How I Use Heart Rate Variability In My Marathon Training

I’m in the process of preparing to run my third marathon. My first marathon took the traditional path of a 16 week program, with a weekly long run that built to about 36km with a four-week cycle where three weeks would be about building endurance and speed with a week of reducing the training load for recovery.

My second marathon suffered from a badly interrupted preparation because of injury and travel. But as I prepare for marathon number three, I’m looking at how I can use data more intelligently. And one of the metrics I’m looking at is Heart Rate Variability.

Heart Rate Variability (HRV) is a measure of the variance in the interval between heart beats. If your heart rate is less variable, your HRV, measured in milliseconds, is a higher value. The higher your HRV, the more rested and better able to train hard you are.

I train with an Apple Watch but many wearable devices can measure your HRV while you sleep as well as a bunch of other handy metrics. The trouble with today’s wearable tech is that it’s really hard to bring the data together, with other information to answer two key questions; what’s the difference between a good day and a bad day and how can I have more good days?

Here’s an example. Three of my recent runs played out like this:

  1. 14km in 1:27 at an average pace of 6:15
  2. 15km in 1:43 at an average pace of 6:52
  3. 16km in 1:41 at an average pace of 6:18

These runs all started at about 7:00AM and were on the same route with the extra distance added with a lap around the park I finish at.

My HRV for those runs was:

  1. 56ms
  2. 34ms
  3. 71ms

When I look at that data, it’s obvious that the day where my HRV was at its worst correlated with my slowest run. The first and third runs in my sample were run in quite different conditions. Even though I was a little slower in Run 3, it was in poor weather. And, the faster run, as well as being shorter was after a rest week.

But it’s clear that HRV is an indicator of when I’ll have better days. So, how can I hack my HRV?

What drives HRV?

In order to understand how to hack your HRV, it’s important to understand how it works.

There are two sides to your nervous system; the autonomic nervous system that controls critical functions like breathing, digestion, heart rate, blood pressure, and organ control. Then there’s the voluntary nervous system. It’s what you use to walk, talk, run, chew and other actions you decide to take.

Your autonomic nervous system works to maintain a continuous optimal operating state in your body. It’s a balance between the sympathetic system that increases your performance in response to a stressor and the parasympathetic system that gets things under control and back to the normal state after you’ve been stressed and the threat has gone.

When you’re able to relax better, your body rests better. And when you rest better, your HRV is higher.

So, the key to improving your HRV is to let your body’s autonomic system keep things in check by reducing stress and letting the parasympathetic system keep you in a more relaxed state.

Your HRV is a measure of how relaxed and well-rested you are.

How to hack your HRV?

In order to hack your HRV there are some things you can do.

  1. Regular bed and wake times: Getting to bed at the same time each night and waking up at the same time is one tool you can use.
  2. Get enough sleep: We all need different amounts of sleep. When you set your regular sleep and wake times make sure it’s enough sleep. It’s why, in our regular “How I Succeeded” stories each week, we ask successful company founders and executives about their sleep routine.
  3. Avoid stimulants: Sure, you might like that cup of coffee but perhaps lay off the coffee, or other caffeinated beverages – particularly before bed time.
  4. Stay hydrated: Your body needs water. The old “eight glasses a day” regime isn’t the key. But having a water bottle or jug near by and sipping on it when you’re thirsty helps. Better yet, sipping through the day will prevent feeling thirsty, which is usually a sign you’re already a little dehydrated.
  5. Don’t over-train: If your HRV is low, take it easy. For example, my HRV has been in the low 50s this week so I’ve laid off the hard training and reduced to a more moderate intensity. Today, instead of a hard treadmill session, I chose a less stressful stationery bike and elliptical session.
  6. Alcohol consumption: Reducing alcohol intake is reported to have a positive impact on HRV. If you’re in the habit of having a glass or two of your preferred drink with dinner maybe try to restrict that to once or twice a week, instead of each day.


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