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, but here’s the breakdown—plus a workout you can run today. The complete video has much more context, so give it a look if you want the full picture.
Key Points
- Longer intervals often fail not because your VO₂‑max work is lacking, but because your lactate threshold and speed‑endurance haven’t developed fast enough to match.
- The solution: a mid‑week interval session that builds V₂‑max and pushes your threshold forward through small, measured steps. For the science behind these kinds of sessions, read our piece on Mastering Interval Training: Science-Backed Workouts and How a Smart App Can Personalize Them.
- Run the session once a week, maintain intensity between 8‑9/10, and dial it back if you feel fatigued or overtrained.
- Combine it with weekend long runs and easy recovery days to build your 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 km/min with 60 s rest (30 s longer each rep)
Week 3 – 10 × 2 min @ 4:00 km/min with 60 s rest
Moving up (when ready):
- 5 × 3 min @ 4:24 km/min (7:05 mi) + 60 s rest (10‑20 % slower than goal 5K pace)
- Immediately follow with 6 × 1 min @ 4:00 km/min (6:26 mi) + 60 s rest
This approach works well for race-time improvement. Looking to drop time on race day? Head over to our guide on Mastering 5K Speed: Proven Interval Strategies to Cut Minutes off Your Time.
Advanced stage (if you’re ready):
- 5 × 4 min @ 4:24 km/min (7:05 mi) + 60 s rest (10 % slower than target 5K pace) – gradually increase reps or shorten rest as needed.
Once you can handle 4-minute repeats, the benefits extend beyond the 5K into longer distances. The lactate threshold work transfers directly to marathon and 10K training—something we explore in detail at Mastering the 10K: Proven Training Plans, Pace Strategies, and How a Smart App Can Elevate Your Performance.
Practical Tips
- Begin with shorter intervals (1 min) to get a feel for race-pace effort.
- Add 30 s to the interval length each week while reducing reps to keep total volume at about 20 min.
- Hold the rest period steady at 60 s—this consistency helps you repeat efforts reliably.
- Target 8‑9/10 effort—you’re working hard but not at maximum intensity.
- If a session proves too challenging, dial back to the previous week or add an extra easy day.
- Use these sessions to build VO₂‑max (with short reps) while also raising lactate threshold (longer reps at a slightly reduced pace).
Closing Note
Test this progressive interval structure and adjust the paces to fit where you are right now using the Pacing app. Stick with it, give yourself time, and you’ll find those longer intervals turning into something manageable—getting you closer to that new personal record! 🚀