Reliability of resting and postexercise heart rate measures.

Area of Science:

• Exercise Physiology
• Autonomic Nervous System Function

Background:

• Heart rate variability (HRV) and heart rate recovery (HRR) are key indicators of autonomic function.
• Assessing the reliability of these measures after different exercise intensities is crucial for accurate interpretation.

Purpose of the Study:

• To compare the reliability of short-term resting HRV and postexercise parasympathetic reactivation (HRR and HRV) indices.
• To evaluate reliability following both submaximal and supramaximal exercise protocols.

Main Methods:

• Beat-to-beat heart rate was recorded in 15 healthy males during rest and after submaximal and supramaximal exercise bouts.
• Reliability was assessed using the coefficient of variation (CV) for various HRV and HRR indices.

Main Results:

• CV for HRV indices varied widely (4-82%), with spectral indices showing lower reliability after supramaximal exercise (26.2%) compared to rest (12.6%).
• HRR reliability was not significantly different between submaximal (25%) and supramaximal (14%) exercise.
• A discrepancy in the reliability of vagal-related heart rate indices was observed.

Conclusions:

• Supramaximal exercise impairs the reliability of HRV spectral indices, suggesting caution when using these measures post-intense exertion.
• HRR demonstrates comparable reliability regardless of exercise intensity.
• Understanding the reliability differences is essential for interpreting changes in autonomic function markers.