Human Bipedal Locomotion Research Articles

Using primate models to study the evolution of human locomotion: concepts and cases

This note introduces the types of models used in functional morphological research in order to clarify certain semantic issues and to present some examples of the use of extant model species to contribute to our understanding of bipedal locomotion. The existing models fall into two broad categories: “abstraction models” are simplifications/abstractions of living organisms, whereas “comparative models” are extant organisms used as models or analogues for other organisms (e.g. extinct species). In a palaeoanthropological context, comparative models may be selected for their close (but always imperfect) resemblance to the organism of interest, but some atypical model species can also produce insights not despite their imperfect resemblance, but because of it. We present three examples of our own work on comparative primate models during studies of terrestrial bipedal locomotion in bonobos (Pan paniscus), olive baboons (Papio anubis), and white-handed gibbons (Hylobates lar), showing how they each provide insights into the evolution of human bipedal locomotion.

36. Principle and conditions of inclusion the hippotherapy in the treatment of neuromuscular disorders

Hippotherapy is a treatment method, which we can with a significant positive effect include in the comprehensive physiotherapy care of neuromuscular disorders. It is a therapy by horses. Gait motion generated pulses, which due to its size and capacity can be transmitted to the patient through contact with the horse’s back. These pulses show a correlation with the motion stereotype of human bipedal locomotion, their essence is cross pattern. The patient is in balance area, which is formed by a moving horse‘s back, reflexively adapts on the external motion stimulus and activates all the means and the level of the central nervous system to activate the executive apparatus in order to maintain control over the center of gravity. As the external stimuli have physiological origins, adaptation takes place on the physiological substrate. There is a setting of desirable muscle tone and muscle chains involvement in physiological pattern. Cyclical effects of the initiative with good physiological response in time, we are trying to create or restore the neuromuscular junction in the body and save the interplay of motion in the form of engrams in order to repeat the connection has been made for the inclusion of this specific link to the spontaneous activity of the organism. The result is a new one, respectively rehabilitated motorized link, usable in the active patient movement. This process is very much influenced by the quality of the input parameters for dynamic stimulation (quality of movement of the horse) and no less then the default position (support base) of a patient, which adapts to the movement. If one of the starting points of error can not be assumed that the outcome of the therapy will be responsible physiology. If gait (speed and space) is not adapted to the needs and possibilities of the patient, does not adapt to the movement, but only the activation of defense mechanisms, when the muscle tension increases and primarily activate postural muscles, instead of stabilizing systems. Can not reach tone adjustment, neither synergy antagonists. In the case of a wrongly selected base supporting the patient and when improper setting root joints leads to a similar result. The patient used to stabilize of the centre of gravity pathological replacement patterns and therefore we can not talk about therapy, but only the fixation of pathological muscle interplays and isolated muscle strengthening on these samples are involved. The horse provides a unique opportunity to cyclic dynamic stimulation of precise parameters within the required time, when the patient’s body has the ability to recall and fix the links, leading to the rehabilitation of its global possibly bipedal locomotor pattern. In practice I proved interconnection The Reflexology by V. Vojta (and other methods) with hippotherapy, which is able to offer controlled realization of the movement in space and time.

Determination of ground reaction force peaks from human footprint depths

The aim of the present study was to estimate ground reaction force (GRF) by means of a linear regression equation with input data from footprints. It can be used to provide further information on locomotion of extinct mammals and/or early humans, thus providing important knowledge about human bipedal locomotion evolution. Fossilized footprints contain information about gait dynamics, but their interpretation is difficult, as they are a combined result of foot anatomy, gait dynamics, and substrate properties. Several approaches are used for modeling and estimating data in biomechanics, simple modeling is useful when trying to understand complex events. Force measurements were performed using a force platform; at the same time a footprint was registered on a clay surface. From the measurements of length, width and depth of the footprint it was possible to estimate body height (BH), body mass (BM) and vertical GRF peaks during human walking. The main findings of the present study were two linear regression equations for estimation of GRF peaks from footprint depths (R 2 =0.81, p<0.001; R 2 =0.56, p<0.001). This study accomplishes a first step to a fully understanding of how to estimate GRF from footprint data, and have further application to locomotion evaluations from fossilized footprints.

Predictive control of ankle stiffness at heel contact is a key element of locomotor adaptation during split-belt treadmill walking in humans

Split-belt treadmill walking has been extensively utilized as a useful model to reveal the adaptability of human bipedal locomotion. While previous studies have clearly identified different types of locomotor adaptation, such as reactive and predictive adjustments, details of how the gait pattern would be adjusted are not fully understood. To gain further knowledge of the strategies underlying split-belt treadmill adaptation, we examined the three-dimensional ground reaction forces (GRF) and lower limb muscle activities during and after split-belt treadmill walking in 22 healthy subjects. The results demonstrated that the anterior component of the GRF (braking force) showed a clear pattern of adaptation and subsequent aftereffects. The muscle activity in the tibialis anterior muscle during the early stance phase was associated with the change of braking force. In contrast, the posterior component of GRF (propulsive force) showed a consistent increase/decrease in the fast/slow leg during the adaptation period and was not followed by subsequent aftereffects. The muscle activity in the gastrocnemius muscle during the stance phase gradually decreased during the adaptation phase and then showed a compensatory reaction during the washout phase. The results indicate that predictive feedforward control is required to set the optimal ankle stiffness in preparation for the impact at the heel contact and passive feedback control is used for the production of reflexively induced propulsive force at the end of the stance phase during split-belt treadmill adaptation. The present study provides information about the detailed mechanisms underlying split-belt adaptation and should be useful for the construction of specific rehabilitation protocols.

High-Performance Interface Electronic System for a 13$\,\times\,$13 Flexible Biomechanical Ground Reaction Sensor Array Achieving a Gait Ground Velocity Resolution of 100 $\mu{\rm m/sec}$

This paper describes a high-performance interface electronics system design for a high-density flexible biomechanical ground reaction sensor array (GRSA). The prototype system can be incorporated into a personal boot heel to measure real-time ground force, shear strain, and sole deformation associated with a human bipedal locomotion, thus providing zero-velocity correction to an inertial measurement unit placed in a close proximity. This approach can greatly reduce inertial error accumulation and improve positioning accuracy. The sensing electronics consist of a front-end multiplexer that can sequentially connect individual sensing nodes from a 13 × 13 GRSA to a capacitance-to-voltage converter followed by a 12-bit algorithmic ADC with a sampling rate of 66.7 k-samples/s. The entire sensor array can be scanned within 10 ms. The GRSA employs capacitive sensing scheme and is fabricated using PDMS deformable dielectric layer. The integrated sensing electronics are fabricated in XFAB 0.35 μm CMOS process and dissipate 3 mW power. The overall system sensing resolution is limited by electrical interferences coupled through long interconnect traces between a GRSA and an electronic sensing module. Dynamic and static pressure testing shows the prototype system functionality achieving a gait ground velocity sensing resolution of 100 μm/s.

S11-3. Neurophysiological basis of body-weight supported step training

The body-weight supported step training (BWSS) has been originally applied to individuals with spinal cord injury (SCI) on the basis of numerous experimental evidences indicating that the central pattern generator (CPG) of quadruped animals can be reorganized and allows those animals walk independently after BWSS training. However, beside the fact that the CPG alone cannot provide full weight-bearing force and stepping in human, it is not known whether the other factors such as central command and sensory afferent information are involved in restoration of bipedal walking especially after incomplete SCI. To address this issue we have conducted a series of experiments, which aimed to reveal effects of both sensory inputs and descending commands on excitability modulation of neural circuits involving human bipedal locomotion. By using the Lokomat robotic gait trainer, we tested effects of sensory inputs on corticospinal (CS) excitabilities during assisted stepping. The results so far demonstrate that sensory inputs, especially body-weight related somatosensory input, have a facilitatory effect on CS pathway of an ankle flexor muscle, whereas those sensory inputs regardless of body-weight related or not have an inhibitory effect on spinal stretch reflex circuits of upper and lower limb muscles during the assisted stepping.

G020032 スプリットベルトトレッドミルを用いた外乱入力に対するヒトニ足歩行運動の位相反応曲線の計測

G020032 スプリットベルトトレッドミルを用いた外乱入力に対するヒトニ足歩行運動の位相反応曲線の計測

New vertebral and rib material point to modern bauplan of the Nariokotome Homo erectus skeleton

The double S shape of the vertebral column is one of the most important evolutionary adaptations to human bipedal locomotion, providing an optimal compromise between stability and mobility. It is commonly believed that a six element long lumbar spine facilitated the critical adoption of lumbar lordosis in early hominins, which contrasts with five lumbars in modern humans and four in chimpanzees and gorillas. This is mainly based on the juvenile Homo erectus skeleton KNM-WT 15000 from Nariokotome, Kenya. Yet, the biomechanical advantage of a long lumbar spine is speculative. Here we present new vertebral and rib fragments of KNM-WT 15000. They demonstrate that the sixth to the last presacral vertebra possesses rib facets and therefore indicate the presence of only five lumbar and twelve thoracic segments, as is characteristic of modern humans. Moreover, they show that no additional element was located between the sixth to the last presacral vertebra and Th11 as suggested in the original description. The transition from thoracic to lumbar type orientation of the facet joints that takes place at Th11 is thus at the same segment as in over 40% of modern humans, suggesting an identical lumbar mobility and capacity for lordosis. Taken together, KNM-WT 15000 had one vertebra less than previously thought irrespective of whether rib-free lumbar vertebrae or vertebrae that bear lumbar-like articular processes are counted. Furthermore, the new rib fragments imply a rearrangement of the ribs that results in a symmetrical rib cage. This challenges previous claims for idiopathic or congenital scoliosis. We conclude that the bauplan of the hominin axial skeleton is more conservative than previously thought.

209204 ヒト二足歩行運動の外乱に対する位相反応曲線の計測(OS05 生体の計測とモデリング2,オーガナイズド・セッション)

209204 ヒト二足歩行運動の外乱に対する位相反応曲線の計測(OS05 生体の計測とモデリング2,オーガナイズド・セッション)

Articular to diaphyseal proportions of human and great ape metatarsals

This study proposes a new way to use metatarsals to identify locomotor behavior of fossil hominins. Metatarsal head articular dimensions and diaphyseal strength in a sample of chimpanzees, gorillas, orangutans, and humans (n = 76) are used to explore the relationships of these parameters with different locomotor modes. Results show that ratios between metatarsal head articular proportions and diaphyseal strength of the hallucal and fifth metatarsal discriminate among extant great apes and humans based on their different locomotor modes. In particular, the hallucal and fifth metatarsal characteristics of humans are functionally related to the different ranges of motion and load patterns during stance phase in the forefoot of humans in bipedal locomotion. This method may be applicable to isolated fossil hominin metatarsals to provide new information relevant to debates regarding the evolution of human bipedal locomotion. The second to fourth metatarsals are not useful in distinguishing among hominoids. Further studies should concentrate on measuring other important qualitative and quantitative differences in the shape of the metatarsal head of hominoids that are not reflected in simple geometric reconstructions of the articulation, and gathering more forefoot kinematic data on great apes to better understand differences in range of motion and loading patterns of the metatarsals.

Evaluating functional roles of phase resetting in generation of adaptive human bipedal walking with a physiologically based model of the spinal pattern generator

The central pattern generators (CPGs) in the spinal cord strongly contribute to locomotor behavior. To achieve adaptive locomotion, locomotor rhythm generated by the CPGs is suggested to be functionally modulated by phase resetting based on sensory afferent or perturbations. Although phase resetting has been investigated during fictive locomotion in cats, its functional roles in actual locomotion have not been clarified. Recently, simulation studies have been conducted to examine the roles of phase resetting during human bipedal walking, assuming that locomotion is generated based on prescribed kinematics and feedback control. However, such kinematically based modeling cannot be used to fully elucidate the mechanisms of adaptation. In this article we proposed a more physiologically based mathematical model of the neural system for locomotion and investigated the functional roles of phase resetting. We constructed a locomotor CPG model based on a two-layered hierarchical network model of the rhythm generator (RG) and pattern formation (PF) networks. The RG model produces rhythm information using phase oscillators and regulates it by phase resetting based on foot-contact information. The PF model creates feedforward command signals based on rhythm information, which consists of the combination of five rectangular pulses based on previous analyses of muscle synergy. Simulation results showed that our model establishes adaptive walking against perturbing forces and variations in the environment, with phase resetting playing important roles in increasing the robustness of responses, suggesting that this mechanism of regulation may contribute to the generation of adaptive human bipedal locomotion.

0921 ヒトの歩行運動における腕振り動作の役割(GS15-2:福祉工学2)

0921 ヒトの歩行運動における腕振り動作の役割(GS15-2:福祉工学2)

Gait analysis and synthesis: Biomechanics, orthotics, prosthetics

The analysis of human bipedal locomotion is of interest to many different disciplines, including biomechanics, human movement science, rehabilitation and medicine in general. Gait is the collective term for the two types of bipedal locomotion, walking and running. In this paper, we will deal only with walking. The objective is to alter pathological walking by means of orthotic or prosthetic aids. Gait analysis involves basic measurements, such as walking speed, step length and cadence, and more detailed measures of the relative motion of body segments and joints, the patterns of forces applied to the ground and the sequence and timing of muscular activity. The movements of joints and segments, including position, velocity and acceleration, are termed kinematics. Kinematic data are obtained by contactless movement tracking systems that use video cameras for tracking reflective markers attached to predetermined anatomical positions on the selected body parts. The pattern of forces is obtained from force platforms, sensors that are imbedded in the floor of a laboratory, that measure the forces exerted by the foot when in contact with the ground. These ground reaction forces, are used together with kinematic and anthropometric data, segment sizes, masses and inertial properties, to calculate net joint torques produced by muscular activity during gait. This calculation requires the application of general equations of motion in the inverse dynamics model of the human body (Koopman paper, Chap1). These models constitute a part of the software of modern movement tracking systems. The ground reaction forces and the net joint torques are termed kinetics. The patterns of muscular activity are termed electromyographs and can be obtained from surface electrodes applied over the skin of the muscle of interest. Kinematics, kinetics and electromyography represent important variables that help the clinicians to understand a particular gait pattern and to discriminate primary gait abnormalities, from the compensatory changes that are the consequence of the former. Based on an understanding of a pathological gait, a treatment procedure or application of suitable orthotics and prosthetics can be devised. However, understanding complex gait patterns is a challenging task for clinicians, as walking is largely defined by biomechanical laws. While understanding normal gait patterns can be learned through descriptions of events and observations during walking, the

Shaping Appropriate Locomotive Motor Output Through Interlimb Neural Pathway Within Spinal Cord in Humans

Direct evidence supporting the contribution of upper limb motion on the generation of locomotive motor output in humans is still limited. Here, we aimed to examine the effect of upper limb motion on locomotor-like muscle activities in the lower limb in persons with spinal cord injury (SCI). By imposing passive locomotion-like leg movements, all cervical incomplete (n = 7) and thoracic complete SCI subjects (n = 5) exhibited locomotor-like muscle activity in their paralyzed soleus muscles. Upper limb movements in thoracic complete SCI subjects did not affect the electromyographic (EMG) pattern of the muscle activities. This is quite natural since neural connections in the spinal cord between regions controlling upper and lower limbs were completely lost in these subjects. On the other hand, in cervical incomplete SCI subjects, in whom such neural connections were at least partially preserved, the locomotor-like muscle activity was significantly affected by passively imposed upper limb movements. Specifically, the upper limb movements generally increased the soleus EMG activity during the backward swing phase, which corresponds to the stance phase in normal gait. Although some subjects showed a reduction of the EMG magnitude when arm motion was imposed, this was still consistent with locomotor-like motor output because the reduction of the EMG occurred during the forward swing phase corresponding to the swing phase. The present results indicate that the neural signal induced by the upper limb movements contributes not merely to enhance but also to shape the lower limb locomotive motor output, possibly through interlimb neural pathways. Such neural interaction between upper and lower limb motions could be an underlying neural mechanism of human bipedal locomotion.

Simulating Adaptive Human Bipedal Locomotion Based on Phase Resetting Using Foot-Contact Information

Humans generate bipedal walking by cooperatively manipulating their complicated and redundant musculoskeletal systems to produce adaptive behaviors in diverse environments. To elucidate the mechanisms that generate adaptive human bipedal locomotion, we conduct numerical simulations based on a musculoskeletal model and a locomotor controller constructed from anatomical and physiological findings. In particular, we focus on the adaptive mechanism using phase resetting based on the foot-contact information that modulates the walking behavior. For that purpose, we first reconstruct walking behavior from the measured kinematic data. Next, we examine the roles of phase resetting on the generation of stable locomotion by disturbing the walking model. Our results indicate that phase resetting increases the robustness of the walking behavior against perturbations, suggesting that this mechanism contributes to the generation of adaptive human bipedal locomotion.

Modelling, stability and biomechanical implications of three DOF passive bipedal gait

Passive dynamic walkers can achieve a steady gait down an inclined plane simply by the influence of gravity. This article presents the modelling of a 3 DOF passive bipedal walker, searching for a relationship between gait characteristics, the robot's physical properties and the slope of the plane. The proposed adimensional dynamical model’s equations are also given, implementing and modelling the dynamics is described and the main results are presented. Limits on robotic parameters leading to establishing stable limit cycles are also analysed as periodic doubling bifurcations appear to be natural in passive gait. Interesting results arose when comparing natural passive walking with human bipedal locomotion.

Resolving Head Rotation for Human Bipedalism

Alignment of the body to the gravitational vertical is considered to be the key to human bipedalism. However, changes to the semicircular canals during human evolution suggest that the sense of head rotation that they provide is important for modern human bipedal locomotion. When walking, the canals signal a mix of head rotations associated with path turns, balance perturbations, and other body movements. It is uncertain how the brain uses this information. Here, we show dual roles for the semicircular canals in balance control and navigation control. We electrically evoke a head-fixed virtual rotation signal from semicircular canal nerves as subjects walk in the dark with their head held in different orientations. Depending on head orientation, we can either steer walking by "remote control" or produce balance disturbances. This shows that the brain resolves the canal signal according to head posture into Earth-referenced orthogonal components and uses rotations in vertical planes to control balance and rotations in the horizontal plane to navigate. Because the semicircular canals are concerned with movement rather than detecting vertical alignment, this result shows the importance of movement control and agility rather than precise vertical alignment of the body for human bipedalism.

Speculation on the responsible sites and pathophysiology of freezing of gait

Freezing of gait (FOG) is a symptom characterized by difficulty in taking the first step when a patient begins to walk; it is experienced most frequently in Parkinson's disease, and is also one of the major symptoms of gait apraxia. The brain sites responsible for FOG have not yet been determined. FOG is believed to derive from dysfunction of higher centers for human bipedal locomotion. Recent brain activation studies have suggested that the medial frontoparietal cortex, including the supplementary motor area (SMA), is a central higher center for bipedal locomotion in humans. FOG is most frequently observed in patients with Parkinson's disease, whose pathophysiology is a functional change in the motor circuit induced by dopaminergic denervation. Overactivity or altered firing patterns of the internal segment of the globus pallidus (GPi) may excessively inhibit or disorganize the thalamocortical projection, of which a major cortical target is the SMA. It has been recognized that gait apraxia is associated with mesial or medial frontal cortical lesions. Considering that the brain activation sites in human locomotion and the brain lesion sites manifesting freezing gait share common areas, the brain sites responsible for FOG are presumably located in the medial frontoparietal area. The SMA may be a major structure in the center; however, the neural network related to FOG may extend to its adjacent areas. FOG can be classified into two types, in terms of responsiveness to treatment: (1) FOG responsive to levodopa and neurosurgery targeting the subthalamic nucleus (STN) or GPi; and (2) FOG unresponsive to either levodopa or neurosurgery. The responsive type is observed in cases with less advanced Parkinson's disease, in which dysfunction of the SMA and adjacent areas can be reversed by normalization of the motor circuit function by levodopa treatment or neurosurgery. The unresponsive type is observed in advanced Parkinson's disease, primary progressive freezing gait, or frontal lobe lesions, and the underlying pathology may consist of irreversible changes of the SMA and adjacent areas, or of the structures of the motor circuit. The involvement of transmitters other than dopamine, including norepinephrine, in the pathophysiology of FOG remains undetermined.

Fossils, feet and the evolution of human bipedal locomotion.

We review the evolution of human bipedal locomotion with a particular emphasis on the evolution of the foot. We begin in the early twentieth century and focus particularly on hypotheses of an ape-like ancestor for humans and human bipedal locomotion put forward by a succession of Gregory, Keith, Morton and Schultz. We give consideration to Morton's (1935) synthesis of foot evolution, in which he argues that the foot of the common ancestor of modern humans and the African apes would be intermediate between the foot of Pan and Hylobates whereas the foot of a hypothetical early hominin would be intermediate between that of a gorilla and a modern human. From this base rooted in comparative anatomy of living primates we trace changing ideas about the evolution of human bipedalism as increasing amounts of postcranial fossil material were discovered. Attention is given to the work of John Napier and John Robinson who were pioneers in the interpretation of Plio-Pleistocene hominin skeletons in the 1960s. This is the period when the wealth of evidence from the southern African australopithecine sites was beginning to be appreciated and Olduvai Gorge was revealing its first evidence for Homo habilis. In more recent years, the discovery of the Laetoli footprint trail, the AL 288-1 (A. afarensis) skeleton, the wealth of postcranial material from Koobi Fora, the Nariokotome Homo ergaster skeleton, Little Foot (Stw 573) from Sterkfontein in South Africa, and more recently tantalizing material assigned to the new and very early taxa Orrorin tugenensis, Ardipithecus ramidus and Sahelanthropus tchadensis has fuelled debate and speculation. The varying interpretations based on this material, together with changing theoretical insights and analytical approaches, is discussed and assessed in the context of new three-dimensional morphometric analyses of australopithecine and Homo foot bones, suggesting that there may have been greater diversity in human bipedalism in the earlier phases of our evolutionary history than previously suspected.

The energetic cost of locomotion: humans and primates compared to generalized endotherms.

A wide range of selective pressures have been advanced as possible causes for the adoption of bipedalism in the hominin lineage. One suggestion has been that because modern human walking is relatively efficient compared to that of a typical quadruped, the ancestral quadruped may have reaped an energetic advantage when it walked on two legs. While it has become clear that human walking is relatively efficient and human running inefficient compared to "generalized endotherms", workers differ in their opinion of how the cost of human bipedal locomotion compares to that of a generalized primate walking quadrupedally. One view is that human walking is particularly efficient in comparison to other primates. The present study addresses this by comparing the cost of human walking and running to that of the eight primate species for which data are available and by comparing cost in primates to that of a "generalized endotherm". There is no evidence that primate locomotion is more costly than that of a generalized endotherm, although more data on adult Old World monkeys and apes would be useful. Further, human locomotion does not appear to be particularly efficient relative to that of other primates.