The effects of heavy eccentric contractions on serum creatine kinase levels

Post-exercise serum creatine kinase (CK) has been frequently used to evaluate muscle damage. The purpose of present study was to examine the effects of 45 eccentric contraction on serum creatine kinase levels during laboratory tests. Using a Lido isokinetic dynamometer, thirteen subjects (five distance runners and eight PE students), average age = 24.0 (yrs), height = 172.5 (cm), weight = 66.5 (kg), and percent body fat = 15.3 (%), completed 5 and 40 eccentric contractions at speed of 60 degrees C/s and 120 degrees/s, respectively. Blood sample was drawn before and 18, 42, 66, 90 hours after exercise protocol. Result indicated that PE students have a significant increase in serum CK levels post-exercise 18 hours (p less than 0.05) only. Both groups in absolute muscular strength or corrected strength have found non-significant difference (p greater than 0.05). Resulting findings showed that training effect may be an important factor for CK leakage rather than lean body mass. In the light of results, it is seem safe to say that the exercise protocol for distance runners using by this study would not contribute to severe CK elevations in blood. This testing protocol can be recommended as an appropriate test for students and distance runners with similar fitness level. Due to large variations occurred during CK testing, follow-up study should try to establish baseline serum CK level by repeated enzyme tests.