The Effect of Hip Joint Angle on Isometric Midthigh Pull Kinetics
Dos'Santos, T, Thomas, C, Jones, PA, McMahon, JJ, and Comfort, P. The effect of hip joint angle on isometric midthigh pull kinetics. J Strength Cond Res 31(10): 2748–2757, 2017—The aim of this study were to compare isometric midthigh pull (IMTP) peak force (PF), time-specific force values (100-, 150-, and 200 ms), rate of force development (RFD) at predetermined time bands (0–100, 0–150, and 0–200 ms) and net forces between 2 commonly adopted hip joint angles (145°[hip145] and 175°[hip175]) with a 145° standardized knee angle. Twenty-eight collegiate athletes (age: 21.7 ± 1.5 years, height: 1.75 ± 0.08 m, mass: 81.5 ± 8.4 kg) performed 2 IMTP trials at each hip joint angle in a randomized counterbalanced order. A subgroup (n = 10) performed the IMTP testing 7 days later to establish the between-session reliability. Intraclass correlation coefficients (ICCs) and coefficient of variation (CV) demonstrated high within-session reliability and acceptable variability for all IMTP kinetics at each posture (ICC ≥ 0.86, CV ≤ 13.7%), excluding hip175 RFD 0–100 ms and net force at 100 ms which demonstrated greater variability (CV = 18.1–18.5%). High between-session reliability and acceptable variability were observed for all IMTP kinetics at each posture (ICC = 0.72–0.97, CV = 4.5–12.8%), excluding RFD 0–100 ms which demonstrated greater variability for both postures. Hip145 produced significantly greater time-specific force values (p ≤ 0.025, g = 0.25–0.28), RFD at predetermined time bands (p ≤ 0.001, g = 0.59–0.78), and net forces (p ≤ 0.001, g = 0.57–0.74) compared with hip175. Trivial nonsignificant differences were demonstrated between postures for PF and force at 100 ms (p > 0.05, g ≤ 0.14). Significantly greater body weights (weighing period force) were observed with hip175 compared with hip145 (p < 0.001, g = 0.74). Coaches should consider administering a hip145 for IMTP testing as greater IMTP kinetics and lower levels of pretension during the weighing period are achieved with this posture.