| What it is | Hard efforts alternated with recovery |
| Intensity | Hard, often near VO2 max |
| Builds | Speed, aerobic power, economy |
| Recovery | Jog or walk between reps |
Interval training alternates repeated bouts of hard running with periods of easier recovery (jogging or walking). By spending time at high intensity — often near VO2 max — with recovery that lets you complete more hard work than one continuous effort would, intervals build speed, aerobic power, running economy, and the ability to handle and recover from hard surges.
Speed and power
Targets VO2 max; the structured, harder counterpart to the tempo run and freeform fartlek.
Frequently asked questions
What is interval training?
Interval training is a workout structure that alternates hard running efforts with recovery periods of easy jogging or walking. For example, repeating 5 × 3 minutes hard with 2 minutes easy between. Breaking the hard work into chunks with recovery lets you accumulate more high-intensity time than you could in one continuous effort.
What do intervals do for runners?
They develop speed, aerobic power (VO2 max), running economy, and your ability to push hard and recover. Working at high intensity stresses the cardiovascular and muscular systems in ways easy running doesn't, improving your top-end fitness and making faster paces feel more manageable.
Intervals vs tempo runs?
Intervals are repeated short, hard efforts (often above threshold, near VO2 max) with recovery between, building speed and aerobic power; a tempo run is one sustained, continuous 'comfortably hard' effort at threshold, building sustainable pace. A well-rounded plan uses both, plus easy running and long runs.
Sources
- Interval training — American Council on Exercise
- Speed work — American Trail Running Association