How to Improve Your HRV: What Actually Moves the Number

A meta-analysis of 16 randomized controlled trials covering 623 healthy adults found exercise training improved RMSSD with a standardized mean difference of 0.84, the largest effect of any HRV parameter measured. Heart rate variability responds to training. It also responds to a single glass of wine, which is why the number is more useful as a trend than as a score.

What raises HRV over weeks?

Aerobic training has the strongest evidence. The 2024 meta-analysis in Cureus found exercise training improved SDNN (SMD 0.58), RMSSD (SMD 0.84) and high-frequency power (SMD 0.89) compared with controls, with effects moderated by sex, age and exercise type. A separate meta-analysis in sedentary adults found a smaller but consistent RMSSD increase (SMD 0.57), and a 2025 analysis in people with metabolic syndrome found resistance training produced less consistent HRV change than aerobic or combined training.

Slow-paced breathing is the other intervention with pooled evidence. A meta-analysis of 31 studies covering 1,133 people found slow breathing produced a moderate increase in RMSSD and SDNN. The effect is largely acute, which makes it useful for the measurement window rather than for the underlying physiology.

What suppresses HRV overnight?

Alcohol, more than most people expect. A 2026 analysis in PLOS Digital Health compared 20,968 adults against their own alcohol-free nights. Drinking one more than personal average was associated with overnight HRV falling 3.8 ms in women and 3.3 ms in men, alongside resting heart rate rising 2.8 and 2.4 bpm. An inverse age gradient meant the disruption was larger in adults in their 20s than in older age groups, and drinking earlier in the day, sleeping longer afterward and training lighter the next day each reduced it.

Age is the slower input. A landmark cohort study of 24-hour time-domain HRV across nine decades of life, published in JACC in 1998, established the pattern that has anchored the field since: variability declines steadily from early adulthood onward, well before any disease is present. The spread at any single age is wide enough that comparing your number to someone else’s tells you almost nothing.

That is the core point about HRV. The absolute value is dominated by age, sex, measurement method and individual anatomy. The trend against your own baseline, tracked over time rather than checked once, is the part that carries information.

The bottom line

• Exercise training improved RMSSD with a pooled effect size of 0.84 across 16 RCTs and 623 adults
• One extra drink was associated with overnight HRV falling 3.3 to 3.8 ms in a study of 20,968 people
• HRV declines with age across essentially the whole adult lifespan, so cross-person comparison is close to meaningless