How to Go from a 4:15 Marathon to Sub-3:30 - Lee Grantham

Aug 13, 2025

This is a quick summary of How to Go from a 4:15 Marathon to Sub-3:30 from Lee Grantham. 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

Start by assessing your current weekly mileage, longest recent run, and any recent speed work; this baseline guides the gradual build‑up. 
Use a 36‑week (≈9‑month) plan that slowly adds volume, long‑run distance, and faster intervals while keeping injury risk low. 
The core speed work is interval training at or slightly faster than marathon pace (≈5 min/km / 8 min/mi). 
Long runs should start easy (zone 2) and progress to progressive or race‑specific runs, gradually increasing to 12‑15 mi (≈20‑24 km) before adding marathon‑pace segments.

Workout Example

Interval session (once per week):
- Warm‑up 10 min easy
- 6 × 1 km at marathon pace (5 min/km) with 60 s rest, or 12 × 500 m with 60 s rest, progressing to 2 × 3 km or 3 × 2 km as you get stronger.
- Cool‑down 10 min easy
Progressive long run (once per week):
- Start with 10 km easy (zone 2).
- Add a middle segment of 6–10 km at marathon pace ± 10‑20 % slower.
- Finish with 6–10 km at true marathon pace.
- Build the total distance by ~10 % each week, aiming for 12‑15 mi (20‑24 km) long runs before adding race‑pace finishes.

Practical Tips

Keep weekly mileage increase <10 % per week to avoid injury.
Mix surface types (tarmac, off‑road, treadmill) to reduce impact stress.
Consistency, discipline, and a gradual progression are the true “secret” to success.
Customize the paces to match your own marathon goal using the Pacing app.

Closing Note Give this plan a try, adapt the paces to your current fitness, and enjoy the process. You’ll be on your way to a sub‑3:30 marathon—customise everything in the Pacing app and keep moving forward!