Supplementary Hmb Protective Effect And Mechanism Of Injury In Rat Skeletal Muscle In Exercise Time

Exercise-induced skeletal muscle injury, the ultrastructural changes of skeletalmuscle, occurred after an intense or/and long-term training. From morphological andbiochemical aspects, this test is to probe into the mechanisms of the protection of HMBintake against skeletal muscle injury following exhausted ecxercise and a high intensitytraining. The objective of this research is aimed at providing experimental envidence inintaking HMB rationally.Methods: 40 Male Sprague-Dawley rats were randomly divided into 5 groups asplacebo or HMB supplemented and exhausted exercise or high-intensity training:controls group(C), acute exhausted exercise+placebo group(Is), acute exhaustedexercise+HMB group(1h), high-intensity training+placebo group(150s) andhigh-intensity training+HMB group(150h). Every group had eight rats. Duringone-week meal adaptation, animals in HMB group were fed with HMB as standard0.75g/kg.bw every morning during 8-9 o'clock. Other groups were fed with doubledistilled water as equal level. After 6 week,1s and 1h groups did exhaustive swimmingat the last day. 150s and 150h groups swam 30 mintes at the first week and then increase20 minutes every week till 150minutes.Every week measured the rats' body weight twotimes to define the dosage of HMB supplementation.After 6 Week examination, thelevel of serum and skeletal muscle CK,LDH,TC and the activity of skeletal musclemembrane Na~+-K~+-ATPase were tested.The results showed that :1) After acute exhausted exercise and high-intensitytraining, ultrastructure was changed and the interity of cell membrane was destroyed.HMB supplementation can decrease the changes of ultrastructure and maintain theinterity of cell membrane. 2) During exhaustive swimming, the exhausted time of rats in1h group was longer than that of 1s group, it shows that HMB supplementation canimprove the exercise ability.3) Activities of serum creatine kinase (CK) andlactatedehydrogenase (LDH) increased significantly following exhausted exercise andhigh-intensity training. HMB supplementation attenuated the CK and LDH response. Itindicates that HMB supplementation reduced signs of exercise-induced musclemembrane damage.4) Activity of tissue CK decreased significantly following exhaustedexercise. HMB supplementation improved the CK activity. It means HMB supplementation can enhance ATP-CP system, providing more energy. 5) Activity ofmembrane Na~+-K~+-ATPase significantly decreased following exhausted exercise andhigh-intensity training. HMB supplementation can raise the Na~+-K~+-ATPase activity toimprove the membrane function and slow down the fatigue. It therefore preventedexercise-induced skeletal muscle damage.The results indicated that: HMB prolonged the exhausted swimming time of ratsnotably, decreased the releasing of serum enzyme CK and LDH. Thus HMBsupplementation protected against exercise-induced skeletal muscle injury, also it canenhance the activation of Na~+-K~+-ATPase, maintaine the function and integrity of cellmembrane.