The Base Makes Everything Else Possible
Your aerobic system is the engine that powers recovery — between reps, between sessions, and across a long season. Distance runners live on it; sprinters and jumpers use it to handle training volume and bounce back faster. Build it patiently and everything else improves.
The 80/20 Principle
Study after study on endurance athletes points the same direction: roughly 80% of running should be easy — truly conversational — with about 20% as harder quality work. Most young runners do the opposite: easy days too hard, hard days too easy, everything stuck in a tiring "gray zone." Flip it. Easy should feel almost too easy.
The Building Blocks
- Easy runs — the bulk of your week. If you can't talk in full sentences, slow down.
- Long run — builds gradually; avoid big weekly jumps.
- Threshold — "comfortably hard," trains your body to clear lactate and hold faster paces longer.
- A small dose of faster intervals/reps — added later to sharpen, never the main course.
Anchor your paces to a recent race rather than guessing — pace systems like Jack Daniels' VDOT translate one race result into the right easy, threshold, and interval paces for you.
Patience Is the Skill
Aerobic fitness compounds over months and years, not weeks. The biggest mistake is the mileage spike — ramping volume too fast is one of the most consistent predictors of running injury. Keep easy days easy, grow the long run slowly, and protect your fueling and sleep (under-fueling a growing distance runner is dangerous — see Recovery).
The runner who builds the base consistently is the one still setting PRs as a senior.