Figure 7. Force recovery versus temperature.

A, records showing force recovery elicited by ramp–restretch protocol at temperatures from 8°C-1° (l-r) in SL control. Fibre cross-section = 5.2 × 10³μm², length = 2.75 mm, SL = 2.33 μm. The record at 1°C was acquired for 6 s (only 3 s shown). The full magnitude of the force spike during the restretch was not sampled. B, dependence of isometric force and T_min on temperature over the temperature range 0–10°C. Three fibres were studied, with n = 4 (sets of two to three repeats at each temperature) at 2–8°C, n = 2 at 10°C, and n = 1 at 0°C. One fibre was studied in both SL and PM control. Isometric force was defined either as the steady force before the ramp (×) or the offset of a two-exponential fit (□ and continuous line); both were divided by their respective values at 5°C within each fibre and then averaged among fibres. The two measures of force varied in the same way with temperature. The variation in T_min with temperature (○ and dashed line) is shown normalized in the same way, but also multiplied by the mean T_min divided by the offset at 5°C to emphasize its relationship to isometric force and to show its smaller temperature dependence. The restretch was adjusted for critical damping. Many error bars (s.e.m.) are smaller than the symbols.