Reproducibility of Heart Rate Variability Indices at Post-maximal Exercise

Area of Science:

• Exercise Physiology
• Cardiovascular Health
• Sports Science

Background:

• Heart rate variability (HRV) is a key indicator of autonomic nervous system function.
• Assessing HRV reproducibility after maximal exercise is crucial for accurate physiological monitoring.
• Understanding recovery's impact on HRV reliability is essential for exercise prescription and interpretation.

Purpose of the Study:

• To evaluate the reproducibility of time-domain and frequency-domain HRV indices following maximal exercise.
• To compare the reliability of HRV measurements between passive and active recovery protocols.
• To determine if HRV indices analyzed in short segments are reproducible after strenuous physical exertion.

Main Methods:

• Eleven healthy, untrained men underwent four incremental exercise tests to exhaustion.
• Heart rate variability was recorded during passive and active recovery periods.
• Key HRV indices, including LnRMSSD and LnSDNN, were analyzed in 30-second segments and 5-10 minute intervals.

Main Results:

• High reliability (ICC: 0.72-0.96) and good agreement were observed for LnRMSSD and LnSDNN in both recovery types.
• Time-domain HRV indices (5-10 min) showed higher reliability (ICC: 0.59-0.88) and better agreement (CV: 7.67-16.26%) than frequency-domain indices.
• Reproducibility was satisfactory for both time-domain and frequency-domain indices, with time-domain measures being more reliable.

Conclusions:

• Time-domain heart rate variability indices demonstrate satisfactory reproducibility after maximal exercise in untrained men.
• Recovery type (passive vs. active) did not significantly impact the reproducibility of most HRV indices.
• Time-domain HRV measures are more reliable than frequency-domain measures for assessing physiological responses post-maximal exercise.