Heart Rate Variability

Here’s a question for all the fitness/exercise/competitor folks in the Cooler.

I’m coming off an almost 2-month-long hiatus from cycling (hip/groin injury stemming from a long ride on a rented bike). I have a tendency of pushing too hard too soon on my rides, and therefore end up not putting in enough miles (if I go too fast, I get knackered out after an hour, rather than the 2-3 I need). In the past, I used a heart rate monitor to make myself hold back early in the rides so I didn’t blow my wad early. But my existing HRM had crapped out, so I’m looking at a newer one.

While researching, I came across a lot of folks talking about Heart Rate Variability (basically the std. deviation of the interval between beats) as an indicator of overall stress (and cardiac capacity in particular). The idea is that your heart rate becomes more even as you get more tired/stressed.

Has anyone used this in their training, and if so, how and what brand (and what’s your experience been)?