Question

1. what is muscle fatigue and when does it commonly occur?

Explanation:

Muscle fatigue is the decline in muscle's ability to generate force. It commonly occurs during prolonged or intense physical activity when energy stores (like ATP) are depleted, there's a buildup of metabolites (such as lactic acid), and ion imbalances (e.g., potassium and calcium) affect muscle function.

Answer:

Muscle fatigue is the reduced ability of muscles to produce force. It commonly occurs during prolonged or intense physical exertion.