The big name in these seems to be Polar. I bought a well reviewed and cheap "Omron" unit, the HR-100C (for $33), made in China, and it serves me well. It displays heart rate or time, and I don't need the time feature. Fancier units have extra fancy features.

Maximum Heart Rate

A commonly recommended first cut at your maximum heartrate is 220 minus your age (which for me at age 59 is 161). Another formula (from Miller) is 217-(0.85*Age), which for me at age 59 yields 167 -- and it is suggested that you add 4 if you are an "elite athelete". I find I can readily go beyond this, which means that either I am in better shape than this rule of thumb (for the "average human") would indicate, or else that I am just somewhere else on the bell curve due to genetics. Of course, I prefer to believe the former, but in the back of my mind suspect the latter may play a part.

It is well documented that there is significant variation in maximum heartrate, even among individuals of closely similar age and conditioning. For example among an olympic rowing team of men in their 20's a range from 160-220 was observed.

What I intend to do is get out at some serious levels of exertion, monitor what my heart rate is, and keep some records. I am told it can be dangerous to push to your maximum heart rate. Apparently it is a way to find out whether you have heart problems the hard way. I have pushed myself to my highest levels hiking steep uphill trails at a sustained pace, not by running.

The following is suggested as a way to determine your maximum heart rate. Note that this can be risky if you are overweight and/or out of shape. Don't blame me if you do this and die of a heart attack. First warm up. Then run for three minutes as fast as you can. Then just "jog" for two minutes. Then run again for three minutes as fast as you can. (Do this on a track or some controlled environment, perhaps with others around to summon the medic). Your maximum heart rate is the maximum rate during the second three minute run.

Back at it again 1-6-2012 on a bike ride. Before the ride my rate was fluctuating between 60 and 71 (so call it 65) - this fluctuation seems to be some quantization anomaly of my heart rate monitor. During the ride my heart rate was 135-155, and probably spiked as high as 160. Now, lets say that at 155 I was at my anaerobic threshold, then my maximum heart rate is about 194. The formulas say 161 or 170. I am not sure what to think yet.

Resting Heart Rate

Intensity and Zones

There are a multitude of systems to categorize workout intensity, and they tend to define either 5 or 6 zones. Most systems seem to agree that 80 percent of your max heart rate is the anaerobic threshold.
Here is one system:

• 50-60 percent of MHR - easy walking, free conversation
• 60-70 percent of MHR - can only speak single sentences
• 70-80 percent of MHR - "aerobic zone" - an only speak short phrases
• 80-90 percent of MHR - "anaerobic zone" - gasp single word
• 90-100 percent of MHR - red-line zone

• Zone 1 "Recovery" - anything less than 70 percent MHR
• Zone 2 "Extensive Endurance" 70-73 percent
• Zone 3 "Intensive Endurance" 73-76 percent
• Zone 4 "Sub-Threshold" 76-80 percent
• Zone 5a "Super-Threshold" 80-83 percent
• Zone 5b "Anaerobic Endurance" 83-86 percent
• Zone 5c "Power" 86-90 percent