Fig. 2. A comparison of mean M_O2 and cardiovascular variables during sustained swimming in adult rainbow trout that had been screened as good or poor swimmers 9 months earlier. The mean values are shown only for those speeds at which measurements were collected for all of the animals in each group, i.e. up to 80 cm s^-1 in poor swimmers and up to 110 cm s^-1 in good swimmers. Values are means ± S.E.M., N=6. Asterisks above the abscissa denote a significant change in the variable relative to a swimming speed of 30 cm s^-1 within either the good (blue) or bad (red) swimmers. There were no significant differences in any variable when compared between good and bad swimmers at any common swimming speed.