Figure 9.

The first set of ten 10-s repetitions from Fig. 8. Note that the repetitions become shorter as ATP runs out during the period of high load; as the ATP level falls below a critical value (which we set to a half of the homeostatic level), the muscle can no longer sustain the load, and the only possibility is to drop the weight and return to the steady-state force. So, the period of loading becomes shorter than the prescribed period, shown in a dashed line in the plot and arrows marking the prescribed period. To see this figure in color, go online.