Question

multiple choice question

a muscle fiber shortens and generates force during the ________ period of a muscle twitch.

• contraction
• latent
• lag
• excitation
• relaxation

Explanation:

Identify the phases of a muscle twitch

Using the Muscle Twitch and Myogram knowledge points
A muscle twitch consists of three distinct phases:

1. Latent period (or lag phase): The delay between stimulus application and the start of contraction.
2. Contraction phase: The period during which tension increases and the muscle shortens.
3. Relaxation phase: The period during which tension declines and the muscle returns to its resting length.

Analyze the question prompt

Using the Contraction Phase and Latent Period Physiology knowledge points

• The question asks for the period during which a muscle fiber "shortens and generates force."
• This active force generation and physical shortening occur specifically during the contraction phase.

Evaluate the given options

Using the Muscle Twitch knowledge point

• contraction: Correct, as this is when cross-bridge cycling occurs, generating tension and shortening.
• latent: Incorrect; this is the preparatory phase before tension is recorded.
• lag: Incorrect; this is synonymous with the latent period.
• excitation: Incorrect; this refers to the electrical signaling events preceding contraction.
• relaxation: Incorrect; this is when calcium is pumped back into the sarcoplasmic reticulum and tension decreases.

Answer:

• contraction (Correct answer)
• latent
• lag
• excitation
• relaxation