The Running Equivalent

The end of another week of training, and on my long run today I started totting up this week's mileage. Just over 10 miles today, a three mile recovery run on Friday, around three miles of intervals around the track on Thursday and a hilly run of about five miles on Tuesday, giving me a weekly total of 21 miles. A little alarmed that this isn't very much, and never much of a whizz at maths, I keep adding it up again but get the same answer.

I've followed my training plan pretty much to the letter but surely this number of weekly miles isn't enough at this stage?

I spend the next couple of miles of the run racking my brain as to how the heck I could've fitted in any more miles than I had this week. The nights I hadn't been running, I had been circuit training. But was this the right thing to do? Should I be running at all times in a bid to simply clock up the miles or does circuit training cut it on the marathon training front?

Enter Bob Glover and the wonderful concept of 'running equivalent' (RE), which he outlines in his book, The Competitive Runner's Handbook, in the chapter around cross training. He suggests that in the so-called RE system, any high-quality aerobic activity can be expressed in terms of running miles by simply replacing running minute for minute with cross-training. This is done by approximating the distance you would have normally gone had you spent the exercise period running.  So, if you normally run four miles in half an hour, then 30 minutes of cross training earns you four RE miles. He argues that fitness is improved when the heart rate stays in the training range for an extended period of time, regardless of what form of exercise gets it there, though he does suggest that RE should comprise no more than 10-25% of weekly mileage.

A little complicated? Yes, I guess it is and I'm hoping I'm not quite so transfixed with mileage that I need to log RE - though FYI, a quick calculation of the lovely RE boosts me up to about 33 miles this week (forgetting the percentage rule)!! - but it puts my mind at rest that I'm doing okay.

On with the circuits...up with the miles.