How does fatigue affect manual muscle testing results?

How does fatigue affect manual muscle testing results?

• A. Fatigue has no effect
• B. Fatigue reduces force production, lowering grade
• C. Fatigue increases force production
• D. Fatigue makes ROM greater

Answer: (B)

Fatigue reduces the muscle's ability to generate force, which directly affects manual muscle testing outcomes. When fatigued, fewer motor units can be recruited effectively and each unit contracts with less force due to metabolic changes (depleted energy substrates and byproducts that impair contraction) and diminished neural drive. In MMT, you’re measuring the maximum force a muscle can oppose against a resistance; if the muscle is fatigued, it cannot sustain peak force, so the grade drops. Fatigue does not increase force production, nor does it increase range of motion, and it certainly doesn’t leave force production unchanged. So fatigue leads to a lower MMT grade because the muscle’s peak force is reduced.

Fatigue reduces the muscle's ability to generate force, which directly affects manual muscle testing outcomes. When fatigued, fewer motor units can be recruited effectively and each unit contracts with less force due to metabolic changes (depleted energy substrates and byproducts that impair contraction) and diminished neural drive. In MMT, you’re measuring the maximum force a muscle can oppose against a resistance; if the muscle is fatigued, it cannot sustain peak force, so the grade drops. Fatigue does not increase force production, nor does it increase range of motion, and it certainly doesn’t leave force production unchanged. So fatigue leads to a lower MMT grade because the muscle’s peak force is reduced.