Figure 5. Force and velocity data points from 11 to 15 contractions from representative fast-twitch fibres at 15°C and pH 7.0 and 6.2 (A) and 30°C and pH 7.0 and 6.2 (B) were plotted and fitted to the Hill equation.

Insets depict sample traces of force (top) and shortening (bottom) during a maximal contraction in which the fibre was switched from P₀ (not shown) to three isotonic loads. For pH 7.0 and 6.2, respectively, the contractile parameters for fibre in A were V_max = 1.62 fl s⁻¹ and 1.38 fl s⁻¹, P₀ = 0.58 mN and 0.37 mN or 125 kN m⁻² and 80 kN m⁻², and the a/P₀ = 0.266 and 0.304, and for the fibre in B, V_max = 7.13 fl s⁻¹ and 6.69 fl s⁻¹, P₀ = 0.46 mN and 0.48 mN or 169 kN m⁻² and 148 kN m⁻², and the a/P₀ = 0.356 and 0.337.