CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN .3. MECHANICAL POWER OUTPUT

The mechanical power output during oscillatory contraction was determi ned for the flagellum abductor muscle of the crab Carcinus maenas usin g the work loop technique. Measurements were made at 10Hz, which is th e normal operating frequency of the muscle. The temperature was 15 deg rees C. Increasing the number of stimuli per cycle (given at an inters timulus interval of 3.3ms) decreased the number of cycles required to reach a work plateau and increased the work per cycle at the plateau t o a maximum at 4-5 stimuli per cycle. The maximum mechanical power out put was 9.7Wkg(-1)muscle (about 26Wkg(-1)myofibril). The optimum strai n for work output (5.7%) was close to the estimated muscle strain in v ivo (5.2%).