system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how are muscle size and muscle strength not 100% correlated?

Question comes from different workout strategies. You can focus on hypertrophy (muscle size) or strength. How is the actual biology of the muscle different if it's big but not as strong? If not biology, what's the physics involved?
gpt
Density and efficiency at utilizing energy (endurance). Big muscles are strong, no doubt. But they are trained to do high weight at low rep. Smaller, denser muscles are trained to do lower weights but at higher repetitions.

Think of it like... a big, thick tree trunk vs a relatively thinner, but denser concrete lamp post.

A power lifter feels like solid rock. A skinny martial artist is described as having muscles like corded steel.

Also, strength is measured by different metrics depending on how it's being leveraged. A length of rebar can chip a boulder down to pebbles with repeated hits, but that same boulder rolling down a hill will warp the same rebar upon impact rendering it bent and useless.