Heart Rate Variability Explained

HRV (heart-rate variability) became the wellness metric of the late 2010s and stayed mainstream through 2026. Whoop, Oura, and Apple Watch all surface it. Here’s what it actually measures, what raises it, and the common mistakes.

What HRV is

Variation in time between heartbeats, measured in milliseconds. Higher = better adapted, more parasympathetic tone, generally fitter. Genetics + age set your baseline; lifestyle moves it ~10-20%.

Typical ranges by age

• Twenties: 60-90 ms (rMSSD, common metric)
• Thirties: 50-80
• Forties: 40-70
• Fifties+: 30-60

Athletes typically run 20-30% above peers. Compare to YOUR baseline, not other people’s.

What raises HRV

• Sleep quality + duration (biggest single lever).
• Zone 2 cardio + strength training.
• Hydration.
• Lower alcohol intake (huge effect — one drink drops it 10-30%).
• Resolved emotional stress.

What lowers it

• Late meals + alcohol within 3 hours of sleep.
• Overtraining without recovery.
• Acute illness (early signal — HRV drops before you feel sick).
• Chronic stress.

Common mistakes

• Comparing your HRV to other people’s. Useless.
• Optimizing daily for HRV at the cost of training stimulus.
• Reading single-day variation as meaningful (look at 7-day rolling average).