Don't believe everything that you read.

Leave it to Twitter to get me riled up. A tweet caught my attention a few days ago. It read:

"Greater improvements in cycling performance parameters following HRV-guided vs. block training."

I was intrigued, so I read the abstract. I didn't have access to the peer review journal at the time, but I could see in the abstract, "Between-group fitness and performance were similar after the study."

So I called out the original "tweeter," saying there was no statistically significant difference between the two groups. Claiming one is superior, misrepresents the study's findings. By this point I noticed the individual is a  professor and researcher and maintains a blog devoted to heart rate variability (HRV) research - which surprised me. If he's a professor, surely he understands statistics - I couldn't help but think he was misrepresenting the findings to support his bias in favor of  HRV-guided training...

After I pointed out there was no difference in performance between groups, the tweeter responded with a screen shot of a figure from the paper:

From the figure, yeah - it looks like HRV-guided training does outperform block periodization... but looks can be deceiving. Again, there is no statistically significant difference between the two groups. You can't say that one training method is superior to the other. So that's what I said - Where's the difference?

The original poster, responded:

"One group showed a mean time trial improvement of ~6%, the other, ~3%. If I’m investing the same time and effort into training either way, I’d opt for the method that might give me an extra 3%."

And most people would agree - Who doesn't want an extra three percent?

But it doesn't work that way - we don't know if that 3% difference was due to error or random chance. If the experiment was done again, you may very well find a different result. The difference between the groups was not great enough to be statistically significant. You'd think a PhD educated professor would understand that. And you'd hope he wouldn't misrepresent research to support his own bias for HRV gadgets and training.

This is all public, you can check my Twitter if you have nothing better to do. I don't have any animosity towards the individual, and this is not a critique of HRV-guided or block periodization - I just wanted to take the opportunity to remind people to be critical and don't believe everything that you read.



  1. A complete lack of integrity and basic honesty - well done for calling him out

  2. The basic idea about HRV is to inspect the health of the parasympathic vs sympathetic balance through various modes of analysis, perhaps it can be used to inspect overreaching. No one really knows for sure what is the right ways of interpretation and long term studies are lacking, specifically for sports like duathlon. Block periodization on the other hand is a method of structuring training such that similar movement abilities are trained within a block to improve those abilities. It seems people on Twitterverse really need to understand the basics of what the two things are meant to address.


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