Pretty much everyone has been told to measure their resting heart rate in the morning to see if they are “recovered”. Not bad advice per se but we are now learning that it is not exactly a very telling measure. As athletes or high performing individuals we strive to balance our training and work load with rest and recovery. We all want to reduce stress as well but how do we measure that?
Enter Heart Rate Variability (HRV) which is a measure of the intervals between heart beats. Let’s say your heart rate is 60 beats per minute. You would assume that means there is 1 second between beats. It is now understood that is not necessarily the case. In a healthy balanced nervous system the time between beats would look like: 0.94; 1.00; 0.97; 0.88, etc. The time between beats should vary a lot. Less variability indicates an imbalance between your sympathetic (fight or flight) and parasympathetic (rest and recovery) nervous systems.
I have been tracking my HRV for about 6 weeks now. What I am seeing has been pretty eye opening. I was always taught that if your resting HR is more than 6 beats higher than normal then you should take it easy that day (or off). While that may be true that method for me means I seldom would take a day off if that was the only measure I used. HRV on the other hand gives me a more detailed look at how my central nervous system is reacting to my training. For example I did a very heavy dead-lift day followed by a very intense interval session on the bike. The next morning my resting HR was normal and my HRV was down slightly but not enough to change my plans that day. I felt really good that day and did a nice endurance ride where my legs felt great and my energy was good. The next day my resting HR was still the same but my HRV went from 81 to 50 indicating I should take it easy that day. I still felt good but my legs felt heavy. I ended up skipping the threshold training I planned that day and doing some very light Turkish Get Ups and 30 minutes Zone 1 on the trainer where my legs felt very heavy and blocked. Later that evening I was fighting to stay awake at 8pm with a bit of a scratchy throat. I took some grapeseed extract and went to bed early and woke up feeling fine the next day. HRV was back up and resting HR was up slightly. Had I just looked at my resting HR that day I am sure I would have ended up sick as a result.
HRV is super easy to measure. All you need is a Bluetooth enabled HR strap and an iPhone app. My Garmin HR strap isn’t Bluetooth but my Suunto is. I have tried a few free apps with Elite HRV being the best. I was looking for more data so I ended up buying the Sweetbeat app for $9.99 and it has been great. All you do is take a 3 minute reading every morning and the app gives you a recommendation to train as normal, take it easy, or take the day off completely. Pretty simple. It is also a great feedback tool to monitor your stress levels. You can actually change your HRV in real time with simple breathing exercises. I have been practicing the Wim Hof Method for some time now (review to come) and this app is great for giving me measurable feedback of those methods.