I am coming from strength training background and recently got into cycling. My RHR was in range of 38-42 before I started cycling training.
I started doing just two zone 2 sessions per week that were about 45min long. After few months I started doing more as I felt more conditioned - 4 sessions of 60min long + 1 to 2 HIIT/VO2max session (usually unstructured but making sure of getting total time spent of 10-15min of 90%+ of my HR Max).
My performance in watts and power improved over time a lot. My conditioning feels superior, I feel like I can keep going forever and I never feel out of breath no matter what I do. However, my RHR went from average of 40 to 47 over last couple of months doing this and it still trends upwards.
One explanation would be overtraining but I do not feel overtrained and my performance keeps getting better. I also measure my HRV, and while it trended little downwards it does not seem so severe as to classify it as overtraining.
What could possibly explain this if it is not overtraining?
There can be a lot of explanations but perhaps when the RHR was at 38-42bpm it was suppressed by overtraining at the time (its difficult to realise sometimes) and now you are fitter and managing improved performances without overtraining its been released to be at its correct value (47bpm).
Also don’t forget about other factors. In winter we tend to have our homes warmer and use thicker bedding… a few degrees higher while sleeping in bed can increase your RHR.
If you don’t have any other symptoms I don’t think it would be overtraining.
How does your heart do on the bike? Is it still responsive? Besides RHR, your heart rate response to exercise can also be indicative of fatigue. It sounds counterintuitive, but sometimes if fatigued we cannot raise our heart rate as high while riding, yet we take that for a sign of increased fitness.
Lots to ponder, but I would go by how you feel and take the other measurements as good info and something to watch, but not worry about. After the past few years of watching my HR change and wondering what is going on, I realized that there are so many factors and as long as i am still improving and having fun, I am doing something right.
It is the opposite for me… first sign of over training or illness (or shit sleep) is an increased RHR.
Whereas while training if HR is suppressed, as in it doesn’t rise to its normal value, or even worse during interval it wont increase and the intervals targets cant be met.
Id say a suppressed RHR due to over training is not the normally the generally accepted way it goes, although Im not saying it doesnt happen.
I’d say illnesses that is taking a long time to clear is most likely or poor diet and sleep given the increased training load, it doesnt need to be chronic over training, just poor sleep or diet or both will have the effect described.
Yes RHR (for me atleast) is pretty unstable and there can be hundreds of explanations.
When I think I might have been overtrained my RHR was at 44bpm, however when I was at my results wise fittest it rose to 48bpm to 50bpm. A sh1t sleep wil see that rise to 52bpm and an illness perhaps 55-57bpm. Then again perhaps I was actually fitter at 44bpm
Have you had covid or a covid/flu vaccine recently? I had both vaccines six weeks ago. My RHR went from 36-38 to 42-44. The year prior to those shots and my RHR was in the 30’s, whether I did 1200 TSS weeks or 300.
Yea, you are right that there is probably many more factors contributing.
As you mention, HR is less responsive in training when you are overtrained or after harder days - I noticed that after hard days my HR is less responsive on my easy ride day after, but this is acute response and is gone usually two days after tough workout. But my RHR raise is chronic over periods of months. As you say, hopefully nothing to worry about as 47 HR is still healthy and fit range, I am just bit worried for this trend to not continue. But my HR is quite responsive during my workouts so it should be good.