HRV (Heart Rate Variability) refers to the natural variations in the time interval between individual heartbeats. It is not the heart rate itself, but the differences in timing between each beat. A healthy heart does not beat like a metronome small fluctuations are a sign of a flexible and responsive autonomic nervous system (ANS).

Why HRV Matters

HRV reflects the balance between the two branches of the autonomic nervous system:

• Sympathetic system – activation, stress, performance

• Parasympathetic system – recovery, calm, restoration

General rule:

Higher HRV = the body switches well between stress and rest
Long-term low HRV = may indicate fatigue, stress, illness, or insufficient recovery

How Elonga Uses HRV

Elonga uses the SA-HRV (Spectral Analysis of HRV) method, which evaluates spectral components of variability and accurately measures both sympathetic and parasympathetic activity. 

From this measurement, Elonga derives key metrics:

• Readiness – how prepared the body is for stress or physical load

• Stress – level of sympathetic activation

• Recovery – degree of physiological restoration

HRV shows how your body responds to sleep, training, psychological load, and overall lifestyle.

What Influences HRV

HRV can be significantly affected by:

• sleep quality and duration

• training and physical load

• alcohol, caffeine, medications

• psychological stress

• illness or skipped meals

• late-evening activity

We recommend measuring every morning, at the same time, fasted, and in calm conditions.

Summary

HRV is one of the most sensitive indicators of the state of the autonomic nervous system and the body’s overall balance. It helps detect early signs of fatigue, overload, and the quality of recovery.

Regular HRV tracking in Elonga helps you plan training, daily routine, and rest more effectively.