Depending on the frequency of the applied stimulus to the muscle, muscle excitatory contractions can be monocontractile and tonic. Both incomplete and complete tonic contractions are known as tonic contractions. When the frequency of the stimulus is low, and the latter stimulus falls after the end of the contraction elicited by the preceding stimulus, only a series of separate monocontractions are elicited, and as the frequency is increased, if the latter stimulus falls in the diastolic phase of the contraction elicited by the preceding stimulus, the contraction formed is known as an incomplete forcible contraction, and if it falls in the systolic phase, it is a complete tonic contraction.