A skeletal muscle twitch is shorter than a tetanic contraction, according to Dr. Paul Deeble of Mary Baldwin College. A twitch contraction is a short, jerky movement in response to a single stimulus in a muscle fiber. A tetanic contraction happens after several stimuli cause a muscle to contract in rapid succession.
The simplest type of muscle contraction in the human body is a twitch. A twitch is a single, brief development of force across a fiber, motor unit or entire muscle. After a twitch, the muscle relaxes. When individual twitches cannot be recognized and the force output is fairly constant, a tetanus or tetanic contraction occurs. When the optimal rate of electrical stimulation in a muscle causes the maximum amount of force exerted in a muscle, this is called maximum tetanic tension.
The human nervous system uses electrical impulses to stimulate muscle contractions at different frequencies. Muscles can also be stimulated with electrical devices in the laboratory. Muscle fibers and motor units need different frequencies of electricity in the body to elicit twitches and tetanic contractions. Muscle contractions occur in one of four basic types: isotonic, isometric, twitch and tetanic.