Biology
How Bones and Muscles Work Together to Move Us
Quick fact
A single human biceps muscle can generate enough force to lift about 35 kilograms, but it only shortens by about one-third of its length; the rest is mechanical advantage from the bone lever.
Why this is interesting
Every time you raise your arm, you're using a built‑in lever system more elegant than any machine – but how does a soft muscle make a hard bone move?