Form Switching During Human Locomotion: Traversing Wedges in a Single Step

2000 ◽  
Vol 84 (2) ◽  
pp. 605-615 ◽  
Author(s):  
Gammon M. Earhart ◽  
Amy J. Bastian
Keyword(s):  
Neural Control ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Single Step ◽  
Level Surface ◽  
Heel Strike ◽  
Joint Angles ◽  
Hip Flexion ◽  
Anterior Tibialis

We examined the neural control strategies used to accommodate discrete alterations in walking surface inclination. Normal subjects were tested walking on a level surface and on different wedges (10°, 15°, 20°, and 30°) presented in the context of level walking. On a given trial, a subject walked on a level surface in approach to a wedge, took a single step on the wedge, and continued walking on an elevated level surface beyond the wedge. As wedge inclination increased, subjects linearly increased peak joint angles. Changes in timing of peak joint angles and electromyograms were not linear. Subjects used two distinct temporal strategies, or forms, to traverse the wedges. One form was used for walking on a level surface and on the 10° wedge, another form for walking on the 20° and 30° wedges. In the level/10° form, peak hip flexion occurred well before heel strike (HS) and peak dorsiflexion occurred in late stance. In the 20°/30° form, peak hip flexion was delayed by 12% of the stride cycle and peak dorsiflexion was reached 12% earlier. For the level/10° form, onsets of the rectus femoris, gluteus maximus, and vastus lateralis muscles were well before HS and offset of the anterior tibialis was at HS. For the 20°/30° form, onsets of the rectus femoris, gluteus maximus, and vastus lateralis and offset of the anterior tibialis were all delayed by 12% of the stride cycle. Muscles shifted as a group, rather than individually, between the forms. Subjects traversing a 15° wedge switched back and forth between the two forms in consecutive trials, suggesting the presence of a transition zone. Differences between the forms can be explained by the differing biomechanical constraints imposed by the wedges. Steeper wedges necessitate changes in limb orientation to accommodate the surface, altering limb orientation with respect to gravity and making it necessary to pull the body forward over the foot. The use of different forms of behavior is a common theme in neural control and represents an efficient means of coordinating and adapting movement to meet changing environmental demands. The forms of locomotion reported here are likely used on a regular basis in real-world settings.

scholarly journals Muscle Activation Differs between Three Different Knee Joint-Angle Positions during a Maximal Isometric Back Squat Exercise

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Paulo Henrique Marchetti ◽  
Josinaldo Jarbas da Silva ◽  
Brad Jon Schoenfeld ◽  
Priscyla Silva Monteiro Nardi ◽  
Silvio Luis Pecoraro ◽  
...  
Keyword(s):  
Knee Joint ◽  
Muscle Activation ◽  
Specific Activity ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Joint Angles ◽  
Back Squat ◽  
Squat Exercise

The purpose of this study was to compare muscle activation of the lower limb muscles when performing a maximal isometric back squat exercise over three different positions. Fifteen young, healthy, resistance-trained men performed an isometric back squat at three knee joint angles (20°, 90°, and 140°) in a randomized, counterbalanced fashion. Surface electromyography was used to measure muscle activation of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), semitendinosus (ST), and gluteus maximus (GM). In general, muscle activity was the highest at 90° for the three quadriceps muscles, yet differences in muscle activation between knee angles were muscle specific. Activity of the GM was significantly greater at 20° and 90° compared to 140°. The BF and ST displayed similar activation at all joint angles. In conclusion, knee position alters muscles activation of the quadriceps and gluteus maximus muscles. An isometric back squat at 90° generates the highest overall muscle activation, yet an isometric back squat at 140° generates the lowest overall muscle activation of the VL and GM only.

Muscle coordination in cycling: effect of surface incline and posture

1998 ◽  
Vol 85 (3) ◽  
pp. 927-934 ◽  
Author(s):  
Li Li ◽  
Graham E. Caldwell
Keyword(s):  
Lower Extremity ◽  
High Speed ◽  
Vastus Lateralis ◽  
Activity Patterns ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extensors ◽  
Emg Activity ◽  
Muscle Coordination

The purpose of the present study was to examine the neuromuscular modifications of cyclists to changes in grade and posture. Eight subjects were tested on a computerized ergometer under three conditions with the same work rate (250 W): pedaling on the level while seated, 8% uphill while seated, and 8% uphill while standing (ST). High-speed video was taken in conjunction with surface electromyography (EMG) of six lower extremity muscles. Results showed that rectus femoris, gluteus maximus (GM), and tibialis anterior had greater EMG magnitude in the ST condition. GM, rectus femoris, and the vastus lateralis demonstrated activity over a greater portion of the crank cycle in the ST condition. The muscle activities of gastrocnemius and biceps femoris did not exhibit profound differences among conditions. Overall, the change of cycling grade alone from 0 to 8% did not induce a significant change in neuromuscular coordination. However, the postural change from seated to ST pedaling at 8% uphill grade was accompanied by increased and/or prolonged muscle activity of hip and knee extensors. The observed EMG activity patterns were discussed with respect to lower extremity joint moments. Monoarticular extensor muscles (GM, vastus lateralis) demonstrated greater modifications in activity patterns with the change in posture compared with their biarticular counterparts. Furthermore, muscle coordination among antagonist pairs of mono- and biarticular muscles was altered in the ST condition; this finding provides support for the notion that muscles within these antagonist pairs have different functions.

Quadriceps H-Reflex Modulation During Pedaling

2006 ◽  
Vol 96 (1) ◽  
pp. 197-208 ◽  
Author(s):  
Birgit Larsen ◽  
Michael Voigt
Keyword(s):  
Neural Control ◽  
Vastus Lateralis ◽  
Phase Speed ◽  
Rectus Femoris ◽  
Quadriceps Muscle ◽  
H Reflex ◽  
Movement Speed ◽  
Reflex Modulation ◽  
Motor Recruitment ◽  
And Task

The main aims of this study were 1) to investigate possible phase-, speed-, and task-dependent changes in the quadriceps H-reflex during pedaling, and to achieve this, 2) to develop an optimized H-reflex recording and processing procedure for recording of quadriceps H-reflexes during movement. It was hypothesized that the behavior of the quadriceps H-reflex concerning phase, speed, and task dependency corresponds to the behavior of the soleus H-reflex during rhythmical leg movements. The applied H-reflex procedure appeared to be reliable for obtaining the quadriceps H-reflex modulation during leg movement. The vastus lateralis (VL) and rectus femoris (RF) H-reflexes showed a phase-dependent modulation during pedaling at a frequency of 80 rpm with almost parallel changes in the reflex amplitude and motor recruitment level. However, when the speed of movement was reduced from 80 to 40 revolutions per minute (rpm) and crank load simultaneously increased (i.e., a halving of the movement speed with a constant motor recruitment level), the quadriceps H-reflex modulation pattern changed significantly in relation to the pattern of motor recruitment, i.e., at 40 rpm, the reflex excitability remained high during a gradual derecruitment during power generation in downstroke. Comparison of the “operationally defined H-reflex gain function” obtained during 1) pedaling at 80 rpm and 2) isometric quadriceps contractions in sitting position showed no significant task-dependent changes in the quadriceps H-reflex. Consequently, the hypothesis was only partly corroborated, and the findings indicate differences in the neural control of the soleus and the quadriceps muscle during rhythmical movements.

scholarly journals Differences in Simulated EMG Activities between a Non-Rotational Shot and an Ordinary Instep Kick Identified by Principal Component Analysis

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 154
Author(s):  
Tasuku Miyoshi ◽  
Yasuhisa Kamada ◽  
Yoshiyuki Kobayashi
Keyword(s):  
Principal Component Analysis ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Principal Component ◽  
Rectus Femoris ◽  
Component Analysis ◽  
Vastus Intermedius ◽  
Longus Muscle ◽  
Instep Kick ◽  
Tensor Fasciae Latae

The aim of this study was to clarify the major differences in the electromyographic (EMG) activities in the hip joint required to achieve a non-rotational (NR) shot as compared with an instep kick from the spatiotemporal data. For this purpose, simulated EMG activities obtained from NR shots and instep kicks were analyzed using principal component analysis (PCA). The PCA was conducted using an input matrix constructed from the time-normalized average and the standard deviation of the EMG activities (101 data x (15 muscles; iliacus, gluteus maximus, rectus femoris, biceos femoris, vastus lateralis, vastus medialis, vastus intermedius, semimembranosus, semitendinosus, sartorius, tensor fasciae latae muscle, adductor magnus muscle, adductor longus muscle, gasctrocnemius, and tibialis anterior)). The PCA revealed that the 3rd, 4th and 8th principal component vectors (PCVs) of the 10 generated PCVs were related to achieving the NR shot (p < 0.05).

scholarly journals Acute effect of partial body weight suspension on the level of cocontraction and gait biomechanics in women with knee osteoarthritis

2020 ◽  
Vol 33 ◽  
Author(s):  
Deborah Hebling Spinoso ◽  
Marcus Vinicius de Sobral Carvalho ◽  
Ana Carolina de Souza Trentin ◽  
Marcelo Tavella Navega
Keyword(s):  
Body Weight ◽  
Knee Osteoarthritis ◽  
Vastus Lateralis ◽  
Functional Limitation ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Treadmill Running ◽  
Significance Level ◽  
Significant Difference ◽  
Partial Body

Abstract Introduction: Knee osteoarthritis (OAK) is one of the most prevalent rheumatic diseases in the population, characterized by functional limitation and gait difficulties with profound clinical relevance, as walking is the most frequently performed daily activity. These functional limitations may be more pronounced when the disease is associated with obesity. Objective: To investigate the effect of different body weight suspension percentages on gait biomechanical variables and co-contraction percentages in women with OAK. Method: Fourteen women aged 50-75 years, with a body mass index between 26 and 35 and radiological diagnosis of OAK participated in the study. On the first day, anamnesis and familiarization with gait on the treadmill was performed. On the second day, treadmill gait assessment was performed using partial body weight support (SPPC) in three conditions-15%, 30%, and 45% suspension. During the evaluation, electromyographic and kinematic data were collected. The variables analyzed were percentage of hip (gluteus maximus/rectus femoris), knee (femoral biceps/vastus lateralis), and ankle (anterior tibial/lateral gastrocnemius), and length and step widths. A one-way analysis of variance was conducted, with a significance level of p < 0.05. Results: There was no significant difference in the length and step width and the level of co-contraction between the running conditions analyzed. Conclusion: Body weight suspension using SPPC during treadmill running did not alter the biomechanical variables of the gait of women with OAK.

scholarly journals THE EFFECT OF LOCAL VIBROSTIMULATION ON ELECTROMYOGRAPHY PARAMETERS IN ROWERS

2017 ◽  
Vol 3 ◽  
pp. 325
Author(s):  
Kalvis Ciekurs ◽  
Viesturs Krauksts ◽  
Daina Krauksta ◽  
Baiba Smila ◽  
Aivars Kaupuzs
Keyword(s):  
Biceps Brachii ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Erector Spinae ◽  
Mathematical Statistics ◽  
Triceps Brachii ◽  
The Mean ◽  
Moving Speed

Local vibrostimulation (further in text - LV) is innovation as a part of training method that helps athletes to regain the power and get ready for next training faster. There are many discussions about how to increase moving speed in rowers. Many scientists research the possibilities of increasing moving speed in this sport. The following methods were used in the study: tests – Concept-2, LV manipulations, electromyography and mathematical statistics. The electromyography was made with Biometric LTD. LV manipulations were done to the muscles erector spinae, latisimus dorsi, teres major, teres minor, trapezius, infraspinatus, deltoideus, slenius capitis, triceps brachii, gluteus maximus, semitendinosus, biceps femoris, semimembranosus, castrocnemius, tendo calcaneus, rectus femoris, vastus lateralis, tensor fascia latae, vastus medialis, sarterius, ligamentum patellae, tibialis anterior, rectus abdominis, pectoralis major and biceps brachii. We using 100 Hz frequency, 2 – 4 mm amplitude and different pressure on the muscles. The total LV application time was 5 to 20  min. The obtained data were processed using mathematical statistics. The results: having stated the result difference before LV and after it. The results testify significant improvement of Concept-2 tests results and electromyography results, what is showed by the difference of the mean results. Comparing the results of the rowers of EG and CG they have differences in the left side muscle latissimus dorsi after the t-test where p>0.05, but stating the percentage of the mean result difference of this muscle it was found out that p>0.05 what also shows significant changes in the muscle biopotential (mV).

scholarly journals A Time Division Multiplexing Inspired Lightweight Soft Exoskeleton for Hip and Ankle Joint Assistance

Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1150
Author(s):  
Xin Ye ◽  
Chunjie Chen ◽  
Yanguo Shi ◽  
Lingxing Chen ◽  
Zhuo Wang ◽  
...  
Keyword(s):  
Gait Cycle ◽  
Vastus Lateralis ◽  
Plantar Flexion ◽  
Rectus Femoris ◽  
Loading Path ◽  
Time Division Multiplexing ◽  
Natural Motion ◽  
Actuation Scheme ◽  
Hip Flexion ◽  
Time Division

Exoskeleton robots are frequently applied to augment or assist the user’s natural motion. Generally, each assisted joint corresponds to at least one specific motor to ensure the independence of movement between joints. This means that as there are more joints to be assisted, more motors are required, resulting in increasing robot weight, decreasing motor utilization, and weakening exoskeleton robot assistance efficiency. To solve this problem, the design and control of a lightweight soft exoskeleton that assists hip-plantar flexion of both legs in different phases during a gait cycle with only one motor is presented in this paper. Inspired by time-division multiplexing and the symmetry of walking motion, an actuation scheme that uses different time-periods of the same motor to transfer different forces to different joints is formulated. An automatic winding device is designed to dynamically change the loading path of the assistive force at different phases of the gait cycle. The system is designed to assist hip flexion and plantar flexion of both legs with only one motor, since there is no overlap between the hip flexion movement and the toe-offs movement of the separate legs during walking. The weight of the whole system is only 2.24 kg. PD iterative control is accomplished by an algorithm that utilizes IMUs attached on the thigh recognizing the maximum hip extension angle to characterize toe-offs indirectly, and two load cells to monitor the cable tension. In the study of six subjects, muscle fatigue of the rectus femoris, vastus lateralis, gastrocnemius and soleus decreased by an average of 14.69%, 6.66%, 17.71%, and 8.15%, respectively, compared to scenarios without an exoskeleton.

EMG Activity of Six Muscles and VMO:VL Ratio Determination during a Maximal Squat Exercise

1995 ◽  
Vol 4 (3) ◽  
pp. 195-202 ◽  
Author(s):  
Peter A. Schaub ◽  
Teddy W. Worrell
Keyword(s):  
Lower Extremity ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Emg Activity ◽  
Kinetic Chain ◽  
Maximal Voluntary Isometric Contraction ◽  
Knee Rehabilitation ◽  
Intraclass Correlations ◽  
Ratio Determination

During knee rehabilitation, squats are a commonly used closed kinetic chain exercise. We have been unable to locate data reporting electromyographic (EMG) activity of lower extremity musculature during maximal effort squats and the contribution of gastrocnemius and gluteus maximus muscles. Therefore, the purposes of this study were (a) to quantify EMG activity of selected lower extremity muscles during a maximal isometric squat and during a maximal voluntary isometric contraction (MVIC), and (b) to determine ratios between the vastus medialis oblique (VMO) and vastus lateralis (VL) during maximal isometric squat and MVIC testing. Twenty-three subjects participated in a single testing session. Results are as follows: intraclass correlations for MVIC testing and squat testing ranged from .60 to .80 and .70 to .90, respectively. Percentage MVIC during the squat was as follows: rectus femoris 40 ± 30%, VMO 90 ± 70%, VL 70 ±40%, hamstrings 10 ± 10%, gluteus maximus 20 ± 10%, and gastrocnemius 30 ± 20%. No statistical difference existed in VMO:VL ratios during MVIC or squat testing. We conclude that large variations in muscle recruitment patterns occur between individuals during isometric squats.

Mono- and Biarticular Muscle Activity during Jumping in Different Directions

2003 ◽  
Vol 19 (3) ◽  
pp. 205-222 ◽  
Author(s):  
Stephanie L. Jones ◽  
Graham E. Caldwell
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Activity Patterns ◽  
Center Of Mass ◽  
Reaction Force ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Jump Condition ◽  
Activity Level ◽  
Biarticular Muscle

This study examined the role of mono- and biarticular muscles in control of countermovement jumps (CMJ) in different directions. It was hypothesized that monoarticular muscles would demonstrate the same activity regardless of jump direction, based on previous studies which suggest their role is to generate energy to maximize center-of-mass (CM) velocity. In contrast, biarticular activity patterns were expected to change to control the direction of the ground reaction force (GRF) and CM velocity vectors. Twelve participants performed maximal CMJs in four directions: vertical, forward, intermediate forward, and backward. Electromyographical data from 4 monoarticular and 3 biarticular lower extremity muscles were analyzed with respect to segmental kinematics and kinetics during the jumps. The biarticular rectus femoris (RF), hamstrings (HA), and gastrocnemius all exhibited changes in activity magnitude and pattern as a function of jump angle. In particular, HA and RF demonstrated reciprocal trends, with HA activity increasing as jump angle changed from backward to forward, while RF activity was reduced in the forward jump condition. The vastus lateralis and gluteus maximus both demonstrated changes in activity patterns, although the former was the only monoarticular muscle to change activity level with jump direction. Mono- and biarticular muscle activities therefore did not fit with their hypothesized roles. CM and segmental kinematics suggest that jump direction was initiated early in the countermovement, and that in each jump direction the propulsion phase began from a different position with unique angular and linear momentum. Issues that dictated the muscle activity patterns in each jump direction were the early initiation of appropriate forward momentum, the transition from countermovement to propulsion, the control of individual segment rotations, the control of GRF location and direction, and the influence of the subsequent landing.

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