Leah Lagos Psy.D, B.C.B. is a licensed clinical psychologist who specialises in health and performance psychology and is known for her pioneering work in Heart Rate Variability (HRV) training. Dr. Lagos treats a broad range of disorders and performance challenges. Her expertise includes strategies to reduce anxiety, boost resilience to adversity, and amplify performance. She offers a framework to help individuals clarify their needs, achieve their goals and increase their effectiveness. (Our conversation has been condensed and edited for clarity.)

What led you to study heart rate variability (HRV) biofeedback as a way to build resilience against life’s stressors?

During graduate school, clinical psychology was my doctoral degree and sports psychology was my specialty. I attended a meeting with Paul Lehrer, who’s considered one of the principal founders of heart rate variability (HRV) biofeedback. He was speaking about his work to treat autonomic conditions, like high blood pressure, diabetes, and insomnia. I asked if the method could help people that aren’t necessarily afflicted, but are trying to manage their stress and perform better in sports, business, and life. Little did I know that would lead to the next 15 years of my research and practice. 

When our fight or flight state kicks in at the wrong time, or stays on too long, we often can’t perform at our true potential. HRV biofeedback helps you to gain precise control over your autonomic nervous system. There’s something called the neuro visceral integration theory, that shows how the heart and the mind are inextricably linked via the vagus nerve. When you gain control over your heart’s reactivity and how it responds to stress, you also begin to impact and have control over how your mind works. 

What exactly happens during your ten week HRV programs?

During the ten week program, we’re helping performers cultivate the ability to fine tune their nervous system to have more control over how their body manages, adapts, responds to, and recovers from, stress. Each week, clients learn specific strategies to let go of stress from their body and enhance recovery.  First, we identify a specific rate of breathing that maximizes the individual’s heart rate oscillations and strengthens what’s called the baroreflex. By strengthening the baroreflex, individuals tighten their control over heart rate and blood pressure. With greater control over how the body reacts and recovers to stress, individuals gain greater control over their thoughts, feelings, and behaviors.  

In the first few weeks, you’re more frequently in a sympathetic state. The breathing process occurs twenty minutes twice a day at the specific rate that amplifies heart rhythms, helping to balance the autonomic nervous system. Around week four, you have the states in balance, but you increasingly strengthen the parasympathetic, so it’s stronger than the sympathetic system. The parasympathetic state becomes the dominant influence of the system, helping you to increase your ability to flexibly respond to stress under pressure. 

What’s amazing is by week four, people experience the ability to let go, and it’s happening naturally. When you have a moment of stress, the parasympathetic kicks in and brings you back down without any conscious activation. The recovery wasn’t always fast, it would happen in time, depending on the external circumstances and the internal wiring. But the ability to let go happens unconsciously. 

From week five to ten, I teach the process to be able to let go on demand. You learn how to reduce pre-performance anxiety, let go during a specific stressor, and recover more quickly between stressors or challenges.

Is the aim for people to be able to develop an awareness of when they’re in the stressed state and know how to respond?

There are two benefits. One is that at baseline, it strengthens the parasympathetic nervous system. That allows an automatic reflex to kick in during moments of stress to help mitigate reactivity. If there’s a specific stressor that makes your heart race and your mind spin, that reactivity will be less just on its own because you’re more frequently  in a parasympathetic state at baseline. The second effect is that during moments of stress, you can let go and recover faster. Using breathing in the moment in a very efficient and effective way to prepare, react and recover to specific stressors. 

You liken the heart to a muscle that needs to be trained in the same way that we train other parts of our body. Could you explain this?

Exactly. Think of a professional tennis player preparing for the US Open. They practice their serve maybe 10,000 times. Why? So when they go to the US Open, they don’t have to think about it. It just happens, it’s natural. It’s the same thing with the heart. Twenty minutes twice a day is like doing a repeated tennis serve. In the moment of performance, your heart knows exactly what to do. And you don’t have to think about it.

Where did you get to this number of twenty minutes twice a day for ten weeks?

I have to give credit to Drs. Evgeny and Bronya Vaschillo who discovered that each person has a rate of breathing, known as resonance frequency, that elicits flow throughout the body and mind. Resonant frequency breathing is not just slowed breathing, but breathing at a specific rate for each individual. It’s between approximately 4.5 and 6.5 breaths per minute, and you need to identify which rate works for each individual, with either an iphone app that detects resonance frequency or a clinician who can identify your resonance frequency.

The Vaschillos, who initially implemented this process with Russian cosmonauts, found that  breathing at resonance frequency for twenty minutes twice a day for ten weeks led to baroreflex gain (e.g. tighter control over the autonomic nervous system). People want to do five minutes a day for thirty weeks, or twenty minutes a day for five weeks. I have tested all of it, but it doesn’t reliably produce greater control over the autonomic nervous system. For whatever reason, the twenty minutes twice a day stimulates the autonomic nervous system in such a way that you’re creating a reflex that kicks in on it’s own during moments of stress to help you reset and return to your baseline self.

It’s incredible to be able to see such drastic results after just 4 weeks! 

It is so incredible and that’s the piece people need to understand. This is an investment in themselves, but it is life changing. When you sit back and think about breathing 20 minutes twice a day for 10 weeks, that’s not that big of a commitment. After the 10 weeks you can reduce it, you can do it once a day for 20 minutes, four or five days a week. It doesn’t have to be the same. But it’s really a nominal investment in oneself to be able to have such control over how your autonomic nervous system functions, when it reacts and when it recovers.

Everyone knows we should exercise five times a week for forty-five minutes a day. Why do you think we aren’t viewing exercising our mind or heart in the same way? 

I love that question. Because that’s just it, we have to change the paradigm. People have been experimenting with exercising the mind, cognitive behavioural techniques, some visualisation, but people haven’t really understood how to exercise the autonomic nervous system in a way that strengthens it and gives us control. It’s such a critical piece for peak performance. You can take someone who is incredibly talented, exceptionally gifted at mental and/or physical tasks, but if they can’t control their nerves, it derails all of their training, practice and natural abilities. You need to have control over your autonomic nervous system to be able to consistently perform at your peak.  

Being able to see the results is key, that’s when you can really start to build changes in your behaviour. What exactly is the link between HRV and stress?

HRV is an index of how adaptable the autonomic nervous system is. There are two measurements; the clinical measurement of heart rate variability is simply the peak to trough in heart oscillations.  When you inhale, your heart rate goes up, and when you exhale, it goes down. You want these to be big, beautiful changes, but under stress, they’re small. Olympians may have this change from a heartbeat of 45 to 115, and back to 45. Someone under stress may have these heart rate oscillations of 60 to 65. By being able to amplify the amplitude of these changes, we are able to increase the dexterity or flexibility of the body managing stress. It’s not just relaxation, it allows you to amp up faster if you need to, and let go faster. You have more precision. 

What are the other variables apart from stress that cause HRV to vary? 

It’s really important for HRV training to get a sense of someone’s range. For example, if you monitor your HRV with an Oura ring you might have a range of 50 to 65. On certain nights your HRV is around 52, and other nights around 65. My job is to understand what’s happening to create this range. Alcohol can, for some people, just decimate HRV. If the reason is alcohol, you often see a big drop in HRV on the night someone drinks a lot of alcohol. 

We are all human beings connected by the heart, and you sometimes see no behavioural reason for a drop in HRV; it’s stress. I’ve seen this a lot with CEOs that just don’t take breaks. They just work, work, work, and their mind operates like a supersonic jet plane going through new galaxies, minute by minute, never slowing down. The mind doesn’t turn off at night, and although they’re sleeping through the night, their REM deep sleep is low and they’re not getting really deep sleep, because they don’t have space in the day for their mind to turn off. 

If HRV is chronically low, it can be indicative of a health condition, or a few other things, such as after eating, when someone’s body doesn’t like the food. Like a smooth, slight allergy, you can see a big drop in HRV.  It’s fascinating, you really learn about the inner being of somebody outside of just their brain.

It’s amazing how much you can essentially live your life to your full potential through monitoring your heart rate variability. What are some key applications?

It’s really astounding, and I really think it’s something all teams should be doing with their members. You just collectively amplify performance so much when you can help members of the same organization increase their nocturnal HRV and reduce their daytime drops in HRV.  When HRV is in lower range at baseline or drops frequently during the day, that person should take a step back and engage in practices to enhance recovery.  HRV is considered an index of autonomic flexibility  as well as blood flow to the brain. So if your HRV dropped, you may not have the same level of adaptability or cognitive agility at that moment. This doesn’t mean you have to stop everything, but you have to be a little more careful.  It has so many different implications. 

The other application is teaching children. We’re teaching kids to read, but we’re not teaching them how to operate their bodies. I think it could be life changing. My vision is to have children in conflict learning to breathe together and seeing their heart rhythm synchronise. There are physiological connections that can transcend psychological barriers. I’ve done it with couples, so why not use it to bring all people together? 


  • Reeva Misra


    Walking on Earth

    Reeva is Founder and CEO of Walking on Earth, a digital wellness platform. She is a certified Jivamukti Yoga Teacher in London and Founder of Vahani Scholarship. She holds a BA in Experimental Psychology from Oxford University and a MA from the Jackson Institute for Global Affairs at Yale University.