[Clinical diagnosis of overtraining using blood tests: current knowledge]

Area of Science:

• Sports Medicine
• Exercise Physiology
• Biochemistry

Background:

• Overtraining stems from an imbalance between training load and recovery, with complex etiology and no current diagnostic tools.
• Chronic training stress can alter myocyte structure, increasing plasma concentrations of myoglobin, troponin I, and creatine kinase.
• Metabolic shifts, including glycogen depletion and altered amino acid/lipid metabolism, contribute to overtraining symptoms like hypoglycemia and immunosuppression.

Purpose of the Study:

• To review and discuss blood chemistry parameters that may be useful for diagnosing overtraining syndrome in athletes.
• To highlight the need for improved diagnostic tools for overtraining in sports.

Main Methods:

• Literature review of studies investigating blood chemistry markers related to overtraining.
• Analysis of physiological responses to chronic training load and fatigue.

Main Results:

• Elevated myoglobin, troponin I, and creatine kinase may indicate myocyte damage.
• Monitoring reactive oxygen species activity can assess metabolic stress in skeletal muscles.
• Changes in amino acid metabolism, including glutamine and branched-chain amino acids, are linked to fatigue, immunosuppression, and neurological symptoms.

Conclusions:

• Early overtraining diagnosis requires a comprehensive battery of analyses, as no single parameter is sufficient.
• Current biomarkers are unpredictable for systematic case determination.
• Longitudinal monitoring of an athlete's physiological status is essential for early overtraining detection.