Ruhr University Bochum, Faculty of Sport Science, Human Movement Science, Germany.
Ruhr University Bochum, Faculty of Sport Science, Human Movement Science, Germany.
J Biomech. 2019 Mar 27;86:225-231. doi: 10.1016/j.jbiomech.2019.01.042. Epub 2019 Jan 30.
In vivo muscle forces are typically estimated using literature-based or subject-specific moment arms (MAs) because it is not possible to measure in vivo muscle forces non-invasively. However, even subject-specific muscle-tendon MAs vary across contraction levels and are impossible to determine at high contraction levels without techniques that use ionized radiation. Therefore, different generic MA functions are often used to estimate in vivo muscle forces, which may alter force predictions and the shape of the muscle's force-length relationship. The aim of this study was to examine the influence of different literature-based patella tendon MA functions on the vastus lateralis (VL) force-angle relationship. Participants (n = 11) performed maximum voluntary isometric knee extension contractions at six knee flexion angles, ranging from 40° to 90°. To estimate in vivo VL muscle force, the peak knee extension torque at each joint angle was multiplied by the VL's physiological cross-sectional area (PCSA) relative to the quadriceps' PCSA (34%) and then divided by the angle-specific patella tendon MA for 19 different functions. Maximum VL force was significantly different across MA functions (p ≤ 0.039) and occurred at different knee flexion angles. The shape of the VL force-angle relationship also differed significantly (p < 0.01) across MA functions. According to the maximum force generated by VL based on its literature-derived PSCA, only the VL force-angle relationships estimated using geometric imaging-based MA functions are feasible across the knee angles studied here. We therefore recommend that an average of these MA functions is calculated to estimate quadriceps muscle forces if subject-specific MAs cannot be determined.
体内肌肉力量通常通过基于文献的或特定于个体的力臂（MA）来估计，因为无法非侵入性地测量体内肌肉力量。然而，即使是特定于个体的肌肉-肌腱 MA 也会因收缩水平而异，并且如果没有使用电离辐射的技术，在高收缩水平下是不可能确定的。因此，通常使用不同的通用 MA 函数来估计体内肌肉力量，这可能会改变力的预测和肌肉的力-长度关系的形状。本研究的目的是研究不同基于文献的髌腱 MA 函数对股外侧肌（VL）力-角度关系的影响。参与者（n=11）在六个膝关节屈曲角度（从 40°到 90°）下进行最大自主等长膝关节伸展收缩。为了估计体内 VL 肌肉力量，将每个关节角度的最大膝关节伸展扭矩乘以 VL 的生理横截面积（PCSA）相对于股四头肌的 PCSA（34%），然后除以 19 种不同功能的特定于关节角度的髌腱 MA。最大 VL 力在 MA 函数之间存在显著差异（p≤0.039），并且在不同的膝关节屈曲角度发生。VL 力-角度关系也在 MA 函数之间存在显著差异（p<0.01）。根据基于其文献推导的 PCSA 的 VL 产生的最大力，只有使用基于几何成像的 MA 函数估计的 VL 力-角度关系在研究的膝关节角度范围内是可行的。因此，如果无法确定特定于个体的 MA，我们建议计算这些 MA 的平均值来估计股四头肌的力量。
