Overview
As explained in the first blog, Heart rate variability (HRV) is a measure of the variation in the time between your heartbeats. It’s an important indicator of your overall health and well-being, as it reflects the balance between your nervous system branches, the sympathetic and parasympathetic nervous systems. A higher HRV generally indicates a healthier heart and a better ability to adapt to stress. This blog post aims to be your guide, delving into the most common HRV metrics and the wearables that harness their power.
Understanding the Orchestra of HRV
Before diving into specifics, let’s remember that HRV isn’t a single value, but an orchestra of metrics reflecting the variability in the time intervals between your heartbeats.
There are a number of metrics, but below are 2 most common HRV metrics used in different wearable devices:
- rMSSD (Root Mean Square of the Successive Differences): This measures the average difference between consecutive heartbeats over a short period. Higher RMSSD is associated with better HRV and improved stress resilience.
- SDNN (Standard Deviation of Normal to Normal Intervals): This measures the standard deviation of all normal RR (NN) intervals over a longer period. Similar to RMSSD, higher SDNN indicates better HRV.
Different HRV metrics are listed below:
Choosing the right wearable device
Wearables Decoding the HRV Symphony
Now, there are many wearables in the market that use HRV and other metrics to give a recovery score. Below are a few significant players in this space on how they translate these metrics into actionable insights:
- Whoop: WHOOP incorporates several key physiological metrics into your daily recovery: Heart Rate Variability (HRV), Resting Heart Rate (RHR), Sleep Performance, and Respiratory Rate in helping you optimize training and minimize overtraining risk.
- Oura Ring: Readiness Score is calculated by using your lowest overnight resting heart rate, body temperature, any physical activity from the previous day, and a few “balance” oriented metrics including HRV, sleep and activity balance.
- Garmin Body Battery: Body Battery is a feature that uses a combination of heart rate variability, stress, and activity to estimate a user’s energy reserves throughout the day. It records and displays a number from 1–100 that represents the individual’s energy level.
- Apple Watch: Apple Watch do measure the HRV using SDNN, but it doesn’t explicitly display recovery or strain score based on that. Third party apps like hrv4training, athlytic, and superset can be used to interpret those HRV to calculate and show the recovery and strain.
- Fitbit Daily Readiness Score: The score compares your recent activity, sleep and heart rate variability (HRV) levels against your personal baseline.List of wearables that can track your HRV
Below is a comprehensive list of wearables that track HRV. This is not an exhaustive list.
Oura Ring
Whoop Band
Apple Watch
Garmin: Fenix 7 & Epix (other Garmin devices measure Stress Level which is derived from HRV)
Fitbit: Charge 3, Charge 4, Charge 5, Inspire series, Versa series, Sense, Luxe devices
Samsung: Samsung Galaxy Watch 4
Polar: Polar Vantage V2, Polar Grit X Pro, Polar Ignite, Polar H10
EliteHRV: CorSense
Rhythm24: Scosche Armband Waterproof Heart Rate Monitor
Biostrap
VIITA: VIITA Race HRV
Wahoo: Wahoo TICKR X
Suunto: Smart Belt
source tryterra
Important considerations when choosing a wearable device
- Accuracy: Wearable HRV accuracy can vary based on sensor technology and placement. Chest straps generally offer higher accuracy than wrist-based devices.
- Interpretation: Understanding your individual HRV baseline and trends is crucial for meaningful interpretation.
- Privacy: Be mindful of data privacy policies when choosing a wearable, ensuring your HRV data is handled responsibly.
Conclusion
Here are a few things to keep in mind when interpreting HRV data:
- HRV can vary significantly from person to person and even throughout the day.
- HRV can be affected by factors such as age, fitness level, stress, and sleep.
- It’s important to track your HRV over time to identify trends and see how it responds to lifestyle changes.
Start exploring the world of HRV! This journey may give you an understanding of your body’s unique rhythms.