Isotonic Contraction

Isotonic Contraction

Isotonic Contraction: In an isotonic contraction, the tension within the muscle remains the same throughout the motion, which is to say the force of the contraction remains constant. This is also called the positive portion of an exercise movement. There are two aspects of isotonic contraction, concentric, and eccentric. Concentric contraction occurs when the muscle fibers shorten as tension develops. At the onset of the movement, the actin and myosin filaments have tremendous pulling force. Thus you will be stronger in the initial phase of most movements. Toward the end or near the peak of contraction, the ability of the filaments to slide toward each other reaches a limit and strength weakens. An eccentric contraction is the type of muscle contraction that involves lengthening the muscle fibers, such as when a weight is lowered through a range of motion. The muscle yields to the resistance, allowing itself to be stretched. Here the actin and myosin slide away from each other. The level of force generated is much higher in the eccentric phase as opposed to the concentric phase. This is due to the added friction in the eccentric portion. Concentric aspect is a form of muscle contraction that occurs when muscle fibers shorten as tension develops. Eccentric aspect is a contraction that involves lengthening the muscle fibers, such as when a weight is lowered through a range of motion. The muscle yields to the resistance, allowing itself to be stretched. This is the age of the focused eccentric contraction. Too often bodybuilders focus their attention only on the positive motion (concentric) and pay little attention to the negative motion (eccentric). It is a matter of common sense to perform the lowering of resistance with at least as much focus and effort given to lifting the same weight.

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