Fig. 8. (A) Three superimposed recordings of active force during tetanic stimulation of a red fibre bundle with stretch at different velocities. (B,C) Force and length change (L) on expanded scales. The horizontal lines in B show the forces that were measured during stretch. Results from the same fibre bundle as in Fig. 5. L₀, the fibre length at which maximum isometric force was produced, was 6.6 mm.