Sub-3 Marathon Speed Session
Workout - Sub-3 Marathon Speed Session
- 15min @ 6'30''/km
- 6 lots of:
- 1.0km @ 3'45''/km
- 1min rest
- 12min @ 7'00''/km
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Intro
Lee Grantham’s The Fastest Way to Run a Sub-3 Hour Marathon (Start Here) breaks down what you need to know. The main takeaways are below so you can run one of these sessions today. Watch the full video for deeper context on each phase.
Key points
- Build your speed foundation. Breaking three hours means first improving as a 5K and 10K runner. Aim for around 3:45 min/km (about 6 min/mi).
- Concrete targets: hitting 5K in around 18:45 and 10K in around 37-38 min gives you the capacity to hold around 4:15 min/km for 42 kilometers.
- Steady progression: start from your current fitness, stay consistent week to week, and pair hard workouts with recovery runs and a structured taper.
- Track heart rate. Watch peak and recovery HR during intervals to verify you’re at a sustainable level.
- Know your limits. Overtraining stalls progress. If you’re still fatigued on long-run day, scale back the previous interval session.
Workout example
Session 1, 1 km repeats:
- 10-15 min of easy running to warm up.
- 6 x 1 km at 3:45 min/km, with 60 s jogging recovery.
- 10 min cool-down at easy pace.
Session 2, 400 m repeats:
- 10-15 min warm-up.
- 15 x 400 m at 3:30 min/km (roughly 15 s quicker than marathon pace) with 60 s between reps.
- 10 min cool-down.
Session 3, 1600 m repeats:
- 10-15 min warm-up.
- 3 x 1600 m at 3:45 min/km (slow it slightly if needed) with 60 s recovery.
- 10 min cool-down.
Progression run (6 km):
- 2 km at 4:10 min/km, then 2 km at 4:00 min/km, then 2 km at 3:50 min/km (optionally finish the last 2 km at 3:45 min/km).
All paces can be customized to your current level. The Pacing app lets you plug in your own numbers.
Closing note
Run these workouts, watch your heart rate and perceived effort, and dial in the paces over time. With consistent sessions, you shift from a pure 5K runner into someone capable of sub-3 hour. Use the Pacing app to adjust intervals.