The evidence-led answer
NST verdict
Mostly yes. Across the trials, lifting through a full range of motion tends to build more lower body muscle and more strength than cutting the movement short. The part that seems to matter most is the stretched portion, the bottom of a squat, the lengthened position of a curl, so that is the part not to skip. The popular idea that doing only the stretched half, so called lengthened partials, is dramatically better than full reps is not well supported yet. A shorter range is a reasonable choice in specific cases: a joint that cannot go further without pain, training a weak point, or squeezing a few extra reps at the end of a set. For general size and strength, use the fullest range you can control with good form.
What "range of motion" means here
Full range of motion means taking a joint through its available movement on each rep, squatting until the hips are below the knees, or lowering a dumbbell curl until the arm is straight. A partial rep stops short. Where it stops matters. A partial done at the stretched end is a different stimulus from a partial done at the shortened, contracted end.
Full range and muscle size
A pooled analysis of 16 studies found full range training produced greater lower limb muscle growth than partial range training, a moderate sized difference, and an earlier review of six studies reached the same conclusion for the lower body. For the upper body the picture is thinner and less consistent. The smaller review found the upper limb evidence limited and conflicting, and noted the response may differ between muscles. So the confident statement is about the lower body. The upper body probably follows the same direction, but the evidence is weaker.
Full range and strength
The same pooled analysis found full range training produced greater strength gains overall. One caveat: strength is somewhat specific to the range you train, so train only quarter squats and you get particularly good at quarter squats. That is a legitimate reason a strength athlete might drill a specific portion of a lift, but for general strength that carries over to daily life and sport, the fuller range is the better default.
Is it the stretch that matters?
Probably. A review of 11 studies found that training a muscle at long lengths, through a full range or a partial range biased to the stretched, early part of the movement, tended to produce the most growth in muscles like the quads, biceps and triceps, while partials at the shortened end did less. Online this has become a strong claim that stretch only partials beat full reps. The evidence does not go that far. A 2025 pooled analysis found only trivial differences in regional growth between shorter and longer muscle lengths, and noted the conditions in those studies were not far apart. Confidence in the lengthened partials claim is low. The safe reading is to make sure your full range reps actually reach the loaded stretch, not to replace them with stretch only partials.
When a shorter range is fine
A partial range is a reasonable choice when a joint genuinely cannot go further without pain, and there you work to a comfortable, controlled range and build depth over time. Also when you are training a specific sticking point as a deliberate accessory, or extending a set with a few partials at the stretched end after full reps run out. Outside those cases, a partial rep is usually just a full rep with the most useful part removed.
Does lifting full range help flexibility?
To some degree, yes. Training through a full range under load can maintain and modestly improve flexibility, which is part of why "I lift, I don't stretch" is not unreasonable for general purposes. If flexibility is a specific goal, see the stretching article for how dedicated stretching compares.
What this means in practice
For size and general strength, pick the fullest range of motion you can control with good technique, and make sure you reach the stretched bottom position under load rather than cutting it short. Progress by adding weight or reps before you consider shortening the range. Use a partial range on purpose only for a pain limited joint, a targeted sticking point, or to extend a set past full range failure. You do not need to chase lengthened partials as a separate method. A proper full rep already trains the stretch.
Practical meaning
For building size and general strength, use the fullest range of motion you can control with good technique on each exercise, and reach the stretched (bottom) position under load rather than cutting it short. Progress load or reps before shortening the range. Use a partial range deliberately only for a pain limited joint, a targeted sticking point, or to extend a set past full range failure. You do not need 'lengthened partials' as a separate method, since a proper full rep already trains the stretch.
Limitations and uncertainty
The strongest evidence is for the lower body; upper body data are thinner and less consistent. 'Full' and 'partial' range are defined differently across studies. Several reviews come from overlapping author groups. Whether range of motion affects injury risk is not settled, and this article makes no injury claim either way. Most participants are young men. These findings are about muscle size and strength, not sport skill or health.
