Training with power has been around for a while now. Power is an expression of how much effort your are putting forth on the bike. Hills don't matter. Wind doesn't matter. You are generating 'X' amount of watts. It's nice to be able to compare heart rate to power, but as you know, heart rate is affected by many other variables outside of what you are doing at that moment. A few that come to mind are: illness, dehydration, elevation, temperature, etc.
Why, then, train with heart rate while running? Pace is a good indicator of the power one is generating while running. Not to mention, it's old school :-) I think they were on to something!
I got particularly interested in pace from the eBook, Training with Pace, from Endurance Nation. If you are interested, you should read this yourself, but basically, the idea is that work is in the muscles, not the cardiovascular system. Work works. period.
There was always a sneaking suspicion in my mind that my fixation on the digits actually affected my heart rate. Elizabeth told me last year that I should race without an HRM. Starting last week, I changed the screen on my Garmin to show: time, current pace, last lap pace, and cadence. The results kind of speak for themselves.
This is my five mile transition run from last Sunday's Ironman simulation:
and from two weeks prior, a thirty minute brick run after a 4.5 hour bike:
As you can see, they are very similar. It took a while (almost 30 minutes) to ramp my heart rate up above 150 on the five mile run. What's important here is that my average pace for the five mile run was sub-10, and the average pace for the three mile run was 11 minutes per mile! OK?! I'll chalk SOME of that up to a change temperature (almost 20 degrees), and some of it up to better fitness, but even if the results were exactly the same, the key thing is that one was run with me looking at my HR every minute, and the other (5 miler) with me NEVER looking at my HR.
Basically, on this day, I was able to run faster by working from pace, with my HR staying in the same general vicinity as my former training paradigm of training by heart rate. Is this the definitive answer? Probably not... I just know that I would like to see some improvement in my running, especially during long course racing, and if this is one way to achieve that, I'm going to give it a go!
Be forewarned that training with pace is not without its perils. Unless you are using a system like Training Peaks to calculate your Training Stress Score, things like hills and wind will affect your pace, and you should use common sense when factoring this variables into your training.
Good luck, and happy running :-)