Figure 5. Changes in unit twitch and tetanic parameters with fatigue.

Initial and post-fatigue maximal tetanic force (A), F₅₀ (B, n = 10 units) and initial, post-tetanic and post-fatigue twitch force (C), CT (D) and hRT (E, n = 16 units). Data are expressed relative to the respective parameters recorded initially (A and B) or after trains of stimuli between 5 and 100 Hz (C, D and E). Each line represents data from 1 unit. In 2 units half-maximal force was attained at 1 Hz before fatigue, and increased substantially to 9.4 Hz and 19.6 Hz post-fatigue (B).