caused by a single stimulus, a quick cycle of contraction and relaxation is called? a . the short delay between the stimulus and the onset of the twitch is called the period. this is the time required for excitation, excitation-contraction coupling, and of the elastic components of the muscle. the force generated during this time is called tension. once elastic components are taut, the muscle produces external . when the external tension moves a load, this is called the phase.