Where in the range you train seems to matter
Range of motion research distinguishes between full repetitions and partial repetitions that emphasize either the lengthened or shortened portion of a movement. A growing body of evidence suggests that partials biased toward the lengthened position, where the muscle is under load while long, can produce hypertrophy at least comparable to and in some studies greater than full range of motion. Partials biased toward the shortened position, where the muscle works while already contracted, tend to underperform.
Some studies report a sizeable lengthened-partial advantage, though the exact magnitude varies and should be read as an estimate rather than a fixed figure.
The proposed explanation
A leading explanation centers on the high tension a muscle experiences at long lengths, where passive force from the elastic protein titin adds to active force, raising the total mechanical stimulus. Training in the stretched position may therefore concentrate the growth signal where it is strongest.
Full range of motion still has merits for strength across joint angles and for joint health, so lengthened partials are best seen as one tool rather than a replacement. This is general educational information about training research, not medical advice; end-range loading should be progressed cautiously.