LAB 6

Motor Unit Recruitment and Fatigue

✅ Why does EMG activity increase with stronger contractions?

• More motor units are recruited, and firing frequency increases.

✅ How do muscle fiber types affect fatigue rate?

• Slow-twitch (Type I): Fatigue-resistant, oxidative metabolism.

• Fast-twitch (Type II): Fatigue quickly, anaerobic metabolism.

Reciprocal Inhibition

✅ What happens if reciprocal inhibition is impaired?

• Antagonist muscles don't relax, causing stiffness and movement issues.

✅ How did EMG activity change when the opposing muscle contracted?

• Agonist EMG increased, antagonist EMG decreased due to reciprocal inhibition.

Length-Tension Relationship

✅ How does muscle length affect force production?

• Max force at mid-range length, too short or long reduces force.

✅ Which contraction produces the most force?

• Eccentric contractions generate the most force.

✅ What structural factors influence force production in eccentric contractions?

• Passive elastic elements (titin), greater actin-myosin engagement, slower cross-bridge detachment.

Force-Velocity Relationship

✅ How can PTs/trainers use force-velocity knowledge for hamstring recovery?

• Slow eccentric training first, then progress to faster movements.

This keeps the critical info while cutting out fluff! 🚀 Let me know if you need any tweaks.

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