Fig. 5. Net power output as a function of strain amplitude from internal red muscle of skipjack tuna at anterior (ANT) and posterior (POST) locations. Strain is the peak amplitude of the imposed length cycle as a percentage of muscle length. The cycle frequency was 4 Hz in all cases. Power is expressed as a percentage of the value at 8 % strain. The muscle was stimulated using conditions measured from swimming fish. Higher strains result in significantly higher power outputs (two-way ANOVA and Tukey’s test, P<0.05). Values are means ± S.E.M., N=3–6.