Microscope 3: the EI

The first introduction of speed I like to incorporate is the extensive interval (EI) workout. Essentially, it is a large number of repetitions of a short distance at a relatively easy pace. It's never been popular, but it never goes away. It originated in the 1930's with a cardiologist that suggested that the heart can be exercised as a muscle; when one speeds up in running, the heart rate increases but with aq time lag, so one briefly runs anaerobically even at an easy pace and the heart adapts to this stress. In the 1950's, it became the focus of a Teutonic "do more useful work" idea; though a mile in 5:00 might be difficult, an eighth of that can easily be done eight times with sufficient rest; in fact, one can do a great deal more at race pace than race distance. At the mile race distance, it is usually possible to do 20-30x200m at race pace. It is the cumulative effect of these individually esy reps that makes it challenging.

In the 1970's, this workout trickled down to the college and high school levels, where athletes routinely balked at the idea of doing the same thing dozens of times, claiming it to be boring (the reason it's never been popular). In fact, it can be as tough mentally to do as it is physically. I can still recall vividly an extensive interval workout I did in my prime: 25x400m in 72 sec. (5K pace) with 75 seconds recovery between repetitions. At first, I felt it was a waste of time and that it would take all day. It was very difficult to keep track of what rep I was on, even though I used a marker that I shifted from one lane of the track to the next as a counter. The repetitions became more difficult and my thoughts went from how I felt and where I was in the workout to how many reps I had left, to actively psyching myself up to do "one more" a few times. I ran one a bit slow, ran the next one too fast (over-compensating) and stopped half-way through the next before goading myself to finish.

To compensate for the inherent sameness of the workout, most coaches of teams substitute a fartlek run. As one speeds up and slows down irregularly, one does the cardiac part of the EI workout. What's lost is the precision and reproducibility - one can easily measure progress by the number of reps, though it's not a linear relationship (it is much easier to go from 24 to 25 reps per workout than it is to go from 14 to 15).

There are two ways I make this workout more manageable. One is by having a 3 mile course with fairly accurately measured quarter miles and doing the repetitions there (for me, a fast 200m is roughly 75 strides or 150 steps). It's easier to track reps this way, though they are a little off. The other way is to divide the workout into sets. 28 repetitions becomes 7 sets of 4 repetitions; generally, the recoveries within a set are less than those between sets - I might walk every fourth recovery "jog" and it's easier to keep track of where one is that way.

Remarkably, the very people who are the first to decry how boring this workout sounds have created their own version of it. Ultramarathon trail runners not uncommonly are doing hill workouts where they walk up and then run down a hill scores of times. They're doing it for a different reason, i.e. trying to reduce "dead quad" problems that come up in long hilly races, but the similarity is there.

During this phase of training, I have a second hard workout per week, a continuous run. That will be the focus of the next installment of this series.