The effects of training and L-carnitine in experimental model of muscle damage in rats

Low intensity eccentric trainings and free radicals have important roles in adaptation periods of muscle to exercise. Ergogenic aids of antioxidants could blunt the effects of free radicals in adaptational period and could reduce the endogen antioxidant capacity of muscle. This study was conducted to determine the effects of carnitine, low intensity eccentric training and both of carnitine and low intensity eccentric training in muscle damage induced with high intensity eccentric exercise. For this purpose, 35 Wistar male rats were divided to 5 groups having equal number of rats. Group1: control, Group 2: oral administration of equal volume of distilled water and muscle damage induction, Group 3: low intensity eccentric training and muscle damage induction, Group 4: oral administration of 100mg/kg carnitine and muscle damage induction Group 5: oral administration of 100mg/kg carnitine + low intensity eccentric training + muscle damage induction. L-carnitine and/or low intensity eccentric training were applied to group 3, 4 and 5 for seven days. At 8th day, muscle damage was induced by strenous eccentric exercise in groups except the control group. Serum creatine kinase (CK) and lactate dehydrogenase (LDH) enzyme levels were determined in blood samples collected before muscle damage induction and at 48th hour after muscle damage induction. Malondialdehyde (MDA), protein carbonyl content (PCO), superoxide dismutase (SOD), catalase, and reducte glutathione (GSH) were determined in gastrocnemius muscle samples collected at 48th hour, after muscle damage induction. Also, in situ contractile properties of gastrocnemius muscle were determined at 48th hour, after muscle damage induction. Although muscle damage increased CK enzyme levels in non-training groups significantly, its effects on LDH levels were not significant. Damage protocol could not create the expected effect in respect of oxidative damage and loss of force. There were not significant changes in MDA levels. Although the mean values of PCO in muscle damaged groups were higher than the control group, statistical significance was not found. Antioxidant enzymes SOD and catalase did not change, whereas GSH levels in training and carnitine/training groups were found to be higher than the injury group. Muscle damage was caused to increase in ½ relaxation time of gastrocnemis muscle. However, force values of gastrocnemius muscle did not change in muscle damage. Forces were significant between the groups in all frequencies except the 80 Hz frequency. Generally, force values of carnitine and control group were lower than the other groups; force enhancement in training and muscle damage groups was significant compared to the control group. There were not significant changes in respect of fatigue period of muscle between the groups. Consequently, low intensity eccentric exercise training facilitates the adaptation to intense exercise and could be protective for muscle damage. It was concluded that combination of carnitine intake and low intensity eccentric training did not create negativity and the effects of carnitine should be determined in different doses and exercise protocols.