Exercise responses in patients with chronically high creatine kinase levels

Area of Science:

• Exercise Physiology
• Biochemistry
• Neuromuscular Disorders

Background:

• Elevated serum creatine kinase (CK) is a common finding.
• The relationship between elevated CK and muscle metabolism during exercise remains unclear.
• Many individuals with elevated CK lack a specific diagnosis.

Purpose of the Study:

• To investigate the relationship between serum creatine kinase (CK) levels and muscle metabolism during incremental exercise.
• To determine if elevated CK levels during exercise can predict underlying muscle conditions.

Main Methods:

• 46 men and 48 women participated in the study.
• Participants underwent incremental exercise testing to assess aerobic, cardiovascular, and ventilatory responses.
• Serum lactate, ammonia, and CK levels were measured at rest, during exercise, and during recovery.

Main Results:

• Subjects with CK ≥300 U/L showed significantly higher lactate and ammonia levels post-exercise compared to controls.
• These high-CK individuals also exhibited increased ventilatory responses during maximal exercise.
• Subjects with CK between 200-300 U/L did not show significant differences in these markers.

Conclusions:

• Lactate and ammonia profiles during maximal incremental exercise can help identify individuals potentially experiencing muscle issues.
• Measurement of these metabolites may guide decisions for further diagnostic procedures like muscle biopsy.
• This approach can aid in ruling out myopathy in individuals with unexplained elevated CK levels.