NETA Personal Trainer Practice Exam

What defines a twitch in muscular terms?

1. A series of electrical impulses

2. A single electrical impulse causing excitation

3. A period of muscle fatigue

4. A sustained contraction of muscle fibers

The correct answer is: A single electrical impulse causing excitation

A twitch in muscular terms is defined as a single electrical impulse that causes excitation of muscle fibers. When a motor neuron sends a single action potential, it results in the release of neurotransmitters at the neuromuscular junction, leading to a brief contraction of the muscle fibers. This contraction represents the muscle's response to a single stimulus and is characterized by a quick, jerky movement. The nature of a twitch is crucial for understanding how muscles function, as it demonstrates the basic physiological response to stimulation. It is a fundamental concept in muscle physiology and is involved in more complex patterns of muscle activity, such as summation and tetanus, where multiple impulses can lead to stronger and more sustained contractions. This understanding of the twitch is essential for personal trainers, as they can apply this knowledge to exercise programming, recognizing how different activities or loads impact muscle performance and recovery.