Flavors of running 5: Intervals

There have been three different approaches to thinking about interval training and they all have faults. Yet all three are useful, nonetheless.

In the 1930's, the idea arose that the heart, being a muscle, could be trained as weightlifters train muscles. The problems with this are numerous: cardiac muscle contracts involuntarily, it prefers keto acids for fuel to sugars and fats, etc. It did, however, create the idea of intermittent runs, rather than continuous runs. Other lessons from weightlifting also apply to some degree, such as an upper limit of 12-15 repetitions (or one's using one's time inefficiently) and the importance of form (one good rep's better than a bunch of sloppy ones). Training the heart as a muscle did lead to at least one world record at 400 meters, so it had some validity.

The next thought about intervals came quickly from those who learned from the first experiments. The idea arose that all the top runners were of about the same level of talent, so winning was a matter of who could train the hardest. At the time, no one was able to run a mile in 4 minutes, but most top runners could run eight quarter miles in a minute each, which is two miles at that pace (and, with longer rest times, 10-12 repetitions were possible). This was considered a great breakthrough, but problems start creeping in for those racing much beyond 10K. A marathoner was not going to run several dozen mile repeats; the time demand was too great and the benefit less than a shorter continuous run at marathon pace. One often finds that experts will have marathoners run mile repeats at faster than marathon pace, saying that "it makes marathon pace seem easier" when in actuality marathon pace repeats just don't work very well, so they substitute what does work.

The third idea was the American assembly line idea of breaking a race into component parts and training for each of them separately. This works beautifully for hurdles and relays and is largely the reason that the US still leads the world in these events. It doesn't work very well for races beyond 800 meters, however, as the "parts" become hard to define. Eventually, attempts were made to divide races up physiologically and this has some basis in truth and has persisted.

The standard thought is as follows: one runs using creatine phosphate as an energy source for only a few seconds. One can run anaerobically, creating lactic acid, for 1-3 minutes. One can run at one's maximum oxygen uptake level for 2-10 minutes. One can run at a level where one is generating just the same amount of lactic acid as one is able to transport out of the muscles for 10-60 minutes. One can run aerobically for hours. This is no more true than that one can train the heart like a muscle, but it is a useful conceit.

Here's where I went with intervals
From an earlier post, I divided runs into those at 75%, 80%, 85%, 90%, and 95% effort. These are, in order: aerobic runs, anaerobic threshold runs, maximal oxygen uptake runs, lactic acid tolerance runs and phosphate system runs.

If one can run a maximum of three minutes at the slowest pace that's at the 90% lactic acid level and one can run only one minute at the fastest pace that doesn't move into the next category, than one can run 3x1 minute at 90% with recoveries in between of about 5 minutes. Similar reasoning leads to the following workouts:

3x 1min. @90%- 5 min.
5x 2min. @85% - 4 min.
9x 6.5(maybe 7) min. @ 80% - 3 min.
15x 8 min. @75% - 2 min.
(the recovery times are admittedly stolen from Gardner & Purdy's "Computerized Running Training Programs" from 1970)

This last turns out to be 15 repeat miles at marathon pace for a 3:30 marathoner. The other workouts are similar to what coaches have had runners do for at least a generation. Repeat miles at 5K or 10K pace fall somewhere between the 80% and 85% examples.

The fact that I use times rather than distances raises the question of whether it is necessary to do interval workouts on a track. And that leads to the next subject, fartlek.