Submaximal power output from the dorsolongitudinal flight muscles of the hawkmoth Manduca sexta.

To assess the extent to which the power output of a synchronous insect flight muscle is maximized during flight, we compared the maximum potential power output of the mesothoracic dorsolongitudinal (dl1) muscles of Manduca sexta to their power output in vivo. Holding temperature and cycle frequency constant at 36 degrees C and 25 Hz, respectively, we varied the phase of activation, mean length and strain amplitude. Under in vivo conditions measured in tethered flight, the dl1 muscles generated only 40-67% of their maximum potential power output. Compared to the in vivo phase of activation, the phase that maximized power output was advanced by 12% of the cycle period, and the length that maximized power output was 10% longer than the in vivo operating length.