Changes in serum creatine kinase and hexose phosphate isomerase activity with exercise duration

Area of Science:

• Exercise Physiology
• Biochemistry

Background:

• Serum enzyme levels can indicate physiological stress.
• Creatine kinase (CPK) and hexose phosphate isomerase (PHI) are key muscle enzymes.
• Understanding exercise-induced enzyme changes is crucial for adaptation assessment.

Purpose of the Study:

• To investigate the impact of exercise type and duration on serum CPK and PHI activity.
• To analyze enzyme changes in relation to maximal aerobic capacity.
• To explore the relationship between prolonged exertion and enzyme kinetics.

Main Methods:

• Studied 166 trained healthy males (17-42 years) across three exercise types: bicycle ergometer, ski race, and impact-type exertion.
• Monitored serum CPK and PHI activity at intensities above 65-70% of maximal aerobic capacity.
• Analyzed enzyme activity changes in relation to exercise duration, including work over 300 minutes.

Main Results:

• Serum enzyme activity increased proportionally to exercise duration above 65-70% maximal aerobic capacity.
• Different exercise types exhibited distinct slopes for enzyme activity increase.
• Work exceeding 300 minutes in impact-type exertion led to an accelerated rise in serum CPK.
• A third-degree equation effectively modeled CPK changes in several subject groups.

Conclusions:

• Exercise intensity and duration significantly influence serum CPK and PHI levels.
• Impact-type exertion shows a distinct pattern of accelerated CPK increase with prolonged duration.
• Enzyme measurements may serve as a valuable tool for evaluating physiological adaptation to sustained exercise.
• Further research is needed to refine analytical methods and interpret enzyme changes in exercise contexts.