Originally Posted by Janez Bobnik
But my question here is - why is my resting heart rate so low when I'm "idle"? I'm asking this because when I go run and I run at average pace of 5:00/km (which I can do quite easily), my heart rate goes well above 170. That's like 88% of my max heart rate (I'm 28, so 220 - 20 = 192)?
Is this normal?
Resting heart rate isn't just about how strong your heart is, aka, how much blood it moves with every beat. It's MUCH MORE about how much oxygen your body needs. Better shape = lower demand. It's a combination of both factors, among others.
So what you are describing is very common, especially for cross training athletes. Crosstraining generates a strong heart, without necessarily training a hugely efficient body. By HIIT, your body gets a chance to recover between rounds, so it doesn't have to adapt to be as efficient DURING the rounds like an endurance training program might generate (learned this lesson the hard way).
So a crossfitter will be able to take on short bursts with a lower average heart rate than an endurance athlete would, whereas an endurance athlete will be able to maintain a lower heart rate over long phase exercises than the crosstrainer would experience. Your body adapts to how you train.
To the OP, I've had a resting heart rate in the 45-55bpm range for about 15yrs that I've been keeping track. I also have hypotension, aka low blood pressure 80/40 resting.
Although I get a clean bill of health from the doctors and trainers I have worked with (the typical "congratulations, you're as fit as a horse"), the downside is that hypotensive shock is never too far away. It's very very easy to pass out from shock when you operate so low. Never usually an issue during an activity and adrenaline is flowing, hr is up, bp is up, but say I get stepped on by a bull and break my leg, about the time I get in the ambulance, resting, laid down, I'll pass out. Nothing really bad, just sucks passing out, and freaks out the paramedics.