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Electromyograms
Published in A. Bakiya, K. Kamalanand, R. L. J. De Britto, Mechano-Electric Correlations in the Human Physiological System, 2021
A. Bakiya, K. Kamalanand, R. L. J. De Britto
In the measurement of EMG signals, there are two categories of contractions, namely, isotonic contraction and isometric contraction (Nazmi et al., 2016). Isotonic contraction is often used for athletic goals, whereas isometric contractions are utilized for physical rehabilitation. The isotonic contraction is a muscle contraction that produces force with respect to the resistance in which the length of the muscle changes. Further, isotonic contraction is classified into two types, namely, the concentric contraction and eccentric contraction (Nazmi et al., 2016). The combination of concentric and eccentric contraction creates a dynamic contraction (e.g., the joint movement during dumbbell bicep curl exercise). Concentric contraction permits the muscle to reduce unstable energy but rigidity remains constant during the contraction. In eccentric contraction, the length of the contraction is longer, disturbing the muscles to stretch in response to a greater opposing force. Isometric contraction is the contraction that creates no change in muscle length but the energy and tension remain unstable (Nazmi et al., 2016).
Kinetics in Linear Motion
Published in Emeric Arus, Biomechanics of Human Motion, 2017
Determining the power output must be done under the dynamic (isotonic) training. During an isotonic contraction, the muscle tension is greater than an external force, and the muscle contracts. Using isokinetic training for calculating the power output is somehow easier because the speed is constant and as we know, only the force input can be changed.
Key human anatomy and physiology principles as they relate to rehabilitation engineering
Published in Alex Mihailidis, Roger Smith, Rehabilitation Engineering, 2023
Qussai Obiedat, Bhagwant S. Sindhu, Ying-Chih Wang
Skeletal muscles produce three types of contractions: (1) isometric, (2) isotonic, and (3) isokinetic. First, during an isometric contraction, a muscle generates a force to hold a joint in its position without any change in the muscle length or motion in the joint (Lippert 2006). For example, when holding a dumbbell in a hand while maintaining the elbow flexed at a 90-degree angle, the biceps brachii muscle, which is one of the elbow flexor muscles, is in isometric contraction. Second, during an isotonic contraction, the muscle's length and joint angle change. For example, when holding a dumbbell in your hand and flexing the elbow to bring it up toward the shoulder, the biceps brachii muscle is in isotonic contraction. The isotonic contraction is further subdivided into two phases: concentric and eccentric contractions. During a concentric contraction, a muscle shortens, bringing the origin and insertion of that muscle closer to each other. Therefore, the earlier example of moving the dumbbell toward the shoulder is an example of isotonic concentric contraction. In contrast, during an eccentric contraction, a muscle lengthens to move the origin and insertion away from each other while controlling the speed of the movement. For example, after bringing the dumbbell toward your shoulder, as in a concentric contraction, when you try to extend your elbow to move the dumbbell back down slowly, the biceps brachii muscle is eccentrically contracting. Last, an isokinetic contraction is less common and requires use of special equipment (Lippert 2006). During an isokinetic contraction, both muscle length and joint angle change, but this change happens under constant speed or velocity while the resistance to the motion varies, which is regulated by special equipment. In contrast to isokinetic contraction, an isotonic contraction involves constant resistance while the motion speed varies. Therefore, in isokinetic contraction, the machine is preset to maintain a constant speed no matter how hard a person pushes, while the resistance will vary. For example, the harder the person pushes, the machine will give more resistance, and if the person does not push as hard, the machine will generate less resistance (Lippert 2006). Several studies have shown that isokinetic exercises can lead to better strength gains in both young and old individuals, and thus can be used as an intervention for individuals with musculoskeletal injuries undergoing rehabilitation (Gault and Willems 2013; Symons et al. 2005; Hortobaágyi and DeVita 2000; Roig et al. 2009).
Modelling and simulation of sprinters’ health promotion strategy based on sports biomechanics
Published in Connection Science, 2021
Wang Huifeng, Achyut Shankar, G.N. Vivekananda
The purpose of this paper is to establish a mechanical simulation model based on the anatomy of the human knee joint, which belongs to the anatomical model of the knee joint mathematical model. An anatomical model is a three-dimensional representation of human anatomy which is used for biological and medical education. This model widely used for educational purposes which has unique pieces carved in wax and fragile today they're made of plastic based resin. This model is a static geometric representation of the different organs, tissues, and regions. This requires us to first establish a geometric anatomical model of the human knee joint. The force of the person on the ground during the movement (the foot force of the Yili movement) is an important parameter of the split plate movement, and the test foot force mostly adopts the multi-dimensional force measuring platform. The constraining nature of the sexual structure makes the hip joint rarely require ligament and soft tissue reinforcement. The cartilage of the hip joint is mainly located on the front and side of the joint, surrounding about two-thirds of the joint hemisphere. Under the action of physiological load, the cartilage can evenly transmit the load, enlarge the weight-bearing surface of the joint, reduce the contact stress, and cushion the shock, which can minimise the friction and wear when the joint surface moves relative to each other. When the subject's foot is on the table, the force and torque values in different directions can be obtained according to the output of the sensor. Multidimensional force measuring platform can be divided into piezoelectric and strain sensors in principle, and can be divided into combination type (composed of multiple multi-dimensional force sensors) and integration type in sensor structure. But in motion, the constant velocity instrument provides a kind of compliance resistance, which varies with the muscle contraction tension, similar to isometric contraction. Therefore, isokinetic muscle contraction has some characteristics and advantages of isotonic contraction and isometric contraction, and it is a special form of muscle contraction. Preparatory exercises can increase body temperature, reduce muscle viscosity, and increase the speed of muscle contraction and relaxation, thus avoiding muscle damage around the knee joint.