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Movement Control (Muscular Physiology)
Published in Emeric Arus, Biomechanics of Human Motion, 2017
Ca2+ discloses the binding sites on the actin filaments. Ca2+ binds to the troponin molecule causing tropomyosin to disclose its position on the actin filament for the attachment of the myosin head.Cross bridges between myosin heads and actin filaments form.ADP and Pi are released and the sliding movement of actin results. The attachment of cross bridges between myosin and actin causes the release of ADP and Pi. The myosin head generates a sliding movement of the actin filaments toward the center of the sarcomere. Z discs are pulled together, contracting the muscle fiber to produce a power stroke.The new ATP arrives at the myosin head, the cross bridge between the actin and myosin breaks, returning the myosin head to its former unattached position. Then the process starts all over again.
New Methods and New Dogmas and Their Shortcomings
Published in Haruo Sugi, Mysteries in Muscle Contraction, 2017
As illustrated in the simplified diagram of the primary structures of myosin head-actin molecule complex (Fig. 20), major myosin-binding sites on actin are localized near its N terminus, while the corresponding actin-binding sites on the myosin head are localized at both sides of the junction between 50 K and 20 K fragments of the myosin heavy chain.
Dynamic post-activation potentiation protocol improves rowing performance in experienced female rowers
Published in Journal of Sports Sciences, 2020
Idan Harat, Nicolas W. Clark, David Boffey, Chad H. Herring, Erica R. Goldstein, Michael J. Redd, Adam J. Wells, Jeffrey R. Stout, David H. Fukuda
Acutely enhancing exercise performance by performing high-intensity activities of similar biomechanical characteristics several minutes prior is termed post-activation potentiation (PAP). The potentiating exercise, or activity, is termed the conditioning activity (CA) while the outcome variable is the performance measure of interest. Muscular contraction induces both fatigue and potentiation (Rassier & MacIntosh, 2000) and the net balance between the two may translate into either positive or negative changes in performance (Hodgson et al., 2005). When muscle potentiation exceeds contraction-induced fatigue, observable performance will be improved, and vice versa. It is believed that the mechanism behind PAP is the phosphorylation of the regulatory myosin lights chains, which render the myosin head more sensitive to Ca+2, and moves the myosin head closer to the actin filament and into its force-generating state (Hodgson et al., 2005; Tillin & Bishop, 2009).
Cross-bridge mechanism of residual force enhancement after stretching in a skeletal muscle
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2018
We assume that a local potential Hlocal(n) in the weak- and strong-binding states is provided by adenosine tri-phosphate (ATP) hydrolysis by the myosin head and the force is active in an area of ±δ (<<La = 5.7 nm) which is in one actin molecule. The local potential moves side by side with the myosin head. The force from the local potential Hlocal from Equation (5) is 2.5 pN (Finer et al. 1994; Tyska et al. 1999) in both the weak- and strong-binding states in the simulation. The force from the local potential moves the myosin head along the actin filament.