I have been working with Eric's programs for about a year now, and no matter what heart rate or speed I run at, I still tend to keep to 21-23 right footfalls per 15 seconds, even in WUs and CDs. What you have to do is shorten your stride to go slower, and lengthen it to go faster. As Eric has said before, the hardest thing to do in the beginning is to run slowly at a regular cadence. I found that the easiest way for that cadence to be engrained into my mind is to run without music, as unless you find music with that particular bpm (or footfalls per minute), you are going to be speeding up and slowing down to the music. For some reason, no matter what I listen to now while running, I always keep the same cadence; but I spent 8 weeks without music to start with.
Theres always a question about cadence, i guess...
I've transformed into natural running and now do all my runs at 180 per minute. I find it very easy to keep this cadence at slow and moderate speeds, but when I start running faster, like 4 min pr kilometer, i tend to increase the cadence to 190-210 per minute.
This feels natural for me, but i guess this pushes my heartrate to the roof faster than if i'm keeping on 180? Should I work on always keeping it at 180 per minute, or is it ok to run at 190-210?
I have the same problem with increasing cadence at higher speeds. I'm pretty sure the objective is to keep cadence at 180 whatever the speed. So to get my cadence back down to 180, during sprints for example, I focus on straightening out my stance leg during push off, driving the knees forward and up, and globally spending more time in the air during each stride. Focusing on form details at high speeds is a nice challenge !