Question

Muscle fatigue arises primarily from failure in

A) neuromuscular transmission.
B) initiation of contraction by the motor cortex.
C) excitation-contraction coupling.
D) signal relay from brain to spinal cord.
E) calcium pumps in the skeletal muscles.

Answer 1

Muscle fatigue primarily arises from issues in excitation-contraction coupling due to ATP depletion and calcium regulation disruption, leading to reduced muscle function.

Step-by-step explanation:

Muscle fatigue arises primarily from excitation-contraction coupling, which is the process that links the action potential generated in a muscle fiber's sarcolemma to the start of a muscle contraction. This involves the release of calcium ions from the sarcoplasmic reticulum (SR) into the sarcoplasm, triggered by a neural signal. When ATP reserves are reduced, muscle function may decline, as ATP is essential for muscle contraction. Moreover, long periods of intense exercise can impair the SR and sarcolemma, leading to disrupted calcium regulation. As a result, the inability to properly manage calcium can contribute to muscle fatigue.