HRV: where it fits if your device captures it

What HRV is

Heart Rate Variability (HRV) is the variation in time between consecutive heartbeats. Higher HRV typically indicates better autonomic recovery and parasympathetic activity. Lower HRV typically indicates stress, fatigue, or illness onset.

The most common HRV metric is RMSSD (root mean square of successive differences), measured in milliseconds. The Hub stores HRV in the hrv field as a positive integer ms value.

How to capture HRV

Two paths:

From a wearable (most common)

• Garmin watches with HRV: report a "morning HRV" value.
• Whoop: morning HRV.
• Oura ring: morning HRV.
• HRV4Training, Elite HRV (phone-based, paired with chest strap): finger-tip or chest-strap measurement taken on waking.

Take the value from your device first thing on waking, before standing up. Log it in /my-wellness/ for that day.

Manual chest strap protocol

• Lie down quietly for 1 to 2 minutes to settle.
• Capture 3 to 5 minutes of HR data with a chest strap and HRV-capable app.
• Take the RMSSD reading.

The HRV concerning flag

The wellness system fires a concerning flag when HRV drops 15 percent or more below the rolling 14-day baseline.

• This is a multi-log trigger, not a per-entry flag like sleep or stress.
• It surfaces on the coach dashboard.
• Multiple consecutive low-HRV days compound the signal.

A single low day in 14 is noise. Three consecutive low days or a clear week-long drop is signal.

What a low HRV trend means in practice

• Heavy training the day before: expected drop, baseline recovers within 24 to 48 hours.
• Illness brewing: HRV often drops 2 to 5 days before symptoms appear.
• Life stress: relationship, work, travel stress all drag HRV down.
• Late-night caffeine or alcohol: shifts HRV down for several days.
• Poor sleep: causes and follows low HRV.

What HRV is NOT

• Not a fitness number. HRV correlates with recovery state, not aerobic capacity.
• Not comparable across people. Two athletes with very different HRV baselines can both be well-trained. Your own trend is the signal.
• Not a workout-canceller. A low-HRV day does not mean you skip training. It is one data point in the larger picture.

What you do with the data

• Log it daily if you have it.
• Watch the 14-day trend against your baseline.
• Combine with sleep, RHR, soreness for a fuller picture.
• Tell your coach if multiple recovery signals stack. Do not unilaterally cancel training.

What the Hub does NOT do

• No dedicated HRV chart yet. Values are visible in the wellness history per day.
• No auto-suggested training adjustment. The flag surfaces; the coach decides.
• No device sync. You have to copy the daily HRV value from your device into the wellness form (or get a copy- paste pattern that suits your routine).

See also: Logging daily wellness, Concerning flags explained, Resting HR deep dive.