THE EFFECT OF PHYSICAL TRAINING ON OXYGEN DEBT AND GLYCOGEN RESERVES IN TROUT

Abstract

Rainbow trout, Salmo gairdneri, conditioned to fast-flowing water, differ from untrained fish in several ways. The trained fish are able to acquire an oxygen debt three times as large as the untrained ones. Almost twice as much of the available glycogen in muscle can be used up during short bursts of swimming. The trained fish have higher levels of blood haemoglobin and relatively larger hearts. Following fatigue, the recovery of glycogen in muscle and liver is more rapid. The data suggest a modus operandi for short but severe bursts of swimming. The two critical factors are: (a) initial energy supplies and (b) tissue buffers. The former preclude the exhaustion of the muscle; the buffers allow a large utilization of the fuel, i.e., a large excess of lactic acid and, consequently, a large oxygen debt. Since even in trained trout only 70% of the muscle glycogen is used, fixed acid probably limits the stamina in both groups of fish.