It is obvious that LeBron James have a much higher percentage of fast twitch muscles compared to an average person. This means that an average person has a higher percentage of slow twitch muscles. Fast twitch muscles will tire out faster than slow twitch muscles.

So why would LeBron James still have more stamina than an average person?


I think this question has more to do with why a person with a lot of fast-twitch muscle types have higher stamina. Especially if you pair it with this question.

First, there are actually three types of muscle fibers. Type 1 (slow-twitch), type 2a (fast-twitch), and Type 2b (super-fast-twitch. Also called Type 2x). Type 2a is kind of an in between between Type 1 and Type 2b. (There's also a Type 2a/2x but that's not really important for the question).

While this doesn't have anything to do with Lebron James or basketball specifically, there was a study that compared muscle fiber types of Olympic Weightlifters. They studied 21 athletes that combined were in


So these were top-tier athletes.

What they found was their muscle composition was around 23% Type 1, 67% Type 2a, and 6% Type 2b.

So, the takeaway as it's related to this question is that athletes don't just train a single muscle fiber type. They train all muscle fiber types with an emphasis on a particular one. If weightlifters didn't train slow-twitch muscle fibers, then the percentages would be closer to 0% as the Type 2 overtook.

Specifically for basketball players like LeBron James, they run fast, but they're not sprinting at full speed every second of the game. They play basketball for many hours a day in addition to any sort of supplemental drills and training they do outside of basketball. That is going to train far more Type 1 and Type 2a muscle fibers which are necessary to perform for very long durations.

  • The muscle fibre type proportions that you cite were measured are the single fibre (SF) distribution results, comparing the number of fibres of each type present as a proportion of the total number of fibres present, rather than the proportion of muscle volume or area taken up by each fibre type. This means that these distributions are a result of their genetics rather than their training, as training is generally accepted as only causing hypertrophy (increase in the size of muscle fibres) and not hyperplasia (increase in the number of muscle fibres), meaning training couldn't alter SF type %. Feb 12 at 3:03

I imagine it has something to do with him being a full-time professional athlete with multiple full-time coaches optimizing his training.

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