Muscle Fatigue and Training - FCs

Fifteen questions and answers covering central fatigue, motor unit recruitment, training principles, reflexes, and factors affecting force production as discussed in the lecture.

What is central fatigue?

Fatigue that arises when the brain/CNS reduces the motor signal to muscles (due to pain), causing a drop in voluntary drive.

What happens to the neural signal as fatigue increases?

The brain’s signal to the muscle decreases (central fatigue).

What causes the brain to send a smaller signal during fatigue?

Pain from lactic acid buildup that distracts the brain and reduces the neural drive.

What is the process called when more motor units are recruited as force demands rise?

Multiple motor unit summation (recruitment).

In what order are muscle fibers recruited as load increases?

Slow-twitch fibers are recruited first; once all local slow-twitch fibers are recruited, fast-twitch fibers are recruited.

What happens to the duration of a repetition when fatigue sets in?

Reps become slower as fatigue builds and cross-bridges try to reform.

What is the principle of specificity of training?

The body adapts specifically to the demands placed on it; speed training improves speed, strength training improves strength, etc. “Train how you play”

What is the baseline stage in the training pyramid?

Foundational training to build general strength and endurance before sport-specific work.

What does sport- or skill-specific training entail?

Drills that mirror the actual sport movements and speeds, often combining speed with the required skill.

What does the force-velocity curve describe?

High force is associated with low velocity; to move fast you must operate with lighter loads, and the two are inversely related.

Which muscle fibers have the highest recruitment threshold?

Fast-twitch fibers.

What are the two reflexes discussed that regulate muscle force?

Muscle spindle (stretch) reflex and Golgi tendon reflex; they can enhance or limit force depending on the situation.

What is the role of hydrogen ions in fatigue?

Hydrogen ions from lactic acid interfere with calcium binding to troponin, reducing contraction and contributing to fatigue.