Absence of acute skeletal and cardiac muscle injuries in amateur triathletes

Abstract

Creatine kinase (CK) and creatine kinase muscle-brain fraction (CK-MB) might be associated with damage to muscle and cardiac tissue, respectively, as a consequence of intense prolonged exercise. The objective of the present study was to determine whether acute changes in CK and CK-MB reflect some risk of damage to skeletal and cardiac muscles in amateur athletes after Ironman 70.3. The sample consisted of 10 male athlete volunteers (age: 34.0 ± 9.2 years). A venous blood sample (2 mL) was collected before and after the competition. The volunteers completed the race in 5h20min to 6 h. CK and CK-MB were analyzed by an enzymatic method using Wiener lab??reagent in an automatic spectrophotometer (Targa bt 3000?). The nonparametric Wilcoxon test showed significant differences (p < .05) in the variables studied before and after the competition. Mean CK was 112.23 ± 34.9 and 458.0 ± 204.9 U/L (?% = 418.2), and mean CK-MB was 7.4 ± 2.6 and 10.8 ± 3.9 U/L (?% = 153.3) before and after the event, respectively. The relative variation in CK-MB compared to CK before (6.9%) and after (2.5%) the competition showed that the former is not a factor of concern during intense prolonged exercise such as Ironman 70.3. In conclusion, the acute increase in CK after the end of intense prolonged exercise indicates skeletal muscle damage which, however, is considered to be normal for athletes. With respect to CK-MB, cardiac muscle injury was inexistent.