. Author manuscript; available in PMC: 2013 Aug 1.

Published in final edited form as: Ann Biomed Eng. 2012 Feb 17;40(8):1708–1720. doi: 10.1007/s10439-012-0531-6

TABLE 2.

Key parameters used in the five muscle models.

Model	Force–velocity curvature, k	Maximum unloaded shortening velocity, v₀	Activation state
Homogeneous, A	k_slow + (k_fast − k_slow)p	v_0;fastp + v_0;slow (1 − p)	â(t)
Hybrid, B	Composite from Hill²⁸	v_0;fast	â(t)
Orderly, C	k_slow + (k_fast − k_slow)p	v_0;slow + (v_0;fast − v_{0 slow})â(t)	â(t)
Reverse, D	k_slow + (k_fast − k_slow)p	v_0;fast + (v_0;fast − v_{0 slow})â(t)	â(t)
Differential, E	k_fast	v_0;fast	â_fast(t)
	k_slow	v_{0 slow}	â_slow(t)

Subscripts “fast” and “slow” denote properties from fast or slow muscle fibers.