| Rep distance | 800 m |
| Target pace | 4:36 / km |
| Rep time | 03:40 |
| Recovery | 03:40 (jog) |
| Reps | 4 |
| Total distance | 3.20 km |
- I pace is roughly 3K-5K race pace, about 97-100% VO2max.
- 800 m per rep, target time 03:40.
- Use 1:1 work:recovery; jog the recoveries rather than stopping.
- Do not exceed 10 km or about 8% of weekly mileage in one interval session.
I - Interval
VO2max work, typically 800-1200 m repeats with roughly 1:1 work:recovery.
T - Threshold
Lactate-threshold work, usually 10-20 minute blocks that improve sustainable endurance.
R - Repetition
Fast 200-400 m reps with enough recovery to train speed, mechanics, and economy.
About 80% easy Zone 1 and 20% high intensity Zone 3, with very little middle-intensity Zone 2 work. This pattern is associated with Seiler 2006 observations in elite endurance athletes.
Best for: advanced runners, middle/long distance breakthroughs
Roughly 70% easy, 20% moderate, and 10% high intensity. Enoksen et al. (2011) studied training distribution among elite marathon and middle/long-distance runners and found this graduated intensity pattern to be the most common.
Best for: marathon-focused runners, 60 km+ weeks
Large amounts of moderate work near T pace, with less easy and high-intensity work. It can feel productive short term, but often stalls progress when used all season.
Best for: short 3-6 week race-specific blocks only
Sources: Stöggl & Sperlich 2014 (PubMed)、 Seiler & Kjerland 2006、 Enoksen et al. 2011 (Int J Sports Sci Coach)
- Daniels guideline: two Q Days per week, separated by at least 48 hours
- Typical layout: Tuesday Q1 (I or R), Thursday E, Saturday Q2 (T or long run with M pace), other days E pace or rest
- Weekly mileage < 40 km: use one Q Day and add strides on another easy day
- Back-to-back hard days increase overtraining risk (Fitzgerald, 80/20 Running)
- If R/I pace slips by >5 sec/km, stop the session; recovery is not ready