Sub 2:20 Marathon: Double Threshold, Zone 2 and Marathon Training Picks Up! - The Welsh Runner

Aug 13, 2025

Intro: This is a quick summary of Sub 2:20 Marathon: Double Threshold, Zone 2 and Marathon Training Picks Up! from The Welsh Runner. It’s a great watch — we’re breaking it down so you can try the workout today. Be sure to check out the full video for all the details.

Key Points:

The week focuses on “double‑threshold” work: short, high‑intensity intervals that still give a lactate‑threshold benefit while keeping total volume manageable.
Zone 2 runs are used to build aerobic base and aid recovery between harder sessions.
Marathon‑pace effort is added after the base work to practice pacing and heart‑rate control at race effort.
Practical tip: monitor lactate (or perceived effort) after each interval; aim for a lactate value around 3.5 mmol/L to stay in the sweet spot of threshold training without over‑loading fast‑twitch fibers.

Workout Example:

Warm‑up – 1 mile easy jog + light strides.
Double‑Threshold Session – 20 × 30‑second intervals on the treadmill (or track) at your threshold power/pace (≈95 % of your 20‑minute FTP). Keep the average lactate ~3.5 mmol/L; recover 60 seconds easy jog between reps.
Zone 2 Run – 8 miles at a comfortable aerobic pace (≈1 min 45 s per mile, HR in the low 150s).
Marathon‑Pace Segment – 3 miles at target marathon effort (≈5 min 20 s per mile, HR ~160‑170).
Cool‑down – 1 mile easy, then stretch. Adjust paces to your own data; the Pacing app lets you set the exact minutes per mile or km you need.

Closing Note: Try this mix of short threshold bursts, steady Zone 2 mileage, and marathon‑pace work to sharpen your lactate handling and endurance. Feel free to customize the paces in the Pacing app to match your current fitness – and keep an eye on your heart‑rate and lactate feedback. Have fun, stay safe, and enjoy the progress toward that sub‑2:20 marathon!

Remember, this is a summary of someone else’s video – watch the full The Welsh Runner episode for deeper insights and the author’s personal race‑day reflections.