A simple tool to begin using HRV to optimize your training

Alan Couzens, MS (Sports Science)

Feb 9th, 2015

This is part of a 5 part series on using Heart Rate Variability to guide your training. You can find part 1 here, part 3 here, part 4 here & part 5 here.

In my last article, I explored the impact that Heart Rate Variability can have on an athlete's response to a given training load.

More accurately, I explored the impact that the excitability of the athlete's autonomic nervous system can have on their response to high intensity training. I suggested that the 'fitness bang' that an athlete gets from a given training load 'buck' can vary quite a lot depending on how ready their system is to handle such a load. I also suggested that heart rate variability provides the coach and athlete with a peek inside the athlete's system to assess their readiness to deal with high intensity training.

So, this all sounds great but it does beg the question just how, in practice, can I simply and quickly use these HRV numbers to guide the athlete's training?

If you explored Dr. Larry's links from the previous article, you would have come across a number of different tools that you can use to implement HRV in your training. Most of these use proprietary algorithms. In other words, we don't know what 'rules' they are using to determine whether your body is ready for a hard or easy day. In terms of being able to see the 'nuts and bolts' of what's going on, Kubios provides a very useful tool for the serious endurance athlete. The software calculates everything that you could possibly want to know about the various HRV metrics outlined by Dr. Larry in the EC series, including that key (& most studied) metric of autonomic function - RMSSD.

As a quick recap, RMSSD is a good indicator of the parasympathetic or vagal component of the autonomic nervous system, the component of the CNS that slows the system down and encourages rest. Therefore, for our purposes, it is a good indicator of when the body is in a 'ready for work' catabolic state or that 'rest and repair' anabolic state. It is the most important HRV number for long course triathletes, who are most prone to overtraining of the parasympathetic (or Addisonoid) type.

To get this number, simply perform a resting (lying) HR test of 1 min or more in the morning with your normal Garmin (or Polar) HRM and upload the file to Kubios as described in the video below.

Make sure 'beat to beat recording' is enabled on your device prior. You can see how to do this for your Garmin 920 here or google it for other devices)

Once you've done that, Kubios will do the math for you and calculate your RMSSD - root mean square of successive (beat to beat interval) differences and will spit that number out in a report as shown below..

You can see the key RMSSD metric that we're looking for circled in red.

OK, so we have a number, what do we do with it?

I've provided a spreadsheet below (you can download a copy via the download button at the bottom of it) that will enable you begin to use HRV is a very simple way to help guide your training

To begin to use, simply enter a start date in the date column and enter your RMSSD number for each day in the corresponding cell next to each date. As you accumulate data, the sheet will refine the mean RMSSD & standard deviation numbers at the top of the sheet & will then compare today's score to them to assess whether it's a 'normal' day, a 'hard' day, an 'easy' day or an 'OFF' day (if you also want to track the other metrics of SDNN and HF/LF you'll find further detail here and here )

This logic is based on the method I outlined in the previous article, i.e. if today's score is in the top ~25% of HRV scores for you, we will prescribe a 'hard' day. If today is in the bottom ~25% of HRV scores for you, we will prescribe an easy day and if today is in the middle 50% of scores for you (indicated by a blank space next to the day) we will prescribe a regular 'bread and butter' aerobic training session

Admittedly, this method involves an extra step compared to using a proprietary method BUT it has distinct advantages in that...

a) you know the math behind it and you can compare that math directly to numbers from other validated research studies on real life athletes (e.g. Hautala et al., 2003; Vesterinen et al., 2011)

b) Perhaps more importantly, the calculations track well with other studies on optimal training distribution or, in popular parlance, the '80/20 rule'. The distribution is set up to keep an average of ~20-25% of your training 'hard', i.e. an average of 1-2 'breakthrough' sessions per week but what it does is time these sessions so that they occur when your system is most ready to deal with them & respond to them to give you the most fitness benefit from the given training session

A couple of caveats before you get rolling:

1. As I outlined in my last post, this method is most applicable to scheduling the high intensity sessions of the week. If you are in a base phase of the early season, it's a great time to keep the focus on just collecting a large amount of data so that when you do begin to use it to guide your training you have very accurate and representative baseline Mean/SD numbers.

2. Don't abandon common sense. The idea of this method is that, rather than rigidly adhering to doing our key sessions every Tuesday and Thursday, we implement a level of flexibility, i.e. we 'listen to' when our body is telling us it is ready for the session. HRV is just a part of this. If you get out there and you find that RPE is disconnected with pace or that movement quality isn't there, don't disregard these additional indicators because your HRM 'told you' you were ready for a hard day! HRV is just another tool to add to the thinking athlete's tool box.

As always…

Train smart,




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