Fig. 1. Muscle blood flow (MBF) during six long apneas of an elephant seal. Apneic MBF decreases progressively but variably; occasional transient increases occur. At the end of apnea, MBF consistently increases prior to the first breath of eupnea. See Table 1 for a statistical summary. Note that MBF can also begin to decrease prior to the last breath of eupnea (apnea 1). Shaded area corresponds to eupnea period.