CJ Swaby is a strength and performance coach, athlete, nutritional therapist, educator and writer. He operates out of the Villain Barbell Club
How do you know how hard to train on any given day? One option is to stick to the plan: however rough you’re feeling, however badly you slept, just suck it up and get it done. Autoregulation is another: get a sense for how you feel as you’re warming up, then up or downshift the volume and intensity accordingly. Both approaches work, but they’re less than ideal: the first doesn’t give you much room to manoeuvre, and the second isn’t very precise.
Tracking your Heart Rate Variability (HRV) is the third way: a non-invasive way to measure your readiness and fatigue, enabling your to harness your body’s natural fight-or-flight and rest- and-digest responses, for optimal health and performance. It can help with body composition and performance, manage the risk of injury or – if you compete – erratic performances, and help you regulate stress and better manage your nutrition strategy. HRV is an extremely well researched area of study. So how does it work?
First, the science. You’re probably already aware that almost every biological process in your body is automatically controlled by your Automatic Nervous System, or ANS, and that your ANS has two different branches:
The Sympathetic Nervous System (Fight or Flight)
This branch of the ANS increases blood pressure, increases heart rate, dilates pupils, and increases activity of the adrenal glands. These are all the things that are preparing you to fight or run. There is no value judgement attached to this. You want your sympathetic side to be strong when you need to perform.
The Parasympathetic Nervous System (Rest & Digest)
This plays a major role in digestion, sexual arousal and muscle repair, lowers blood pressure and lowers heart rate. Clearly you want to spend most of your time leaning towards the parasympathetic side, you also need to find the optimal balance for you specifically.
So, to reiterate: the sympathetic nervous branch increases heart rate, while the parasympathetic branch decreases heart rate. These tiny changes in heart rate are the main cause of Heart Rate Variability, and these are the changes that we look to measure.
True HRV calculations require accurate measurement of the time in milliseconds between each heartbeat, called an R-R interval or sometimes an Inter-Beat Intervals (IBI’s), and measured in milliseconds.
HRV looks at the small fluctuations of the heart that happens because of changes both inside and outside our body. The readings of your HRV can tell us how ready we are to handle things like intense exercise, or other stressful situations. We can gauge when to push it, when to ease off and if we need to adjust our nutrition for better recovery.
Both branches of the ANS are needed – the problem occurs when either is stimulated chronically. Over stimulation of the sympathetic branch, for instance, can lead to erratic sleep patterns, increased fat tissue, hormonal disruptions, decreased performance and muted sex drive via several mechanisms.
Biological factors can play an important in role in sympathetic/parasympathetic balance – sleep, nutrition, physical training, environmental pathogens and medication can all have an effect. But psychological factors are also important: family and social relationships, mental health, grief or worries about job security can have huge effects.
Tracking your HRV can give you an objective measure on how overall these are affecting your health.
How to track HRV
I use a simple, inexpensive combination of a Polar H7 Heart rate monitor and EliteHRV app downloaded onto my phone to track my HRV.
Morning readiness is the most important reading. At any given time, many things can affect your heart rate variability. This includes physical and emotional experiences, internal processes like circadian rhythm and hormonal fluctuations.By taking it first thing in the morning , you can eliminate many of the variables that impact your HRV. Take a reading for 2 – 5 minutes first thing in the morning, and it will help you to identify your unique stress and recovery patterns. The key word here is ‘patterns’ – taken in isolation, an individual reading gives limited information – use the first week of readings as a kind of baseline.
Finding Your Balance: What The Readings Mean
Here is a snapshot of my weekly reading as well as a single day, using the EliteHRV app. I could have given you a weekly snapshot where everything was perfect, but I wanted to give you an honest insight to how I use HRV to improve my performance and recovery. But first, let’s look at what these colours mean.
As you can see in the picture, I hit a red on Saturday. This indicates a deeper level of recovery activity within my body, in response to accumulated stress. According to this reading my body was reaching an overtrained state. On the Friday I did a weight training session that was at a high intensity (in the technical sense: a high percentage of my 1RM) and was high volume, combine that with going out friday night and not getting to bed until around 2 am, and my nutrition not being on point, and there you have it, all up in the RED ZONE.
On red days, it’s highly recommended to prioritise rest. So I tweaked my nutrition ensuring it was nutrient rich and anti-inflammatory. Plus I allowed myself to indulge in a power nap in the park and my active recovery was going for a walk.
Generally speaking, on a green day you can test your limits, and push yourself that little bit further. But make sure that you get adequate recovery in the form of sleep, and watch your nutrition, or chances are that you will end up in the yellow zone for a few days.
On yellow days it’s a good idea to reduce your exercise load, whether that means a reduction in intensity, volume or time. However the suggested tactic is to maintain intensity but decrease volume.
Now, there are times where you or your coach will want to push your training on a yellow day to achieve a specific adaptation in your training. If this is a case, it’s usually followed by two days or so of reduced intensity and volume. It’s doubly important to keep an eye on your HRV during this period. Only do this if you/your coach know what you are doing. If you are unsure, it’s best to just ease back on the training.
That’s the simplified version, but it’s not always that easy. For instance, let’s say that a client hit a 3 sympathetic (red score) – does this automatically mean they do not train as my sympathetic branch is overstimulated? Not necessarily.
Maybe prior to the red score my client had seen straight 10 scores all week – nutrition was on point all week, recovery strategies in place – then, last night the neighbours had a party, and this stressor (emotional and lack of sleep) dropped the score.
Their program calls for them to train at 80% 1RM. The client is pent up and stressed and needs a physical release to channel the stress. In this case, the sympathetic nervous system hasn’t been overreaching all week, so training can go ahead at same intensity at a reduced volume. The correct approach is to see how they respond and ensure that adequate stress management techniques and recovery nutrition are in place post training. Now if the client had been red sympathetic during the week/erratically then would need to look at alternative training and what aspect needs to be addressed to restore balance – nutrition, physical factors or emotional well-being.
The ideal situation, in fact, is to have a change in your HRV every few days, caused by acute stressors, followed by adequate recovery that allows improved performance.
While this is a very simplified overview, it serves to illustrate the importance of tracking your HRV. If you are a busy highly stressed professional, who gets less than seven hours sleep, has kids, wants to workout 3-5 times a week, something’s going to give: but this can also be true for high-level athletes who wonder why their times are erratic, improvements in performance drop, sex drive plummets and they’re plagued with frequent colds and illness. It’s a question of taking everything into account, but sometimes it’s hard to be honest with yourself: and having hard numbers can help. For most people and the average athlete tracking the foundation numbers and highlighting patterns in their HRV readings over time can not only enhance the effectiveness of a training program but highlight improvements (or regressions) too.
Remember: HRV is a tool to help better inform your training not a simplistic ‘Should I train or not?’ indicator. Used correctly, it’s very powerful.
Don’t just track your performance. Improve it.