Fig. 5. The mean plasma lactate concentration in blood samples from seals during and after naive (filled circles) and trained (open circles) submersions. The cross-hatched area represents a 3.0 min submersion period. Values are means ± S.E.M. (N=15). For simplicity, 3.0 and 3.5 min submersion values are plotted together following the 3.0 min time line.