How to Improve Heart Rate Variability (HRV) for Men Over 40

Key Takeaways

• In people without known heart disease, the lowest SDNN group had a 35% higher risk of a first cardiovascular event than the highest (2013 Europace meta-analysis, 21,988 people)
• On a 24-hour Holter recording, SDNN above 100 ms is classed as healthy, 50 to 100 ms as compromised and below 50 ms as unhealthy
• Wearable and short readings are not interchangeable with 24-hour SDNN; track your own trend
• Exercise training raises vagal HRV measures, with smaller responses in older people (2005 meta-analysis)
• Alcohol lowers HRV during sleep in a dose-dependent way, even at low intake (study of 4,098 Finnish employees)

Low heart rate variability goes with higher cardiovascular risk in people who have no heart disease yet. A 2013 meta-analysis in Europace pooled 8 studies of 21,988 people: the lowest SDNN group had a 35% higher risk of a first cardiovascular event than the highest (relative risk 1.35, 95% CI 1.10 to 1.67). In the Framingham Heart Study, each standard-deviation drop in SDNN went with a 47% higher risk of new cardiac events after adjustment for other risk factors. HRV reflects how your autonomic nervous system adjusts your heart from beat to beat, and your habits move it. Run your numbers below, then work through the changes.

What Your HRV Score Means

The calculator uses the 24-hour SDNN bands summarised by Shaffer and Ginsberg (2017) from a 1987 study of heart attack survivors. In that study, survivors above 100 ms had a death rate 5.3 times lower than those below 50 ms.

Above 100 ms: classed as healthy on a 24-hour recording. Keep the habits that got you here and watch your trend.

50 to 100 ms: classed as compromised on a 24-hour recording. HRV falls with age, which pushes readings toward this band. This is the range where training, sleep and alcohol changes are worth the effort.

Below 50 ms: classed as unhealthy on a 24-hour recording. If a Holter recording shows this, or your wearable trend stays low and you have other risk factors, talk to your doctor.

A wearable reading is a different measurement. Shorter recordings give smaller SDNN values and estimate 24-hour values poorly, so use the bands as a rough guide.

What HRV Actually Measures

Your heart does not beat at perfectly even intervals. The variation between beats, measured in milliseconds, reflects the push and pull between your sympathetic nervous system (the accelerator) and your parasympathetic nervous system (the brake).

SDNN, the standard deviation of normal-to-normal intervals, captures total variability across a recording. Over 24 hours it is the standard measure for cardiac risk. RMSSD captures short-term, beat-to-beat change and mostly reflects the parasympathetic branch.

HRV falls with age. In 260 healthy people aged 10 to 99 with 24-hour recordings, every HRV measure declined with age (Umetani, JACC 1998). SDNN fell gradually, to 60% of its second-decade value by the tenth decade. RMSSD fell faster, to 47% of baseline by the sixth decade, and then levelled off.

The Research on HRV and Heart Risk

The evidence behind HRV as a risk marker comes from several studies:

• Kleiger et al., 1987 (American Journal of Cardiology): 808 heart attack survivors with 24-hour Holter recordings, followed for a mean 31 months. The death rate was 5.3 times higher with SDNN below 50 ms than above 100 ms, and SDNN stayed a significant predictor after adjustment for other factors, including ejection fraction.
• Framingham Heart Study, 1996 (Circulation): 2,501 people free of heart disease, mean age 53, 2-hour recordings, mean follow-up 3.5 years. A one-standard-deviation drop in (log) SDNN went with HR 1.47 (95% CI 1.16 to 1.86) for new cardiac events.
• ARIC Study, 2000 (Circulation): adults aged 45 to 65 without coronary heart disease. Low HRV on a 2-minute rhythm strip went with higher risk of coronary heart disease and death from several causes.
• Hillebrand et al., 2013 (Europace): meta-analysis of 8 studies, 21,988 people without known cardiovascular disease. Lowest vs highest SDNN: RR 1.35 for a first cardiovascular event.

All are observational. They show that low HRV marks higher risk, not that raising HRV lowers it.

Measurement limitation worth noting: the 24-hour bands do not transfer to wearables. Shaffer and Ginsberg note that 5-minute SDNN values do not predict future heart attack risk the way 24-hour values do.

Why HRV Drops After 40

Age itself. HRV declines with age in healthy people, with the pattern depending on the measure (Umetani, 1998).

Fitness. Exercise training raises vagal HRV measures. Less training, less of that effect.

Sleep. Most wearables measure HRV overnight, so short or broken sleep shows up in the number. The sleep quality guide covers how to fix it.

Alcohol. In 4,098 Finnish employees tracked in daily life, alcohol lowered parasympathetic activity and recovery during the first 3 hours of sleep, in a dose-dependent way. HRV-derived recovery fell by 9.3, 24.0 and 39.2 percentage units after low, moderate and high intake.

5 Evidence-Based Ways to Improve HRV

1. Aerobic Training

A 2005 meta-analysis in Medicine & Science in Sports & Exercise found that exercise training raised high-frequency HRV power (effect size 0.48), a marker of vagal activity, and lengthened the interval between beats. Older people showed smaller responses.

Zone 2 work, steady aerobic exercise at a pace where you can still talk, is a practical way to build volume. Start with 20 minutes and build up over weeks. The full protocol is in the Zone 2 longevity guide. If you have been inactive or have heart disease, talk to your doctor first.

2. Slow Breathing and HRV Biofeedback

HRV biofeedback trains paced breathing at about 4.5 to 7.5 breaths a minute, guided by live heart rate feedback. A 2020 meta-analysis of 58 randomized studies found a small to moderate benefit across many outcomes, largest for anxiety, depression, anger and athletic and artistic performance.

The practice is simple: breathe in and out slowly and evenly, for example about 5 seconds in and 5 seconds out, for a few minutes a day. A pacing app or the breathing feature on Apple Watch helps you hold the rhythm.

3. Regular, Sufficient Sleep

Your overnight HRV reading depends on the night you just had. Fragmented sleep, late alcohol and late meals all work against it. Fix the habits that wake you up first. The sleep quality guide has the full protocol.

4. Cut or Reduce Alcohol

Alcohol lowered HRV-derived recovery during sleep at every dose in the Finnish study, including low intake, and regular exercise did not protect against it. If your HRV runs low and you drink regularly, a few alcohol-free weeks is a clean test: compare your average before and after.

5. Use HRV to Guide Recovery

Use your morning trend as one recovery signal alongside how you feel: if your 7-day average drops well below its usual level, take an easier day or prioritise sleep.

What about cold exposure, sauna and humming? They are popular HRV tips. We did not find trial evidence on long-term HRV gains that met our source check, so we leave them out of the list. The cold plunge guide and the sauna longevity guide cover what the evidence does say about them.

How to Measure HRV at Home

Apple Watch calculates HRV as SDNN from background recordings taken while you are still, according to Apple's own documentation. Find it in the Health app under Heart Rate Variability.

Other wearables (for example Garmin, Oura and Whoop) report HRV in their own way, often as RMSSD. RMSSD and SDNN are different measures, and there is no fixed factor to convert one into the other. Check your device documentation.

Chest strap with an HRV app: a short morning reading taken lying down right after waking gives a consistent daily number. Short readings like this are good for tracking your own trend, not for comparing with 24-hour bands.

When to measure: at the same time each day, before caffeine or exercise. HRV moves with meals, caffeine, exercise and stress.

How to use the data: single readings are noisy. Track a 7-day or 30-day average against your own baseline. A sustained drop without a clear reason is worth noting.

Frequently Asked Questions

What is a good HRV for a man in his 40s?

On a 24-hour Holter recording, SDNN above 100 ms is classed as healthy and below 50 ms as unhealthy. HRV varies a lot between people and falls with age, and wearable readings are not the same measurement. Focus on your personal trend over time rather than a fixed threshold.

Does HRV actually predict heart attack risk?

At the population level, yes: low HRV goes with more cardiac events in people without heart disease, for example a 35% higher risk of a first cardiovascular event in the lowest SDNN group of a 2013 meta-analysis. That does not predict what will happen to one man. Use HRV alongside blood pressure, cholesterol and your doctor's assessment.

How long does it take to improve HRV?

It varies. Alcohol lowers HRV the same night, so cutting it shows up quickly. Fitness-driven change takes longer and tends to be smaller in older people. Assess progress with a 30-day average, not week to week.

My wearable shows RMSSD, not SDNN. How do I use the calculator?

The calculator's bands are for SDNN, and there is no fixed factor that turns RMSSD into SDNN. Use your RMSSD to track your own trend instead of entering it into the calculator.

Can HRV be too high?

For a healthy man, a high reading is usually a good result. A sudden, unexplained change in either direction, or an irregular pulse, is worth mentioning to your doctor.

Does stress reduction improve HRV without changing anything else?

HRV biofeedback, a form of slow-breathing training, showed small to moderate benefits for anxiety, depression and other outcomes in a 2020 meta-analysis of 58 randomized studies. Stress works through the same autonomic system HRV measures, so managing it is worth trying and tracking.

Consult your healthcare provider before starting any new exercise or supplement program. The calculator and content on this page are for educational purposes only and do not constitute medical advice or diagnosis.