PowerMuscular power
Force produced quickly: work divided by time, the combination of strength and speed.
Power is force produced quickly: work divided by time, or force multiplied by velocity. Strength asks how much you can move; power asks how fast you can move it. A heavy grinding deadlift is a strength expression; a jump, a throw or a clean is a power expression.
The distinction matters because they are trained differently and they decline differently. Power depends on fast twitch fibres and on the nervous system's ability to fire motor units rapidly, and both of those fade earlier and faster with age than maximal strength does.
That is why power work belongs in later life training rather than being reserved for athletes. Catching a stumble, standing up quickly and stepping out of the way of something are power tasks, and they fail before the ability to carry shopping does. Falls are a power problem before they are a strength problem.
Training it requires intent as much as load. Moderate weights moved with maximum acceleration, jumps, throws and short sprints all develop it, and the common failure is doing them tired: power work at the end of a long session becomes slow work, which trains something else entirely.
It is also position specific and skill heavy, so it improves quickly at first through coordination and then more slowly as it starts to depend on tissue. Small amounts, done fresh and often, beat occasional long sessions.
Measuring it is straightforward enough. A vertical jump is the classic field test, and the standard equations convert jump height and bodyweight into an estimate of peak power output.
In practice, keep some fast work in every training week whatever your age, place it early in the session, and use our vertical jump calculator to track it over the years rather than the weeks.