Fig. 4. U_crit2-U_crit1 versus the plasma lactate concentration prior to the second U_crit test (recovery 1) for individual rainbow trout. Fish were divided into two sub-groups: cold-acclimated (filled symbols) fish and warm-acclimated (open symbols) fish. The data could be described by either a polynomial (broken line; r²=0.74) or a 2-parameter power (solid line; r²=0.65) relationship.