Adaptations to explosive resistance training with partial range of motion are not inferior to full range of motion

We tested whether explosive resistance training with partial range of motion (ROM) would be as effective as full ROM training using a noninferiority trial design. Fifteen subjects with strength training experience took part in an explosive -concentric only- leg press training program, three times per week for 10 weeks. One leg was randomly assigned to exercise with partial ROM (i.e. 9º) and the other leg to full ROM. Before and after training, we assessed leg press performance, isokinetic concentric and isometric knee extension torque, and vastus lateralis muscle architecture. Overall, both training modalities increased maximal strength and rate of force development. Training with partial ROM yielded noninferior results compared to full ROM for leg press peak power (+69 ±47% vs. +61±64%), isokinetic strength (4-6±6-12% vs. 1-6±6-10% at 30, 60, and 180˚s-1 ), and explosive torque after 100 (47±24 vs. 35±22) and 150 ms (57±22% vs. 42±25%). The comparison was inconclusive for other functional parameters (i.e. isokinetic peak torque (300˚s-1 ), joint angle at isokinetic peak torque, explosive torque after 50ms, and electrically evoked torque) and for muscle fascicle length and thickness, although noninferiority was established for pennation angle. However, partial ROM was not found statistically inferior to full ROM for any measured variable. Under the present conditions, the effects of explosive heavy resistance training were independent of joint ROM. Instead, these data suggest that the distinct timing of muscle work in explosive contractions confers more influence to the starting joint angle than ROM on adaptations to this type of training.