Palmer Ty B, Pineda Jose G, Durham Rachel M
Texas Tech University.
J Appl Biomech. 2018 Apr 1;34(2):111-117. doi: 10.1123/jab.2017-0213. Epub 2018 Apr 6.
This study aimed to examine the effects of knee position on the reliability and production of peak force (PF) and rate of force development (RFD) characteristics during an isometric squat. Fourteen resistance-trained females performed isometric squats at 90, 120, and 150° knee angles (corresponding to parallel, half, and quarter squat positions, respectively) on 2 different occasions, from which PF, peak RFD, and early (RFD30, RFD50, RFD100) and late (RFD200) phase RFD variables were extracted. PF and RFD200 were highly consistent across trials for all 3 squat positions, with intraclass correlation coefficients (ICCs) ranging between 0.812-0.904 and coefficients of variation (CVs) between 6.6-19.4%. For peak and early RFD characteristics, higher ICCs and lower CV values were observed for the quarter squat (ICCs = 0.818-0.852, CVs = 17.3-19.4%) compared to the parallel (ICCs = 0.591-0.649, CVs = 30.1-55.9%) and half squats (ICCs = 0.547-0.598,CVs = 31.1-34.2%). In addition, isometric PF and RFD200 increased (P ≤ .001-0.04) with squat position (parallel < half < quarter); however, there were no differences for peak RFD (P ≥ .27), RFD30 (P ≥ .99), RFD50 (P ≥ .99), and RFD100 (P ≥ .09). These findings suggest that performing isometric squats at higher (150°) rather than lower knee joint angles (90-120°) may provide for an improved capacity to produce greater PF and RFD200 as well as a more reliable testing position for measuring peak and early RFD characteristics.
本研究旨在探讨膝关节位置对等长深蹲过程中峰值力（PF）和力发展速率（RFD）特征的可靠性及产生情况的影响。14名经过抗阻训练的女性在两个不同场合分别于膝关节角度90°、120°和150°（分别对应平行深蹲、半程深蹲和四分之一深蹲姿势）进行等长深蹲，从中提取PF、峰值RFD以及早期（RFD30、RFD50、RFD100）和晚期（RFD200）阶段的RFD变量。对于所有三种深蹲姿势，PF和RFD200在各次试验中高度一致，组内相关系数（ICC）在0.812 - 0.904之间，变异系数（CV）在6.6 - 19.4%之间。对于峰值和早期RFD特征，与平行深蹲（ICC = 0.591 - 0.649，CV = 30.1 - 55.9%）和半程深蹲（ICC = 0.547 - 0.598，CV = 31.1 - 34.2%）相比，四分之一深蹲观察到更高的ICC和更低的CV值（ICC = 0.818 - 0.852，CV = 17.3 - 19.4%）。此外，等长PF和RFD200随深蹲姿势增加（平行深蹲 < 半程深蹲 < 四分之一深蹲）（P ≤ 0.001 - 0.04）；然而，峰值RFD（P ≥ 0.27）、RFD30（P ≥ 0.99）、RFD50（P ≥ 0.99）和RFD100（P ≥ 0.09）没有差异。这些结果表明，在较高膝关节角度（150°）而非较低膝关节角度（90 - 120°）进行等长深蹲，可以提高产生更大PF和RFD200的能力，以及为测量峰值和早期RFD特征提供更可靠的测试姿势。
