Explain how it makes sense physiologically that the last fibers to be recruited to contract are the first to fatigue, while the first fibers to be recruited to contract would be the last to fatigue.
Explain how it makes sense physiologically that the last fibers to be recruited to contract are the first to fatigue, while the first fibers to be recruited to contract would be the last to fatigue.
Fatigue is a term used to describe an overall feeling of tiredness or lack of energy. It isn’t the same as simply feeling drowsy or sleepy. When you’re fatigued, you have no motivation and no energy. Being sleepy may be a symptom of fatigue, but it’s not the same thing.
Muscle fibers are categorized into slow-twitch fibers and fast-twitch fibers. Slow-twitch fibers (also called Type 1 muscle fibers) are slow to contract, but they are also very slow to fatigue. Fast-twitch fibers are very quick to contract and come in two varieties: Type 2A muscle fibers which fatigue at an intermediate rate, and Type 2B muscle fibers which fatigue very quickly. The main reason the slow-twitch fibers are slow to fatigue is that they contain more mitochondria than fast-twitch fibers and hence are able to produce more energy. Slow-twitch fibers are also smaller in diameter than fast-twitch fibers and have increased capillary blood flow around them.
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