Foundational Threshold Run

Aug 13, 2025

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Intro: Seth James DeMoor covers threshold training in a video worth watching. Here’s what you need to run the workout today.

Key points

Threshold or tempo runs work the lactate-threshold zone, where lactate starts building up and the legs burn. Training there extends how long you can sustain a faster pace without breaking down.
Find threshold pace by taking your recent 5K PR’s average mile pace and dropping 20–30 seconds. An 18-minute 5K is 6:00/mi, so target 5:40–5:50/mi for threshold (5:20–5:30/mi if your 5K was 15 minutes).
Marathon runners can do 3–4 threshold runs weekly, gradually lengthening the threshold portion while reducing long-slow-distance mileage.
Hilly terrain (Seth uses the dirt roads near Greenland, CO) builds strength while you hold the same pace target.

Workout example

Warm-up: 3 miles at easy pace (~6:20/mi).
Threshold segment: 3 miles at 5:35–5:40/mi (adjust to 6:20–6:30/mi for an ~18-min 5K). Hold an even effort, checking the watch at mile markers.
Cool-down: Easy pace for the rest of a 22-mile (35 km) run.
Progression: Every other week, extend the threshold segment by 3 miles, reaching 6, 9, 12, and 15 miles, while reducing LSD mileage. Over time, tempo pace will exceed your easy running pace.

Closing note: Try this workout today, set pace to your 5K fitness, and adjust distances in the Pacing app as needed.

References