Figure 1

Flow chart of the testing protocol and the model parameters identified from each test. The train duty cycle for the general non-isometric contractions varied with pulse duration (PD; see results). Parameter τ ₁ was identified separately using the force at the end of each contraction. Parameters a and b were identified by fitting parameter A predicted by Equation (2a) to parameter A from Equation (2) for all four knee angles. Fitting A ₉₀ , K _m , and τ ₁ predicted by the fatigue model to A ₉₀ , K _m , and τ ₁ from the force model for the isometric pre-fatigue and isometric fatiguing contractions identified the fatigue model parameters α _A , α _Km , α _τ1 , and τ _fat (Equations 4–8). Initially, parameter β _τ1 (Equation 8) was identified by fitting model predicted angles and angular velocities to the measurements collected at 170, 200, and 600 μs during the fatiguing leg extensions. An equation for β _τ1 (Equation 9) was then derived from correlations with the parameters in the model.