Plasma creatine kinase activity and glutathione after eccentric exercise

Area of Science:

• Exercise physiology
• Biochemistry
• Muscle damage and repair

Background:

• Plasma total glutathione levels exhibit intersubject variability.
• Eccentric exercise induces muscle damage and elevates creatine kinase (CK) and myoglobin (Mb) levels.
• The role of glutathione in modulating the response to eccentric exercise is not fully understood.

Purpose of the Study:

• To investigate if plasma total glutathione levels influence the creatine kinase (CK) response to eccentric exercise.
• To determine if individuals with low plasma total glutathione (<2.5 micromol x L-1) show a different CK response compared to those with high levels (>3.8 micromol x L-1).
• To assess other indicators of muscle damage and recovery in relation to plasma total glutathione levels.

Main Methods:

• Sixty subjects were analyzed for plasma total glutathione.
• Eight subjects with low glutathione (LG) and nine with high glutathione (HG) performed eccentric elbow flexor actions.
• Measurements included maximal voluntary contraction (MVC), relaxed arm angle (RANG), plasma CK, Mb, and total glutathione pre- and post-exercise at various time points.

Main Results:

• A significant interaction between group and time was observed for MVC, RANG, total glutathione, CK, and Mb.
• The LG group demonstrated a smaller increase in plasma CK and Mb compared to the HG group.
• The LG group also exhibited faster recovery of MVC and RANG, and an increase in plasma total glutathione post-exercise.

Conclusions:

• Subjects with low plasma total glutathione levels experienced a reduced plasma CK and Mb response to eccentric exercise.
• Faster recovery from eccentric exercise was observed in individuals with low plasma total glutathione.
• A blunted inflammatory response in subjects with low glutathione may underlie these observed differences.