Thank you for the query. I would like to enquire abour your age and gender, and whether you have any family history of muscular dystrophy, mypopathy or thyroid dysfunction. CPK (abbreviation of Creatine Phosphokinase) is an enzyme which is found in the skeletal muscle, heart and brain. Normal values are usually between 60-180, however, athletes are definitely recorded to have higher values. This enzyme is released from the cells of the organs where it is found as a result of injury - for eg from the heart (in myocardial infarctionor myocarditis ) , from the skeletal muscle (in rhabdobyolysis, in overstraining of skeletal muscle as in exercise, myositis, muscular dystrophy etc.) and in convulsions. As you have mentioned your CPK was elevated to 30,000, which implies that there was a significant muscle injury. Muscle injury releases a protein called myoglobin, which if precipitates in the kidney can lead to renal failure. Liberal hydration with intravenous fluids is required in this case, as you had received, which causes a reversal of the condition. Since you are into strenuous exercise, your CPK levels will be slightly elevated than the reference values. I would want to know if you have muscle pain and tenderness associated with the raised CPK levels. If so you may need to consult your physician to rule out any pathological cause of the elevated enzymes wherein some other investigations may be needed. Please drink liberal amounts of fluid while exercising and avoid any sort of overstraining exercise, which might damage your muscle. Hope this helps you out.