HRV, RHR & Training fatigue indicators

The most important battle I face as a Coach daily is trying to help athletes make better training decisions. It’s a battle that will never be fully won and will be ongoing for the rest of my years as a Coach. This is because we are all human and that means we all make mistakes. The only goal we can try to work towards is to try to make good decisions a higher percentage of the time.

With the explosion of the technological age in endurance sports there are now more gadgets on show promising to do this and that than ever before. It’s head spinning to be honest, what’s even more frustrating is that most athletes seem to pay way more attention to what technology tells them in favour of what their body is trying to tell them. Even when what you are feeling is the most accurate indicator of what state your body is in.

It trumps technology every time.

This can then help you make one of 3 very important decisions you need to make daily:

  1. Do I need to take a rest day?
  2. Do I need to go easier and adapt the session?
  3. Train as planned  

All too often athletes ignore the very clear signs of what their body is telling them and default to option 3.


Because it’s on the plan or can only be fitted in on that day.

Day in day out I see athletes continue to flog themselves thinking they are being mentally tough. Usually because they have a high level of insecurity about missing training. What’s even more frustrating is they think they are gaining from doing this when it’s what’s holding them back.

Athletes with this mindset are usually injured more, get ill more, plateau more and wonder why with all the hard work they are putting in they seem to get very little in return. They have also taken the art of moaning about all of this to new levels.

In my experience as an athlete the three best indicators that help me make better training decisions are non-technology based. These are my mood, level of motivation & my sleeping patterns.

When I get tired, I get grumpy, I also start sleeping poorly. My sugar cravings increase and my motivation to train decreases.

When I’m in a good place and my body is responding positively to training, I usually sleep through the night for 7-8 hours. When I start getting overly tired the first thing that happens is that I start to wake up early at 4-5am I then struggle to go back to sleep.

I also feel much moodier and a little less patient with myself and others. A good indicator of this would be if I drop something on the kitchen floor (I seem to be quite clumsy in the kitchen), if in good place I can handle it well…if not I usually shout expletives loudly at myself. So much so my neighbour heard me the other day and came check to see if I was ok.

It’s the little things that become unusually trivial.

My motivation for training also starts to wane and the thought of doing it becomes a struggle. For someone that simply loves to train this is a classic sign of fatigue kicking in. There’s nothing seriously wrong, I’m just tired. If you are a triathlete re-read that last sentence, then read it a few more times for fun.

I joke, but I’m quite serious as its these little signs that tells me my body is due for some well needed recovery. I usually then take a rest day (at least one weekly) or rest period (2 days off) when these factors start to come together. Or if I’ve just come off the back of a very big block of training, I’ll take a recovery week where I will reduce training by about 50%.

Without question the biggest improvements in performance I’ve ever seen as an athlete have been when I have followed a 2 week build with a 1-week recovery factored in. By the 4th week I can swim, bike and run through brick walls.

Recovery works.

It takes a level of athletic maturity, intelligence and confidence to do this, but it’s taken me many years to get better at it. The battle will be ongoing, I can just control my inner Chimp a lot better these days because I know how good I feel when I return to training after a period of well-timed rest.

Some of the metrics I do use to help me with understanding my body is monitoring heart rate variability (HRV) and rest heart rate (RHR) daily. The reason I believe these have value is because they are a physiological response to what state your body is currently in. When you monitor these values over an extended period they present information, patterns and trends that can be a good tool to help you make better training decisions.

And note I said ‘tool’ they are not fully exclusive in favour of how you feel on that day.

My RHR is typically around 45-50bpms when fresh and well rested. Usually after a recovery week or two days off from training.

When I’m in a training block and absorbing training well my RHR is 50-58 bpms

When I starting to stretch too far and really fatigue it can be anything from 60-70 bpms

I had bad flu over Christmas and for a 14-day period my RHR was 8085  I have never felt more ill, and the response in both HR and HRV was immediate.

HRV is the physiological phenomenon of variation in the time interval between heart beats. It’s measured in the beat-to-beat interval which depending on your level of fatigue or freshness can vary significantly. It’s not constant as many presume. It’s a good measure of the stress your body and nervous system are under. These ‘stressors’ can come in many forms; work related, lack of sleep, over training, a late-night drinking alcohol, work, travel, relationship related, the list goes on.

When HRV is low that’s a sign your body is under stress, when it’s higher your body is in a better place. Consistent stable trending of values over time is what we look for.

When I’m tired or my body is under stress my HRV is roughly 6.3 – 7

When I’m in a good place and I’m absorbing training well it’s 7.2 – 8.0

When I got flu recently my HRV dropped to 5.7 – 6.0. It then took nearly 4 weeks for it to get back to normalised values and this correlated directly to the slow progress I felt I was making whilst trying to recover.

These numbers are specific to me and only me. Yours might have a very different range and have been worked out over an extended period of months. You must collect the data first over time to make sense of it.

Depending on what you are using to measure HRV the metrics they show can vary from one piece of technologically to the other. There are rings, watches and apps available to do this. I use the HRV4 Training app as it measures both RHR & HRV. It does this by sending a light beam from the camera at the back of my phone into my finger each morning on waking for 60 seconds. It then records, tracks and monitors patterns over time. It also colour codes the reading and makes suggestions based on this data.

Is it 100% accurate?

No piece of technology ever is so don’t solely rely on it. But it’s a very useful tool amongst many others that can help you understand your body better and its response to stress which can then help you make better training decisions.

If you can learn to listen to your body and then manipulate your training in the right way, you will be well on your way to finding that magic bullet that helps you training more affectively.

And the result of all of this?

You get fitter faster and it’s such a much more rewarding experience. You’ll also kick yourself for being so silly for so long in ignoring these signs when the results really do start to happen.

For more info see:

HRV4Training Website

HRV for triathletes with Dr Dan Plews