I'm 21 years old, resting heart rate about 55bpm, I'm 6'3 and 190lbs. I never used to pay too much attention to my heart rate, but I recently got a heart rate monitor, and even during intense exercise, i can only ever get my heart rate into the high 80's, even when I'm trying to get my heart rate up as high as possible. I'm in relatively good shape, and according to everything I read, my max heart rate should be at least double what it is. Just wondering why this might be, and if I should be worried.
I think your heart-rate monitor is configured to showing you the percentage of your maximum heart-rate, not your actual heart rate.
Make sure you set your max correctly, if you don't know your correct max HR (I assume you don't :) ) you can go with that formula (220-age) and adjust it when you start noticing that you are actually going above it.
Heart Rate training is not a hard science like physics or math - it is a soft science meaning it generally applies to most populations or sample groups.
If you think of the bell curve, standard HR Training applies to maybe 80% (or whatever) of the sample population. It does not exactly apply to the two groups of 10% at either outlying sides of the graph.
You are an outlier, which is fine. Some people can get their HR up to 240bpm, and some can't get their HR above 100bpm. The "220 minus your age" max HR formula doesn't work for outliers.
I would just use the percentage of Max HR or the "talk test" and ignore the whole 140-150bpm numbers.
I coached a kid swimming who couldn't get his heart rate above 120 or so and he eventually was a finalist at Canadian swimming Nationals. It has no bearing on how hard you are working or not.
Heart rate monitors often don't work well, when I tried to use one, the band had to fit so tight around my waste that this was just uncomfortable. But I don't need to use one because I can always feel my heart beating so I just need to count and look at my watch. When running your heart rate should be around 150 bmp, it can be somewhat lower or higher, but if it is around 100 then you're probably not running fast enough and if it is well above 180 then you're probably running too fast for optimal training results.
To measure the heart rate when you can't feel it, you need to put a finger on your wrist below the thumb. But this is not easy to do while running, so you may need to stop for ten seconds and then count the beats. Your heart rate immediately after stopping can then be a lot lower than what it was while you were running, even if the measurement took just ten seconds. The fitter you are the faster your heart rate will go down, this rate of decline is the fastest during the first few seconds and it's also a lot more when you do the measurement when you've just started to run. That's why I think it's better to learn to feel your heart beating without having to feel your pulse by putting a finger on your wrist.
When you're doing strength exercises and you have excellent cardio fitness, you may find that your heart rate doesn't get very high. In my case, immediately after doing 50 pushups in a row, my heart rate will be around 90 bpm. But this is then up from the resting heart rate which in my case is slightly below 40 bpm.