Climbing in repeated waves rather than a straight line
Wave loading arranges sets into ascending clusters that repeat, for example a descending-rep ascending-load sequence done once, then run again at slightly heavier weights. Within each wave the reps drop as the load rises, and the next wave starts heavier than the last. The pattern lets a lifter accumulate quality work at progressively higher loads inside a single session without simply grinding upward in one long ramp.
The repeating shape is the defining feature: you come back down in load, then go up again past where you were.
The proposed potentiation rationale and its limits
Part of the reasoning leans on post-activation potentiation: the heavier early sets are thought to leave the nervous system briefly primed so that later, heavier sets feel more manageable than they otherwise would. Whether this potentiation contributes meaningfully or whether the benefit is mostly thorough warming-up and pacing is debated, and the effect is individual.
Loads, rep schemes, and wave count vary by program and should match a lifter's training age and recovery. This is general educational information, not an individualized prescription.