Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.
Department of Biomedical Sciences, University of Padua, Via Marzolo 3, 35131, Padua, Italy.
Eur J Appl Physiol. 2023 Oct;123(10):2239-2248. doi: 10.1007/s00421-023-05237-w. Epub 2023 May 31.
This study aimed (i) to investigate the role of regional characteristics of the knee extensors muscles (vastus lateralis: VL, vastus intermedius: VI and rectus femoris: RF) in determining maximum-voluntary force (MVF); and (ii) to understand which regional parameter of muscle structure would best predict MVF. Muscle architecture (e.g., pennation angle and fascicle length), muscle volume (Vol), anatomical (ACSA) and physiological cross-sectional-area (PCSA) were measured in the proximal (0-33% of the muscle length), middle (33-66% of the muscle length) and distal (66-100% of the muscle length) portions of each muscle in fifteen healthy males using ultrasound and Magnetic Resonance Imaging (MRI). Knee extensors force was calculated in isometric condition at a single knee joint angle of 90 degrees. Regional ACSA, Vol and PCSA were correlated with MVF production. Regional muscle geometry showed no significant correlations with MVF. Among regions, the middle portion of each muscle was largely correlated with MVF compared to all the other regions (distal and proximal). To understand which regional structural parameter best predicted MVF, a stepwise multiple linear regression was performed. This model showed a significant explanatory power (P < 0.001, R = 0.76, adjusted R = 0.71), including muscle Vol collected in the mid portions of VL and RF. Even if no significant differences were reported between Vol, PCSA and ACSA in determining MVF, our results showed that the RF and VL volume collected in the middle portion of the muscle length are strong determinants of MVF produced by the knee extensors at 90 degrees joint angle.
（i）探究膝关节伸肌（股外侧肌：VL、股中间肌：VI 和股直肌：RF）的区域性特征在最大自主力（MVF）中的作用；（ii）理解肌肉结构的哪个区域性参数能最好地预测 MVF。使用超声和磁共振成像（MRI）在每个肌肉的近端（肌肉长度的 0-33%）、中部（肌肉长度的 33-66%）和远端（肌肉长度的 66-100%）部分测量了 15 名健康男性的肌肉结构（如肌节角和肌纤维长度）、肌肉体积（Vol）、解剖横截面积（ACSA）和生理横截面积（PCSA）。在单个膝关节角度为 90 度的等长条件下计算了膝关节伸肌的力。区域性 ACSA、Vol 和 PCSA 与 MVF 产生相关。区域性肌肉几何形状与 MVF 无显著相关性。在各个区域中，与其他所有区域（远端和近端）相比，每个肌肉的中部与 MVF 相关性最大。为了理解哪个区域性结构参数能最好地预测 MVF，进行了逐步多元线性回归。该模型显示出显著的解释力（P<0.001，R=0.76，调整 R=0.71），包括在 VL 和 RF 的中部收集的肌肉 Vol。尽管在确定 MVF 时，Vol、PCSA 和 ACSA 之间没有显著差异，但我们的结果表明，在肌肉长度的中部收集的 RF 和 VL 体积是膝关节伸肌在 90 度关节角度下产生的 MVF 的重要决定因素。
