Sagittal plane inclination of the trunk and tibia have been shown to independently modulate hip and knee extensor moments during squatting. The purpose of this study was to determine if the difference between sagittal plane trunk and tibia inclinations can be used to approximate the relative demand of the hip and knee extensors across a range of squatting conditions. Kinematic and kinetic data were obtained from 16 participants during 8 squat conditions in which trunk and tibia inclination were manipulated. The average hip/knee extensor moment ratio (HKR) was calculated during the lowering (eccentric) phase of each squat condition using inverse dynamics equations. Linear regression evaluated the association between the difference in trunk and tibia inclination at peak knee flexion and the average HKR. Across all squat conditions, the difference between trunk and tibia inclinations explained 70% of the variance in the average HKR (p < 0.001). The squat was knee extensor biased (HKR ≤ 1.0) when the tibia was at least 8 degrees more inclined than the trunk. The results of this study indicate that the relationship between sagittal plane trunk and tibia inclination can be used to estimate the relative demand of the hip and knee extensors.

躯干和胫骨的矢状面倾斜已显示出在下蹲期间独立调节髋部和膝部伸肌力矩。这项研究的目的是确定矢状面躯干和胫骨倾斜度之间的差异是否可用于估算一系列蹲坐条件下髋和膝伸肌的相对需求。运动和动力学数据来自16位参与者在8个深蹲条件下的情况，在这些条件下，躯干和胫骨的倾斜度得到了控制。使用反向动力学方程，在每个下蹲状态的降低（偏心）阶段计算平均髋/膝伸肌力矩比（HKR）。线性回归评估了屈膝高峰时躯干和胫骨倾斜度差异与平均HKR之间的关联。在所有下蹲状态下 躯干和胫骨倾斜度之间的差异解释了平均HKR差异的70％（p <0.001）。当胫骨的倾斜度比躯干高至少8度时，深蹲是膝伸肌偏斜（HKR≤1.0）。这项研究的结果表明，矢状面躯干和胫骨倾角之间的关系可以用来估计髋和膝伸肌的相对需求。