Motor Patterns for Human Gait: Backward Versus Forward Locomotion

1998 ◽  
Vol 80 (4) ◽  
pp. 1868-1885 ◽  
Author(s):  
R. Grasso ◽  
L. Bianchi ◽  
F. Lacquaniti
Keyword(s):  
Time Course ◽  
Cross Correlation ◽  
Gait Cycle ◽  
Human Gait ◽  
Emg Activity ◽  
Ground Reaction Forces ◽  
Motor Patterns ◽  
Cross Correlation Analysis ◽  
Reaction Forces ◽  
Forward Locomotion

Grasso, R., L. Bianchi, and F. Lacquaniti. Motor patterns for human gait: backward versus forward locomotion. J. Neurophysiol. 80: 1868–1885, 1998. Seven healthy subjects walked forward (FW) and backward (BW) at different freely chosen speeds, while their motion, ground reaction forces, and electromyographic (EMG) activity from lower limb muscles were recorded. We considered the time course of the elevation angles of the thigh, shank, and foot segments in the sagittal plane, the anatomic angles of the hip, knee, and ankle joints, the vertical and longitudinal ground reaction forces, and the rectified EMGs. The elevation angles were the most reproducible variables across trials in each walking direction. After normalizing the time course of each variable over the gait cycle duration, the waveforms of all elevation angles in BW gait were essentially time reversed relative to the corresponding waveforms in FW gait. Moreover, the changes of the thigh, shank, and foot elevation covaried along a plane during the whole gait cycle in both FW and BW directions. Cross-correlation analysis revealed that the phase coupling among these elevation angles is maintained with a simple reversal of the delay on the reversal of walking direction. The extent of FW–BW correspondence also was good for the hip angle, but it was smaller for the knee and ankle angles and for the ground reaction forces. The EMG patterns were drastically different in the two movement directions as was the organization of the muscular synergies measured by cross-correlation analysis. Moreover, at any given speed, the mean EMG activity over the gait cycle was generally higher in BW than in FW gait, suggesting a greater level of energy expenditure in the former task. We argue that conservation of kinematic templates across gait reversal at the expense of a complete reorganization of muscle synergies does not arise from biomechanical constraints but may reflect a behavioral goal achieved by the central networks involved in the control of locomotion.

Interactions Between Posture and Locomotion: Motor Patterns in Humans Walking With Bent Posture Versus Erect Posture

2000 ◽  
Vol 83 (1) ◽  
pp. 288-300 ◽  
Author(s):  
R. Grasso ◽  
M. Zago ◽  
F. Lacquaniti
Keyword(s):  
Gait Cycle ◽  
Emg Activity ◽  
Muscle Synergies ◽  
Ground Reaction Forces ◽  
Motor Patterns ◽  
Erect Posture ◽  
Body Segments ◽  
Plane Orientation ◽  
Temporal Coupling ◽  
Reaction Forces

Human erect locomotion is unique among living primates. Evolution selected specific biomechanical features that make human locomotion mechanically efficient. These features are matched by the motor patterns generated in the CNS. What happens when humans walk with bent postures? Are normal motor patterns of erect locomotion maintained or completely reorganized? Five healthy volunteers walked straight and forward at different speeds in three different postures (regular, knee-flexed, and knee- and trunk-flexed) while their motion, ground reaction forces, and electromyographic (EMG) activity were recorded. The three postures imply large differences in the position of the center of body mass relative to the body segments. The elevation angles of the trunk, pelvis, and lower limb segments relative to the vertical in the sagittal plane, the ground reaction forces and the rectified EMGs were analyzed over the gait cycle. The waveforms of the elevation angles along the gait cycle remained essentially unchanged irrespective of the adopted postures. The first two harmonics of these kinematic waveforms explain >95% of their variance. The phase shift but not the amplitude ratio between the first harmonic of the elevation angle waveforms of adjacent pairs was affected systematically by changes in posture. Thigh, shank, and foot angles covaried close to a plane in all conditions, but the plane orientation was systematically different in bent versus erect locomotion. This was explained by the changes in the temporal coupling among the three segments. For walking speeds >1 m s−1, the plane orientation of bent locomotion indicates a much lower mechanical efficiency relative to erect locomotion. Ground reaction forces differed prominently in bent versus erect posture displaying characteristics intermediate between those typical of walking and those of running. Mean EMG activity was greater in bent postures for all recorded muscles independent of the functional role. The waveforms of the muscle activities and muscle synergies also were affected by the adopted posture. We conclude that maintaining bent postures does not interfere either with the generation of segmental kinematic waveforms or with the planar constraint of intersegmental covariation. These characteristics are maintained at the expense of adjustments in kinetic parameters, muscle synergies and the temporal coupling among the oscillating body segments. We argue that an integrated control of gait and posture is made possible because these two motor functions share some common principles of spatial organization.

Single-Neuron Analysis of Human Thalamus in Patients With Intention Tremor and Other Clinical Signs of Cerebellar Disease

2002 ◽  
Vol 87 (4) ◽  
pp. 2084-2094 ◽  
Author(s):  
F. A. Lenz ◽  
C. J. Jaeger ◽  
M. S. Seike ◽  
Y. C. Lin ◽  
S. G. Reich
Keyword(s):  
Neuronal Activity ◽  
Cross Correlation ◽  
Clinical Signs ◽  
Emg Activity ◽  
Phase Lag ◽  
Cerebellar Disease ◽  
Intention Tremor ◽  
Cross Correlation Analysis ◽  
Relay Nucleus ◽  
Cerebellar Tremor

Tremor that occurs as a result of a cerebellar lesion, cerebellar tremor, is characteristically an intention tremor. Thalamic activity may be related to cerebellar tremor because transmission of some cerebellar efferent signals occurs via the thalamus and cortex to the periphery. We have now studied thalamic neuronal activity in a cerebellar relay nucleus (ventral intermediate—Vim) and a pallidal relay nucleus (ventralis oral posterior—Vop) during thalamotomy in patients with intention tremor and other clinical signs of cerebellar disease (tremor patients). The activity of single neurons and the simultaneous electromyographic (EMG) activity of the contralateral upper extremity in tremor patients performing a pointing task were analyzed by spectral cross-correlation analysis. EMG spectra during intention tremor often showed peaks of activity in the tremor-frequency range (1.9–5.8 Hz). There were significant differences in thalamic neuronal activity between tremor patients and controls. Neurons in Vim and Vop had significantly lower firing rates in tremor patients than in patients undergoing thalamic surgery for pain (pain controls). Other studies have shown that inputs to Vim from the cerebellum are transmitted through excitatory connections. Therefore the present results suggest that tremor in these tremor patients is associated with deafferentation of the thalamus from cerebellar efferent pathways. The thalamic X EMG cross-correlation functions were studied for cells located in Vim and Vop. Neuronal and EMG activity were as likely to be significantly correlated for cells in Vim as for those in Vop. Cells in Vim were more likely to have a phase lag relative to EMG than were cells in Vop. In monkeys, cells in the cerebellar relay nucleus of the thalamus, corresponding to Vim, are reported to lead movement during active oscillations at the wrist. In view of these monkey studies, the present results suggest that cells in Vim are deafferented and have a phase lag relative to tremor that is not found in normal active oscillations. The difference in phase of thalamic spike X EMG activity between Vim and Vop may contribute to tremor because lesions of pallidum or Vop are reported to relieve cerebellar tremor.

Twisting and Bending: The Functional Role of Salamander Lateral Hypaxial Musculature During Locomotion

2001 ◽  
Vol 204 (11) ◽  
pp. 1979-1989 ◽  
Author(s):  
Wallace O. Bennett ◽  
Rachel S. Simons ◽  
Elizabeth L. Brainerd
Keyword(s):  
High Intensity ◽  
High Speed ◽  
The Body ◽  
Transversus Abdominis ◽  
Fine Motor ◽  
Emg Activity ◽  
Ground Reaction Forces ◽  
Terrestrial Locomotion ◽  
Reaction Forces ◽  
Hypaxial Muscle

SUMMARY The function of the lateral hypaxial muscles during locomotion in tetrapods is controversial. Currently, there are two hypotheses of lateral hypaxial muscle function. The first, supported by electromyographic (EMG) data from a lizard (Iguana iguana) and a salamander (Dicamptodon ensatus), suggests that hypaxial muscles function to bend the body during swimming and to resist long-axis torsion during walking. The second, supported by EMG data from lizards during relatively high-speed locomotion, suggests that these muscles function primarily to bend the body during locomotion, not to resist torsional forces. To determine whether the results from D. ensatus hold for another salamander, we recorded lateral hypaxial muscle EMGs synchronized with body and limb kinematics in the tiger salamander Ambystoma tigrinum. In agreement with results from aquatic locomotion in D. ensatus, all four layers of lateral hypaxial musculature were found to show synchronous EMG activity during swimming in A. tigrinum. Our findings for terrestrial locomotion also agree with previous results from D. ensatus and support the torsion resistance hypothesis for terrestrial locomotion. We observed asynchronous EMG bursts of relatively high intensity in the lateral and medial pairs of hypaxial muscles during walking in tiger salamanders (we call these ‘α-bursts’). We infer from this pattern that the more lateral two layers of oblique hypaxial musculature, Mm. obliquus externus superficialis (OES) and obliquus externus profundus (OEP), are active on the side towards which the trunk is bending, while the more medial two layers, Mm. obliquus internus (OI) and transversus abdominis (TA), are active on the opposite side. This result is consistent with the hypothesis proposed for D. ensatus that the OES and OEP generate torsional moments to counteract ground reaction forces generated by forelimb support, while the OI and TA generate torsional moments to counteract ground reaction forces from hindlimb support. However, unlike the EMG pattern reported for D. ensatus, a second, lower-intensity burst of EMG activity (‘β-burst’) was sometimes recorded from the lateral hypaxial muscles in A. tigrinum. As seen in other muscle systems, these β-bursts of hypaxial muscle coactivation may function to provide fine motor control during locomotion. The presence of asynchronous, relatively high-intensity α-bursts indicates that the lateral hypaxial muscles generate torsional moments during terrestrial locomotion, but it is possible that the balance of forces from both α- and β-bursts may allow the lateral hypaxial muscles to contribute to lateral bending of the body as well.

A Robotic Cadaveric Flatfoot Analysis of Stance Phase

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Lyle T. Jackson ◽  
Patrick M. Aubin ◽  
Matthew S. Cowley ◽  
Bruce J. Sangeorzan ◽  
William R. Ledoux
Keyword(s):  
Surgical Treatment ◽  
Degrees Of Freedom ◽  
Stance Phase ◽  
Gait Cycle ◽  
Ground Reaction Forces ◽  
Pes Planus ◽  
Reaction Forces ◽  
Vertical Ground

The symptomatic flatfoot deformity (pes planus with peri-talar subluxation) can be a debilitating condition. Cadaveric flatfoot models have been employed to study the etiology of the deformity, as well as invasive and noninvasive surgical treatment strategies, by evaluating bone positions. Prior cadaveric flatfoot simulators, however, have not leveraged industrial robotic technologies, which provide several advantages as compared with the previously developed custom fabricated devices. Utilizing a robotic device allows the researcher to experimentally evaluate the flatfoot model at many static instants in the gait cycle, compared with most studies, which model only one to a maximum of three instances. Furthermore, the cadaveric tibia can be statically positioned with more degrees of freedom and with a greater accuracy, and then a custom device typically allows. We created a six degree of freedom robotic cadaveric simulator and used it with a flatfoot model to quantify static bone positions at ten discrete instants over the stance phase of gait. In vivo tibial gait kinematics and ground reaction forces were averaged from ten flatfoot subjects. A fresh frozen cadaveric lower limb was dissected and mounted in the robotic gait simulator (RGS). Biomechanically realistic extrinsic tendon forces, tibial kinematics, and vertical ground reaction forces were applied to the limb. In vitro bone angular position of the tibia, calcaneus, talus, navicular, medial cuneiform, and first metatarsal were recorded between 0% and 90% of stance phase at discrete 10% increments using a retroreflective six-camera motion analysis system. The foot was conditioned flat through ligament attenuation and axial cyclic loading. Post-flat testing was repeated to study the pes planus deformity. Comparison was then made between the pre-flat and post-flat conditions. The RGS was able to recreate ten gait positions of the in vivo pes planus subjects in static increments. The in vitro vertical ground reaction force was within ±1 standard deviation (SD) of the in vivo data. The in vitro sagittal, coronal, and transverse plane tibial kinematics were almost entirely within ±1 SD of the in vivo data. The model showed changes consistent with the flexible flatfoot pathology including the collapse of the medial arch and abduction of the forefoot, despite unexpected hindfoot inversion. Unlike previous static flatfoot models that use simplified tibial degrees of freedom to characterize only the midpoint of the stance phase or at most three gait positions, our simulator represented the stance phase of gait with ten discrete positions and with six tibial degrees of freedom. This system has the potential to replicate foot function to permit both noninvasive and surgical treatment evaluations throughout the stance phase of gait, perhaps eliciting unknown advantages or disadvantages of these treatments at other points in the gait cycle.

Predicting Complete Ground Reaction Forces and Moments During Gait With Insole Plantar Pressure Information Using a Wavelet Neural Network

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Taeyong Sim ◽  
Hyunbin Kwon ◽  
Seung Eel Oh ◽  
Su-Bin Joo ◽  
Ahnryul Choi ◽  
...  
Keyword(s):  
Neural Network ◽  
Prediction Model ◽  
Plantar Pressure ◽  
Prediction Models ◽  
Pressure Sensors ◽  
Principal Component ◽  
Wavelet Neural Network ◽  
Human Gait ◽  
Ground Reaction Forces ◽  
Reaction Forces

In general, three-dimensional ground reaction forces (GRFs) and ground reaction moments (GRMs) that occur during human gait are measured using a force plate, which are expensive and have spatial limitations. Therefore, we proposed a prediction model for GRFs and GRMs, which only uses plantar pressure information measured from insole pressure sensors with a wavelet neural network (WNN) and principal component analysis-mutual information (PCA-MI). For this, the prediction model estimated GRFs and GRMs with three different gait speeds (slow, normal, and fast groups) and healthy/pathological gait patterns (healthy and adolescent idiopathic scoliosis (AIS) groups). Model performance was validated using correlation coefficients (r) and the normalized root mean square error (NRMSE%) and was compared to the prediction accuracy of the previous methods using the same dataset. As a result, the performance of the GRF and GRM prediction model proposed in this study (slow group: r = 0.840–0.989 and NRMSE% = 10.693–15.894%; normal group: r = 0.847–0.988 and NRMSE% = 10.920–19.216%; fast group: r = 0.823–0.953 and NRMSE% = 12.009–20.182%; healthy group: r = 0.836–0.976 and NRMSE% = 12.920–18.088%; and AIS group: r = 0.917–0.993 and NRMSE% = 7.914–15.671%) was better than that of the prediction models suggested in previous studies for every group and component (p < 0.05 or 0.01). The results indicated that the proposed model has improved performance compared to previous prediction models.

scholarly journals Effects of Cooling on Ankle Muscle Strength, Electromyography, and Gait Ground Reaction Forces

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Amitava Halder ◽  
Chuansi Gao ◽  
Michael Miller
Keyword(s):  
Cold Water ◽  
Isometric Force ◽  
Force Plate ◽  
Muscle Performance ◽  
Emg Activity ◽  
Ground Reaction Forces ◽  
Local Cooling ◽  
Ankle Muscle ◽  
Reaction Forces ◽  
And Performance

The effects of cooling on neuromuscular function and performance during gait are not fully examined. The purpose of this study was to investigate the effects of local cooling for 20 min in cold water at 10°C in a climate chamber also at 10°C on maximal isometric force and electromyographic (EMG) activity of the lower leg muscles. Gait ground reaction forces (GRFs) were also assessed. Sixteen healthy university students participated in the within subject design experimental study. Isometric forces of the tibialis anterior (TA) and the gastrocnemius medialis (GM) were measured using a handheld dynamometer and the EMG was recorded using surface electrodes. Ground reaction forces during gait and the required coefficient of friction (RCOF) were recorded using a force plate. There was a significantly reduced isometric maximum force in the TA muscle (P<0.001) after cooling. The mean EMG amplitude of GM muscle was increased after cooling (P<0.003), indicating that fatigue was induced. We found no significant changes in the gait GRFs and RCOF on dry and level surface. These findings may indicate that local moderate cooling 20 min of 10°C cold water, may influence maximal muscle performance without affecting activities at sub-maximal effort.

Torque patterns of the limbs of small therian mammals during locomotion on flat ground

2002 ◽  
Vol 205 (9) ◽  
pp. 1339-1353 ◽  
Author(s):  
Hartmut Witte ◽  
Jutta Biltzinger ◽  
Rémi Hackert ◽  
Nadja Schilling ◽  
Manuela Schmidt ◽  
...  
Keyword(s):  
Ankle Joint ◽  
Hip Joint ◽  
Time Course ◽  
Wrist Joint ◽  
Ground Reaction Forces ◽  
Inverse Dynamic ◽  
Scanning Method ◽  
Joint Torques ◽  
Joint Forces ◽  
Reaction Forces

SUMMARY In three species of small therian mammals (Scandentia: Tupaia glis, Rodentia: Galea musteloides and Lagomorpha: Ochotona rufescens) the net joint forces and torques acting during stance phase in the four kinematically relevant joints of the forelimbs (scapular pivot,shoulder joint, elbow joint, wrist joint) and the hindlimbs (hip joint, knee joint, ankle joint, intratarsal joint) were determined by inverse dynamic analysis. Kinematics were measured by cineradiography (150 frames s-1). Synchronously ground reaction forces were acquired by forceplates. Morphometry of the extremities was performed by a scanning method using structured illumination. The vector sum of ground reaction forces and weight accounts for most of the joint force vector. Inertial effects can be neglected since errors of net joint forces amount at most to 10 %. The general time course of joint torques is comparable for all species in all joints of the forelimb and in the ankle joint. Torques in the intratarsal joints differ between tailed and tail-less species. The torque patterns in the knee and hip joint are unique to each species. For the first time torque patterns are described completely for the forelimb including the scapula as the dominant propulsive segment. The results are compared with the few torque data available for various joints of cats(Felis catus), dogs (Canis lupus f. familiaris),goats (Capra sp.) and horses (Equus przewalskii f. caballus).

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