The magnitude of the force generated by muscle is also related to the velocity of muscle shortening, the length of the muscle when it is stimulated, and the period of time since the muscle received a stimulus. Because these factors are significant determiners of muscle force.
(a) Force-Velocity Relationship
The maximal force that a muscle can develop is governed by the velocity of the muscle’s shortening or lengthening.
(b) Length-Tension Relationship
The amount of maximum isometric tension a muscle is capable of producing is partly dependent on the muscle’s length. In single muscle fibers, isolated muscle preparations, and in vivo human muscles, force generation is at its peak when the muscle is slightly stretched. Conversely, muscle tension development capability is less following muscle shortening. Both the duration of muscle stretch or shortening and the time since stretch or shortening affect force generation capability.
(c) Electromechanical Delay
When a muscle is stimulated, a brief period elapse before the muscle begins to develop tension and is referred to as electromechanical delay(EMD), this time is believed to be needed for the contractile component of the muscle to stretch the series elastic component(SEC). During this time, muscle laxity is eliminated. Once the SEC is sufficiently stretched, tension development proceeds.
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