Resting heart rate cycles

[teeger]

It seems inevitable that my(36M) RHR goes through cycles throughout the year that swings about 10 to 15%. Like for example mine could be 65 to 67 for a couple months, then gradually cycle down to 58 to 60, and then cycle back up. All typically in the span of 3 to 5 months.

Sometimes there are reasons that would suggest direct correlation, such as big stress events, but usually it just seems to happen.

I’m assuming this is normal. But my question - does anyone know why? Is this just how the body/heart works, going through these cycles? Does it correlate with other physiological phenomena?

[RiekoC]

Hello & welcome @teeger 

Great question! According to the Fitbit article on heart rate (<-- click link), there are multiple factors that can affect resting heart rate.

Several factors can affect resting heart rate: stress, alcohol or caffeine intake, or fever usually raise resting heart rate, while regular exercise or meditation can lower it. Air temperature and certain medications can also affect resting heart rate.

I don't doubt that there are more factors. For example, I recently had bad allergies that resulted in congestion in my sinus system and conjunctivitis. Looking back at my resting heart rate during that time, I noticed my RHR rose relatively significantly as I started to get sick. After taking medications prescribed by the doctor, my RHR is back to pre-illness rates.

Now you've got me interested in doing some research and reading to get a better understanding of how & what factors affect our RHR. 🤔

[Triletics]

@teeger resting HR isn't cyclic by nature. RHR is more like a response to what's happening with you and your daily life. If you see any cycles it means there are some cyclic events in your life that contribute to those variations. In my case, my RHR usually stays within the same range unless something happens and affects it. I'll show you an example from the last 365 days. In my case, the main factors affecting RHR are training load, sleep and sicknesses.

The history of my RHR looks pretty steady (always within a few beats) and spikes are little but for good reasons. I chose three periods when RHR was either very low or very high for my normal range:

If I look at more in-depth data and analyse training load (without taking it out of context, for same periods as in the chart above) that shows not only how training/detraining affected my RHR but also how fitness level (CTL) changed:

Sure, there is kind of cyclic trend (CTL goes up and down) but this is because my lifestyle is also cyclic. If not sick, I train for an event, the peak, taper, do the event and deload and that repeats. This also may (doesn't have to) reflect in my RHR. RHR is only a response to what I do and for everyone that response will be individual.