Individual-based Creatine Kinase Reference Values in Response to Soccer Match-play

Area of Science:

• Sports Medicine
• Exercise Physiology
• Biochemistry

Background:

• Creatine kinase (CK) is a biomarker for muscle damage.
• Establishing player-specific reference limits is crucial for accurate interpretation of CK levels in athletes.
• Previous studies often lack athlete-specific, longitudinal data for post-exercise CK analysis.

Purpose of the Study:

• To determine creatine kinase reference limits for professional soccer players based on their individual post-match responses.
• To differentiate between normal CK elevations and potential muscle overload following soccer matches.
• To provide a practical guide for monitoring muscle status in elite soccer players.

Main Methods:

• Analysis of creatine kinase concentration in 25 professional soccer players over a 3-year period.
• Collection of samples 36-43 hours post-match from 70 official games.
• Calculation of absolute reference limits (2.5th and 97.5th percentiles) and percentage change from individual season means.

Main Results:

• Absolute reference limits for CK were 115.8 U.L⁻¹ (2.5th percentile) and 1480 U.L⁻¹ (97.5th percentile).
• Percentage change from individual season mean showed players at 90th, 95th, and 97.5th percentiles with increases of 50.01%, 66.7%, and 71.34%, respectively.
• A significant percentage change (97.45±35.92%) was observed post-match.

Conclusions:

• The study provides specific creatine kinase reference ranges for professional soccer players.
• These personalized reference limits aid in assessing typical post-match CK responses.
• The findings offer a practical tool for detecting muscle overload and guiding training load in elite soccer.