Table 3.

Mechanical and Physiological Muscle Parameters

Parameter	Definition	MR	LR
b	Material parameter for isotropic matrix	15.2	15.2
c	Material parameter for isotropic matrix (MPa)	0.1 × 10−3	0.1 × 10−3
σ0	Maximum isometric stress (MPa)	0.04	0.04
D	Compressibility constant (MPa−1)	10	10
k	Length ratio SEE: CE	0.3	0.3
α	Material constant in SEE	10	10
β	Material constant in SEE (MPa)	0.4 × 10−3	0.4 × 10−3
${\dot{\lambda }}_m^{min}$	Minimum stretch rate (s−1)	−10	−10
kc	Shape parameter in force-velocity function	5	5
ke	Shape parameter in force-velocity function	5	5
d	Offset of the eccentric function	1.5	1.5
t 0	Activation time (s)	0	0
t 1	Deactivation time (s)	0.4	0
S	Exponential factor in activation function	100	100
A	Material parameter for stress in PE	4	4
n 1	Activation level before and after activation	0.6	0
n 2	Activation level during activation	1	0
λopt	Optimal fiber stretch	1.05	1.05
$f_{PE}^0$	Initial normalized force within PE	0	0.2
m 1	First component of unit vector along the muscle fiber direction	0	0
			Posterior	Anterior
m 2	Second component of unit vector along the muscle fiber direction	0.25	0.175	−0.43
m 3	Third component of unit vector along the muscle fiber direction	−0.97	0.984	0.902
${\lambda }_f^0$	Initial stretch for muscle	0.02	1.03	1.01