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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).
Muscle
Published in Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella, Essentials of Human Physiology and Pathophysiology for Pharmacy and Allied Health, 2019
Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella
Isotonic contraction occurs when the muscle changes length under a constant load. For example, when lifting an object, the muscle contracts and becomes shorter while the weight of the object remains constant. Because shortening of the muscle occurs, this is referred to as concentric contraction. When placing the object back down, once again, the muscle is generating tension. However, in this case, the muscle is lengthening. This is referred to as eccentric contraction. In addition to moving external objects, isotonic contractions are performed for movement of the body, such as moving the legs when walking.
Functional Properties of Muscle
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
Muscle contraction can take one of the following forms, depending on how the length of the muscle changes while force is developed by the muscle: Isometric contraction is the development of force by the muscle without a change in length, as when one tries to lift too heavy a load, or when holding or gripping an object without moving it.Isotonic contraction is shortening of the muscle while a constant force is developed by the muscle. Strictly isotonic contractions can only be produced in the laboratory. In the body, the eyeball is rotated by extraocular muscles. Since the rotation occurs at practically constant resistance, particularly for small movements, the contraction of the extraocular muscles is isotonic under these conditions.Concentric contraction is shortening of the muscle while developing a varying force of contraction. This is the usual case. For example, the force diagram for lifting a weight W by a force F developed by the biceps brachii muscle is illustrated in Figure 10.1, where O represents the elbow joint, segment Oc the upper arm, segment Ob the forearm from the elbow to where the weight W is applied to the hand, and “a” is the point of insertion of the biceps muscle on the radius bone of the forearm. Equating moments about the fulcrum O: (Fcosα)d1 = (Wcosθ)d2, where F is the force developed by the muscle, d1 is the length Oa, and d2 is the length Ob. As the weight is lifted, the muscle shortens, and α, θ, and F change.Eccentric contraction is lengthening of the muscle while developing a force of contraction. In Figure 10.1, for example, if W is increased beyond what the arm muscles can support, the weight moves downward, and the biceps brachii will lengthen while still developing force. Eccentric contraction plays important roles in the control of movement, as in braking and control of joint stiffness (Section 13.1.2). The force developed during eccentric contraction is larger than that for an isometric contraction at the same muscle length. Thus, one can set down a heavier weight that one can lift. Eccentric contractions are important for muscle strengthening during athletic training and rehabilitation.
The synergic effects of alpha-lipoic acid supplementation and electrical isotonic contraction on anthropometric measurements and the serum levels of VEGF, NO, sirtuin-1, and PGC1-α in obese people undergoing a weight loss diet
Published in Archives of Physiology and Biochemistry, 2022
Majid Mohammadshahi, Elahe Zakizadeh, Kambiz Ahmadi-Angali, Majid Ravanbakhsh, Bijan Helli
In the other hand, multiple interactions are existed between diet, physical activity and obesity (Kalantari et al. 2017). Simultaneous diet and physical activity interventions are recommended to management of obesity (Kalantari et al. 2017, Razavi et al. 2012). Faradic is an electrical stimulating system that increased muscle contraction, physiological activity, blood flow and lymph evacuation and causes isotonic contraction (like the exercise isotonic contraction) to reduce body weight and size (Razavi et al. 2012). One study reported that the Faradic and aerobic training affected the abdominal circumference and significant reduction of fat percentage of whole body and abdomen fat (Ziegler et al. 2011; Razavi et al. 2012).
Muscular strength and cardiovascular risk factors in adults: a systematic review
Published in The Physician and Sportsmedicine, 2021
Tiago Rodrigues De Lima, Priscila Custódio Martins, Paulo Henrique Guerra, Diego Augusto Santos Silva
The systematic search of the potential articles occurred during the month of November of 2019 through manual searches in the lists of references of articles evaluated by their integral texts and by the application of systematic searches in six electronic databases: Lilacs, Pubmed, Scielo, Scopus, Sportdiscus, and Web of Knowledge. The systematic searches were adjusted and applied in the other databases from the construct elaborated for Pubmed: (((‘muscle strength’[Title/Abstract] OR ‘Resistance Training’[Title/Abstract] OR ‘Muscle Contraction’[Title/Abstract] OR ‘weight training’[Title/Abstract] OR ‘muscular strength’[Title/Abstract] OR ‘muscular endurance’[Title/Abstract] OR ‘muscular power’[Title/Abstract] OR ‘muscular fitness’[Title/Abstract] OR ‘lower body explosive strength’[Title/Abstract] OR ‘upper body isometric strength’[Title/Abstract] OR ‘upper body strength’[Title/Abstract] OR ‘lower body strength’[Title/Abstract] OR ‘musculoskeletal fitness’[Title/Abstract] OR ‘isometric strength’[Title/Abstract] OR ‘dynamic strength’[Title/Abstract] OR ‘isometric contraction’[Title/Abstract] OR ‘isotonic contraction’[Title/Abstract])) AND (adult[Title/Abstract] OR adults[Title/Abstract] OR ‘young adult’[Title/Abstract] OR ‘young adults’[Title/Abstract])) AND (Obesity[Title/Abstract] OR ‘Obesity, abdominal’[Title/Abstract] OR ‘body fatness’[Title/Abstract] OR ‘Waist Circumference’[Title/Abstract] OR ‘Blood Pressure’[Title/Abstract] OR ‘Arterial Pressure’[Title/Abstract] OR ‘hypertension’[Title/Abstract] OR ‘Glycemic Index’[Title/Abstract] OR ‘Glycemic Load’[Title/Abstract] OR ‘Blood Glucose’[Title/Abstract] OR ‘Cholesterol’[Title/Abstract] OR ‘Cholesterol, LDL’[Title/Abstract] OR ‘Cholesterol, HDL’[Title/Abstract] OR ‘Hypercholesterolemia’[Title/Abstract] OR ‘dyslipidemia’[Title/Abstract] OR ‘Triglycerides’ [Title/Abstract] OR ‘Glucose’[Title/Abstract] OR ‘Glucose Metabolism Disorders’[Title/Abstract]). There was no restriction by time of publication of original articles (More information is available at Appendix A).