Physical activity and heart rate variability measured simultaneously during waking hours

Area of Science:

• Cardiology
• Physiology
• Biomedical Engineering

Background:

• Heart rate variability (HRV) assessment during ambulatory monitoring is crucial for understanding cardiac autonomic function.
• Individual physical activity (PA) levels may influence HRV, but the precise impact on different HRV metrics is not fully understood.

Purpose of the Study:

• To investigate the association between objectively measured physical activity and various heart rate variability indexes during waking hours in healthy adults.

Main Methods:

• Simultaneous measurement of HRV and physical activity using accelerometers in 45 healthy adults.
• PA data analyzed by metabolic equivalent (METs) for 30-minute bouts.
• Within-individual correlation and sign tests used to analyze relationships between HRV and PA.

Main Results:

• Average heart rate and sample entropy showed significant relationships with PA (P < 0.022).
• Short-term HRV index SD1 also demonstrated a significant relation to PA (P = 0.037).
• Long-term HRV indexes were stable across different activity levels, indicating robustness.

Conclusions:

• Physical activity significantly influences average heart rate, HRV complexity (sample entropy), and short-term HRV (SD1) during ambulatory conditions.
• Long-term HRV indexes are more robust for assessing cardiac autonomic function during free-living conditions due to their stability across varying activity levels.