Lack of relaxation between successive stimuli in sustained muscle contraction is known as:

Step-by-step solution

Tonus → Low-level activity of muscles at rest to maintain posture Spasm → Sudden involuntary muscle contraction Fatigue → Decline in muscle activity Tetanus → Sustained muscle contraction in response to successive stimuli. Tetanus is also known as lockjaw disease and is caused by the bacterium Clostridium tetani.