Estimation of anaerobic threshold by cardiac repolarization instability: a prospective validation study

Area of Science:

• Sports Medicine
• Cardiology
• Exercise Physiology

Background:

• Lactate (LT) and anaerobic thresholds (AT) are crucial for controlling training intensity and estimating athletic performance.
• Previous research demonstrated ECG-based assessment of cardiac repolarization instability for non-invasive AT estimation in recreational athletes.
• This study validates the ECG-based method in professional and amateur team sports athletes.

Purpose of the Study:

• To validate a non-invasive, ECG-based method for estimating anaerobic thresholds (AT) in professional and amateur team sports athletes.
• To compare the ECG-derived AT (AT_dT°) with traditional lactate-based AT measurements (LT_Mader and LT_Dickhuth).
• To assess the reliability of using cardiac repolarization instability to determine AT in elite athletes.

Main Methods:

• Sixty-five team sports athletes (32 professional, 33 amateur) underwent standardized incremental cycle ergometry.
• High-resolution ECGs were recorded in the Frank-leads configuration, assessing beat-to-beat cardiac repolarization changes (dT°).
• Repolarization-based AT (AT_dT°) was estimated using dT° signal patterns, compared against LT_Mader and LT_Dickhuth.

Main Results:

• AT_dT° demonstrated a highly significant correlation with both LT_Dickhuth (r=0.96) and LT_Mader (r=0.98) across all athletes (p<0.001).
• Strong correlations were consistent in subgroups of professional and amateur athletes.
• The mean AT_dT° was 187.6 W, closely aligning with LT_Dickhuth (181.1 W) and LT_Mader (184.3 W).

Conclusions:

• The ECG-based assessment of cardiac repolarization instability (AT_dT°) reliably estimates anaerobic thresholds in professional and amateur athletes.
• This non-invasive method, utilizing maximal discordance between dT° and heart rate, offers a valuable tool for sports science.
• The findings support the use of high-resolution ECG for AT determination, enhancing training prescription and performance analysis.