Elonga measures heart rate variability (HRV) using spectral analysis (SA-HRV) a highly precise method that monitors the autonomic nervous system (ANS), i.e., the balance between its sympathetic (stress) and parasympathetic (recovery) branches.
How It Works
The measurement is performed:
in the morning
at rest, lying down
before food / coffee or any physical activity
takes about 3 minutes
using a sensor placed on the forearm
The device captures tiny time differences between heartbeats (RR intervals) and transforms them into the frequency domain. This reveals how strongly the sympathetic and parasympathetic systems are active.
Spectral Analysis and Frequency Bands
The SA-HRV result is processed into a 3D spectrum and a table of power values across frequency bands, following European Society of Cardiology (ESC) standards.
Frequency Bands
| Frequency Band | Range | Physiological Meaning |
|---|---|---|
| VLF (Very Low Frequency) | 20–50 mHz | Reflects thermoregulatory sympathetic activity, catecholamine levels (e.g., adrenaline) and renin–angiotensin system influencing blood pressure. |
| LF (Low Frequency) | 50–150 mHz | Includes Mayer waves linked to baroreflex blood pressure regulation; reflects sympathetic activity but not total sympathetic output. |
| HF (High Frequency) | >150 mHz | Fully dependent on vagal (parasympathetic) activity — recovery and restorative processes. |
From these data, Elonga evaluates:
stress load (sympathetic activity)
recovery capacity (parasympathetic activity)
readiness (preparedness for physical or mental load)
How Elonga Processes the Data
For scientific purposes, SA-HRV provides raw data (VLF/LF/HF power).
For everyday users, these are converted into clear, understandable indicators such as percentage-based stress and recovery levels.
Elonga tracks over 60 HRV parameters, analyzed automatically by algorithms built from 1,000,000+ measurements from tens of thousands of users.
The goal is lab-grade accuracy with simple, actionable outputs.
Evolution of the Method — From Laboratory to Your Nightstand
SA-HRV is based on 30+ years of research led by physiologist Radim Šlachta, co-founder of Elonga.
1996 — first HRV lab tests at Palacký University lasted up to 20 minutes
2016 — validated with professional athletes
2019 — after 300,000+ measurements, researchers developed a model reducing analysis to 3 minutes
2020 — machine learning (AI) enabled a model with lab-level precision in a fraction of the time
2021–2023 — Elonga brought the technology into everyday life; thousands now use it daily for stress and recovery insights
Elonga at a Glance
measures ANS activity using spectral HRV analysis
uses three key frequency components: VLF, LF, HF
reduced lab-style measurements from 20 minutes → 3 minutes
combines scientific precision with user-friendly simplicity
provides clear insights into stress, recovery, and readiness
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