Fig. 8. Recovery of cardiac function following 30 min of severe hypoxia, measured as the percent recovery of maximum force by ventricular strips [Gesser, 1977; open circles, rainbow trout (N=5) and filled circles, carp (N=5)], or as the percent recovery of _MAX in the present study (open square, N=8). The workload during the hypoxic period was similar between studies. The ventricular strips used by Gesser (1977) were developing maximum force, but at a contraction rate (0.2 Hz, 12 contractions min^–1) much lower than measured in vivo, whereas the power output of the hearts used in the study was approx. one sixth of maximum.