gradient (from 5.0 +/- 0.8 km/h at 0% to 3.0 +/- 0.9 km/h at +25%) and seems to be approximately 30% higher than the speed that minimizes the metabolic energy cost of walking, obtained from the literature, at all the investigated gradients. The advantages, limitations, and potential applications of the newly proposed methodology in physiology, biomechanics, and pathology of locomotion are discussed in this paper.     

Symmetrical and asymmetrical gaits in the mouse: patterns to increase velocity

The gaits of the adult SWISS mice during treadmill locomotion at velocities ranging from 15 to 85 cm s^–1 have been analysed using a high-speed video camera combined with cinefluoroscopic equipment. The sequences of locomotion were analysed to determine the various space and time parameters of limb kinematics. We found that velocity adjustments are accounted for differently by the stride frequency and the stride length if the animal showed a symmetrical or an asymmetrical gait. In symmetrical gaits, the increase of velocity is provided by an equal increase in the stride length and the stride frequency. In asymmetrical gaits, the increase in velocity is mainly assured by an increase in the stride frequency in velocities ranging from 15 to 29 cm s^–1. Above 68 cm s^–1, velocity increase is achieved by stride length increase. In velocities ranging from 29 to 68 cm s^–1, the contribution of both variables is equal as in symmetrical gaits. Both stance time and swing time shortening contributed to the increase of the stride frequency in both gaits, though with a major contribution from stance time decrease. The pattern of locomotion obtained in a normal mouse should be used as a template for studying locomotor control deficits after lesions or in different mutations affecting the nervous system.     

Effects of Aging on Arm Swing during Gait: The Role of Gait Speed and Dual Tasking

Healthy walking is characterized by pronounced arm swing and axial rotation. Aging effects on gait speed, stride length and stride time variability have been previously reported, however, less is known about aging effects on arm swing and axial rotation and their relationship to age-associated gait changes during usual walking and during more challenging conditions like dual tasking. Sixty healthy adults between the ages of 30–77 were included in this study designed to address this gap. Lightweight body fixed sensors were placed on each wrist and lower back. Participants walked under 3 walking conditions each of 1 minute: 1) comfortable speed, 2) walking while serially subtracting 3’s (Dual Task), 3) walking at fast speed. Aging effects on arm swing amplitude, range, symmetry, jerk and axial rotation amplitude and jerk were compared between decades of age (30–40; 41–50; 51–60; 61–77 years). As expected, older adults walked slower (p = 0.03) and with increased stride variability (p = 0.02). Arm swing amplitude decreased with age under all conditions (p = 0.04). In the oldest group, arm swing decreased during dual task and increased during the fast walking condition (p<0.0001). Similarly, arm swing asymmetry increased during the dual task in the older groups (p<0.004), but not in the younger groups (p = 0.67). Significant differences between groups and within conditions were observed in arm swing jerk (p<0.02), axial rotation amplitude (p<0.02) and axial jerk (p<0.001). Gait speed, arm swing amplitude of the dominant arm, arm swing asymmetry and axial rotation jerk were all independent predictors of age in a multivariate model. These findings suggest that the effects of gait speed and dual tasking on arm swing and axial rotation during walking are altered among healthy older adults. Follow-up work is needed to examine if these effects contribute to reduced stability in aging.     

A comparison of algorithms for body-worn sensor-based spatiotemporal gait parameters to the GAITRite electronic walkway

This study compares the performance of algorithms for body-worn sensors used with a spatiotemporal gait analysis platform to the GAITRite electronic walkway. The mean error in detection time (true error) for heel strike and toe-off was 33.9 ± 10.4 ms and 3.8 ± 28.7 ms, respectively. The ICC for temporal parameters step, stride, swing and stance time was found to be greater than 0.84, indicating good agreement. Similarly, for spatial gait parameters--stride length and velocity--the ICC was found to be greater than 0.88. Results show good to excellent concurrent validity in spatiotemporal gait parameters, at three different walking speeds (best agreement observed at normal walking speed). The reported algorithms for body-worn sensors are comparable to the GAITRite electronic walkway for measurement of spatiotemporal gait parameters in healthy subjects.     

The walk of the Silver gull (Larus novaehollandiae) and of other birds

A total of 317 steps of walking Silver gulls ( Larus novaehollandiiae ) and filmed sequences of 24 other species of medium-sized and large birds were analyzed. The angles made by the tibiotarsus-tarsometatarsus joint of each leg during walking were measured. These varied depending on the species. In the Silver gull, where the angles were correlated with speed, the leg bent more sharply the slower the step; otherwise the angles were not correlated with speed. In all but the four largest birds, as in man, the leg was more bent in the middle of its stance phase than it was at the beginning or end of this phase. Thejoint was never completely straight, or 180". In general the larger the bird, the slower was its step. The Silver gull and other birds do not bob their heads back-and-forth as they walk, but many birds do. It is not known why some birds bob their heads, although it may be correlated in part with a relative horizontal body posture, with seeing effectively, with balance during locomotion, or with habitat. The Silver gull does not hop, but some birds do, usually birds that live in the bush, or that are small.     

Locomotion patterns in two South American gymnophthalmid lizards: Vanzosaura rubricauda and Procellosaurinus tetradactylus

We quantified gait and stride characteristics (velocity, frequency, stride length, stance and swing duration, and duty factor) in the bursts of locomotion of two small, intermittently moving, closely related South American gymnophthalmid lizards: Vanzosaura rubricauda and Procellosaurinus tetradactylus. They occur in different environments: V. rubricauda is widely distributed in open areas with various habitats and substrates, while P. tetradactylus is endemic to dunes in the semi-arid Brazilian Caatinga. Both use trot or walking trot characterised by a lateral sequence. For various substrates in a gradient of roughness (perspex, cardboard, sand, gravel), both species have low relative velocities in comparison with those reported for larger continuously moving lizards. To generate velocity, these animals increase stride frequency but decrease relative stride length. For these parameters, P. tetradactylus showed lower values than V. rubricauda. In their relative range of velocities, no significant differences in stride length and frequency were recorded for gravel. However, the slopes of a correlation between velocity and its components were lower in P. tetradactylus on cardboard, whereas on sand this was only observed for velocity and stride length. The data showed that the difference in rhythmic parameters between both species increased with the smoothness of the substrates. Moreover, P. tetradactylus shows a highly specialised locomotor strategy involving lower stride length and frequency for generating lower velocities than in V. rubricauda. This suggests the evolution of a central motor pattern generator to control slower limb movements and to produce fewer and longer pauses in intermittent locomotion.     

Modulation of limb dynamics in the swing phase of locomotion

A method was presented for quantifying cat (Felis catus) hind limb dynamics during swing phase of locomotion using a two-link rigid body model of leg and paw, which highlighted the dynamic interactions between segments. Comprehensive determination was made of cat segment parameters necessary for dynamic analysis, and regression equations were formulated to predict the inertial parameters of any comparable cat. Modulations in muscle and non-muscle components of knee and ankle joint moments were examined at two treadmill speeds using three gaits: (a) pace-like walk and trot-like walk, at 1.0 ms-1, and (b) gallop, at 2.1 ms-1. Results showed that muscle and segment interactive moments significantly effected limb trajectories during swing. Some moment components were greater in galloping than in walking, but net joint maxima were not significantly different between speeds. Moment magnitudes typically were greater for pace-like walking than for trot-like walking at the same speed. Generally, across gaits, the net and muscle moments were in phase with the direction of distal joint motion, and these same moments were out of phase with proximal joint motion. Intersegmental dynamics were not modulated exclusively by speed of locomotion, but interactive moments were also influenced significantly by gait mode.     

Locomotion in the quail (Coturnix japonica): the kinematics of walking and increasing speed

Hindlimb segmental kinematics and stride characteristics are quantified in several quail locomoting on a treadmill over a six-fold increase in speed. These data are used to describe the kinematics of a walking stride and to identify which limb elements are used to change stride features as speed increases. In quail, the femur does not move during locomotion and the tarsometatarsus-phalangeal joint is a major moving joint; thus, quail have lost the most proximal moving joint and added one distally. The tibiotarsus and tarsometatarsus act together as a fixed strut swinging from the knee during stance phase (the ankle angle remains constant at a given speed) and the tarsometatarsus-phalangeal joint appears to have a major role in increasing limb length during the propulsive phase of the stride. Speed is increased with greater knee extension and by lengthening the tibiotarsus/tarsometatarsus via increased ankle extension at greater speeds. Because the femur is not moved and three distal elements are, quail move the limb segments through a stride and increase speed in a way fundamentally different from other nonavian vertebrates. However, the three moving joints in quail (the knee, ankle, and tarsometatarsophangeal joint) have strikingly similar kinematics to the analogous moving joints (the hip, knee, and ankle) in other vertebrates. Comparisons to other vertebrates indicate that birds appear to have two modes of limb function (three- and four-segment modes) that vary with speed and locomotory habits.     

The role of vibrissal sensing in forelimb position control during travelling locomotion in the rat (Rattus norvegicus,Rodentia)

In the stem lineage of therians, a comprehensive reorganization of limb and body mechanics took place to provide dynamic stability for rapid locomotion in a highly structured environment. At what was probably the same time, mammals developed an active sense of touch in the form of movable mystacial vibrissae. The rhythmic movements of the limbs and vibrissae are controlled by central pattern-generating networks which might interact with each other in sensorimotor control. To test this possible interaction, we studied covariation between the two by investigating speed-dependent adjustments in temporal and spatial parameters of forelimb and vibrissal kinematics in the rat. Furthermore, the possible role of carpal vibrissae in connecting the two oscillating systems was explored. We compared locomotion on continuous and discontinuous substrates in the presence and absence of the mystacial or/and carpal vibrissae across a speed range of 0.2–0.5 m/s and found that a close coupling of the kinematics of the two oscillating systems appears to be precluded by their differential dependence on the animal's speed. Speed-related changes in forelimb kinematics mainly occur in temporal parameters, whereas vibrissae change their spatial excursion. However, whisking frequency is always high enough that at least one whisk cycle falls into the swing phase of the limb, which is the maximum critical period for sensing the substrate on which the forepaw will be placed. The influence of tactile cues on forelimb positional control is more subtle than expected. Tactile cues appear to affect the degree of parameter variation but not average parameters or the failure rate of limbs during walking on a perforated treadmill. The carpal vibrissae appear to play a role in sensing the animal's speed by measuring the duration of the stance phase. The absence of this cue significantly reduces speed-related variation in stride frequency and vibrissal protraction.     

Dynamic plantar pressure distribution during terrestrial locomotion of bonobos (Pan paniscus)

We collected high-resolution plantar pressure distributions of seven bonobos during terrestrial bipedal and quadrupedal locomotion (N = 146). Functional foot length, degree of hallux abduction, and total contact time were determined, and plots, showing pressure as a function of time for six different foot regions, were generated. We also studied five adult humans for comparison (N = 13). Both locomotion types of the bonobo show a large variation in plantar pressure distributions, which could be due to the interference of instantaneous behavior with locomotion and differences in walking speed and body dimensions. The heel and the lateral midfoot typically touch down simultaneously at initial ground contact in bipedal and quadrupedal walking of bonobos, in contrast with the typical heel-strike of human bipedalism. The center of pressure follows a curved course during quadrupedalism, as a consequence of the medial weight transfer during mid-stance. Bipedal locomotion of bonobos is characterized by a more plantar positioning of the feet and by a shorter contact time than during quadrupedal walking, according to a smaller stride and step length at a higher frequency. We observed a varus position of the foot with an abducted hallux, which likely possesses an important sustaining and stabilizing function during terrestrial locomotion.     

Gait transitions in simulated reduced gravity

Gravity has a strong effect on gait and the speed of gait transitions. A gait has been defined as a pattern of locomotion that changes discontinuously at the transition to another gait. On Earth, during gradual speed changes, humans exhibit a sudden discontinuous switch from walking to running at a specific speed. To study the effects of altered gravity on both the stance and swing legs, we developed a novel unloading exoskeleton that allows a person to step in simulated reduced gravity by tilting the body relative to the vertical. Using different simulation techniques, we confirmed that at lower gravity levels the transition speed is slower (in accordance with the previously reported Froude number ～0.5). Surprisingly, however, we found that at lower levels of simulated gravity the transition between walking and running was generally gradual, without any noticeable abrupt change in gait parameters. This was associated with a significant prolongation of the swing phase, whose duration became virtually equal to that of stance in the vicinity of the walk-run transition speed, and with a gradual shift from inverted-pendulum gait (walking) to bouncing gait (running).     

Muscular coordination of knee motion during the terminal-swing phase of normal gait

Children with cerebral palsy often walk with diminished knee extension during the terminal-swing phase, resulting in a troublesome "crouched" posture at initial contact and a shortened stride. Treatment of this gait abnormality is challenging because the factors that extend the knee during normal walking are not well understood, and because the potential of individual muscles to limit terminal-swing knee extension is unknown. This study analyzed a series of three-dimensional, muscle-driven dynamic simulations to quantify the angular accelerations of the knee induced by muscles and other factors during swing. Simulations were generated that reproduced the measured gait dynamics and muscle excitation patterns of six typically developing children walking at self-selected speeds. The knee was accelerated toward extension in the simulations by velocity-related forces (i.e., Coriolis and centrifugal forces) and by a number of muscles, notably the vasti in mid-swing (passive), the hip extensors in terminal swing, and the stance-limb hip abductors, which accelerated the pelvis upward. Knee extension was slowed in terminal swing by the stance-limb hip flexors, which accelerated the pelvis backward. The hamstrings decelerated the forward motion of the swing-limb shank, but did not contribute substantially to angular motions of the knee. Based on these data, we hypothesize that the diminished knee extension in terminal swing exhibited by children with cerebral palsy may, in part, be caused by weak hip extensors or by impaired hip muscles on the stance limb that result in abnormal accelerations of the pelvis.