Moderate Intensity Resistance Training With Partial Range-of-Motion at Long Muscle Lengths Elicits Similar Hypertrophy and Architectural Adaptations as High Intensity Resistance Training Using Full Range-of-Motion

ABSTRACT: McMahon, G, Morse, C, Burden, A, Winwood, K, and Onambele-Pearson, G. Moderate intensity resistance training with partial range-of-motion at long muscle lengths elicits similar hypertrophy and architectural adaptations as high intensity resistance training using full range-of-motion. J Strength Cond Res XX(X): 000-000, 2026-Resistance training (RT) elicits varying magnitudes of active and passive forces in muscle. Evidence is lacking comparing chronic RT outcomes including muscle thickness (MTH) and muscle architecture (fascicle length [Lf], pennation angle [pen]) performing training at shorter, longer, and full ranges-of-motion (ROM). A total of 45 subjects were randomly assigned to 1 of 4 groups-shortened partial ROM (SP, 0-50° knee flexion, 80% 1 repetition maximum [1RM]), lengthened partial ROM (LP, 40-90° knee flexion, 55% 1RM), full ROM (FROM, 0-90° knee flexion, 80% 1RM), or control (CON)-completing 8 weeks of knee extensor exercise. Vastus Lateralis MTH, PEN, and Lf were measured at 25, 50, and 75% femur length pre-post training and analyzed as delta (Δ) change (%); statistical significance was set at p < 0.05. ΔMTH was greater in LP and FROM (p < 0.05) vs. SP at 75%. ΔMTH LP was greater than SP at 25% (p < 0.05) and ΔMTH FROM was greater than SP at 50% (p < 0.05) with no differences between LP and FROM at any location. ΔLf was greater in LP vs. FROM (p < 0.05) at 25 and 75%, and LP vs. SP (p < 0.05) at all sites. ΔLf was greater in FROM vs. SP (p < 0.05) at 50 and 75%. Absolute and normalized baseline Lf was inversely correlated with ΔLf in all groups (p < 0.001). This study provides novel evidence that moderate-intensity RT with partial ROM at long muscle lengths elicits similar hypertrophic and superior Lf adaptations as high-intensity full ROM training. These findings challenge traditional RT prescription, offering new insights for optimizing muscle size and architecture in athletic populations.