From full to partials: Investigating the impact of range of motion training on maximum isometric action, and muscle hypertrophy in young women.

We compared maximum voluntary isometric action (MVIA), electromyographic (EMG) amplitude, and hypertrophy of rectus femoris (RF) and vastus lateralis (VL) between groups training in different ranges of motion (ROM). Fifty untrained women were randomised into control group (CON) or to perform knee extension exercise in one of the following groups (0°=extended knee): Full ROM (FULL100°-30°), Initial ROM (INITIAL:100°-65°), Final ROM (FINAL:65°-30°), and Varied ROM (VAR: alternating between INITIAL and FINALROM). Pre- and post-training assessments included MVIA at 30º, 65º and 100º of knee flexion, during which EMG amplitude of RF and VL was recorded. Summed changes in cross-sectional area, assessed via ultrasound, were measured at four locations along muscles. Results showed greater improvements in INITIAL and VAR for MVIA at 100º (20.63%-25.5%) and FINAL and VAR for MVIA at 30º (17.28%-17.97%) compared to other groups (-2.92%-9.83% and 0.84%-3.31%, respectively). EMG response was larger in INITIAL than FINAL and CON at 100º (15.84% vs -6.61%-1.16%). FINAL had a higher EMG response than INITIAL at 30º (4.52% vs -14.95%). For hypertrophy, INITIAL, FULL, and VAR showed greatest increases (13.20%-17%). Greater MVIA gains aligned with trained ROM, leading to better VAR results. INITIAL, FULL, and VAR were more effective than FINALROM in hypertrophy.