lower HR is generally good, until it gets too low (<= low 30's). 40's-50's is probably optimal. just means you are more efficient. too low and it means you might have desensitized it.
That's not true bro. Not in general re health. Endurance athletes having low resting HRs but this does not make them healthier, for example when it comes to the heart, if anything it predisposes them to biochemically signalling problems like arrythmias than the general population. The risk goes up b/c the time between heart beats is longer, then errant signals that arise somewhere else (not from the natural pacemaker) can mess with the normal beating of the heart. But if your HR is more normal, then there is less of an opportunity for that to happen b/c the normal signal will come more often. That's how i understood it. Also low HR can be a sign of underactive thyroid (i think in my case this is part of it).
so, if you are a dedicated athlete, you'd want your resting HR to be the same as someone who trains maybe 1/10th or 1/100th as much as you? not going to happen. Training hard, often, and for considerable time is going to lower your resting HR. It's an adaptation that's unavoidable.
It implies efficiency: if the heart needed to beat more, it would -> but it doesn't, thus efficiency (less fat tissue usually, greater capillary density, greater stroke volume). The only way to keep it from happening is to stop training as hard and/or as long. It happens to boxers, futbol players, tennis players, runners, sprinters, cyclists, etc. People who train "too hard" for "too long" may actually shorten their life span, but the averages for dedicated athletes that i've seen, is greater than sedentary folks.
regarding signaling problems & arrhythmias, there isn't some trend of this happening to athletes that i'm aware of. Some dedicated athletes may drop dead "early", or suffer heart problems and such later on in life, but I don't recall it being any more likely than people who don't exercise seriously.
Also, your idea of "low" might be skewed. 50 is "low" compared to the avg of ~60. And the avg of 60 is for a barely active lifestyle. So how would 50 be low in that context?
If you move around all day like humans were meant to, there's no way your avg resting HR is going to be 60+. If it's 60+ and you are highly active, then it is probably more related to weight, or even diet. 40's-50's is optimal. < 40 is where it starts getting to be a problem. <= 30's is where it gets dangerous. But that's if it's like that pretty much every day, at rest. That's when it could indicate that those whatever-they-are-called receptors have been desensitized. If they are desensitized too long, they can become permanently damaged.
as for caffeine making your HR lower, not sure. it almost always makes mine higher. I really try to avoid it as much as possible now. My best races/workouts have all come without caffeine. Though, my best dunk sessions came with caffeine. I think it helps me more for sprint/explosive efforts, definitely not aerobic. I've had it completely destroy my aerobic abilities several times. So I try to avoid it now, seems like a problem.
If you rarely consume caffeine and then you have once in a while then i can expect it to increase HR. But if you have it regularly, maybe b/c it makes your heart work more efficiently too (thus lower resting HR?). Im not sure but ive noticed it decreases mine. I think your observations are explained by being more sensitive to caffeine that it reduces performance with too large a dose? smaller dose prob wud help performance while you're not sensitised to it
i was sensitized to caffeine when it destroyed my stomach.
now, my GU packets with caffeine is 20-40mg, which is nothing. Even that can cause my RPE to shift negatively.
IMHO, if you're not getting caffeine from "natural sources", and instead in artificially high concentrations, probably not the best thing if you're worried about your heart. Have to be careful, especially with supplements that are full of junk.
pc!