The Threshold Sandwich

Workout - The Threshold Sandwich

• 15min @ 6'00''/km
• 10min @ 5'20''/km
• 2min @ 6'00''/km
• 5 lots of:
  • 3min @ 4'45''/km
  • 1min 30s rest
• 2min @ 6'00''/km
• 10min @ 5'20''/km
• 12min @ 6'30''/km

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Intro

Quick look at How FAST are my thresholds? Training for a SUB 2:20 Marathon! from The Welsh Runner. The full video is worth watching. The key insights are below so you can start working on this session right away.

Key points

• The runner did a 4-minute step lactate test on a treadmill, with a lactate sample taken during the 1-minute recovery between steps.
• LT1 registered at about 16.5 km/h (roughly 5:50 min/mile). The point where lactate starts accumulating above resting levels.
• LT2 appeared around 18.5 km/h (about 5:13 to 5:15 min/mile). Above this, lactate rises sharply and the body shifts toward carb-based energy.
• Heart-rate ranges lined up: roughly 160 bpm for LT1 and mid-170s for LT2.
• Treadmill speeds run a touch faster than outdoor equivalents. Slow down a bit when taking the workout outside.
• Use this test at the start of a training block and again a few weeks before race day to measure improvement.

Workout example

Gym threshold session (based on the test results):

1. Warm-up: 10 minutes easy.
2. 2 × 10 minutes at a just-below-LT1 pace (a step slower than 5:50 min/mile). Heart rates around the LT1 zone.
3. 10 × 3 minutes at a near-LT2 pace (≈5:13 min/mile). Heart rates in the mid-170 bpm range.
4. Cool-down: 10 minutes easy.

Short on time? Swap the 10 × 3 set for a pyramid: 3 minutes, then 2, then 1 at LT2 pace, reverse it (1, 2, 3), and push hard on each short burst.

Long run example (outside):

• A 2-hour run at ≈6:40 to 6:50 min/mile (close to the LT1 to LT2 band) with the final 3 miles quicker if energy allows. The kind of session the runner did on weekends with Andy.

Practical tips

• Use 4-minute steps for cleaner lactate readings. 3-minute steps work too but give noisier data.
• Keep the lactate sample window to about 1 minute to avoid extra tiredness.
• Note both pace and heart rate. Easier to translate gym results to road running.
• Drop treadmill speeds by 5 to 10 seconds per mile when shifting outdoors.
• Retest after 4 to 6 weeks to check progress.
• Load paces into the Pacing app and dial them in based on recent runs.

Closing note

Try these workouts and watch your marathon pace rise. Adjust the intervals to fit your fitness, and log results in the Pacing app to track progress. Watch the full video for the deeper breakdown.

References

• How FAST are my thresholds? Training for a SUB 2:20 Marathon! - YouTube (YouTube Video)