Effects Of Exercise Training On Swimming Performance And Metabolic Regime In Juvenile Common Carp (Cyprinus Carpio)

To study whether exercise training can affect juvenile carp's aerobic swimmingability, and to reveal the metabolic mechanism, we randomly divided eighty fourjuvenile common carps (Cyprinus carpio)(weight:4.59±0.54g), with good physicalcondition, into two groups (control group, training group). The training group fish wretrained6h a day, for28days(25.0±1.0℃). All the fish trained at the speed of60%ofthe pre-training U_crit). The control group,s experimental fish were in the same water,maintaining micro-water. When the training was over, we measured the criticalswimming speed (U_crit)), oxygen consumption rate (VO₂), excess post-exercise oxygenconsumption (EPOC) for each group of experimental fish. When training wascompleted,we dissected the muscle, liver and blood from the fish with exhaustiveexercise, determination U_crit),determination EPOC. We assessed the muscle glycogen,muscle free glucose, muscle lactate, liver glycogen, liver free glucose, muscle lacticacid content, blood lactic acid content. The maximum activity of lactate dehydrogenase(LDH), citrate synthase (CS), pyruvate kinase (PK) in red muscle and white musclewere also measured.The results as follows:1. The critical swimming speed (U_crit)) of control group was9.3±0.7BLs-1, while theexercise group was10.6±0.6BLs-1, the latter was higher than the formersignificantly(p<0.05).2. There was no significant difference of active metabolic (MO₂active) between thecontrol group and the treatment. The MO₂restand MO₂maxtreatment group andcontrol group were226.8O₂.kg^-1.h^-1,1086.1O₂.kg^-1.h^-1and173.7O₂.kg^-1.h^-1,807.4O₂.kg^-1.h^-1, the values of treatment were all significantly higher compared with the control group(p<0.05). The EPOC of experiment fish indicate no changesafter exercise.3. Muscle glycogen and liver glycogen of exercise group were12.58±1.17umol.g-1and219.2±13.9umol.g-1, both of them were indicate significant differencescompared with control of9.07±1.06umol.g-1and163.06±20.27umol.g-1. Theconcentration of glucose in liver of treatment group was higher than control group,while the concentration of glucose in muscle was lower. After exhaustive exercise,liver glycogen decreased significantly (p<0.05) in an hour, however, exercise groupshow no changes.4. There was no significant difference of muscle lactate and blood lactate betweentraining group and control group dropped, muscle lactate of exercise group dropped11.0umol.g-1, while control group dropped8.27umol.g-1, they indicated significantdifference(p<0.05). The value of muscle lactate in two groups reached themaximum after exhaustive exercise, while blood lactate formed after U_crit).5. The CS activity in the red muscle and LDH activity in the white muscle of treatmentgroup were21.5±0.9U.g-1and112.4±3.9U.g-1, both of them were all significanthigher than the control group of14.5±0.7U.g-1and93.1±9.3U.g-1. However, PKactivity in the red muscle and white muscle of treatment group and control groupshowed no significant difference.The indications as follows:1. Prolong exercise training can significantly enhance the ability of aerobic swimmingfor experimental fish.2. The improvement of experimental fish's aerobic swimming ability is closed withmaximal aerobic metabolic power.3. Exercise training improved the levels of experimental fish's liver glycogen andmuscle glycogen, which was benefic to the storage of metabolic substrate for theexperimental fish's prolonged aerobic exercise.4. There was a close relationship between aerobic swimming ability and the activity ofmitochondrial metabolic enzymes CS.5. Exercise training enhanced the experimental fish's anaerobic tolerance (lactic acidchanges) and anaerobic metabolism (LDH activity), so, to a certain extent, exercise training improved the energy supply during anaerobic exercisehe for experimentalfish.