How To Improve Your Heart Rate Variability - Dr Leah Lagos

Chris Williamson introduces Leah Lagos as a clinical psychologist, HRV performance coach and an author, and frames the episode around a problem most wearable owners recognise: heart rate variability is easy to watch and hard to improve. Lagos answers the historical question first, and her answer is not the one a fitness audience would expect.

Doctors, she says, were already using it before delivery, to predict the vitality of the unborn baby and whether the infant would be healthy at birth. From there it moved into clinical medicine as a marker of cardiovascular health, then into conditions far from cardiology: fibromyalgia, irritable bowel syndrome, depression, anxiety.

“what about people that aren't afflicted by a condition, but just wanted to get better?”

That question, she says, has been the last seventeen years of her research and practice. It also sets the tone for the conversation: Lagos is not selling a treatment for the sick so much as a measurement for the functional, and the distinction changes what counts as a good result.

Asked for the thirty-thousand-foot version, Lagos offers two definitions and quietly recommends one. The technical definition concerns the oscillatory variability in between each heartbeat, measured in milliseconds. The working definition, the one a user can grasp from a wrist device, is simpler: look at the peak to trough.

“when you inhale, your heart rate goes up, and when you exhale, it goes down”

This is respiratory sinus arrhythmia, and the image she reaches for is deliberately non-clinical: the variation should be as big and beautiful as possible, almost like ocean-like waves. Life does not cooperate, she adds. We get stuck, stressors arrive, and the oscillations flatten.

Williamson checks his understanding with the term autonomic flexibility, and Lagos accepts it while sharpening it. People ask whether they are stressed or not stressed; the better question is agility in handling it, meaning how long it lasts, whether you can let it go, how long that takes, and which stressors take longer than others.

She pushes further: HRV is a measure of who they are, what amplifies them, what takes away from their natural gifts. The protocol is set out in her book Heart, Breath, Mind, but the metric comes first, because someone who does not know their own range cannot tell whether an intervention helped.

Williamson then asks a question he admits he has never heard answered: what is the adaptive reason for HRV falling when we are stressed? If variability signals resilience, a stress response that reduces it looks like a design flaw. Lagos's answer is evolutionary, and hedged as a hypothesis.

“Our body immobilizes even in prehistoric days to conserve energy.”

She links the drop to the reptilian response of immobilisation, a shutdown that once conserved energy in genuine danger. The response served a function and can still serve one in certain stressful situations, but usually it does not, and it stays longer than we need.

Williamson tests this with a deliberately absurd counterexample: surely a lizard basking on a warm rock would recover more energy with high variability than low. Lagos concedes that light exposure can enhance HRV, then separates it from the stress case. Under stress the system is not optimising for recovery; it is optimising for conservation.

Her phrase for what gets conserved is autonomic bandwidth. If a listener's range runs from 42 to 75, the useful work is to find what is reducing it on a given day, whether that is staying up too late or a conflict with a good friend. Narrowing the bandwidth may keep the body safe by spending less, but a fraction of ourselves is not enough for a dynamic world.

The cost shows up as duration. We ruminate on the stressor so long that we extend it, and for most people that extension is beyond conscious control. Telling someone to let it go is a great idea, she says, but it does not tell them how; letting go is much more a physiological construct than a cognitive one.

Williamson restates the position to check it: go from the body up to the mind, rather than from the mind down, telling yourself to calm down and wondering why the instruction makes things worse. Lagos agrees, then supplies the sequencing her protocol depends on.

“But first, you have to teach the autonomic nervous system how to let go.”