Training & Nutrition - Resting Heart Rate

What can be gleaned from one's resting heart rate? There seems to be several resting heart rates. One is during your awake hours without much physical exertion. Another is when resting and lying flat on the sofa or bed. Another is measured in intervals after a long taxing ride over 2 hours like 1 hour, 4 hours etc.

I always tend to wake up with a "jolt" and kick start my heart, so my "waking up" resting heart rate is not so accurate for me. My lowest resting heart rate is usually sitting in front of the computer at night before bed on a no-ride day (usually Monday). Actual resting heart rate is about as useful as max heart rate, but a downward trend in resting heart rate can be indicative of increased cardio fitness. However, cardio fitness does not necessarily mean lowered resting heart rate.

If I am sleeping or lounging for 1/3 of my day (8 hours?!) then I am taking that one into consideration.
Your low level of exertion will always be based on the sleep number anyway.

My nighttime, sleeping HR is 49. My baseline during the day is 56-61.

Digestion and standing or sitting is always going to account for a higher HR than lying prone.

Your eyes, kidneys and skin requires the most blood perfusion.
When you are not needing to digest or filter, etc then of course it will be lower.


Also, many experts rely on the resting HR when figuring your zones instead of using the maxHR.
Many people never see their true maxHR, and that is no man's land up there anyway. A truer measure of your zones uses both resting and LT. You can train the resting HR and your LT, but your maxHR is pretty much steady and in your gene pool.

42 just before bed, 45-48 when I wake. Is that too low?

If it's too low, I'm screwed. My sitting/reading the bikeforums is 36...