Skeletal muscle structure at different phases after eccentric exercise and changes of blood interleukin-6, creatine kinase and creatine kinase isoenzyme in rats

Bing HUA; Rou DONG; Quansheng SU

ABSTRACT

BACKGROUND:

Exercise preconditioning can lighten exercise-induced muscle damage, thereby to avoid delayed onset muscle soreness. At present, experimental research is scarce that apply intedeukin-6 (IL-6), creatine kinase (CK) and creatine kinase isoenzyme (CK-MM) to evaluate skeletal muscle damage.

OBJECTIVE:

To observe the effects of exercise precondiUoning on muscle damage at different phases after eccentric exercise and changes of blood IL-6, CK and CK-MM.DESIGN, TIME AND

SETTING:

The randomized control animal expedmant was carded out in the Animal Laboratory of Chengdu Sports University between 2006 and 2007. MATERIALS Eighty female adult SD rats, weighing (231.3+12.44) g, were adopted. Eighty rats were randomly divided into without exercise preconditioning group (n=40) and exercise preconditioning group (n=40). Each group was assigned into 5 subsets, termed before exercise, immediately after exercise, 24, 48, 72 hours after exercise, with 8 rats in each subset.

METHODS:

Except before exercise subset, other rats in the without exercise preconditioning group were forced to do treadmill exercise (19-21 m/min, -16° incline, 90 minutes). All rats of exercise preconditioning group were forced to do eccentric treadmill exercise for two weeks. After two weeks, treadmill test was made for rats except before exercise subset. MAIN OUTCOME

MEASURES:

Soleus muscle structure, blood IL-6, CK and CK-MM immediately, 24, 48, 72 hours after eccentric exercise.

RESULTS:

The soleus muscle was damaged after exercise, especially in without exercise preconditioning group at 24-48 hours after exercise. Blood IL-6 of without exercise preconditioning group increased significantly immediately after exercise and then gradually decreased, but again raised at 72 hours after exercise. In the exercise preconditioning group, blood IL-6 slightly reduced immediately after exercise and then gradually increased. Peak value appeared at 48 hours. After exercise, IL-6 of exercise preconditioning group was obviously lower than that of without exercise preconditioning group. Before exercise, serum CK and CK-MM of exercise preconditioning group were less than that of without exercise preconditioning group. After exercise, the CK and CK-MM were firstly raised and then reduced in two groups. Except 72 hours after exercise subset, the variation of CK and CK-MM of exercise preconditioning group was lower than that of without of exercise preconditioning group.

CONCLUSION:

Exercise preconditioning is redounded to lighten the ultrastructure injury of skeletal muscle induced by eccentric exercise and blood indices changes induced by exercise stress. The individual variation of CK and CK-MM is so tremendous that they fit the comparison of intrasubject variability.