scholarly journals Common muscle synergies for control of center of mass and force in nonstepping and stepping postural behaviors

2011 ◽  
Vol 106 (2) ◽  
pp. 999-1015 ◽  
Author(s):  
Stacie A. Chvatal ◽  
Gelsy Torres-Oviedo ◽  
Seyed A. Safavynia ◽  
Lena H. Ting
Keyword(s):  
Muscle Activity ◽  
Center Of Mass ◽  
Initial Position ◽  
Neural Mechanisms ◽  
Muscle Synergies ◽  
Support Surface ◽  
Ground Reaction Forces ◽  
Postural Responses ◽  
Reaction Forces ◽  
Base Of Support

We investigated muscle activity, ground reaction forces, and center of mass (CoM) acceleration in two different postural behaviors for standing balance control in humans to determine whether common neural mechanisms are used in different postural tasks. We compared nonstepping responses, where the base of support is stationary and balance is recovered by returning CoM back to its initial position, with stepping responses, where the base of support is enlarged and balance is recovered by pushing the CoM away from the initial position. In response to perturbations of the same direction, these two postural behaviors resulted in different muscle activity and ground reaction forces. We hypothesized that a common pool of muscle synergies producing consistent task-level biomechanical functions is used to generate different postural behaviors. Two sets of support-surface translations in 12 horizontal-plane directions were presented, first to evoke stepping responses and then to evoke nonstepping responses. Electromyographs in 16 lower back and leg muscles of the stance leg were measured. Initially (∼100-ms latency), electromyographs, CoM acceleration, and forces were similar in nonstepping and stepping responses, but these diverged in later time periods (∼200 ms), when stepping occurred. We identified muscle synergies using non-negative matrix factorization and functional muscle synergies that quantified correlations between muscle synergy recruitment levels and biomechanical outputs. Functional muscle synergies that produce forces to restore CoM position in nonstepping responses were also used to displace the CoM during stepping responses. These results suggest that muscle synergies represent common neural mechanisms for CoM movement control under different dynamic conditions: stepping and nonstepping postural responses.

scholarly journals Ground reaction forces intersect above the center of mass even when walking down visible and camouflaged curbs

2019 ◽  
Vol 222 (14) ◽  
pp. jeb204305 ◽  
Author(s):  
Johanna Vielemeyer ◽  
Eric Grießbach ◽  
Roy Müller
Keyword(s):  
Center Of Mass ◽  
Ground Reaction Forces ◽  
Reaction Forces

scholarly journals The effect of walking speed on the foot inter-segment kinematics, ground reaction forces and lower limb joint moments

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5517 ◽  
Author(s):  
Dong Sun ◽  
Gusztáv Fekete ◽  
Qichang Mei ◽  
Yaodong Gu
Keyword(s):  
Lower Limb ◽  
Walking Speed ◽  
Sagittal Plane ◽  
External Rotation ◽  
Center Of Mass ◽  
Ground Reaction Forces ◽  
Joint Moments ◽  
Angle Variation ◽  
Foot Kinematics ◽  
Reaction Forces

Background Normative foot kinematic and kinetic data with different walking speeds will benefit rehabilitation programs and improving gait performance. The purpose of this study was to analyze foot kinematics and kinetics differences between slow walking (SW), normal walking (NW) and fast walking (FW) of healthy subjects. Methods A total of 10 healthy male subjects participated in this study; they were asked to carry out walks at a self-selected speed. After measuring and averaging the results of NW, the subjects were asked to perform a 25% slower and 25% faster walk, respectively. Temporal-spatial parameters, kinematics of the tibia (TB), hindfoot (HF), forefoot (FF) and hallux (HX), and ground reaction forces (GRFs) were recorded while the subjects walked at averaged speeds of 1.01 m/s (SW), 1.34 m/s (NW), and 1.68 m/s (FW). Results Hindfoot relative to tibia (HF/TB) and forefoot relative to hindfoot (FF/HF) dorsiflexion (DF) increased in FW, while hallux relative to forefoot (HX/FF) DF decreased. Increased peak eversion (EV) and peak external rotation (ER) in HF/TB were observed in FW with decreased peak supination (SP) in FF/HF. GRFs were increased significantly with walking speed. The peak values of the knee and ankle moments in the sagittal and frontal planes significantly increased during FW compared with SW and NW. Discussion Limited HF/TB and FF/HF motion of SW was likely compensated for increased HX/FF DF. Although small angle variation in HF/TB EV and FF/HF SP during FW may have profound effects for foot kinetics. Higher HF/TB ER contributed to the FF push-off the ground while the center of mass (COM) progresses forward in FW, therefore accompanied by higher FF/HF abduction in FW. Increased peak vertical GRF in FW may affected by decreased stance duration time, the biomechanical mechanism maybe the change in vertical COM height and increase leg stiffness. Walking speed changes accompanied with modulated sagittal plane ankle moments to alter the braking GRF during loading response. The findings of foot kinematics, GRFs, and lower limb joint moments among healthy males may set a reference to distinguish abnormal and pathological gait patterns.

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.

Changes in Muscle Activity and Ground Reaction Forces with Differing Shoes

2011 ◽  
Vol 43 (Suppl 1) ◽  
pp. 314
Author(s):  
Bryson H. Nakamura ◽  
Heidi A. Orloff ◽  
Sean D. Field-Eaton ◽  
Erienne V. Olesh
Keyword(s):  
Muscle Activity ◽  
Ground Reaction Forces ◽  
Reaction Forces

scholarly journals Effect of Horizontal Ground Reaction Forces during the Golf Swing: Implications for the Development of Technical Solutions of Golf Swing Analysis

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 45
Author(s):  
Maxime Bourgain ◽  
Christophe Sauret ◽  
Grégoire Prum ◽  
Laura Valdes-Tamayo ◽  
Olivier Rouillon ◽  
...  
Keyword(s):  
Center Of Mass ◽  
Field Performance ◽  
Golf Swing ◽  
Ground Reaction Forces ◽  
Technological Developments ◽  
Reaction Forces ◽  
Analysis Laboratory ◽  
Technical Solutions ◽  
Vertical Ground Reaction Forces ◽  
Full Body

The swing is a key movement for golf. Its in-field performance could be estimated by embedded technologies, but often only vertical ground reaction forces (VGRF) are estimated. However, as the swing plane is inclined, horizontal ground reaction forces (HGRF) are expected to contribute to the increase of the club angular velocity. Thus, this study aimed at investigating the role of the HGRF during the golf swing. Twenty-eight golf players were recruited and performed 10 swings with their own driver club, in a motion analysis laboratory, equipped with a full body marker set. Ground reaction forces (GRF) were measured with force-plates. A multibody kinematic optimization was performed with a full body model to estimate the instantaneous location of the golfer’s center of mass (CoM). Moments created by the GRF at the CoM were investigated. Results showed that horizontal forces should not be neglected regarding to VGRF because of their lever arm. Analyzing golf swing with only VGRF appeared not enough and further technological developments are still needed to ecologically measure other components.

Landing Constraints Influence Ground Reaction Forces and Lower Extremity EMG in Female Volleyball Players

2004 ◽  
Vol 20 (1) ◽  
pp. 38-50 ◽  
Author(s):  
Mark D. Tillman ◽  
Rachel M. Criss ◽  
Denis Brunt ◽  
Chris J. Hass
Keyword(s):  
Muscle Activity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Vertical Jump ◽  
Lateral Loading ◽  
Initial Contact ◽  
Ground Reaction Forces ◽  
Vertical Loading ◽  
Volleyball Players ◽  
Reaction Forces

The purposes of this study were to analyze double-limb, dominant-limb, and nondominant-limb landings, each with a two-footed takeoff, in order to detect potential differences in muscle activity and ground reaction forces and to examine the possible influence of leg dominance on these parameters. Each of the three jump landing combinations was analyzed in 11 healthy female volleyball players (age 21 ± 3 yrs; height 171 ± 5 cm, mass 61.6 ± 5.5 kg, max. vertical jump height 28 ± 4 cm). Ground reaction forces under each limb and bilateral muscle activity of the vastus medialis, hamstrings, and lateral gastrocnemius muscles were synchronized and collected at 1,000 Hz. Normalized EMG amplitude and force platform data were averaged over five trials for each participant and analyzed using repeated-measures ANOVA. During the takeoff phase in jumps with one-footed landings, the non-landing limb loaded more than the landing limb (p= 0.003). During the 100 ms prior to initial contact, single-footed landings generated higher EMG values than two-footed landings (p= 0.004). One-footed landings resulted in higher peak vertical loading, lateral loading, and rate of lateral loading than two-footed landings (p< 0.05). Trends were observed indicating that muscle activation during one-footed landings is greater than for two-footed landings (p= 0.053 vs.p= 0.077). The greater forces and rate of loading produced during single-limb landings implies a higher predisposition to injury. It appears that strategic planning and training of jumps in volleyball and other jumping sports is critical.

scholarly journals The Influence of External Additional Loading on the Muscle Activity and Ground Reaction Forces during Gait

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Bartłomiej Zagrodny ◽  
Michał Ludwicki ◽  
Wiktoria Wojnicz
Keyword(s):  
Temperature Distribution ◽  
Musculoskeletal System ◽  
Muscle Activity ◽  
Thermal Field ◽  
Reaction Force ◽  
External Loading ◽  
Ground Reaction Forces ◽  
Load Carrying ◽  
Reaction Forces ◽  
Force Pressure

Asymmetrical external loading acting on the musculoskeletal system is generally considered unhealthy. Despite this knowledge, carrying loads in an asymmetrical manner like carrying on one shoulder, with one hand, or on the strap across the torso is a common practice. This study is aimed at presenting the effects of the mentioned load carrying methods on muscle activity assessed by using thermal field and ground reaction forces. Infrared thermography and pedobarographic force platform (ground reaction force/pressure measurement) were used in this study. Experimental results point out an increased load-dependent asymmetry of temperature distribution on the chosen areas of torso and the influence of external loading on ground reaction forces. Results point out that wearing an asymmetrical load should be avoided and are showing which type of carrying the external load is potentially less and the most harmful.

scholarly journals Landing Styles Influences Reactive Strength Index without Increasing Risk for Injury

2018 ◽  
Vol 02 (02) ◽  
pp. E35-E40
Author(s):  
Dana Guy-Cherry ◽  
Ahmad Alanazi ◽  
Lauren Miller ◽  
Darrin Staloch ◽  
Alexis Ortiz-Rodriguez
Keyword(s):  
Muscle Activity ◽  
Knee Flexion ◽  
Gluteus Maximus ◽  
Ground Reaction Forces ◽  
Drop Jump ◽  
Strength Index ◽  
Jumping Performance ◽  
Landing Mechanics ◽  
Reaction Forces ◽  
Increasing Risk

AbstractThe aim was to determine which three landing styles – stiff (ST), self-selected (SS), or soft (SF) – exhibit safer landing mechanics and greater jumping performance. Thirty participants (age: 26.5±5.1 years; height: 171.0±8.8 cm; weight: 69.7±10.1 kg) performed five trials of three randomized drop jump (40 cm) landing styles including SF (~60° knee flexion), ST (knees as straight as possible), and SS. Knee flexion and valgus angles and kinetics were measured. An electromyography system measured muscle activity of the gluteus maximus, quadriceps, hamstrings, tibialis anterior, and gastrocnemius. Reactive strength index (RSI) was used to measure jumping performance. ANOVAs were used to compare the three landings. All landings differed in knee flexion (p<0.001; effect size (η2): 0.9) but not valgus (p=.13; η2:.15). RSI (mm·ms-1) showed differences for all jumps (p<0.001; η2: 0.7) with SS (0.96) showing the highest value, then ST (0.93), and SF (0.64). Ground reaction forces were different between jumps (p<0.001; η2: 0.4) with SF (1.34/bodyweight (bw)) showing lower forces, then SS (1.50/bw), and ST (1.81/bw). No between-jump differences were observed for EMG (p>0.66; η2: 0.3). No landing demonstrated valgus landing mechanics. The SS landing exhibited the highest RSI. However, the 1.8/bw exhibited by the ST landing might contribute to overload of musculotendinous structures at the knee.

A Feedback Model Reproduces Muscle Activity During Human Postural Responses to Support-Surface Translations

2008 ◽  
Vol 99 (2) ◽  
pp. 1032-1038 ◽  
Author(s):  
Torrence D. J. Welch ◽  
Lena H. Ting
Keyword(s):  
Postural Control ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Control Process ◽  
Temporal Patterns ◽  
Human Dimensions ◽  
Support Surface ◽  
Level Control ◽  
Muscle Activation Patterns ◽  
Postural Responses

Although feedback models have been used to simulate body motions in human postural control, it is not known whether muscle activation patterns generated by the nervous system during postural responses can also be explained by a feedback control process. We investigated whether a simple feedback law could explain temporal patterns of muscle activation in response to support-surface translations in human subjects. Previously, we used a single-link inverted-pendulum model with a delayed feedback controller to reproduce temporal patterns of muscle activity during postural responses in cats. We scaled this model to human dimensions and determined whether it could reproduce human muscle activity during forward and backward support-surface perturbations. Through optimization, we found three feedback gains (on pendulum acceleration, velocity, and displacement) and a common time delay that allowed the model to best match measured electromyographic (EMG) signals. For each muscle and each subject, the entire time courses of EMG signals during postural responses were well reconstructed in muscles throughout the lower body and resembled the solution derived from an optimal control model. In ankle muscles, >75% of the EMG variability was accounted for by model reconstructions. Surprisingly, >67% of the EMG variability was also accounted for in knee, hip, and pelvis muscles, even though motion at these joints was minimal. Although not explicitly required by our optimization, pendulum kinematics were well matched to subject center-of-mass (CoM) kinematics. Together, these results suggest that a common set of feedback signals related to task-level control of CoM motion is used in the temporal formation of muscle activity during postural control.

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