The Sub-3 Threshold Cornerstone

Workout - The Sub-3 Threshold Cornerstone

• 10min @ 6'00''/km
• 3 lots of:
  • 5.0km @ 4'00''/km
  • 1min rest
• 10min @ 6'00''/km

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Intro

This summary covers How to Break 3 Hours in a Marathon: 15K Strategy by Lee Grantham, from a helpful video worth watching in full. We’re unpacking the key takeaways so you can put them into action right away.

Key Points

• Lactate threshold pace—the fastest speed you can hold for roughly an hour—is what separates a sub‑3‑hour marathon from missing it.
• Running a solid 15 km in ≤ 1 hour (≈ 4:00 min/km or 6:26 min/mi), or matching that pace in a 10‑mile race, shows you’re on track.
• Test yourself with a 10‑mile race 4‑5 weeks before race day; it’s easy on the body but tells you plenty.
• Mix threshold repeats, marathon‑pace runs, long runs with a faster section, sub‑threshold intervals, and short quick reps—this combination raises your threshold while keeping your marathon speed solid.

Workout Example

Session 1 – Lactate Threshold Intervals

• 3 × 5 km at 4:00 min/km (6:26 min/mi), 60 s jogging between each. (Building up? Start with 3 × 3 km and progress from there.)

Session 2 – Marathon‑Pace Run

• 15 km at marathon goal pace of 4:15 min/km (6:50 min/mi). You’re holding about 10% slower than your threshold target, which lets you experience the marathon tempo.

Session 3 – Long Run with Marathon‑Pace Finish

• Example: 20 km steady, then 10 km at 4:15 min/km, then 5 km easy. Trains you to close strong without cutting into your weekly volume.

Session 4 – Above‑Threshold Repeats

• 6 × 1 km at 3:45 min/km (≈ 6:00 min/mi), 60 s recovery between. Pushes your threshold up; give yourself proper rest and fuel between efforts.

Session 5 – Speed Work

• 8‑20 × 400 m at 3:30‑3:35 min/km (≈ 5:35 min/mi), about 10% faster than threshold. Begin with 8‑10 repeats and work toward 15‑20 as you build fitness.

Closing Note

Take these workouts for a spin, dial in the paces to your current level, and log everything in the Pacing app to dial in what works for you. Stick with it, and that 15 km = 1 hour benchmark—and your sub‑3‑hour marathon—will be within reach.

References

• How to Break 3 Hours in a Marathon: 15K Strategy - YouTube (YouTube Video)