We now know that endurance athletes achieve the best results with polarized training. Sports scientist Dr. Stephen Seiler has led this movement. Master coaches Joe Friel and Matt Fitzgerald are two of many who agree. You can find lots more about polarized training on the FastTalk website.
Joe Friel likes to say that too many athletes make their easy days too hard, and their hard days too easy. Everything ends up in the middle. It makes sense, because exercising at a proper easy pace feels as though it can’t possibly be doing any good. Meanwhile, other folks are flying past you. As for hard workouts, well, those hurt. It is hard enough to work at such high intensity, even harder when you are still carrying fatigue from doing easy stuff too hard.
The concept of polarized training is very simple. Do only ten to twenty percent of your workouts at high intensity, and everything else at low intensity. Every workout should be categorized as high or low intensity. While high intensity workouts will include some low intensity - warm up, cool down, and rests between intervals - the opposite is not true; low intensity workouts should avoid any high intensity efforts.
You will often see polarized training referred to as 80/20. You may very well ask, eighty percent and twenty percent of what? Duration? Distance? Dr. Seiler was counting workouts.
Do not confuse intensity with stress. A one hour bike ride at low intensity will cause a small amount of stress. Afterwards, a fit athlete should feel great. A two hour ride at the same intensity should produce a little stress, and a three or four hour ride will produce a great deal of stress. These are all low intensity, and count the same in the 80/20 division. High intensity workouts have the potential of creating a lot of stress, which is why they should be relatively short. Managing intensity is one thing, managing stress is another.
The 80/20 concept is not universally accepted. There are plenty of skeptics. One cyclist quipped that it only applies to cross country skiing, because that was what Dr. Seiler studied. Maybe they didn’t understand that cross country is one of the most demanding endurance sports, and that cross country skiers are famous for their endurance performance. I believe it to be the best way to train.