CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN - MECHANICAL POWER OUTPUT.

The mechanical power output during oscillatory contraction was determined for the flagellum abductor muscle of the crab Carcinus maenas using the work loop technique. Measurements were made at 10 Hz, which is the normal operating frequency of the muscle. The temperature was 15 °C. Increasing the number of stimuli per cycle (given at an interstimulus interval of 3.3 ms) decreased the number of cycles required to reach a work plateau and increased the work per cycle at the plateau to a maximum at 4­5 stimuli per cycle. The maximum mechanical power output was 9.7 W kg-1 muscle (about 26 W kg-1 myofibril). The optimum strain for work output (5.7 %) was close to the estimated muscle strain in vivo (5.2 %).