HRV response to perceived training load – Observations from 2.5 months of data

About two months ago the new version of iThlete was released with some really cool new features. These new features included;

  • The ability to rate your sleep on a score of 1-5
  • A comment section that allows you to make notes about the previous day’s events, stressors, etc.
  • The ability to input training loads that appear on your HRV trend chart so you can see how your HRV responds to your training
  • The ability to export data to drop box

Here is a video that shows the updated features;

The most significant addition in my opinion is the ability to track your training loads with your HRV trend. This really puts into perspective how stressful your workouts are. There is no specific method or formula that you have to use for your training load data. There are several methods that have been used in research to quantify training load, some of which I’ll describe below.

Training Impulse (TRIMP) – this is calculated using training duration, maximal heart rate, resting heart rate and average heart rate during the session

Session Rating of Perceived Exertion (RPE) for Endurance Athletes – Session RPE score x duration of exercise in minutes (for endurance training)

Session Rating of Perceived Exertion (RPE) for Strength/Power Athletes – Session RPE score x repetitions

*See Borrensen & Lambert (2009) for a more elaborate review and explanation of the above methods.

       Training Volume – Weight Used x Sets x Reps

Other methods exist, but these tend to be the most commonly used. In deciding how I would monitor my training I simply decided to use an RPE of the session, however, not like the method listed above. Instead, I simply rated my workout on a scale of 1-10 based on how hard, or how much effort I put into the session. I would consider volume, strain, RPE of my main sets, how hard I pushed my assistance work and so forth. I realize this isn’t the most valid or reliable measure of training load, but it’s been working well for me.

To give you an idea of how I grade my workouts, see below. This will make interpreting the charts I attach below of my trends much easier.

Session RPE of 10 – 3 or more top sets for my main exercise, RPE of 9-10 for each set, high volume of assistance work (3+ sets to failure), complete exhaustion by workouts end. I have yet to perform a 10 workout and likely never will.

Session RPE of 9 – 2-3 top sets for my main exercise, RPE of 8-10 for each set, moderate volume of assistance work (2-3 sets not to failure), considerable fatigue at end but not exhaustion.

  • I’ll typically perform these workouts when HRV is above baseline

Session RPE of 8 – 1-2 top sets for my main exercise, RPE of 8-9 for each set, low to moderate volume of assistance work (1-3 sets not to failure), moderate fatigue at end

  • I’ll typically perform these workouts when HRV is at the lower end of baseline

Session RPE of 7 – 1 top set for main exercise with an RPE of 8 or less, low volume of assistance work with reduced weight, minimal fatigue at end.

  • I’ll perform this workout when HRV is below baseline with an amber indication (deload)

Session RPE of 5 – No main exercise performed, light weight, moderate volume

  • This is what I’ve been doing on Sunday’s to hit delts and arm’s since I don’t do much work for them during my main sessions on Mon-Wed-Fri

Session RPE of 3 – Active recovery work for 20-40 minutes. This can be in the form of light jogging, sled dragging, circuits, etc.

  • I try and perform these workouts the day after each workout to facilitate recovery and maintain an aerobic base level of conditioning

Session RPE of 1 – Leisurely walk for 30-40 minutes. This can hardly be described as a workout but it’s more than a zero so I will log it when it happens.

  • This happens sometimes instead of an active recovery session.. usually when I’m visiting my folks as we’ll take a lot of walks.

So as you can see there is no sexy formula (I’ve never been a math guy anyway), but I’m pretty consistent and I’ve noticed some fairly common trends in my recovery (based on HRV). Below I have attached a couple screen shots of my HRV Trends with Training Load (Session RPE ala Andrew Flatt). The purple bars reflect training load (9 being the highest you’ll see) while the horizontal trend is my HRV daily fluctuations with the blue line representing my baseline.


  • See here and here for previous posts about observations I’ve made from monitoring my HRV
  • A session rated as 9 is almost always going to cause a pronounced drop in HRV the following day. This is why I don’t typically train on consecutive days.
  • If circumstance causes me to train two days in a row, I’ll use a Session RPE of 8. My HRV will usually drop moderately after the first workout out and drop even more after the second one.
  • During the passed 2.5 months I experienced approximately 16 instances where my HRV dropped enough causing an amber or red indication. The majority of these occurred the day after a session and therefore fell on a recovery day.
  • There were 5 days in which a red or amber indication fell on a training day and therefore out of the 2.5 months, I only deloaded for a total of 5 days. In the past I would typically take a week off after every 3 week cycle however with my new system of training I simply deload on a given day when my HRV is well below baseline.
  • The lowest dip on the graph (around 04/20) I purposefully trained harder than normal on a below baseline day (amber indication) to see how my body would react. The next day my HRV dropped even lower with a red indication. This, as well as other incidences from the past solidifies my stance that training hard when HRV is low delays recovery. You’ll see that it takes several days until my HRV gets back up to previous levels. This negatively effects future training sessions. In my opinion, it’s much better to reduce loads for one day to improve the effect of your following sessions as opposed to just training through a bad day and ruining the next few sessions. This is also what has inspired me to stop deloading at pre-determined times for pre-determined periods. There certainly is value in doing this as the body needs time to recover and adapt to weeks of hard training. However, with HRV monitoring, it seems (atleast to me, for right now) that you can get away with just reducing loads on days when HRV is low.
  • I’m presently the leanest I’ve ever been at my current body weight. I’m about 232lbs at 17%. The leanest I’ve ever been is 14.8% at 218 while the heaviest I’ve ever been was nearly 270lbs when I played collegiate football (I’m the ogre in purple below from back in 2006).

  • I’m presently the strongest I’ve ever been at this body weight.
  • I’ve been able to remain injury and illness free since using HRV to guide my training. I no longer experience any tendonitis in my elbows either which used to be a big problem.

Final Thoughts:

I realize that I may appear overly biased towards HRV’s usefulness in my writing. However, I feel that I’ve been training long enough to know when something’s all in my head (placebo) or when it’s actually making a difference. The science supports HRV (see here) and my experience up to and including the present also seems to support it. The whole concept of planning training in advance and sticking to it no matter what is not as effective as manipulating training on a day to day basis according to an objective measure of your body’s current adaptive capacity. This doesn’t mean you can’t have a general plan, it just means that you need to be prepared to make adjustments along the way to ensure the quickest and safest way to reach your training goal. HRV provides, in my opinion, the simplest and most accurate information to allow you to do this. I will continue with this method of monitoring and training since it has been so successful. I’ll be sure to provide another update in a few months.

Thanks for reading.

9 thoughts on “HRV response to perceived training load – Observations from 2.5 months of data

  1. reading users reviews , i see relationship between HR and HRV, when my HR goes UP my HRV goes down. Theres a link between two ( HR and HRV)

    So why i really need use HRV for measurement if i can only use the HR ? I really understand this relationship , some users can tell if its right , see the same?


  2. Thanks for the comment Rafael,

    Monitoring your heart rate is certainly better than not monitoring anything at all. However, HRV will provide a much more accurate indication of the balance of the Autonomic Nervous System. The balance between the sympathetic and parasympathetic branches of the ANS can inform us about how rested and recovered we are. With more variability between each heart beat, we know that the parasympathetic nervous system is elevated. With less variation between between beats we know that the sympathetic nervous system is elevated.

    Generally speaking, the higher your heart rate, the lower your HRV (higher stress) and the lower your heart rate, the higher your HRV (as you mentioned). This isn’t always the case however. I’ve experienced an HRV score of 85 on a day where my heart rate was 59 bpm. I’ve experienced a score of 76 on a different day when my heart rate was 59 bpm. So even though my heart rate was pretty low, on one day I was above baseline HRV and on another day with the same heart rate I was below baseline. This is what makes HRV more accurate than simply tracking resting heart rate.

    Then there’s the convenience factor. HRV monitoring with the app’s keeps trends and graphs of your data.

    Lastly, having a low heart rate (usually a good thing) can also indicate an excessive predominance of the parasympathetic nervous system. This tells us the body is in a deep state of recovery and therefore intense training would be contraindicated.

    So as you can see, HRV provides a more accurate indication of your level of recovery than simply resting heart rate. If you would prefer not to use HRV, I’d suggest looking into the Rusko Heart Rate test. This is a test you can do without any special devices. See the link below

    I hope this answered your question.

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  5. I just purchased my Bioforce system last weekend. I currently have a weeks worth of data. I was wondering if I need to have a longer accumulation of data before accurately applying it. I’m coming off of a 4 week recovery from overreaching(almost overtraining) and my values have consistently been an average of 97 with GREEN indicator, even after a heavy-load training day. I’m concerned that the high values could mean parasympathetic activity from the overtraining with no history to indicate a change. Just want to make sure I’m not overdoing it too early. (FWIW, I’m a 36 yr old competitive mountian biker at altitude >7000ft so I’m very aerobically fit, hence, higher values.)
    Would appreciate any input.

  6. Hi Jeremy,
    Has your performance suffered? Do you “feel” overtrained (sluggish, tired, fatigue easy, etc.?).
    Additionally, what position do you measure your HRV in? Supine or seated?


    • I’ve been racing for a few years now with a coach so I’m familiar with the ups and downs of overreaching/overtraining, however this winter I began incorporating some max weight lifting with my base miles and began to bury myself. My performance numbers were decreasing and I was experiencing deep fatigue near the middle of February. I completely stopped training for two weeks and then began very light recovery training for two more weeks. I feel really great right now (5 weeks post overtraining). I have begun incorporating intervals at LT back into the program and a twice weekly kettlebell tabata routine along with 10-12 hours on the bike at 65% MHR. I have a naturally low RHR of around 35-38 which is what my HRV readings have been showing. I measure every day after first getting up , within 10 minutes, and do it lying down. My overtraining never reached the point where my HR was perpetually low. It was staying higher than normal with less wattage produced.

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