Over the last few weeks, I've tried a few different heart rate monitors.
The first was the Polar RS 300X. I was given this by a teammate. Depending on the accessories used, the RS300X can measure heart rate, speed, and speed by counting strides. It's designed more-or-less assuming running. The RS 300X can remember intervals workouts with up to three intervals and any number of repeats. This means that it can remember a warmup, a work unit, and a cooldown, or intervals using two or three intervals, but not the warmup or cooldown. I had the heart rate sensor only, no GPS sensor, and in that setup, the device can remember structures only by time - distance and location can't play into it.
In practice, this meant that I could program mine to follow my current running workout pretty well, as long as I guessed the amount of time taken by my warmup reasonably well. But if I was doing something more complex than a warmup, run, and cooldown, I'd have had to change the program for different parts of the workout.
As far as recording, the Polar tracked elapsed time and time spent in each heart rate zone. Heart rate zones are manually configurable, as percentage of max heart rate only. I track my training volume and the Polar does a cool training load measurement, but it makes it difficult to figure out things like trends over the course of a race, or to do a Lactate Threshold measurement protocol easily. The Polar does have a lap button, so all the same information can be broken out by laps.
I want to be able to see my heart rate on a time axis. Being able to see my lap times this way in the past has told me a bit about how my speed at a race compares to how I feel at a race - they're not the same thing. So if I can measure heart rate at all, I want to be able to measure it pinned to time and location in a way that lets me mix it into the same set of data. I was also very curious about Garmin's Advanced Workout feature.
The next device that I tried was the Garmin ForeRunner 405CX. This thing is big! It's a GPS and Garmin's tcx format seems to be pretty dominant as a standard for a lot of the fitness software to use. So uploading to Strava and Garmin's own site, Garmin Connect, is pretty easy. The 405 also has the Advanced Workout feature I was so curious about. It's quite straightforward to program a pretty involved workout protocol with this feature. So far, I haven't done much with it, but I now have my run workout setup so that the warmup lasts until I press the lap button, then I do the work unit and it ends automatically at the preset time. It can be set with alerts to help me maintain the same pace or effort level, something I find handy since sometimes my mind wanders and I slow down and sometimes I go out too fast, and I've been trying to limit speed so I don't hurt myself again. The advanced workouts are quite straightforward and transparent. I'm a fan.
As far as recording, being able to see pace and heart rate together has made it easy for me to set up pace guides for a run that I want to be in heart rate zone 2. With the Polar, I could only set them up for the heart rate itself, and it turns out to take a couple minutes for my heart rate to reach its steady-state rate when I come up to speed, and about a minute for it to drop down to its steady-state walking rate when I stop running. So using pace directly means that I don't have that delay.
I still haven't gotten to doing a LT test, but it was easy to set up the protocol as a workout. Garmin Connect can show average heart rate broken up by lap, so it'll be easy to read threshold rate right off the main screen describing the workout.
Since the 405 was a loan, I still had the question of which device to talk my "sponsor" out of. The current model is the 410, and another model, the 610, has a similar feature set but uses a touchscreen instead of the weird bezel used by the 405 and 410, and it adds a distinct cycling mode. It's also smaller. I decided to go for the 610.
I played with it some today and went for a run with it. The separate running and cycling modes are pretty cool - the training screens are already set up according to the sport, and playing with one sport's screens won't mess up the other's. So in running mode, it displays pace and there's no cadence screen while in cycling mode, the display shows speed and there's a cadence screen ready should I get the appropriate toy to be able to measure it. Pretty cool. An irritation I had with trying to load workouts onto the 405 has also been solved by the 610 - I can put several advanced workouts on it without having to do the little hack required to save more than one onto the 405.
I'll be curious to try to follow some more complex workouts with the 610 over the next season, but so far it's looking very promising for doing the two things I'm looking for - guiding me through a workout that I'd lose track of on my own and giving me more data about what actually happened during a race.