Answer
If the strength of a stimulus is inadequate a muscle fiber will not twitch. Nevertheless, even if one applies an adequate stimulus of the same strength to skeletal muscle, twitch response will vary, dependent on certain factors. Some of these factors are stimulus frequency; the temperature of the muscle; the degree of hydration of the muscle , and how stretched-out the muscle is before stimulation.
Work Step by Step
Effect of temperature:
A warm muscle contracts more strongly than a cool muscle. This is so because enzymes, for example in those in the myosin head, work more quickly in warmer ( optimal )temperatures.
Effect of hydration:
The amount of fluid in the myocyte affects the spacing between myosin and actin filaments. More fluid keeps them farther apart and decreases the efficiency of formation of myosin-actin cross-bridges.
Effect of stimulus frequency:
Stimulus frequency affects twitch strength. Stimuli arriving close together increase twitch strength due to summation effects. Stimuli that arrive at longer intervals ( with slower frequencies) induce weaker twitches
Effect of Stretch ( stretchedness) .
The degree to which the fiber is stretched or contracted relative to original length has influence on the strength of the twitch response. If sarcomeres of myofibrils are 60% shorter
or 175% longer than optimal resting (original ) lengths, even threshold stimulation may fail to induce any twitch response at all.
