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Depiction of smooth muscle contraction. Muscle contraction is the activation of tension-generating sites within muscle cells. [1] [2] In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. [1]
The second paper, by Hugh Huxley and Jean Hanson, is titled "Changes in the cross-striations of muscle during contraction and stretch and their structural interpretation". It is more elaborate and was based on their study of rabbit muscle using phase contrast and electron microscopes. According to them: [19]
Cardiac cells have two refractory periods, the first from the beginning of phase 0 until part way through phase 3; this is known as the absolute refractory period during which it is impossible for the cell to produce another action potential. This is immediately followed, until the end of phase 3, by a relative refractory period, during which a ...
An isometric exercise is an exercise involving the static contraction of a muscle without any visible movement in the angle of the joint. The term "isometric" combines the Greek words isos (equal) and -metria (measuring), meaning that in these exercises the length of the muscle and the angle of the joint do not change, though contraction ...
The contractile component itself has also been associated with the ability to increase contractile performance through muscle potentiation [5] while other studies have found that this ability is quite limited and unable to account for such enhancements (Lensel and Goubel, 1987, Lensel-Corbeil and Goubel, 1990; Ettema and Huijing, 1989).
This force is withstood in eccentric contraction. When muscle contraction is sufficiently great, it is able to stop the downward movement very quickly. This phase is sometimes called the phase of amortization in which the athlete absorbs some of the force and stops downward movement by the strong eccentric contraction of the muscles.
There are 3 main stages in the generation of an action potential in a pacemaker cell. Since the stages are analogous to contraction of cardiac muscle cells, they have the same naming system. This can lead to some confusion. There is no phase 1 or 2, just phases 0, 3, and 4.
The function of the antagonist muscle contraction is believed to control the amplitude and timing of ballistic movements. Antagonist muscle contraction may serve to prevent injury to joints by preventing the limb from overextending itself and also function to control the distance and time the limb is being moved.