The force-velocity relationship in muscle physiology: as contraction velocity increases, force production decreases. Maximum force is generated at zero velocity (isometric); maximum velocity occurs at zero external load.

This has practical implications for training: heavy slow lifts (high force, low velocity) don't transfer to fast explosive movements, and vice versa. A complete strength program trains across the curve.

The power peak — where force × velocity is maximized — is the sweet spot for athletic performance. It's somewhere in the middle, roughly 30–40% of maximum isometric force.

Related: [[movement-efficiency]], [[progressive-overload]]