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Biomechanical Modeling of Muscular Contraction
Published in Yuehong Yin, Biomechanical Principles on Force Generation and Control of Skeletal Muscle and their Applications in Robotic Exoskeleton, 2020
We took experiments on human rectus femoris of thigh to verify the steady relation between the isometric tension of muscle and the frequency of APs. Rectus femoris is located at the front of thighs, and it connects the tendons of the knee joint and hip joint; thus its contraction will raise the thigh or the leg. The experimental apparatus is shown in Figure 2.11, and tension signals and electromyogram (EMG) signals were collected with the lower-limb exoskeleton robot designed by our research group. EMG signals are formed by the superposition of massive APs of muscle fibers in a muscle, and the analysis of EMG can be used to diagnose muscle diseases [26] or identify the motion pattern of muscles [27], while here we judged the stimulation level of rectus femoris via the characteristic frequency of EMG.
Fundamentals of human gait and gait analysis
Published in Ivan Birch, Michael Nirenberg, Forensic Gait Analysis, 2020
Ambreen Chohan, Jim Richards, David Levine
Toe off occurs at approximately 60% of the gait cycle, and marks the transition from the stance phase to the swing phase of gait. Toe off is also sometimes referred to as terminal contact, as some pathologies can result in parts of the foot other than the toes being the last to leave the ground during walking. Ankle: Just after toe off, the ankle reaches peak plantarflexion. The calf muscles have relaxed before toe off, and tibialis anterior now dorsiflexes the foot to clear the ground during the swing phase of gait.Knee: By toe off, the knee has flexed to around half its peak swing phase amount. During this phase of the gait cycle the lower limb acts as a double pendulum, with knee flexion resulting from hip flexion as the foot is left behind. The eccentric contraction of rectus femoris prevents the knee from flexing excessively at higher walking speeds (Nene et al. 1999).Hip: The hip continues to undergo flexion as the foot leaves the ground, as the result of a combination of gravity, passive soft tissue tension and muscle contraction.Trunk: After toe off, the trunk, shoulders and arms all begin to move from their rotated positions back towards neutral positions, as the trunk rises and moves towards the side of the now supporting lower limb.
Functional Anatomy and Biomechanics
Published in Emeric Arus, Biomechanics of Human Motion, 2017
Quadriceps femoris has the primary role of action as the extensor of the knee. Only rectus femoris has a biarticular role being also a flexor of the hip. The action of the quadriceps has the utmost importance for both locomotion and static positions. With muscular contraction of the quadriceps standing up from a sitting position or walking up stairs are achieved. The contraction of the quadriceps can suddenly extend the knee to get a longer step when walking. With all these different actions the quadriceps is certainly the most important muscle in human locomotion.
Comparison of soccer instep kicking kinematics with and without elastic taping
Published in Sports Biomechanics, 2023
Nahoko Sato, Hiroyuki Nunome, Yuichi Mizukami
The rectus femoris is a bi-articular muscle which contributes to both hip flexion and knee extension. In the present study, of these two relevant joint motions, ET application solely worked to increase the peak hip flexion angular velocity during kicking; however, the peak knee extension angular velocity did not change. It is logical to assume that a significant increase in hip flexion angular velocity mainly contributed to a significant increase in the linear velocities of the distal body parts (knee and foot CG). During soccer instep kicking, knee extension angular velocity continues to increase towards ball impact, while knee extension muscle moment rapidly decreases and changes to flexion moment just before ball impact (Nunome, Ikegami, et al., 2006). Nunome, Ikegami, et al. (2006) indicated that the moment due to motion-dependent interaction plays a dominant role in continuously increasing the knee extension angular velocity during the final phase of kicking. The finding that knee muscle moment does not substantially contribute to knee extension motion during the final phase of instep kicking may explain why ET application did not alter the peak knee extension angular velocity during kicking. Furthermore, the rectus femoris is not the only muscle responsible for altering knee extension velocity, which may also explain why the knee extension angular velocity did not change despite the thickening of the rectus femoris muscle after ET application.
Effects of backrest and seat-pan inclination of tractor seat on biomechanical characteristics of lumbar, abdomen, leg and spine
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Qichao Wang, Yihuan Huo, Zheng Xu, Wenjie Zhang, Yujun Shang, Hongmei Xu
In this study, the muscles with high activities, including gluteus maximus, semitendinosus, Rectus femoris, iliopsoas, vastus lateralis and sartorius, were analyzed, and those muscles with low activities or small muscle tissues were not taken into account. Gluteus maximus has a wide and thick quadrilateral shape, and mainly drives the extension and external rotation of the thigh. Semitendinosus is located at the back of the thigh and helps the extension of the hip joint and bending of the knee joint. Rectus femoris is located in the front of the thigh, whose main function is to extend the knee joint and bend the thigh. Iliopsoas is composed of psoas major muscle and iliacus, which is mainly responsible for the external rotation of the thigh and forward flexion of the pelvis and trunk. The sartorius is flat and banded, and is one of the longest in the leg muscles, starting from the anterior superior iliac spine, passing through the inner side of the knee joint, and finally to the inner side of the upper end of the tibia. The main function of sartorius is for the bending of the hip and knee.
Effects of biofeedback on whole lower limb joint kinematics and external kinetics
Published in Journal of Sports Sciences, 2021
Franky Mulloy, Gareth Irwin, David R. Mullineaux
All three joints of the BFb group lower limb kinematic chain showed significant increases in kinematic extension patterns, while no changes occurred in the Control group across any kinematic measures. Importantly, both Peak Hipω and Peak Kneeω significantly increased in the BFb group. The increases in hip and knee extension, as elicited in this study, are beneficial for a propulsive task. The more proximal joints are considered as the large power generators of the lower limb in propulsive tasks (Jacobs et al., 1996; Wong et al., 2016). A large hip extensor contribution is necessary to initiate movement of the heavy trunk segment, and also to produce large muscular forces which are transferred to more distal joints via bi-articular muscle power transfer (Bobbert & Van Soest, 2001; Cleather et al., 2015; Jacobs et al., 1996). Hip extension is coupled with, and contributes to, knee extension through an isometric contraction of the bi-articular rectus femoris (Gregoire et al., 1984; Jacobs et al., 1996; Van Ingen Schenau, 1989). In this way, increasing the contribution of the hip joint alone should prove beneficial in a propulsive task. However, pairing this transfer with additional contraction of the large mono-articular vastii group is also needed to counteract excessive knee flexion; a paradoxical by-product of the bi-articular hamstrings role in hip extension (Cleather et al., 2015). Indeed, the vastii have been shown to contribute the largest muscular force in jumping (Jacobs et al., 1996). Therefore, monitoring both hip and knee extension simultaneously in an explosive lower-limb task is clearly important.