Effect of the ACTN3 R577X Polymorphism on Serum Creatine Kinase and Interleukin-6 Levels After Maximal Eccentric Exercise.

OBJECTIVE

This study explored the interaction among ACTN3 R577X polymorphism, muscle damage, and postexercise inflammatory response by assessing changes over time in serum creatine kinase and interleukin-6 levels.

DESIGN

Ninety-five active Japanese participants (50 men and 45 women: 22.2 ± 2.3 yrs) who did not perform daily upper limb strength exercises were enrolled. Participants executed five sets of six maximal eccentric elbow flexion exercises. The exercise duration was 9 mins, including rest between sets (90 secs). Maximum voluntary isometric contraction, range of motion, muscle soreness, and serum creatine kinase and interleukin-6 levels were assessed pre and post and 1, 2, 3, and 5 days after exercise. Genotype groups were classified as RR + RX and XX based on the absence of ACTN3 expression.

RESULTS

A significant time and group interaction ( P = 0.045) on creatine kinase levels was observed between the groups, indicating that the absence of ACTN3 significantly affects creatine kinase changes. Conversely, no significant interaction on change in interleukin-6, maximum voluntary isometric contraction, range of motion, and muscle soreness was observed between groups.

CONCLUSIONS

The results highlight an interaction on creatine kinase activity after exercise by ACTN3 R577X polymorphism, with elevated activity in the XX genotype.