Heart Rate Variability (HRV) probably isn't a new concept for many athletes these days, but it’s something that I’d only taken a passing interest in until recently.
The reason for my apathy was that I had (wrongly) assumed it was primarily something used to monitor the effect of heavy training loads on recovery for athletes.
Since I now only train a few hours per week and often without serious structure or intent, I didn't think it was a metric that would be worth me tracking nowadays.
But, after publishing a blog about how I’d suffered burnout and illness a number of times in recent years – largely due to my work-travel schedule (and other factors such as having two small children who love getting up in the middle of the night!) - Simon Wegerif, founder of HRV monitoring company ithlete, got in touch.
Simon suggested I try looking at my HRV as part of a plan to try to avoid similar burnout episodes happening again. Here's what I discovered...
Why collect HRV data?
Keen to try anything to improve my lifestyle, I agreed to give Simon’s suggestion a try and started collecting HRV data using the ithlete system in June 2019.
This involves clipping a small device onto my index finger that then plugs into my iPhone lightning port first thing every morning. I then take deep breaths for 1 minute while the software reads my pulse.
After some experimentation I found that leaving the monitoring device nestled in the pot of capsules for our coffee machine was the most reliable way of making sure I remembered to do it every day - reaching for an early morning coffee is the one rock-solid routine in my life!
Since starting, I’ve tracked the numbers pretty consistently and gradually started to get to grips with the utility of the data and how it can help keep me functioning at my best. It’s been an interesting journey and it’s been extremely helpful in teaching me about managing travel, fatigue and stress.
What follows is a high-level overview of HRV and the process I’ve followed to incorporate it into my day-to-day lifestyle.
What is HRV?
Heart Rate Variability may sound a lot like ‘Heart Rate’ (HR), but it’s fundamentally different in that HR simply measures the average number of heart beats every minute, whereas HRV tracks the small but significant differences in intervals between individual heart beats.
For example, you may have a HR of 60 bpm but that doesn’t mean 1 beat on each second exactly. There will be some beats marginally more or less often than 1 second apart over a period of time.
HRV is interesting because it’s essentially a sensitive surrogate marker for the status of your nervous system and whether it’s predominantly in Sympathetic (‘fight or flight’), Parasympathetic (‘rest and digest’) mode, or - more than likely - balanced somewhere on the continuum between the two.
In this way, it essentially correlates with total body health status which is why it’s of interest to anyone seeking to pursue optimum performance.
In very basic terms, the higher your HRV (i.e. the more the interval between individual heart beats varies) the more the parasympathetic system is dominating and so the more relaxed and recovered you are, in theory.
In contrast, when HRV is low (so heartbeats are more regimented) Sympathetic nervous activity is dominant and you’re highly likely to be in more of an activated or stressed mode. There are exceptions to this rule but it’s a fair generalisation of the most important principle involved with HRV.
For tracking purposes, HRV is almost always combined with resting HR measurements because the relationship between these two factors can help to interpret what’s going on with the body and mind more accurately than just looking at either in isolation.
If HRV is high and resting heart rate is low (compared to your own normal baseline – this is very important as there are no universally ‘good’ or ‘bad’ HRV readings per se) it’s generally a sign you are in a well-balanced, low-stress state, and so you’re coping with training and anything else life might be throwing at you.
By contrast, a low HRV score and high HR are signs of stress or a lack of recovery. A de-coupling of this HRV/HR relationship can also be notable for a number of reasons and so most good HRV monitoring software packages (such as ithlete Pro) show you a single number that combines HRV and HR into one score and then codes it as Green, Amber or Red for ease of interpretation.
Analysing my HRV data
When I first started collecting HRV data, Simon recommended that I take the readings first thing in the morning to be as rested as possible (ideally at about the same time of day) and to take the readings standing up. This is a common recommendation for fitter people as it helps make the reading more meaningful than taking it lying down (as is often the case for monitoring it clinically in hospitals).
He also made it clear that I needed to take it for quite a few days or even weeks before attempting to draw too many conclusions from it. This is because an individual’s HRV score is extremely, well, individual.
It’s critical to start to understand what your own baseline numbers look like because deviations from baseline (up and down) are more important than absolute numbers when it comes to HRV.
I noticed after a while that my HRV seemed to settle in at around 66-70 when I was at home for a while and when life-stress was under control (or as under control as it ever is with a growing business and young family!) and this seems to be a relatively normal baseline for me.
Simon had suggested that it was a good idea to try to identify what the key ‘life-stresses’ I tended to experience were and to look at ways in which managing or manipulating them could influence my readings.
For athletes, very hard training load and specific big training days often exert a strong influence on HRV, whereas I identified periods of long-haul travel (particularly across multiple time zones), lack of sleep, alcohol consumption and work stress as the key things that tend to mess with my 'mojo'.
As an example; during the monitoring period I’ve seen a strong trend towards HRV taking a rapid decrease from baseline on the first day or two when I undertake air travel.
This snippet of my daily graph (below) clearly shows what happened when I travelled for nearly 24 hours non-stop to Reno, Nevada, as part of a trip that included recording a podcast with the guys at Trainer Road.
The next example is from a shorter trip to Monaco to visit Eugene Laverty when our flight was delayed, we missed picking up our rental car, and had to sleep 3 people in a small hotel bedroom, before getting up early to do a video shoot.
Sometimes stressful situations outside of your control do happen, so I now make sure I do as much as I can to reduce stress by:
- Booking flights from smaller regional airports (often those closer to home) to make that part of the journey easier
- Flying at the most sensible rather than the cheapest time of day when the budget allows
- Cramming less flying into trips and often staying 2 nights in the same hotel room where possible
- Staying hydrated when flying because dehydration can play havoc with HRV due to the reduced blood volume it causes
- Avoiding alcohol when travelling because it messes with sleep patterns and recovery
- Napping more on planes. I used to work a lot on flights as they can be a good time for focused writing, but I try to catch some shut-eye as well to avoid being up for 20+ hours at a stretch
- Managing my schedule to have meetings at times when I know my body clock will be in ‘awake’ rather than ‘sleep’ mode when I first get into a new country
One other period of time I found really interesting was in the immediate build-up to the OTILLO Swimrun World Championships that I raced with JP in September 2019. I didn’t prepare badly for that race and was feeling confident of a good showing, but my HRV readings literally nose-dived in the days before the event. This was mildly concerning to me as I wondered if it was a sign I was getting ill.
But, Simon explained that it was highly likely to have been because I was subconsciously getting ready for the task ahead so my Sympathetic (‘fight or flight’) system was ramping itself up in readiness.
Interestingly, my HRV rebounded back closer to baseline on the actual day of the race once I’d got all of the annoying pre-race admin done and was feeling ready to go.
What I've learned from my HRV data
Having now undertaken a good few months of HRV analysis, I've found myself taking more interest in the relationship between all manner of lifestyle factors and what the data is telling me.
At first, I was definitely looking through the microscope too much and seeking to find a single definitive trend in HRV and my health/performance, and got a bit frustrated when seeing low readings didn’t immediately correlate with getting a cold or having a poor training session.
On the flip-side, I was vexed when a series of higher readings didn't coincide with feeling fantastic and performing at the top of my game.
But, I’ve begun to see some of the subtleties involved with using and interpreting HRV data and some solid global trends have emerged.
Specifically, I seem to get more stable and higher scores when I manage to get a solid period of time at home, with regular sleep patterns and a sensible balance between working hours, training and family life; while there are a few triggers that seem to send my readings in the wrong direction.
For example, I’ve continued to see a dip in readings when travelling, but this has stimulated a lot of thinking and positive steps to mitigate the negative effects as much as possible.
It’s also prompted me to try to take better care of myself on a day-to-day basis (i.e. in terms of workload, diet, sleep, alcohol consumption and training load) and to cut myself some slack when I start to see signs of HRV heading in the wrong direction for an extended period because, rather than just having a general sense that I’d be better off doing this, there’s a tangible outcome I can see daily if I don’t.
Giving HRV monitoring a try is something I’d certainly recommend to anyone leading an active, busy or stressful life. You don’t have to be training and competing at a high level to get something from it.
It’s important to remember that it requires dedication and patience over a period of time to really get to grips with - even after about 9 months, I’m only beginning to feel like I’m getting a lot out of the process. I’ll be continuing to monitor it going forward to see what else I can learn in the future.
The team at ithlete have kindly set up a discount code for PH readers to get 20% off any sensor on their website. Simply head over to myithlete.com and enter the code phn20 at the checkout to get 20% off your purchase.
There are a lot of great resources available online for anyone interested in learning more about HRV and I’ve compiled a very short list here if you want to do some further investigation: