Sub-20 5k: Interval Foundation
Workout - Sub-20 5k: Interval Foundation
- 12min @ 6'00''/km
- 20 lots of:
- 1min @ 4'00''/km
- 1min rest
- 12min @ 6'00''/km
to import the workout after you install it.
Intro
Lee Grantham’s video on Why You Struggle With Longer Intervals (And How to Fix It Fast!) is worth watching in full. Here’s the breakdown plus a workout you can run today.
Key points
- Longer intervals often fail not because VO2-max is lacking, but because lactate threshold and speed-endurance haven’t kept up.
- The fix: a mid-week interval session that builds VO2-max and pushes threshold up in small steps. For more on the science, see Mastering Interval Training: Science-Backed Workouts and How a Smart App Can Personalize Them.
- Run it once a week at 8-9/10 effort. Back off if you feel fatigued.
- Combine with weekend long runs and easy recovery days for aerobic base.
Workout example
Week 1: 20 × 1 min @ 4:00 min/km (6:26 mi) with 60 s rest.
Week 2: 13 × 90 s @ 4:00 min/km with 60 s rest (30 s longer each rep).
Week 3: 10 × 2 min @ 4:00 min/km with 60 s rest.
Moving up (when ready):
- 5 × 3 min @ 4:24 min/km (7:05 mi) + 60 s rest (10-20% slower than goal 5K pace).
- Then 6 × 1 min @ 4:00 min/km (6:26 mi) + 60 s rest.
This works well for race-time improvement. To drop time on race day, see Mastering 5K Speed: Proven Interval Strategies to Cut Minutes off Your Time.
Advanced stage (if you’re ready):
- 5 × 4 min @ 4:24 min/km (7:05 mi) + 60 s rest (10% slower than target 5K pace). Gradually add reps or shorten rest as needed.
Once 4-minute repeats are manageable, the benefits go beyond 5K. Lactate threshold work transfers directly to 10K and marathon training, covered in Mastering the 10K: Proven Training Plans, Pace Strategies, and How a Smart App Can Elevate Your Performance.
Practical tips
- Start with shorter intervals (1 min) to get a feel for race-pace effort.
- Add 30 s to the interval length each week, drop reps to keep total volume at about 20 min.
- Hold rest steady at 60 s. The consistency makes reps comparable.
- Aim for 8-9/10 effort: hard but not all-out.
- If a session is too tough, drop back a week or add an easy day.
- Short reps build VO2-max, longer reps at slightly slower pace lift lactate threshold.
Closing note
Try this progressive interval structure and set paces to your current fitness in the Pacing app. Stick with it and the longer intervals start to feel manageable.