Why is my HRV so low?
A consistently low HRV (relative to your baseline) usually has an identifiable cause:
Lifestyle factors - Poor or insufficient sleep (most common cause) - Alcohol consumption in the past 2-5 days - High stress at work or home - Dehydration - Illness or fighting off infection - Jet lag or disrupted sleep schedule
Training factors - Accumulated training fatigue - Recent high-intensity workout - Overtraining or under-recovery - Starting a new, challenging program
Other factors - Late meal the night before - Caffeine too close to bedtime - Hot sleeping environment - Menstrual cycle phase (luteal phase is naturally lower) - Aging (HRV naturally declines with age)
What to do: Don't panic about a single low reading. If HRV stays suppressed for 5+ days despite good sleep and no hard training, investigate non-training stressors or consider seeing a doctor if you also feel unwell.
Why is my HRV suddenly very high?
An unusually high HRV reading can indicate:
Good reasons - Excellent recovery after a rest day - Successful taper before an event - Positive adaptation to training - Great night of sleep
Concerning reasons - Parasympathetic overactivation (rare, usually with extreme overtraining) - Measurement artifact (bad sensor contact, movement during reading) - Irregular heartbeat affecting the calculation
The paradox of very high HRV
Extremely elevated HRV (significantly above your normal high range) can sometimes indicate overtraining, not recovery. If you see very high readings alongside fatigue, poor performance, and feeling "flat," your body may be in a parasympathetic-dominant state from accumulated stress.
What to do: If high HRV matches how you feel (rested, energetic), great. If high HRV contradicts how you feel (exhausted despite the number), trust your body and take it easy.
Why does my HRV vary so much day to day?
Daily HRV variation of 10-25% is completely normal. This variability is actually the useful signal—it reflects your body's changing state.
Normal causes of variation - Sleep quality differences night to night - Training load from previous days - Daily stress fluctuations - Meal timing and content - Hydration status - Menstrual cycle (for women)
When variation is a problem
Concern arises when: - Variation increases dramatically (suggests instability) - Baseline is declining week over week - You can't identify patterns
What to do: Focus on the 7-day rolling average, not daily readings. Look for trends over weeks, not fluctuations over days. Tag your readings with lifestyle factors to identify what drives YOUR variation.
My readings are inconsistent—is my device broken?
Before blaming equipment, check your measurement protocol:
Common user errors - Measuring at different times (6am vs 9am) - Different body positions (lying vs sitting) - Moving or fidgeting during the reading - Checking phone/thinking stressful thoughts during measurement - Not waiting long enough after waking
Sensor issues - Chest strap not wet enough (dry electrodes = poor contact) - Chest strap too loose or too tight - Wrist device not positioned correctly - Ring worn on different fingers - Low battery affecting accuracy
App/software issues - Different apps calculate HRV differently - Firmware updates can change algorithms - Some apps use different time windows
How to test your device
Take 3 readings in a row under identical conditions. If they vary by more than 10-15%, you may have a sensor contact issue. Try wetting the chest strap electrodes more thoroughly or adjusting device position.
When it's actually the device
If you've ruled out protocol issues and readings remain erratic, try a different device. Chest straps are generally most reliable; wrist devices can struggle with some skin types or during movement.
Why is my HRV lower than my friend's?
This comparison is meaningless. HRV varies enormously between individuals:
- A healthy 25-year-old athlete might have 80-100ms RMSSD
- A healthy 50-year-old might have 30-45ms RMSSD
- Both are perfectly normal for their age and fitness
Factors that determine your baseline - Age (HRV declines 1-2% per year after 30) - Genetics (significant hereditary component) - Fitness level (aerobic fitness raises baseline) - Sex (women often have slightly lower HRV) - Resting heart rate (lower RHR often correlates with higher HRV)
What actually matters
Your HRV trend relative to YOUR baseline. A 35ms reading that's 20% above your baseline indicates better recovery than a 70ms reading that's 10% below someone else's baseline.
Stop comparing, start tracking your own trends.
My HRV hasn't improved despite training—why?
HRV improvements from training take time and aren't guaranteed:
Timeline expectations - Initial changes: 2-4 weeks of consistent training - Significant baseline shifts: 8-12 weeks - Major improvements: 3-6 months
Why you might not see improvement
1. Not enough recovery: Training hard without adequate rest suppresses HRV chronically. You might be fitter but too fatigued to show it.
2. Life stress: Work, relationships, and other stressors can mask training adaptations.
3. Sleep debt: Chronic sleep restriction prevents HRV gains regardless of training quality.
4. Already well-trained: If you're already fit, further HRV gains are harder. You may be improving without HRV changes.
5. Age-related decline: After 40, maintaining HRV is success; increasing it is harder.
What to do
Ensure recovery matches training load. Focus on sleep quality. Take a full recovery week and see if baseline rises—if it does, you're under-recovering during normal training.
Should I trust my device or how I feel?
Use both. HRV and subjective feel provide different information:
Trust the device when: - You feel fine but HRV is consistently suppressed (hidden fatigue) - You're tempted to train hard despite multiple low readings - You're returning from illness and eager to resume training - Pre-race nerves make you feel bad but HRV is actually fine
Trust how you feel when: - Single-day HRV dip but you slept great and feel energetic - HRV is high but you feel genuinely exhausted (parasympathetic overload) - Life circumstances make the reading unreliable (major stress, travel)
The integration approach
| HRV | Feel | Action | |-----|------|--------| | High | Good | Train hard—you're ready | | High | Bad | Easy day—trust your body | | Low | Good | Moderate intensity—stay alert | | Low | Bad | Rest—clear signal |
When HRV and feel agree, the signal is strong. When they disagree, err on the side of caution.
Why does alcohol affect my HRV so much?
Alcohol is one of the strongest HRV suppressors:
What happens
Alcohol disrupts sleep architecture (even if you sleep long), increases resting heart rate, and shifts autonomic balance toward sympathetic dominance. Even moderate drinking (2-3 drinks) can suppress HRV for 2-5 days.
The timeline - Night of drinking: Sleep HRV severely suppressed - Next morning: Noticeably lower reading - Days 2-3: Gradual recovery - Days 4-5: Return to baseline (for moderate consumption)
Heavy drinking can take even longer to recover from.
What to do
If you drink, expect lower HRV and don't train hard during the recovery period. Use this information to make informed choices—not as a guilt trip, but as data about true recovery cost.
Is it bad if my HRV doesn't match the app's 'normal' range?
No. App "normal" ranges are population averages, not individual targets.
Why ranges are misleading
- Based on averages across all ages and fitness levels
- Don't account for individual variation
- Some apps have poorly calibrated ranges
- Your optimal HRV depends on YOUR physiology
What to look for instead
- Your personal baseline (established over 2+ weeks)
- Your typical variation range (your high and low normal)
- Trends relative to your baseline
- How HRV correlates with how you feel and perform
Example
If your baseline is 42ms and the app says "normal" is 50-70ms, ignore the app's range. What matters is whether today's 38ms is concerning (8% below YOUR baseline) or whether 48ms means you're recovered (14% above YOUR baseline).
Can HRV predict illness?
Sometimes, yes—HRV often drops 1-3 days before symptoms appear.
What the research shows
Your immune system activation triggers sympathetic nervous system response, which suppresses HRV before you feel sick. Many users report seeing HRV drops 24-72 hours before cold/flu symptoms emerge.
How to use this
If HRV drops unexpectedly with no training or lifestyle explanation: - Prioritize sleep and rest - Avoid hard training - Support immune function (vitamin C, zinc, hydration) - Don't push through—you might avoid getting sick
Limitations
Not all illness shows up in HRV, and not every unexplained HRV dip means illness. But if you see a pattern where sudden drops precede getting sick, use that information proactively.
My morning reading was bad—should I skip my workout?
Not necessarily. One low reading is weak evidence. Consider:
Skip/modify the workout if: - Multiple consecutive days of suppressed HRV - You also feel tired, sore, or unwell - The planned workout is high-intensity - You're in a high-stress life period - You're fighting off illness
Proceed with caution if: - Single-day dip with no obvious cause - You feel reasonably good - Workout is moderate intensity - You have a solid warmup to reassess
Proceed normally if: - Single-day dip but you feel great - You slept well and have no unusual stress - HRV is only slightly below baseline (5-10%)
The warmup test
If unsure, start your warmup. If you feel good and heart rate responds normally, proceed. If you feel sluggish and HR is elevated, back off. The warmup provides real-time data that complements the morning reading.
Why do different apps show different HRV numbers?
Different apps calculate and display HRV differently:
Measurement differences - Different reading durations (1 min vs 2.5 min vs overnight) - Different time of day (morning vs sleep vs random) - Different metrics (RMSSD vs SDNN vs proprietary scores) - Different algorithms for the same metric
Display differences - Raw milliseconds vs normalized scores (1-10, 0-100) - Single reading vs rolling average - Different baseline calculation periods
What to do
Pick one app and stick with it. Your trend within that app is valid even if the absolute numbers don't match another app. Don't try to compare readings across different apps—it's not meaningful.
If you must switch apps
Allow 2 weeks to establish a new baseline. Expect different numbers but similar trends if both apps are using quality algorithms.
When should I see a doctor about my HRV?
HRV tracking is not medical diagnosis, but certain patterns warrant attention:
See a doctor if: - Persistently suppressed HRV (weeks) with no lifestyle explanation - HRV drop accompanied by symptoms: chest pain, shortness of breath, dizziness, extreme fatigue - Irregular heartbeats showing up in your readings - Dramatic sudden change in baseline without cause - You're recovering from illness and HRV won't normalize
HRV and heart conditions
Low HRV is associated with various cardiovascular issues in research, but your consumer device isn't designed for medical screening. If you have heart disease risk factors and notice concerning patterns, discuss with your doctor.
What to tell your doctor
Share your HRV trend data (most apps can export). Note when changes started and any correlating symptoms. Be clear that you're using a consumer device, not medical equipment—but the trend information may still be useful context.
Bottom line
HRV tracking is for optimizing wellness and training. If something feels wrong with your health, don't rely on your app for answers—see a professional.