ConcentricConcentric phase · Lifting phase

The concentric phase is the part of a rep where the working muscle shortens as it overcomes the load — standing up out of a squat, pressing a bar up, or curling a dumbbell toward you.

It matters because it is the phase most people think of as 'the lift', and it is typically where a rep fails: you can lower far more weight than you can raise. Understanding it helps you set loads and interpret why the sticking point of a lift is where it is.

In practice, driving the concentric with intent — moving the load quickly even when it feels slow under heavy weight — is a common cue for strength and power, paired with a controlled lowering phase.