scholarly journals Transition versus Continuous Slope Walking: Adaptation to Change Center of Mass Velocity in Young Men

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Yoon No Gregory Hong ◽  
Jinkyu Lee ◽  
Choongsoo S. Shin
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Force Plate ◽  
Human Locomotion ◽  
The Body ◽  
Initial Contact ◽  
Horizontal Distance ◽  
Downhill Walking ◽  
Walking Adaptation ◽  
Propulsion Phase

During continuous uphill walking (UW) or downhill walking, human locomotion is modified to counteract the gravitational force, aiding or impeding the body’s forward momentum, respectively. This study aimed at investigating the center of mass (COM) and center of pressure (COP) velocities and their relative distance during the transition from uphill to downhill walking (UDW) to determine whether locomotor adjustments differ between UDW and UW. Fourteen participants walked on a triangular slope and a continuous upslope of 15°. The kinematics and COPs were obtained using a force plate and a motion capture system. The vertical velocity of the COM in the propulsion phase, the horizontal distance between the COM and COP at initial contact, and the duration of the subphases significantly differed between UDW and UW (all p<0.05). Compared with the results of UW, longer durations and the deeper downward moving COM in the propulsion phase were observed during UDW (all p<0.05). Additionally, a shorter horizontal distance between the COM and COP at initial contact was associated with a slower vertical COM velocity in the propulsion phase during UDW. The reduced velocity is likely a gait alteration to decrease the forward momentum of the body during UDW.

scholarly journals Can Muscle Stiffness Alone Stabilize Upright Standing?

1999 ◽  
Vol 82 (3) ◽  
pp. 1622-1626 ◽  
Author(s):  
Pietro G. Morasso ◽  
Marco Schieppati
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Muscle Stiffness ◽  
The Body ◽  
Ankle Muscles ◽  
Upright Standing ◽  
Stiffness Control ◽  
Control Patterns ◽  
Physiological Values

A stiffness control model for the stabilization of sway has been proposed recently. This paper discusses two inadequacies of the model: modeling and empiric consistency. First, we show that the in-phase relation between the trajectories of the center of pressure and the center of mass is determined by physics, not by control patterns. Second, we show that physiological values of stiffness of the ankle muscles are insufficient to stabilize the body “inverted pendulum.” The evidence of active mechanisms of sway stabilization is reviewed, pointing out the potentially crucial role of foot skin and muscle receptors.

scholarly journals Human kinematic, kinetic and EMG data during different walking and stair ascending and descending tasks

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Tiziana Lencioni ◽  
Ilaria Carpinella ◽  
Marco Rabuffetti ◽  
Alberto Marzegan ◽  
Maurizio Ferrarin
Keyword(s):  
Lower Limb ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Simulation Models ◽  
Human Locomotion ◽  
Surface Emg ◽  
Whole Body ◽  
Bipedal Robots ◽  
Lower Limb Muscles ◽  
Reaction Forces

AbstractThis paper reports the kinematic, kinetic and electromyographic (EMG) dataset of human locomotion during level walking at different velocities, toe- and heel-walking, stairs ascending and descending. A sample of 50 healthy subjects, with an age between 6 and 72 years, is included. For each task, both raw data and computed variables are reported including: the 3D coordinates of external markers, the joint angles of lower limb in the sagittal, transversal and horizontal anatomical planes, the ground reaction forces and torques, the center of pressure, the lower limb joint mechanical moments and power, the displacement of the whole body center of mass, and the surface EMG signals of the main lower limb muscles. The data reported in the present study, acquired from subjects with different ages, represents a valuable dataset useful for future studies on locomotor function in humans, particularly as normative reference to analyze pathological gait, to test the performance of simulation models of bipedal locomotion, and to develop control algorithms for bipedal robots or active lower limb exoskeletons for rehabilitation.

Validating Determinants for an Alternate Foot Placement Selection Algorithm During Human Locomotion in Cluttered Terrain

2007 ◽  
Vol 98 (4) ◽  
pp. 1928-1940 ◽  
Author(s):  
Renato Moraes ◽  
Fran Allard ◽  
Aftab E. Patla
Keyword(s):  
Dynamic Stability ◽  
Center Of Mass ◽  
Frontal Plane ◽  
Human Locomotion ◽  
The Body ◽  
Selection Algorithm ◽  
Foot Placement ◽  
Double Support ◽  
One Step ◽  
Base Of Support

The goal of this study was to validate dynamic stability and forward progression determinants for the alternate foot placement selection algorithm. Participants were asked to walk on level ground and avoid stepping, when present, on a virtual white planar obstacle. They had a one-step duration to select an alternate foot placement, with the task performed under two conditions: free (participants chose the alternate foot placement that was appropriate) and forced (a green arrow projected over the white planar obstacle cued the alternate foot placement). To validate the dynamic stability determinant, the distance between the extrapolated center of mass (COM) position, which incorporates the dynamics of the body, and the limits of the base of support was calculated in both anteroposterior (AP) and mediolateral (ML) directions in the double support phase. To address the second determinant, COM deviation from straight ahead was measured between adaptive and subsequent steps. The results of this study showed that long and lateral choices were dominant in the free condition, and these adjustments did not compromise stability in both adaptive and subsequent steps compared with the short and medial adjustments, which were infrequent and adversely affected stability. Therefore stability is critical when selecting an alternate foot placement in a cluttered terrain. In addition, changes in the plane of progression resulted in small deviations of COM from the endpoint goal. Forward progression of COM was maintained even for foot placement changes in the frontal plane, validating this determinant as part of the selection algorithm.

Attributes of Quiet Stance in the Chronic Spinal Cat

1999 ◽  
Vol 82 (6) ◽  
pp. 3056-3065 ◽  
Author(s):  
Joyce Fung ◽  
Jane M. Macpherson
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Close Relation ◽  
Daily Basis ◽  
The Body ◽  
Spinal Reflexes ◽  
Emg Activity ◽  
Axis Orientation ◽  
Dynamic Task ◽  
Horizontal Orientation

Standing is a dynamic task that requires antigravity support of the body mass and active regulation of the position of the body center of mass. This study examined the extent to which the chronic spinal cat can maintain postural orientation during stance and adapt to changes in stance distance (fore-hindpaw separation). Intact cats adapt to changes in stance distance by maintaining a constant horizontal orientation of the trunk and changing orientation of the limbs, while keeping intralimb geometry constant and aligning the ground reaction forces closely with the limb axes. Postural adaptation was compared in four cats before and after spinalization at the T6 level, in terms of the forces exerted by each paw against the support, body geometry (kinematics) and electromyographic (EMG) activity recorded from chronic, indwelling electrodes, as well as the computed net torques in the fore and hindlimbs. Five fore-hindpaw distances spanning the preferred distance were tested before spinalization, with a total range of 20 cm from the shortest to the longest stance. After spinalization, the cats were trained on a daily basis to stand on the force platform, and all four cats were able to support their full body weight. Three of the four cats could adapt to changes in stance distance, but the range was smaller and biased toward the shorter distances. The fourth cat could stand only at one stance distance, which was 8 cm shorter than the preferred distance before spinalization. All cats shifted their center of pressure closer to the forelimbs after spinalization, but the amount of shift could largely be accounted for by the weight loss in the hindquarters. The three cats that could adapt to changes in stance distance used a similar strategy as the intact cat by constraining the trunk and changing orientation of the limb axes in close relation with the forces exerted by each limb. However, different postures in the fore- and hindlimbs were adopted, particularly at the scapula (more extended) and pelvis (tipped more anteriorly). Other changes from control included a redistribution of net extensor torque across the joints of the forelimb and of the hindlimb. We concluded that the general form of body axis orientation is relatively conserved in the spinal cat, suggesting that the lumbosacral spinal circuitry includes rudimentary set points for hindlimb geometry. Both mechanical and neural elements can contribute toward maintaining body geometry through stiffness regulation and spinal reflexes.

A Comprehensive Evaluation of Spine Kinematics, Kinetics, and Trunk Muscle Activities During Fatigue-Induced Repetitive Lifting

2021 ◽  
pp. 001872082098362
Author(s):  
Zeinab Kazemi ◽  
Adel Mazloumi ◽  
Navid Arjmand ◽  
Ahmadreza Keihani ◽  
Zanyar Karimi ◽  
...  
Keyword(s):  
Center Of Pressure ◽  
Comprehensive Evaluation ◽  
Center Of Mass ◽  
Force Plate ◽  
Compressive Force ◽  
Biomechanical Model ◽  
Trunk Muscle ◽  
Abdominal Muscles ◽  
Spine Kinematics ◽  
Posterior Direction

Objective Spine kinematics, kinetics, and trunk muscle activities were evaluated during different stages of a fatigue-induced symmetric lifting task over time. Background Due to neuromuscular adaptations, postural behaviors of workers during lifting tasks are affected by fatigue. Comprehensive aspects of these adaptations remain to be investigated. Method Eighteen volunteers repeatedly lifted a box until perceived exhaustion. Body center of mass (CoM), trunk and box kinematics, and feet center of pressure (CoP) were estimated by a motion capture system and force-plate. Electromyographic (EMG) signals of trunk/abdominal muscles were assessed using linear and nonlinear approaches. The L5-S1 compressive force (Fc) was predicted via a biomechanical model. A two-way multivariate analysis of variance (MANOVA) was performed to examine the effects of five blocks of lifting cycle (C1 to C5) and lifting trial (T1 to T5), as independent variables, on kinematic, kinetic, and EMG-related measures. Results Significant effects of lifting trial blocks were found for CoM and CoP shift in the anterior–posterior direction (respectively p < .001 and p = .014), trunk angle ( p = .004), vertical box displacement ( p < .001), and Fc ( p = .005). EMG parameters indicated muscular fatigue with the extent of changes being muscle-specific. Conclusion Results emphasized variations in most kinematics/kinetics, and EMG-based indices, which further provided insight into the lifting behavior adaptations under dynamic fatiguing conditions. Application Movement and muscle-related variables, to a large extent, determine the magnitude of spinal loading, which is associated with low back pain.

scholarly journals Effect of ultrasound-guided percutaneous neuromodulation in ankle instability: a case study

2019 ◽  
Vol 02 (02) ◽  
pp. 100-101
Author(s):  
Rodríguez Rosal M. ◽  
Sánchez Sixto A. ◽  
Álvarez Barbosa F. ◽  
Yáñez Álvarez A.
Keyword(s):  
Effect Size ◽  
Center Of Pressure ◽  
Tibial Nerve ◽  
Ankle Instability ◽  
Center Of Mass ◽  
Force Plate ◽  
Chronic Ankle Instability ◽  
Balance Test ◽  
Eyes Closed ◽  
Eyes Open

Abstract Background and Aims Ankle proprioception can be tested in many ways. Some studies have found improvements in individuals with chronic ankle instability after receiving treatment and training proprioceptive acuity and speed. Currently, there is a scarcity of evidence concerning percutaneous neuromodulation. The first findings were reported in the post-surgical stage after total knee arthroplasty and in neural improvements and symptoms in patients with hyperactive bladder. Aim To evaluate the effectiveness of percutaneous neuromodulation on the tibial nerve for the improvement of various proprioception parameters in patients with chronic ankle instability. Material and Methods Five men (age: 24.8 ± 4.9 years; height: 1.78 ± 0.08 m; weight: 86 ± 9.8 kg) with chronic ankle instability, who regularly practiced sports activities participated in the present study. People who had undergone an injury in the previous three months were excluded from the speed. Currently, there is a scarcity of evidence concerning test before and immediately after percutaneous neuromodulation. A single leg balance test was performed with eyes open and closed, maintaining the single-legged position on a force plate during 30 seconds (Accupower; AMTI, Watertown, MA) registering 1000 Hz. The displacement of the center of pressure (DOT) was determined based on the distances of its antero-posterior axes (DOT_AP) and medio-lateral (DOT_ML). Furthermore, the amplitudes of anteroposterior and mediolateral displacement were evaluated (ACPap and ACPml). The posterior tibial nerve was stimulated under ultrasound guidance using a 100 Vpp current, with a pulse width of 250 μs and a repetition frequency of 2 to 10 Hz. The process was performed on three occasions during 30 seconds, with an intensity that was acknowledged by the patient but which did not go beyond a score of 3 in the visual analog scale (VAS). The means and standard deviations were calculated for all variables. The effect size was calculated establishing the confidence interval at 90% and the probability of the change being significant was qualitatively calculated. Results A decrease was found in the ACPap (Pre-test eyes open: 5.42 ± 0.62 and eyes closed: 15.99 ± 0.60; Post-test eyes open 4.05 ± 0.36 and eyes closed 10.33 ± 0.49) after the neuromodulation intervention on the tibial nerve. This was a significant change and a “possible” effect size was found in the closed eyes condition (-0.54; ± 0.72), according to Hopkins. For the remaining variables, no significant differences were observed. Conclusions A decreased displacement of the center of mass was found in the antero-posterior axis after performing the neuromodulation technique on the tibial nerve in patients with chronic ankle instability.

scholarly journals A Novel Viewpoint on the Anticipatory Postural Adjustments During Gait Initiation

2021 ◽  
Vol 15 ◽  
Author(s):  
Veronica Farinelli ◽  
Francesco Bolzoni ◽  
Silvia Maria Marchese ◽  
Roberto Esposti ◽  
Paolo Cavallari
Keyword(s):  
Center Of Pressure ◽  
Force Plate ◽  
Anticipatory Postural Adjustments ◽  
The Body ◽  
Erector Spinae ◽  
Trunk Muscles ◽  
Gait Initiation ◽  
Concentrated Force ◽  
Postural Adjustments ◽  
Leg Muscles

Anticipatory postural adjustments (APAs) are the coordinated muscular activities that precede the voluntary movements to counteract the associated postural perturbations. Many studies about gait initiation call APAs those activities that precede the heel-off of the leading foot, thus taking heel-off as the onset of voluntary movement. In particular, leg muscles drive the center of pressure (CoP) both laterally, to shift the body weight over the trailing foot and backward, to create a disequilibrium torque pushing forward the center of mass (CoM). However, since subjects want to propel their body rather than lift their foot, the onset of gait should be the CoM displacement, which starts with the backward CoP shift. If so, the leg muscles driving such a shift are the prime movers. Moreover, since the disequilibrium torque is mechanically equivalent to a forward force acting at the pelvis level, APAs should be required to link the body segments to the pelvis: distributing such concentrated force throughout the body would make all segments move homogeneously. In the aim of testing this hypothesis, we analyzed gait initiation in 15 right-footed healthy subjects, searching for activities in trunk muscles that precede the onset of the backward CoP shift. Subjects stood on a force plate for about 10 s and then started walking at their natural speed. A minimum of 10 trials were collected. A force plate measured the CoP position while wireless probes recorded the electromyographic activities. Recordings ascertained that at gait onset APAs develop in trunk muscles. On the right side, Rectus Abdominis and Obliquus Abdominis were activated in 11 and 13 subjects, respectively, starting on average 33 and 54 ms before the CoP shift; Erector Spinae (ES) at L2 and T3 levels was instead inhibited (9 and 7 subjects, 104 and 120 ms). On the contralateral side, the same muscles showed excitatory APAs (abdominals in 11 and 12 subjects, 27 and 82 ms; ES in 10 and 7 subjects, 75 and 32 ms). The results of this study provide a novel framework for distinguishing postural from voluntary actions, which may be relevant for the diagnosis and rehabilitation of gait disorders.

scholarly journals The effect of music on body sway when standing in a moving virtual environment

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0258000
Author(s):  
Shaquitta Dent ◽  
Kelley Burger ◽  
Skyler Stevens ◽  
Benjamin D. Smith ◽  
Jefferson W. Streepey
Keyword(s):  
Virtual Reality ◽  
Virtual Environment ◽  
Center Of Pressure ◽  
Force Plate ◽  
The Body ◽  
Body Sway ◽  
Visual Environment ◽  
Auditory Information ◽  
Eyes Closed ◽  
Do So

Movement of the visual environment presented through virtual reality (VR) has been shown to invoke postural adjustments measured by increased body sway. The effect of auditory information on body sway seems to be dependent on context with sounds such as white noise, tones, and music being used to amplify or suppress sway. This study aims to show that music manipulated to match VR motion further increases body sway. Twenty-eight subjects stood on a force plate and experienced combinations of 3 visual conditions (VR translation in the AP direction at 0.1 Hz, no translation, and eyes closed) and 4 music conditions (Mozart’s Jupiter Symphony modified to scale volume at 0.1 Hz and 0.25 Hz, unmodified music, and no music) Body sway was assessed by measuring center of pressure (COP) velocities and RMS. Cross-coherence between the body sway and the 0.1 Hz and 0.25 Hz stimuli was also determined. VR translations at 0.1 Hz matched with 0.1Hz shifts in music volume did not lead to more body sway than observed in the no music and unmodified music conditions. Researchers and clinicians may consider manipulating sound to enhance VR induced body sway, but findings from this study would not suggest using volume to do so.

Characterization of a System for Studying Human Gait during Slope Walking

2005 ◽  
Vol 21 (2) ◽  
pp. 153-166 ◽  
Author(s):  
Andrea N. Lay ◽  
Chris J. Hass ◽  
D. Webb Smith ◽  
Robert J. Gregor
Keyword(s):  
Neural Control ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Force Plate ◽  
Human Locomotion ◽  
Human Gait ◽  
Testing System ◽  
Force Data ◽  
Kinetics Of

Sloped walking surfaces provide a unique environment for examining the bio-mechanics and neural control of locomotion. While sloped surfaces have been used in a variety of studies in recent years, the current literature provides little if any discussion of the integrity, i.e., validity, of the systems used to collect data. The goal of this study was to develop and characterize a testing system capable of evaluating the kinetics of human locomotion on sloped surfaces. A ramped walkway system with an embedded force plate was constructed and stabilized. Center of pressure and reaction force data from the force plate were evaluated at 6 ramp grades (0, 5, 15, 25, 35, and 39%). Ground reaction force data at 0% grade were effectively the same as data from the same force plate when mounted in the ground and were well within the range of intrasubject variability. Collectively, data from all tests demonstrate the fidelity of this ramp system and suggest it can be used to evaluate human locomotion over a range of slope intensities.

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