Training guide · Marathon
Threshold Training for Marathoners: The Complete Guide
Threshold work is the most reliable lever an experienced marathoner can pull. Done right, it raises the pace you can hold before fatigue snowballs. Done wrong, it's a weekly race you didn't sign up for.
Key takeaways
- Threshold is roughly the effort you could race for about an hour.
- Control beats intensity: finish every session feeling you could do more.
- Broken-up threshold (cruise intervals) lets you accumulate more quality time with less fatigue.
- One to two threshold sessions a week is plenty for most marathoners.
What is threshold?
As intensity rises, your body produces lactate faster. Below a certain point, you clear it about as fast as you make it. Above that point, it accumulates and fatigue builds quickly. That transition — usually called lactate threshold — is what threshold training targets.
In practical terms, threshold pace is close to what a trained runner could race for about an hour. For many experienced runners that lands somewhere between 10K and half marathon race pace.
Why it matters for the marathon
You race a marathon below threshold. But the higher your threshold, the more comfortably marathon pace sits beneath it — which means less glycogen burned per mile and a later, smaller fade. Threshold work also builds the mental skill of holding a steady, uncomfortable effort for a long time.
How to find your threshold pace
- Recent race: a race of roughly an hour (often 15K to half marathon for advanced runners) is a solid proxy.
- Talk test: you can speak a few words at a time, not full sentences.
- Heart rate: establish your threshold heart rate from a field test and use it to keep easy days easy and threshold days controlled.
- Lactate testing: the most precise option, used by many high-level athletes and coaches.
Plug a recent race into our pace calculator to convert it into per-mile and per-kilometer paces.
Five threshold workouts that work
1. Continuous tempo
20–30 minutes at threshold effort after a full warm-up. The classic. Start shorter and extend over weeks.
2. Cruise intervals
Repeats of about a mile at threshold with short jog recoveries (around a minute). Breaking the work up lets you accumulate more time at threshold while staying controlled.
3. Long threshold intervals
Two or three repeats of 10–15 minutes with a few minutes of easy running between. Good bridge from cruise intervals toward longer continuous efforts.
4. Progressive tempo
Start at marathon effort and gradually work up to threshold over the session. Teaches pace judgment and finishes strong without overreaching.
5. Threshold + marathon pace combo
In the final block, alternate threshold segments with marathon-pace segments inside a long run. Highly specific — and demanding, so place it carefully.
What about double threshold?
Popularized by Norwegian middle- and long-distance runners, double threshold means two controlled threshold sessions in one day, typically guided by lactate measurements so the intensity stays below the point where recovery costs spike.
It can work for high-volume, experienced athletes with the schedule to recover. For most amateur marathoners, the core lesson transfers better than the format: keep threshold work controlled, and you can do more of it.
Sample week for an experienced marathoner
| Day | Session |
|---|---|
| Mon | Easy or rest |
| Tue | Cruise intervals |
| Wed | Easy + strides |
| Thu | Easy, or a second controlled threshold session in a high-volume block |
| Fri | Easy |
| Sat | Long run with marathon-pace segments |
| Sun | Easy recovery |
Common mistakes
- Racing the workout. If the last rep is a sprint, it wasn't a threshold session.
- Chasing pace on bad days. Heat, hills and wind change pace; run the effort.
- Grey-zone easy days. Threshold only works if easy days are actually easy.
- Too much, too soon. Build threshold time gradually across a training block.
Threshold training FAQ
Is a tempo run the same as a threshold run?
Usage varies. Many coaches use "tempo" for continuous threshold efforts; others use it more loosely for anything comfortably hard. We use "threshold" for the specific intensity and "tempo" for continuous sessions at it.
How often should I do threshold workouts?
Most marathoners do well with one or two sessions a week, alongside a long run and plenty of easy mileage.
Should I use pace or heart rate?
Both, with effort as the tiebreaker. Pace is precise on flat, cool days; heart rate adapts better to heat and hills but lags on short repeats.