A subgroup of the fitness industry that saw a massive spike in growth a few years back was the fitness tracking and wearable sector. One of the first was the Fitbit, to be later outdone by the Apple watch. I like to spot a trend by observing how much space it takes on the trade floor at the International Health and Racquet Sportsclub Association or IHRSA annual conference, (which I try to attend every year). I can remember walking the floor in 2014, prior to opening my studio, on the search for heart rate monitors. We feature 2 HIIT workouts at the studio, and I wanted to see which device would be a good fit for my needs. In 2014, there were 4 companies on display- Polar, Garmin, My Zone, and Fitbit. A couple of years later, there would over 20. All the craze was in tracking your heart rate during your workout and activity throughout the day. All good metrics. The research would soon tell us the most important number we should be watching is a number that’s determined when we sleep, heart rate variability (HRV).
Dr. Marcelo Campos, MD, a contributing writer for the Harvard Health Publishing Journal, explains HRV as “a measure of the variation in time between each heartbeat”. This variation is controlled by a primitive part of the nervous system called the autonomic nervous system (ANS). It helps regulate our heart rate, blood pressure, breathing, and digestion. The ANS is broken into 2 subgroups, the sympathetic and the parasympathetic nervous system. The sympathetic nervous system is more commonly known as our fight or flight mechanism and the parasympathetic nervous system is our relaxation and digest response. This can explain why your digestion is upset from a meal when you are stressed out.
I came across HRV a few years ago when I read how strength coaches for professional athletes were using this metric to determine the intensity of the workout for their athletes. No coach wants to get a reputation for injuring athletes during practices from being overworked. I started to observe my own HRV a couple of years ago when I started monitoring my sleep. What I came to see gave me concern.
There’s a dance between the parasympathetic and sympathetic nervous systems. You should be able to quickly go between the two. A great example of this is the lion in the wild. He lies and sleeps most of the day, to awake and make a kill in a matter of minutes for a meal. It’s been documented how they can explode and pounce on their prey to then fall back asleep for up to 24 hours as they digest their meal. Your goal is to hover between these two.
A sign that your body is not recovered from the prior day’s activities is having a low HRV. Here is a picture of my HRV monitored during my sleep from a couple days ago.
You can see as I went into a deeper sleep the spikes within the graph become larger. This is a sign my body was phasing into a recovered state from the prior day. When I initially started tracking this, I would consistently be more flatlined. I was able to improve this by improving the quantity and quality of my sleep along with adjusting the intensity of my workouts and activity based upon this number. I collect my data using the Oura sleep ring.
I’m not suggesting you run out and purchase a wearable, but if you were in the market, I would make sure you can see this number. Counting steps is OK, but I think you will get more value out of the HRV number. I’ll see you at the studio.