Which of the following best distinguishes muscle tone from muscle strength?

• A. Tone is the baseline passive tension.
• B. Strength is the rate of fatigue during activity.
• C. Tone is the speed of a muscle's contraction.
• D. Strength is the maximum force a muscle can generate during active contraction.

Answer: (D)

The main idea here is the difference between baseline neural activity that keeps a muscle ready (tone) and the maximum force a muscle can generate during a true contraction (strength). Muscle tone is the ongoing, low-level tension that provides readiness and helps maintain posture, driven by continual neural input even when the muscle isn’t actively working. Strength, by contrast, is measured by how much force a muscle can produce in a single, maximal voluntary contraction.

That’s why defining strength as the maximum force a muscle can generate during active contraction is the best answer. It separates peak capability in a controlled effort from the resting or ready state reflected by tone.

The other ideas don’t fit as well: tone is not simply baseline passive tension, since it involves active neural drive and sets how the muscle resists stretch rather than how hard it can contract. Fatigue rate describes endurance over time, not peak force. Contraction speed describes how fast the muscle shortens, not the total force it can produce.