QUESTION: Can I reach my full marathon potential on lower mileage and higher intensity?

ANSWER: Just as you can’t shortcut a marathon’s 26.2 miles and claim to have gone the distance, you can’t shortcut the training it takes to run your best.

It’s like clockwork. A runner approaches me for coaching. He or she wants to PR at a certain race distance.

I explain the physiological requirements of the race. I explain the training that can get us there.

The runner sighs, then says, “That sounds good for you, but I was hoping to do it on about half that much training—and in half the time.”

To which I reply, “If I could run less and run faster, don’t you think I’d do it?”

It’s human nature to look for shortcuts. And in recent years, HIIT (high-intensity interval training) has seemed to offer that shortcut to endurance athletes. A series of high-profile studies (Tabata, I’m looking at you) have shown big gains in aerobic energy production as a result of short, intense repetitions. The marathon is 98–99% fueled by aerobic energy, so this sounds like you can get what you need with less time investment.

But you need to read the small print. First, most of these studies compare an HIIT regimen against a truly useless fitness regimen (e.g., eating pizza while riding downhill on a motorcycle—okay, I made that up, but you get the point), then declare HIIT the winner. Second, these studies rarely bother to determine which muscle fibers (i.e., muscle cells) are affected by the training. Since the marathon relies mainly upon slow-twitch fibers, it wouldn’t do you a lot of good to stimulate a big upgrade in only fast-twitch fibers. When I asked Martin Gibala, one of the world’s top HIIT researchers, about this, he said, “That’s actually a really good question that I don’t have a full answer [for]. There actually isn’t a lot of experimental evidence [about that].”

So here’s the thing: Don’t kid yourself. Sure, you can run a good marathon off a low-volume, high-intensity training program. Just as thousands of runners do the same off high-volume, low-intensity training. But to reach your full potential, you have to run it all: volume and intensity.

Here are 5 reasons why:

  • Aerobic energy production: To run a faster marathon, you need more of it. To produce more of it, you’ll need more capillaries (small blood vessels) to carry more oxygen to your muscle cells, and more mitochondria (microscopic, aerobic energy-producing factories) within those cells. You achieve that with long runs and tempo for slow-twitch fibers, and with tempo, 5K-paced reps, and hill reps for faster fibers.
  • Running economy: Your economy is analogous to a car’s gas mileage. Better economy allows you to run farther and faster on the same amount of energy. In other words, you become more efficient. Higher overall mileage leads to better overall stride efficiency. Tempo runs improve marathon pace efficiency. And hill sprints and hill repeats improve your nervous system’s ability to recruit all muscle fiber types simultaneously.
  • Energy stores: When your muscle fibers’ carbohydrate tanks run dry in a marathon, you hit the wall. Proper training can double the size of these tanks. Do either runs exceeding 90 minutes or double workouts (best if the day’s second workout is tempo or intervals).
  • Muscle & connective tissue strength: These take a beating in a marathon. To strengthen both, you’ll need resistance training, distance runs, and long tempo runs.
  • Brain training: Your brain is a worry wart. It thinks that running too hard might kill you. So it limits how far and fast you can run until it’s sure you’ll be safe. Long tempo runs and distance runs that match the projected length, in time, of your marathon should convince your brain that you’ll be okay.

Bottom line: If you truly want to run your best, forget the run less, run faster method. Instead, run longer, harder, faster, slower, up, down, and on and on. Eventually, after running it all, you’ll reach your marathon potential.