Muscle Fibers
Andy explains how counting muscle fibers is a challenging task and how fast twitch fibers are generally wider than slow twitch fibers. He also mentions that slow twitch fibers can be bigger than fast switch fibers in an individual person.In this clip
From this podcast

The Peter Attia Drive Podcast
250 ‒ Training principles for longevity | Andy Galpin, Ph.D. (PART II)
Related Questions
How do fast-twitch fibers differ from slow-twitch fibers in the episode "Why Muscle Matters & How to Build Muscle | Perform with Dr. Andy Galpin" and the clip "Muscle Fiber Types"?
How do fast-twitch fibers differ from slow-twitch fibers in the episode Why Muscle Matters & How to Build Muscle | Perform with Dr. Andy Galpin and the clip Muscle Fiber Types?
Can you explain the difference between fast and slow twitch muscle fibers as discussed in the episode Why Muscle Matters & How to Build Muscle | Perform with Dr. Andy Galpin and the clip Muscle Fiber Types?