Turning Strategies During Human Walking

1999 ◽  
Vol 81 (6) ◽  
pp. 2914-2922 ◽  
Author(s):  
K. Hase ◽  
R. B. Stein
Keyword(s):  
Postural Sway ◽  
Gluteus Medius ◽  
Biceps Femoris ◽  
The Body ◽  
Erector Spinae ◽  
Human Walking ◽  
Step Cycle ◽  
Foot Placement ◽  
The Right ◽  
Step Turn

Turning strategies during human walking. The mechanisms involved in rapidly turning during human walking were studied. Subjects were asked to walk at a comfortable speed and to turn toward the instructed direction as soon as they felt an electrical stimulus to the superficial peroneal nerve. Stimuli were presented repeatedly at random over 10- to 15-min periods of walking for turning in both directions. Electromyograms (EMGs), joint angular movements of the right leg, and forces under both feet were recorded. The step cycle was divided into 16 parts, and the responses to stimuli in each part were analyzed separately. Two turning strategies were used, depending on which leg was placed in front for braking. For example, to turn to the right when the right foot was placed in front, subjects generally altered direction by spinning the body around the right foot (spin turn). To turn left when the right foot was in front, subjects shifted weight to the right leg, externally rotated the left hip, stepped onto the left leg, and continued turning until the right leg stepped in the new direction (step turn). The step turn is easy and stable because the base of support during the turn is much wider than in the spin turn, so some subjects used it in all parts of the cycle. Initially, the deceleration of walking is similar to a rapid stopping task, which has been previously examined. The deceleration mechanism involves a sequence of distal-to-proximal activation of muscles on one side of the body (soleus, biceps femoris, and erector spinae). This pattern is similar to the “ankle strategy” used in postural control during forward sway. The control of foot placement in the swing leg and muscle activities for rotating the trunk in the stance leg occurred within a step after the cue. The action of ankle inverters and elevation of the pelvis by activity of gluteus medius may contribute to the control of trunk rotation. This activity was closely related to the timing of the opposite foot strike, independent of the part of the step cycle when the stimulus was applied. In most subjects, the turn was completed without resetting the underlying walking rhythm. This first EMG analysis of rapid turning shows how common strategies for postural sway and stopping can be combined with one of two turning strategies. This simplifies the complex task of turning at a random time in the step cycle.

scholarly journals Analysis of Rapid Stopping During Human Walking

1998 ◽  
Vol 80 (1) ◽  
pp. 255-261 ◽  
Author(s):  
K. Hase ◽  
R. B. Stein
Keyword(s):  
Center Of Mass ◽  
Electrical Stimulus ◽  
The Body ◽  
Human Walking ◽  
Human Gait ◽  
Electromyographic Activity ◽  
Superficial Peroneal Nerve ◽  
Step Cycle ◽  
Additional Step ◽  
The Right

Hase, K. and R. B. Stein. Analysis of rapid stopping during human walking. J. Neurophysiol. 80: 255–261, 1998. The mechanisms involved in rapidly terminating human gait were studied. Subjects were asked to walk at a comfortable speed and to stop walking as soon as they felt an electrical stimulus to the superficial peroneal nerve. This simulated hitting an obstacle with the top of the foot. Stimuli were presented repeatedly at random during a 20-min period of walking. Electromyograms and joint angular movements of the right leg and forces under both feet were recorded. The step cycle was divided into 16 parts, and the responses to stimuli in each part were analyzed separately. Subjects generally stopped with the right foot in front of the left or vice-versa, depending on when the stimulus was applied in the step cycle. There was also a transition region in which subjects would rise up on their toes and either back down or take one more quick, short forward step. Three different mechanisms were used to produce a stop. 1) An extension synergy in the swing leg was initiated just before this leg hit the ground to brake the forward momentum of the body. 2) The push-off phase of the stance leg was inhibited to reduce the forward thrust and maintain the stance leg on the ground behind the body. 3) If these mechanisms were insufficient, the body rose up onto the toes of the extended forward leg and thereby converted more kinetic energy to potential energy. A decision to take an additional step depends on whether the momentum of the body is sufficient to carry the center of mass in front of its support on the forward leg. If so, an additional step is taken. Despite the complexity of the decisions that must be made, changes in electromyographic activity are seen throughout the legs and trunk in 150–200 ms.

Short-Latency Crossed Inhibitory Responses in Extensor Muscles During Locomotion in the Cat

2008 ◽  
Vol 99 (2) ◽  
pp. 989-998 ◽  
Author(s):  
Alain Frigon ◽  
Serge Rossignol
Keyword(s):  
Gluteus Medius ◽  
Short Latency ◽  
Triceps Surae ◽  
Step Cycle ◽  
Bipolar Electrodes ◽  
Cutaneous Reflex ◽  
Cuff Electrode ◽  
Short Period ◽  
Excitatory Responses ◽  
The Right

During locomotion, contacting an obstacle generates a coordinated response involving flexion of the stimulated leg and activation of extensors contralaterally to ensure adequate support and forward progression. Activation of motoneurons innervating contralateral muscles (i.e., crossed extensor reflex) has always been described as an excitation, but the present paper shows that excitatory responses during locomotion are almost always preceded by a short period of inhibition. Data from seven cats chronically implanted with bipolar electrodes to record electromyography (EMG) of several hindlimb muscles bilaterally were used. A stimulating cuff electrode placed around the left tibial and left superficial peroneal nerves at the level of the ankle in five and two cats, respectively, evoked cutaneous reflexes during locomotion. During locomotion, short-latency (∼13 ms) inhibitory responses were frequently observed in extensors of the right leg (i.e., contralateral to the stimulation), such as gluteus medius and triceps surae muscles, which were followed by excitatory responses (∼25 ms). Burst durations of the left sartorius (Srt), a hip flexor, and ankle extensors of the right leg increased concomitantly in the mid- to late-flexion phases of locomotion with nerve stimulation. Moreover, the onset and offset of Srt and ankle extensor bursts bilaterally were altered in specific phases of the step cycle. Short-latency crossed inhibition in ankle extensors appears to be an integral component of cutaneous reflex pathways in intact cats during locomotion, which could be important in synchronizing EMG bursts in muscles of both legs.

scholarly journals Kinematic and EMG Comparison Between Variations of Unilateral Squats Under Different Stabilities

2020 ◽  
Vol 4 (02) ◽  
pp. E59-E66
Author(s):  
Roland van den Tillaar ◽  
Stian Larsen
Keyword(s):  
Muscle Activity ◽  
Rectus Femoris ◽  
Gluteus Medius ◽  
Biceps Femoris ◽  
Peak Force ◽  
Erector Spinae ◽  
Trunk Muscles ◽  
Training Experience ◽  
Free Weight ◽  
Weight Condition

AbstractThe purpose of the study was to compare kinematics and muscle activity between two variations of unilateral squats under different stability conditions. Twelve male volunteers (age: 23±5 years, mass: 80±17 kg, height: 1.81±0.11 m, strength-training experience: 4.3±1.9 years) performed four repetitions with the same external load (≈4RM). Two variations (with the non-stance leg forwards vs. backwards) were performed in a Smith-machine and free-weight condition. The variables were barbell velocity, lifting time and surface electromyography activity of the lower extremity and trunk muscles during the descending and ascending phase. The main findings were 1) peak force was higher when performing the unilateral squats in the Smith machine; 2) peak ascending barbell velocity increased from repetition 3–4 with free weight; and 3) muscle activity from the rectus femoris, vastus lateral, biceps femoris, gluteus medius, and erector spinae increased with repetitions, whereas gluteus, and medial vastus and shank muscles were affected by the conditions. It was concluded that more peak force could be produced because of increased stability. However, peak barbell velocity increased from repetition to repetition in free-weight unilateral squats, which was probably because the participants grew more comfortable. Furthermore, increased instability causes more gluteus and vastus medial activation and foot variations mainly affected the calf muscles.

scholarly journals Interlimb communication following unexpected changes in treadmill velocity during human walking

2015 ◽  
Vol 113 (9) ◽  
pp. 3151-3158 ◽  
Author(s):  
Andrew J. T. Stevenson ◽  
Svend S. Geertsen ◽  
Thomas Sinkjær ◽  
Jens B. Nielsen ◽  
Natalie Mrachacz-Kersting
Keyword(s):  
Dynamic Stability ◽  
Stance Phase ◽  
Biceps Femoris ◽  
The Body ◽  
Context Dependency ◽  
Human Walking ◽  
Human Gait ◽  
Velocity Change ◽  
Leg Muscles ◽  
Interlimb Reflex

Interlimb reflexes play an important role in human walking, particularly when dynamic stability is threatened by external perturbations or changes in the walking surface. Interlimb reflexes have recently been demonstrated in the contralateral biceps femoris (cBF) following knee joint rotations applied to the ipsilateral leg (iKnee) during the late stance phase of human gait (Stevenson AJ, Geertsen SS, Andersen JB, Sinkjær T, Nielsen JB, Mrachacz-Kersting N. J Physiol 591: 4921–4935, 2013). This interlimb reflex likely acts to slow the forward progression of the body to maintain dynamic stability following the perturbations. We examined this hypothesis by unexpectedly increasing or decreasing the velocity of the treadmill before (−100 and −50 ms), at the same time, or following (+50 ms) the onset of iKnee perturbations in 12 healthy volunteers. We quantified the cBF reflex amplitude when the iKnee perturbation was delivered alone, the treadmill velocity change was delivered alone, or when the two perturbations were combined. When the treadmill velocity was suddenly increased (or decreased) 100 or 50 ms before the iKnee perturbations, the combined cBF reflex was significantly larger (or smaller) than the algebraic sum of the two perturbations delivered separately. Furthermore, unexpected changes in treadmill velocity increased the incidence of reflexes in other contralateral leg muscles when the iKnee perturbations were elicited alone. These results suggest a context dependency for interlimb reflexes. They also show that the cBF reflex changed in a predictable manner to slow the forward progression of the body and maintaining dynamic stability during walking, thus signifying a functional role for interlimb reflexes.

scholarly journals The Effect of Step Width on Muscle Contributions to Body Mass Center Acceleration During the First Stance of Sprinting

2021 ◽  
Vol 9 ◽  
Author(s):  
Ruoli Wang ◽  
Laura Martín de Azcárate ◽  
Paul Sandamas ◽  
Anton Arndt ◽  
Elena M. Gutierrez-Farewik
Keyword(s):  
Lower Limb ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Gluteus Medius ◽  
Biceps Femoris ◽  
The Body ◽  
Step Width ◽  
Acceleration Analysis

BackgroundAt the beginning of a sprint, the acceleration of the body center of mass (COM) is driven mostly forward and vertically in order to move from an initial crouched position to a more forward-leaning position. Individual muscle contributions to COM accelerations have not been previously studied in a sprint with induced acceleration analysis, nor have muscle contributions to the mediolateral COM accelerations received much attention. This study aimed to analyze major lower-limb muscle contributions to the body COM in the three global planes during the first step of a sprint start. We also investigated the influence of step width on muscle contributions in both naturally wide sprint starts (natural trials) and in sprint starts in which the step width was restricted (narrow trials).MethodMotion data from four competitive sprinters (2 male and 2 female) were collected in their natural sprint style and in trials with a restricted step width. An induced acceleration analysis was performed to study the contribution from eight major lower limb muscles (soleus, gastrocnemius, rectus femoris, vasti, gluteus maximus, gluteus medius, biceps femoris, and adductors) to acceleration of the body COM.ResultsIn natural trials, soleus was the main contributor to forward (propulsion) and vertical (support) COM acceleration and the three vasti (vastus intermedius, lateralis and medialis) were the main contributors to medial COM acceleration. In the narrow trials, soleus was still the major contributor to COM propulsion, though its contribution was considerably decreased. Likewise, the three vasti were still the main contributors to support and to medial COM acceleration, though their contribution was lower than in the natural trials. Overall, most muscle contributions to COM acceleration in the sagittal plane were reduced. At the joint level, muscles contributed overall more to COM support than to propulsion in the first step of sprinting. In the narrow trials, reduced COM propulsion and particularly support were observed compared to the natural trials.ConclusionThe natural wide steps provide a preferable body configuration to propel and support the COM in the sprint starts. No advantage in muscular contributions to support or propel the COM was found in narrower step widths.

scholarly journals Muscular Responses and Movement Strategies During Stumbling Over Obstacles

2000 ◽  
Vol 83 (4) ◽  
pp. 2093-2102 ◽  
Author(s):  
A. M. Schillings ◽  
B.M.H. van Wezel ◽  
Th. Mulder ◽  
J. Duysens
Keyword(s):  
Behavioral Response ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Response Strategy ◽  
Response Modulation ◽  
Step Cycle ◽  
Foot Placement ◽  
Response Strategies ◽  
Proprioceptive Afferents

Although many studies have investigated reflexes after stimulation of either cutaneous or proprioceptive afferents, much less is known about responses after more natural perturbations, such as stumbling over an obstacle. In particular, the phase dependency of these responses and their relation to the stumbling behavior has received little attention. Hence response strategies during stumbling reactions after perturbations at different times in the swing phase of gait were studied. While subjects walked on a treadmill, a rigid obstacle unexpectedly obstructed the forward sway of the foot. All subjects showed an “elevating strategy” after early swing perturbations and a “lowering strategy” after late swing perturbations. During the elevating strategy, the foot was directly lifted over the obstacle through extra knee flexion assisted by ipsilateral biceps femoris (iBF) responses and ankle dorsiflexion assisted by tibialis anterior (iTA) responses. Later, large rectus femoris (iRF) activations induced knee extension to place the foot on the treadmill. During the lowering strategy, the foot was quickly placed on the treadmill and was lifted over the obstacle in the subsequent swing. Foot placement was actively controlled by iRF and iBF responses related to knee extension and deceleration of the forward sway. Activations of iTA mostly preceded the main ipsilateral soleus (iSO) responses. For both strategies, four response peaks could be distinguished with latencies of ∼40 ms (RP1), ∼75 ms (RP2), ∼110 ms (RP3), and ∼160 ms (RP4). The amplitudes of these response peaks depended on the phase in the step cycle. The phase-dependent modulation of the responses could not be accounted for by differences in stimulation or in background activity and therefore is assumed to be premotoneuronal in origin. In mid swing, both the elevating and lowering strategy could occur. For this phase, the responses of the two strategies could be compared in the absence of phase-dependent response modulation. Both strategies had the same initial electromyographic responses till ∼100 ms (RP1-RP2) after perturbation. The earliest response (RP1) is assumed to be a short-latency stretch reflex evoked by the considerable impact of the collision, whereas the second (RP2) has features reminiscent of cutaneous and proprioceptive responses. Both these responses did not determine the behavioral response strategy. The functionally important response strategies depended on later responses (RP3-RP4). These data suggest that during stumbling reactions, as a first line of defense, the CNS releases a relatively aspecific response, which is followed by an appropriate behavioral response to avoid the obstacle.

Role of the Unperturbed Limb and Arms in the Reactive Recovery Response to an Unexpected Slip During Locomotion

2003 ◽  
Vol 89 (4) ◽  
pp. 1727-1737 ◽  
Author(s):  
Daniel S. Marigold ◽  
Allison J. Bethune ◽  
Aftab E. Patla
Keyword(s):  
Imaging System ◽  
Center Of Mass ◽  
Rectus Femoris ◽  
Gluteus Medius ◽  
Biceps Femoris ◽  
Erector Spinae ◽  
Lower Limbs ◽  
Upper Body ◽  
Recovery Response

Understanding reactive recovery responses to slipping is fundamental in falls research and prevention. The primary purpose of this study was to investigate the role of the unperturbed limb and arms in the reactive recovery response to an unexpected slip. Ten healthy, young adults participated in this experiment in which an unexpected slip was induced by a set of steel free-wheeling rollers. Surface electromyography (EMG) data were collected from the unperturbed limb (i.e., the swing limb) rectus femoris, biceps femoris, tibialis anterior, and the medial head of gastrocnemius, and bilateral gluteus medius, erector spinae, and deltoids. Kinematic data were also collected by an optical imaging system to monitor limb trajectories. The first slip response was significantly different from the subsequent recovery responses to the unexpected slips, with an identifiable reactive recovery response and no proactive changes in EMG patterns. The muscles of the unperturbed limb, upper body, and arms were recruited at the same latency as those previously found for the perturbed limb. The arm elevation strategies assisted in shifting the center of mass forward after it was posteriorly displaced with the slip, while the unperturbed limb musculature demonstrated an extensor strategy supporting the observed lowering of the limb to briefly touch the ground to widen the base of support and to increase stability. Evidently a dynamic multilimb coordinated strategy is employed by the CNS to control and coordinate the upper and lower limbs in reactive recovery responses to unexpected slips during locomotion.

scholarly journals Idiopathic scoliosis. Mechanisms of development

2021 ◽  
Vol 8 (11) ◽  
pp. 628-635
Author(s):  
Late Serdyuk Valentyn Viktorovich ◽  
Serdiuk Oleksandr Valentinovich ◽  
Grigory Tishkin
Keyword(s):  
Idiopathic Scoliosis ◽  
Pain Syndrome ◽  
Spinal Pain ◽  
Ethnic Origin ◽  
Intervertebral Discs ◽  
The Body ◽  
Erector Spinae ◽  
Lateral Spine ◽  
The Right ◽  
Spinal Pain Syndrome

Objective: One of the most complicated problems of Orthopaedics is the treatment of scoliosis. More than 90% of cases are attributable to Idiopathic deformation, the cause of which is unknown. We investigated the cause of pathogenesis of this disorder. Methods: At our institution more than 6900 patients aged 1-89 years have undergone inpatient and outpatient treatment in connection with spinal pain syndrome and different neurological disorders associated with idiopathic scoliosis. This study was undertaken between February 1996 and February 2010.  All patients had a clinical, radiography and laboratory examinations. Results: The 29.6% of patients were aged 31-50 years old. 60% were men and 40% were women. While examining patients with scoliosis deformation, we noted symptoms of body asymmetry i.e. different volumes of the right and left halves of face body and limbs. These features were typical for all patients irrespective of sex, age, and ethnic origin. 83,2% of patients had underdevelopment of the left part of the body, and only 16,8% of the right side. Analysis of published work in anatomy, physiology, neurophysiology, vertebrology, done simultaneously with analysis of the clinical material, allowed us to make some conclusions. Conclusions: First asymmetrical structure of the human body is based on laws of nature and is linked with difference of sizes of brain’s hemispheres, particularly of the right and left gyrus centralis anterior which controls the muscle’s function and our movements. Second asymmetrical tension of Erector spinae muscles, leads to inclination of the pelvis on a side of weak muscles; thus initiating development of the lateral spine curves. Since such a situation is typical for all people, this deformation is known as functional scoliosis. Third, further development of the bodies of vertebrae, their arches, processes, intervertebral discs, ligaments, and other anatomical elements in position of the deviation leads to one sided underdevelopment of these structures. As a result the areas of instability appear in each segment of spine ( neck, chest, lumbar and sacral areas ). Fourth, the  muscles in a growing body misbalance and on the ground of rotating movement, start rotatory dislocation of vertebrae in zones of instability in all parts of the spine. As a result torsion of the deformed wedge-shaped vertebrae leads to formation of the structural scoliosis. The rotation of the vertebrae, described above, does not depend on sex, age and ethnic origin of the patient and has a character of the natural development. Thus from our point of view, the term idiopathic scoliosis, must be changed to spinal muscle asymmetrical deformation of a reflex origin. Understanding of this rotation allowed us to establish an effective non-surgical method of treatment of scoliosis and spinal pain syndrome in patients of all ages.

Pendular energy transduction within the step in human walking

2002 ◽  
Vol 205 (21) ◽  
pp. 3413-3422 ◽  
Author(s):  
G. A. Cavagna ◽  
P. A. Willems ◽  
M. A. Legramandi ◽  
N. C. Heglund
Keyword(s):  
Body Weight ◽  
Kinetic Energy ◽  
Energy Transduction ◽  
The Body ◽  
African Women ◽  
Human Walking ◽  
Gravitational Potential Energy ◽  
Effective Energy ◽  
Centre Of Mass ◽  
Step Cycle

SUMMARY During walking, the centre of mass of the body moves like that of a `square wheel': with each step cycle, some of its kinetic energy, Ek, is converted into gravitational potential energy, Ep, and then back into kinetic energy. To move the centre of mass, the locomotory muscles must supply only the power required to overcome the losses occurring during this energy transduction. African women carry loads of up to 20% of their body weight on the head without increasing their energy expenditure. This occurs as a result of an unexplained, more effective energy transduction between Ek and Ep than that of Europeans. In this study we measured the value of the Ek to Ep transduction at each instant in time during the step in African women and European subjects during level walking at 3.5-5.5 km h-1, both unloaded and carrying loads spanning 20-30% of their body weight. A simulation of the changes in Ek and Ep during the step by sinusoidal curves was used for comparison. It was found that loading improves the transduction of Ep to Ek during the descent of the centre of mass. The improvement is not significant in European subjects, whereas it is highly significant in African women.

scholarly journals A neuromechanical strategy for mediolateral foot placement in walking humans

2014 ◽  
Vol 112 (2) ◽  
pp. 374-383 ◽  
Author(s):  
Bradford L. Rankin ◽  
Stephanie K. Buffo ◽  
Jesse C. Dean
Keyword(s):  
Muscle Activity ◽  
Center Of Mass ◽  
Frontal Plane ◽  
Gluteus Medius ◽  
Swing Phase ◽  
Electromyographic Activity ◽  
Mechanical State ◽  
Foot Placement ◽  
The Right ◽  
Clinical Populations

Stability is an important concern during human walking and can limit mobility in clinical populations. Mediolateral stability can be efficiently controlled through appropriate foot placement, although the underlying neuromechanical strategy is unclear. We hypothesized that humans control mediolateral foot placement through swing leg muscle activity, basing this control on the mechanical state of the contralateral stance leg. Participants walked under Unperturbed and Perturbed conditions, in which foot placement was intermittently perturbed by moving the right leg medially or laterally during the swing phase (by ∼50–100 mm). We quantified mediolateral foot placement, electromyographic activity of frontal-plane hip muscles, and stance leg mechanical state. During Unperturbed walking, greater swing-phase gluteus medius (GM) activity was associated with more lateral foot placement. Increases in GM activity were most strongly predicted by increased mediolateral displacement between the center of mass (CoM) and the contralateral stance foot. The Perturbed walking results indicated a causal relationship between stance leg mechanics and swing-phase GM activity. Perturbations that reduced the mediolateral CoM displacement from the stance foot caused reductions in swing-phase GM activity and more medial foot placement. Conversely, increases in mediolateral CoM displacement caused increased swing-phase GM activity and more lateral foot placement. Under both Unperturbed and Perturbed conditions, humans controlled their mediolateral foot placement by modulating swing-phase muscle activity in response to the mechanical state of the contralateral leg. This strategy may be disrupted in clinical populations with a reduced ability to modulate muscle activity or sense their body's mechanical state.

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