Factors Affecting Muscular Force Generation
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
(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.