Optimization problem parameter bounds.

The maximum isometric force (Fmax) values for each muscle were constrained to fall in a fairly wide window surrounding the scaled value from SIMM. The scaling factor for lslack and lopt was chosen to ensure that each muscle fascicle length stayed within physical operating ranges. Here the parameter w governs the width of the active force-length relation of the muscle; its value varies by muscle and all values are given in S2 Text. The bounds for Ksh and λref were taken from [16]. The bounds for the spring constant of the hip flexor ligament was chosen so that the ligament could provide anywhere from none to all of the required hip flexion moment near toe off. The engagement angle was chosen so that the tendon could engage with the hip no more than 10° flexed, as its physiological role is to prevent overextension.

每块肌肉的最大等长肌力（Fmax）取值被限定在围绕SIMM输出的缩放值的较宽区间内。松弛长度（lslack）与最优长度（lopt）的缩放因子经选取后，可确保每根肌束的长度处于生理可行的工作区间范围内。此处参数w用于控制肌肉主动力-长度关系的曲线宽度；该参数的取值因肌肉类型而异，所有参数值均详见补充材料S2文本。Ksh与λref的取值范围源自文献[16]。髋屈肌韧带的弹簧常数取值范围经选取后，可使该韧带在趾离地阶段能够提供从无到全部所需的髋屈力矩。肌腱啮合角经选取后，可使肌腱在髋关节屈曲不超过10°时即可与髋关节啮合，因其生理功能为防止髋关节过度伸展。