TRAINING FOR A 50K ULTRA MARATHON - Ben Is Running

Aug 13, 2025

Quick Summary

This is a quick summary of “TRAINING FOR A 50K ULTRA MARATHON” from Ben Is Running. 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

Heart‑rate specific training is the core focus – using a chest‑strap monitor (B20) to keep easy runs truly easy and avoid the “gray zone” (the middle ground between easy and tempo where heart‑rate drifts high).
Set a hard upper limit for easy‑run HR (e.g., 150 bpm) and let the monitor vibrate if you exceed it.
Aim for high weekly volume (≈140–240 km / ≈ 100 mi per week) with most miles at an easy pace.
Keep easy‑run pace around 8 min / mile (4:45 / km) and heart‑rate 125‑130 bpm for recovery and building endurance.

Workout Example

1.5‑hour treadmill run (or equivalent outdoor run)
- Target distance: ≈20 km (12‑13 mi)
- Pace: 8 min / mile (≈4:45 / km)
- Heart‑rate target: 125‑130 bpm (set monitor to vibrate at 150 bpm to stay in zone).
- After the first hour, pause, reset treadmill, then continue to reach the 20 km total.
Add a 10 km easy run later in the day to hit 30 km total for the day, building toward the 30‑40 km weekly base.
Use the chest‑strap monitor for accurate HR data, upload to Strava, and adjust pace based on HR zones.

Closing Note

Give this HR‑guided easy‑run approach a try today, and feel free to tweak the paces to match your own fitness in the Pacing app. Happy training, and see you out on the trail!