Run cadence and heart rate question

Ok, so i don't want to hijack JJ's thread, but i've a quick one about this run cadence malarkey. I took a run the other night and measured my cadence at about 80, which i take to be bad. However, by trying to up it to 90 it feels really weird, as if i'm putting in more effort to go the same distance (even allowing for using different muscles, as above). Surely more steps = more work?

I don't want to draw comparisons between my miserable efforts and a cheetah, but our friend from the jungle takes whacking great strides and goes really fast. It seems counter-intuitive to me that short steps are quicker.

I may be getting in over my head here and there are certainly more qualified people to answer this, but isn't it also a lot like cycling theory with regards to cadence?  In general spinning at a higher cadence in a lower gear is more efficient and ultimately faster than mashing low cadences in higher gears? 

also, when you take shorter/quicker strides, you are more likely to be moving horizontally, forward, rather than the more agressive up and down that bigger (slower) strides cause. so less braking, less jamming on your joints. unscientific, but true. for me anyway. and as my logs will demonstrate, I am a fabulous runner.

that was a joke, obviously, but once upon a time, a long time ago, i could run a 5k in under 20 minutes with the above observations...

My normal cadence is around 83.  I recently bought a temp trainer metronome and am working on getting used to 90cadence.  It's going pretty well.  My HR is somewhat higher for the same speed at 90 than it was at 83, but more than that I find that my RPE is higher at lower HR's.  I know this will get better, and it slowly is.  I just thought I would share.

I will say that I do find my legs feel better after a run than they used to at the slower cadence.  That's a very nice thing. 

It will feel that way at first.  I have developed a higher run cadence naturally over the past year or so althugh I do focus on my form and technique from time to time.  I wouldn't say that running at 80 is necessarily "bad" but research shows that a higher turn-over is more efficient...regardless of how long your legs are.  Watch elite runners and you'll see that they aren't taking super long strides...they are turning over their feet very fast and have proper foot placement.  Think of spinning on your bike as an similar situation.  By increasing your cadence you decrease the amount of force required for each pedal revolution which reduces the stress on your fast twitch fibers.  You can maintain a fast light stride longer than a powerful long stride, not to mention the shorter stride is mechanically more efficient.  I'd suggest picking up Ken Mierke's book "The Triathlete's Guide to Run Training".  Lots of good information on proper mechanics and the specifics of efficient running.