My Go‑To Half Marathon Workouts and Interval Sessions Leading up to a PR Attempt - Seth James DeMoor

Aug 13, 2025

Intro This is a quick summary of My Go‑To Half Marathon Workouts and Interval Sessions Leading up to a PR Attempt from Seth James DeMoor. 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

Choose workouts that match your training block length and race date; volume ramps up to a peak (e.g., 85 mi in week 11).
Build a solid aerobic base (first 60 % of the block) before adding threshold and interval sessions.
Use mile repeats (6 × 1 mi, 2 min rest) and progress to 10 × 1 mi as you near race day.
Add hill‑repeats (½ mi up ~4‑6 % grade, jog back) to boost leg strength for the final miles of the race.
Calculate your threshold pace by adding 20‑30 sec to your 5K average mile time.

Workout Example

1. Warm‑up: 1‑2 mi easy
2. Ladder interval (threshold):
   - 4 mi @ threshold pace
   - 5 mi @ threshold pace
   - 6 mi @ threshold pace
   - 7 mi @ threshold pace (next week 8 mi)
   - 100 m jog recovery between each mile
3. Mile repeats:
   - 6 × 1 mi @ 5K race‑pace with 2 min jog recovery
   - Progress to 10 × 1 mi as you get stronger
4. Hill repeats (optional):
   - 6 × ½ mi uphill (4‑6 % grade) at near‑max effort
   - Jog back down for recovery
5. Cool‑down: 1‑mi easy

Tip: If your 5K average mile is 5:15, your threshold pace is about 5:35–5:50 per mile.

Closing Note Give these sessions a go, adjust the paces to fit your current fitness in the Pacing app, and watch your legs get stronger and faster. Have fun, and don’t forget to watch Seth’s full video for deeper insight and more variations!