Table 1.

Mathematical symbols used; (t) indicates time-dependent variable; Sch = Scheme

Symbol	Section	Definition
A(t)	2	Concentration of cross-bridges in A
A1	2	Steady-state concentration of A
AC	5	Cross-sectional area
AT	2, 18	Total concentration of myosin S1
α	2, 6	Rate constant of detachment (A → B), Sch 1–3
α′	2, 6	Rate constant of attachment (B → A), Sch 1–3
B(t)	2, 6	Concentration of detached cross-bridges
B1	2	Steady-state concentration of B β 6 Rate constant of attachment (B → C), Sch 3
β′	6	Rate constant of detachment (C → B), Sch 3
C(t)	6	Concentration of attached cross-bridges in C
C1	6	Steady-state concentration of C D 12 MgADP concentration
δ, δx	3	Perturbation
δl	4	Stretch applied to a cross-bridge (δl>0). δl<0 for release
δW	4	Work performed on a cross-bridge by stretch (δW>0). δW<0 for release. Eq. 16
Eα	4	Activation energy of α (A → B), Fig. 4A
$E_{\alpha }^{\prime }$	4	Activation energy of α′ (B → A), Fig. 4B
ε	12	ε ≡ K1S/(1 + K0D + K1S), Eq. 49
η	19	Step size
F(t)	5	Force time course
F0	19	Isometric force at steady sate
FA(t)	5	Force contribution by state A
FG(t)	5	Force contribution by state G
φ	4, 9	Unitary force, force/cross-bridge
G(t)	5	Concentration of strained cross-bridges, Sch 2
G1	5	Steady-state concentration of G
γ	6	Rate constant of C → A, Sch 3
γ′	6	Rate constant of A → C, Sch 3
H	A2	Reaction matrix, Eq. A12
J	8, 18	Turnover rate (ATPase), Eqs. 40, 58
K0	12	Association constant of MgADP, Sch 6
K1	11	Association constant of MgATP, Sch 5
k1b	16	Rate constant of step 1b, Sch 9
k−1b	16	Reversal rate constant of step 1b, Sch 9
k2	11	Rate constant of step 2, Sch 5
k−2	11	Reversal rate constant of step 2, Sch 5
K2	12	Equilibrium constant of step 2, K2 ≡ k2/k−2
k4	13	Rate constant of step 4, Sch 7
k−4	13	Reversal rate constant of step 4, Sch 7
K4	15	Equilibrium constant of step 4, K4 ≡ k4/k−4
K5	13	Association constant of Pi, Sch 7
k6	14, 18	Rate constant of step 6, Sch 8
k−6	14	Reversal rate constant of step 6, Sch 8
K6	14	Equilibrium constant of step 6, K6 ≡ k6/k−6
Kα	7	Equilibrium constant of A ↔B. Kα ≡ α/α′
Kβ	7	Equilibrium constant of B ↔C. Kβ ≡ β/β′
kB	4	Boltzmann’s constant, kB = 1.381 × 10−23 JK−1
l0	5	Half sarcomere length
λ	2	Apparent rate constant, λ ≡ α + α′, Eq. 4
λ2	7, 11	Apparent rate constant of phase 2. λ2 = 2πc. Eqs. 32, 44, 50
λ3	7, 13	Apparent rate constant of phase 3. λ3 = 2πb. Eqs. 37, 53, 54
λ4	19	Rate constant of force development, Eq. 63
M	8, A2	Eqs. 39, A16
μ	5	Perturbed rate constant α by stretch δl. μ ≡ α + δα
NA	5	Avogadro’s number, NA = 6.022 × 1023/mole
ν	19	Number of cross-bridge cycles in 1 sec
P	13	Phosphate concentration
2πa	19	Rate constant of process A (phase 4)
2πb	10	Rate constant of process B (phase 3)
2πc	10	Rate constant of process C (phase 2)
q	17	Series compliance of half sarcomere
R	15	Gas constant, R≡kBNA = 8.314 JK−1mol−1
ρ	5	Cross-bridge stiffness
ρ′	19	Stiffness of half sarcomere
S	11	Substrate (MgATP) concentration
σ	12	σ ≡K1SK2/[1 + K0D + K1S(1 + K2)], Eq. 52
SP	17	Parallel stiffness of half sarcomere
t	2	Time
T	4	Absolute temperature
T0	15	Tension supported by X0 (AM.ADP)
T1	15	Tension supported by X1 (AM), Eq. 55
T1b	15	Tension supported by X1b (AM†ATP)
T2	15	Tension supported by X2 (AM*ATP), Eq. 55
T34	15	Tension supported by X34 (Det), T34 = 0
T5	15	Tension generated/supported by X5 (AM*ADP.P)
T6	15	Tension generated/supported by X6 (AM*ADP)
TC	15	Tension of standard activation, C=control
U	A2	3×3 eigen matrix consisting of 3 eigen (column) vectors. Eq. A20
X0(t)	12	Probability of cross-bridges at AM.ADP
X1(t)	11	Probability of cross-bridges at AM
X1b(t)	11	Probability of cross-bridges at AM†ATP
X2(t)	11	Probability of cross-bridges at AM*ATP
X34(t)	14	Probability of cross-bridges at Det state
X5(t)	13	Probability of cross-bridges at AM*ADP.Pi
X6(t)	13	Probability of cross-bridges at AM*ADP
Xa(t)	12	Probability of strongly attached cross-bridges, Eq. 57, Xa ≡ X0 + X1 + X2 + X5 + X6
Ya	17	Stiffness of cross-bridges in half sarcomere when all are strongly attached
ζ	21	ζ ≡ K5P/(1 + K5P), Eq. 73