Target/Maximum Heart Rate

I have figured my THR/MHR to be between 125 (70%) - 156 (85%) (depending on method used). When I exercise - especially c25k & kickboxing my heart rate spikes for a few seconds throughout to 160 - 170. Is this dangerous? Should I try harder to keep it below 156? I am looking for knowledgable (I know, I should ask my doctor - next time) answers, not just opinions. Thanks for all you help.

First of all the MHR formula is just an estimate and can vary quite a bit from individual to individual. I'm 57 so my predicted MHR is 163 yet when I did a stress test last year the doctor terminated the test when my HR reached 174 and I wasn't maxed out yet.

As I regularly push myself into the high 160s when I do HIIT I asked him if it was safe for me to work out at those levels and his answer was that since my fitness level was extraordinarily high (for an old fart ) it wan't a problem to push it as long as I wasn't gasping for breath or experiencing any discomfort. The key is to listen to your body. The fitter you are the higher you can push it

As already posted, unless you do a stress test, you really don't know your max heart rate. I'm 47, so using the basic formula of 220-age, I should be at 173, but I can push to around 180 just in normal workouts. I've not done a Dr supervised stress test, just some of the basic ones you can find by googling it. Point is, MHR varies from person to person. Remember, though, you cannot increase MHR through fitness, it is simply genetics and age. You can lower your resting heart rate, and tracking resting heart rate can be a good indicator of overall health.

Pushing your heart into 90-100% exertion is good, you just need to limit the amount of time you spend in that zone, as you are risking injury. If you start to feel faint, definitely slow down!

When I do HIIT my MHR goes as high as 205 - is this worrying? o.O