Fig. 7. Stimulus duration as a function of cycle frequency. (A) Data from anterior (ANT) locations; (B) data from posterior (POST) locations. Filled lines and solid symbols show optimal stimulus durations required to maximize net work output from isolated muscle (optimized). Dotted lines and open symbols show stimulus durations used by swimming fish (in vivo) (Shadwick et al., 1999); the heavy portions highlight speeds at which fish actually swim using only red muscle; the remainder of the in vivo curve is an extrapolation from these data. Values are means ± S.E.M., N=3–6.