HRV-G Training vs Block Periodization

I found this to be interesting.

Looks like the heart rate variablity guided (HRV-G) group had better improvements in Max Aerobic Power (5-min) over the tradition block training group.


The number of athletes studied is way too small to come to any real conclusions.
Small groups are very prone to false positives.

This is a very interesting article, thanks for posting!
The takeaways from my perspective:

  1. I think Block Periodization is a very challenging type of training, and not many of us “average Joes/Janes” can do it well, with all of life’s other stress we have to deal with.

  2. The study group size was very small, which means you have to take the results with a grain of salt. One thing I learned in grad school research was that you can make any study support whatever you want to believe/see from that study, and small group/sample sizes make it that much easier. I.e. If you expect/want to believe that HRV training is better, you’ll see the improvements in that group as proof that it works. If you want to believe that Block training is better, you can see the performance declines and use the small group size to use it as a reason for failure, or speculate that the members of that group didn’t have athletes experienced enough to handle block periodization - or whatever other reason you can come up with. That’s pretty typical with research, anyway.

  3. The concept of adjusting your training based on your morning HRV reading is great. Knowing how to adjust your training accordingly takes a level of knowledge/training/sport science that not everyone has. So the practicality of it can be hard to implement for the average joe.

  4. Personally, I do monitor my HRV and sometimes I take it into account, and other times I don’t. This morning I had a high-intensity session on schedule but my HRV had been low for two days in a row, and my resting HR was high. I knew I hadn’t slept well for the past few nights AND knew that I had a strength session later in the day. I decided to swap my MAP session for G.O.A.T and a short brick run. I chose G.O.A.T. because it’s a moderate intensity session that would still give me a stimulus I need (NM training, strength, and moderate threshold work), pairs well with strength training, and was short enough to allow me to also do a brick run afterward. Bottom line, it was hard enough to still give me some adaptations while still being easy enough that recovery needs won’t be significant. A good night’s sleep tonight and tomorrow should set me up well for a high-intensity session on Thursday (tomorrow’s scheduled training is a swim with a focus on speed, so not terribly taxing). Had my HRV been high up until today but low this morning, I probably would have still done the MAP session. But I trends are important to consider, which is why I opted to take it down a notch. *And I think that is really the most important thing to take away from this approach.

So at the end of the day, I’m not confident enough in either approach to say one is better than the other. But hopefully, these points give you more to think about when it comes to evaluating your training plan and/or training results!


In physics it’s known as confirmation bias. I think in general from what I’ve seen, there’s a lot of misunderstanding of sample sizes and statistical significance in most of these kinds of studies. Although some of it is probably as much to do with the practicalities of doing a study of sufficient size I guess.

I tried monitoring HRV but found the accuracy to which I could get the readings meant it was less reliable than my gut feel. More than once it showed me as needing rest and I went and set a PR that very same day.

Don’t get me wrong, I can totally believe there’s merit in it as a metric. But I think as well as knowing exactly what to do with the results, getting results that are genuinely accurate is more difficult than you sometimes realise.


Yes - that happened to me today. HRV was low and yet I crushed it on There Is No Try on increased MAP numbers. In fairness to HRV I have read that it is really not as useful for athletes on a day to day basis - more a weekly trend. I came into today with pretty strong readings so wasn’t put off by today’s numbers. Also I think @Coach.Suzie.S makes some great points about sleep, stress and workload as other factors to consider. We all keep searching for the app that will tell us when to train and when to back off but if we listen to our bodies enough then we have probably already found it.


Weird. Just did GOAT today, in the vague hope that it wouldn’t kill me after working hard for a few days, with a view to recovering for some hard work on Thursday.
Funny old world.

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Basically at this point I’m recording HRV in the hopes that eventually I’ll have a large enough personal dataset to do some interesting analysis on. Like maybe it doesn’t correlate all that well to performance, but correlates well to perceived fatigue on subsequent days? or RPE for a given TSS?


The problem is multi-fold.

First, double blind studies are almost impossible in most exercise research because both the administrator of the study and the participants know which protocol they are in. The danger here is not so much confirmation bias as the placebo and nocebo effects.

Second, there are no known biological markers for recovery. Hence you have no real way of knowing what is being studied.

Third, the number of people being studied is usually way too small. This is probably for practical reasons. This does not change the fact that small groups are subject to false positives - statistical outliers result in seeing correlations, much less causation, where there is none.

Fourth, results are extremely dependent on what level of statistical significance you choose.

Fifth, in any statistical analysis, the individual may or may match the characteristics of the groups studied. To pick a clear example, studies of athletes probably do not apply to sedentary people. Also, how well a given individual fits into a statistical study is open to question.

This is a big problem in medical research. This is the basis of the famous Ioannidis research that has demonstrated that much medical research is not reproducible.


My own thoughts.

  1. The test and control groups were small. Have they repeated the experiment to validate their results? Have others?

  2. HRV is the current shiny object. Like @JSampson said the trend is probably more useful than the day to day numbers. Maybe the day-to-day is more of a lagging indicator? I definitely agree with you @Coach.Suzie.S that most people (self included) don’t know how to use it to adjust their training

  3. I’ve noticed I have my biggest gains in monthly HRV and lower RHR (monthly trend) when I am following a SUF plan with 2 repeated effort workouts a week + are prioritizing sleep and recovery.

Enjoying the discussion and perspectives.


My HRV results have said rest every day since I started recording it 6 weeks ago, I took 2 rest days and nothing changed, then tested it within 30 mins of 9H and AVDP , the stress was slightly higher , energy a bit lower and productivity lower, but not huge differences, I stayed in the yellow band suggesting rest was needed

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Found HRV to be a reliable predictor of my general health. I’ve also found that when I think I’m good but HRV says take it easy, HRV is usually spot on, about 1/2 the way through the ride. However, I’ve found the opposite to be just about as true. Get 1/2 way through a recovery effort and look down and my heart rate is good. That’s when I stop and put on Nine Hammers. Ooops for the next few days.