Full range of motion is the default for good reason - it builds strength across the entire movement, keeps connective tissue healthy, and prevents the kind of abbreviated technique that becomes a habit without you noticing. None of that changes. But somewhere along the way, the instruction to train through a full range hardened into a rule that made partial reps feel like laziness or ego-lifting. They’re neither.
A partial rep is a deliberate choice to load a specific portion of a movement. That’s the distinction that matters. The person doing half-squats because the full depth feels uncomfortable is not doing the same thing as a lifter consciously overloading the top range of a Romanian deadlift to build tension through lockout. Same abbreviated movement, completely different intent and outcome.
Where They Actually Work
The strongest case for partial reps is in ranges where you can handle significantly more load than your weakest point allows. The bottom of a bench press is mechanically disadvantaged - the chest is fully stretched, the bar is farthest from the fulcrum. The top third of that same press is where most people are genuinely strong. Rack lockouts, top-range presses, pin squats from just above parallel: these let you expose the muscle to loads it rarely experiences, which is a real stimulus for strength adaptation in that range.
There’s also a fatigue management use case. Late in a set, when full-range reps have degraded, controlled partials at the strongest portion of the lift can extend productive tension without the form breakdown that full reps would require. This is different from grinding out ugly reps - it’s shortening the range to maintain quality.
The Misuse Is What Earned Them the Reputation
Partials get associated with bad training because most people use them as an exit ramp - a way to claim more reps, load more plates, or avoid the hard part of a lift. That version is counterproductive. The bottom of a squat is uncomfortable precisely because it’s doing something. Skipping it consistently doesn’t make you stronger there; it just means you stop training that position.
Used selectively - a few sets of heavy top-range work added after full-range sets, not instead of them - partial reps are a legitimate way to vary the mechanical stress a muscle receives. The lift doesn’t have to be one fixed thing every time you touch the bar.