please explain target heart rate zone

I am a personal trainer. Here is my experience. I use a F11 every day and most all of my clients us a HR monitor. I like Polar very much. You are right that you did not need anything more than the F6 but the F11 is fine.
I find that the standard ranges are to low for most fit people. That said. Here is how yours is determined.
200 - 60(age) = 140bpm That's your "heart rate reserve, HRR"
140 * .4 + 60 = 116bpm That's your 40%. Max HR
140 * .6 + 60= 144bpm That's your 60%. MHR
140 * .85 + 60 = 179bpm That's your 85% MHR

For a fit person, as you say you are, you would train for 40 - 60 minutes 4-5 times per week at around your 60% max HR. That's for weight loss and health benefits.

If you wish to grow your heart muscle (yes it will grow just like a bicep muscle) you must over load it and that takes
20 minutes at 70% - 80% of MHR. I give you this as an FYI not that I really expect you to train at this level.

I have my clients do the following. Do some kind of cardio for at least 20 minutes. Treadmill, jogging, speed walking, etc... Whatever you like and you can push to your limit.
While training ask yourself the following and make note of your HR at each point.
Somewhat Hard? That's 40%
Hard? That's 50%
Very Hard? That's 70%
Very, Very, Hard? That's 85% (as we say, sucking air)

When your find your "Somewhat Hard" bpm and "very, very, hard" bpm. Go into your F11 and Manually set your HR upper and lower limits.

Hope this was helpful and not to confusing. Good luck. And good for you.

Your experience with your HRM is typical for many people. There are a number of people out there (more often w/females in my experience) who have a normal HR response to exercise that is higher than the "recommended" target heart rate listed in the Polar literature and many/most fitness guidelines.

It's not that there is anything "unusual" about them, it's just the variability that exists in maximum heart rates (which is the basis for estimating target heart rate). For most people, using an age-prediction formula will get them in the ballpark, but for about 10%-15% of the population it doesn't work as well because their maximum heart rate is notably higher than average.

So, you might have to use a little trial and error. Any HRM is only as good as the data used to set it up--the HRM itself has no inherent ability to determine what your rate should be. It is programmed with "standard" calculations--if you are "average" it can do the setup for you, but if you are not, then you cannot rely on the HRM.

First of all, if you are exercising at a level that feels comfortable, and that you can sustain for 30-60 min, then whatever heart rate is displayed is most likely an appropriate heart rate for you--regardless of what your "guidelines" say.

(At this point, you may be asking why you just spent the $$ on a fancy HRM if it is only going to tell you what you already knew --well, not only is that verification valuable, the HRM is helpful for other things as well).

You can calculate some training intensity heart rates using the formulae and compare those numbers to what you actually see in your workouts. In the Polar setup, use 170 as a maximum heart rate and input your resting heart rate (whatever that is). Set up a target range of 55% to 70% and see what it tells you. Again, if you find that your exercise heart rate is higher than expected, then you will need to adjust the input settings--the best way is to just increase the maximum heart rate number.

A 60% effort level is usually characterized as "mild breathlessness in which you can carry out a conversation, but the listener should be able to tell you are exerting yourself"; a 65%-70% effort still lets you do some talking, but only with some effort and concentration, and not in long sentences ;-); a 75%-85% effort will require a lot of concentration and allow for little or no conversation.

Most fitness/health exercise workouts will be in the 55%-70% range. Again, I would try some workout intensities that match the descriptions in the previous paragraph and establish your own 'training range" if necessary.

Bottom line: you should not be reducing a comfortable and effective exercise effort in order to match some artificial "target heart rate" range. Again, the fact that the book SAYS it's a "60% effort" range for someone your age doesn't mean it is a 60% effort for you.

Because of that, I am reluctant to go into any more detail about the so-called "dangers" of "going over the target zone" since I don't think it has been determined what your target zone should be. I have been though this situation hundreds of times, both with online queries and with "real" people in the testing lab. For general liability reasons, it's something they really can't do into in the general fitness literature or your HRM user manual, but it is a fairly common problem. It's pretty straightforward to deal with in person, but a little trickier from a distance.

Feel free to send me a message with any additional data and I'll be happy to add whatever insights I can.