Easy or slow running seems to be an "easy" target for a lot of fitness writers. From outside appearances, it would seem that easy running doesn't produce many benefits. One perspective I've heard countless times is that slow running in training makes for a slow runner. But there is much more to this issue.
I think of easy running as a means to an ultimate end: aerobic capacity. My logic on the subject goes like this:
- Usually, the higher a person's aerobic capacity, the more health benefits a person receives
- Middle and long-distance runners have some of the highest measures of aerobic capacity, higher than that of sprinters
- All top middle and long-distance perform a large volume of easy running
Easy running by itself does not produce much gains in aerobic capacity. But it does help build an aerobic base, to which more intense interval training (which does build aerobic capacity) can be added.
For example, here's an article about Alan Webb and his quest for a faster mile. Though he can run a mile in under 4 minutes, which is a relatively short amount of time, he still performs a large volume of easy running in training.
Some people confuse the whole issue by stating that interval training is more effective than moderate or slow running in terms of increasing aerobic capacity (vo2max). This is true, but it is short-sighted. Again, middle and long-distance runners have higher aerobic capacity than sprinters. Middle and long-distance runners perform both interval training and lots of easy running, while sprinters perform mostly interval training/sprints and maybe a bit of easy running. Therefore, it seems apparent that easy running is an essential part of maximizing aerobic capacity.
