Fig. 9. Simulation of relative power output of red muscle from anterior (ANT) (0.42L) and posterior (POST) (0.70L) locations in a 43 cm skipjack tuna during cyclic contractions at 4 Hz (the tail-beat frequency for steady swimming at approximately 3 L s–1). L, fork body length. Plots show instantaneous power versus time (see Altringham et al., 1993), where power (i.e. force x shortening velocity) was calculated from work loop data; velocity is the time derivative of the length trace, with positive velocity occurring during shortening. The traces for POST muscle have been delayed by 40° to show the proper temporal relationship between the two locations. The amplitudes of ANT and POST power curves are scaled to account for the differences in cross-sectional area of red muscle and mass-specific power output at these locations (see text for details).
