If a lab test is not what you want, go do a max HR test on a treadmill and from that set your zones. We all have different HRmax levels. But without that known much is a crapshoot as to what your zones are.

Calc. of HRmax. on a treadmill

1) Start in your easy pace, the speed at which you can converse well at.. Run 10 min warm up. Take a couple min. and lightly stretch if needed.

2) Then start by running 2-3 minutes at an easy pace. Start increasing the pace about 10-15 sec. per mile every minute.

3) After the first 30 seconds, start another 1 min. cycle by increasing the grade 0.5% of the treadmill, so every other 30 seconds, you are either increasing pace or grade.

4) Continue this until you literally have to step off the treadmill because of exhaustion.

5) Take 3-5 min. to lightly stretch and repeat. Take the higher of the 2 numbers. This should be your HRmax.

But I have to agree w Vanjames. The lab test is the best.

How long are you keeping the HR monitor on when this happens? It is common for heart rates to spike suddenly at random times due to stress(starting the workout), caffeine(drinking any beforehand- can keep HR elevated for 1 hour or more), enhanced automaticity, etc. I have started out myself and my HR shot up to 206 bpm. It went back down after about 10 sec- 1 minute. Or it has happened in the middle of my workouts randomly. For those short durations, it won't throw off your ranges much at all.

You may want to try warming up first by perceived exertion and then turn the HR monitor on.

Also, some HRM's respond to electrical interference. When I run by certain power lines, the HRM goes nuts. Also sometimes happens indoors on the treadmill--the number will get "stuck" in a range that I know I'm not in (because I'd be dead if that was my actual HR!).