The Seiler 4x8: four 8-minute efforts at 102–110% of FTP, with just 2 minutes' recovery. 32 minutes just above threshold in a 63-minute session. For intermediate to advanced riders with an up-to-date FTP.
| Target | Zone | Time | FTP 200 W | FTP 250 W | FTP 300 W |
|---|---|---|---|---|---|
| 102–110% | 5VO2 Max | 32 min | 204–220 W | 255–275 W | 306–330 W |
| 50–60% | 1Recovery | 6 min | 100–120 W | 125–150 W | 150–180 W |
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Is harder always better? Stephen Seiler's 2013 study suggests not. He compared three sessions, each ridden as hard as could be held evenly: 4 × 4 minutes, 4 × 8 minutes and 4 × 16 minutes. The 4 × 8 produced the biggest gains, in VO₂max and in power at threshold. The takeaway: accumulating more time at a slightly lower intensity, just above your threshold, can pay off more than shorter, harder efforts.
It's a VO₂max session that also works threshold: at 102–110% of FTP, you're not at your maximum oxygen uptake from the first minute, but you creep towards it through each effort, and 2 minutes' recovery doesn't let everything settle. A larger later study adds a caveat: with the same total load, the order of the formats made little difference.
Intermediate to advanced riders with a recent FTP and a few VO₂max sessions behind them, such as the 4 × 5 min. The study looked at trained amateur cyclists riding around six hours a week: a familiar profile for anyone preparing for sportives or club racing.
In the study, riders did it twice a week for seven weeks, with everything else easy. One or two hard sessions a week remains a good guide, with an easy day between them and none the day before a race. To ease in, take 3 to 4 minutes' recovery the first few times, then bring it down to 2. After that, keep the structure and let the power follow your FTP.
5′ at 45–55% FTP + 5′ at 56–65% FTP + 5′ at 66–75% FTP
15 minutes building from 45 to 75% of FTP, in 5-minute steps. Use the end to get settled, bottle within reach: the short recoveries leave no time to go looking.
4 × 8′ at 102–110% FTP, 2′ recovery
Four 8-minute efforts at 102–110% of FTP, or 255 to 275 W for an FTP of 250 W, with 2 easy minutes at 50–60% between them. Seiler's principle: the highest level you can hold evenly across all four. Start the first at the bottom of the range and only go up if the second goes well. Ride by feel as much as by power, and keep a steady cadence.
10′ at 40–55% FTP
10 very easy minutes at 40–55% of FTP. Compare your four average powers: if the fourth effort is well below the first, aim a notch lower next time.
The first effort feels manageable, almost too much so. The second settles in, the third stings, the fourth is very hard: that's the sign the pacing was right. The 2-minute recoveries go by far faster than the 8-minute efforts, unsurprisingly. Guide: 9 out of 10 on the last effort.
Same total, 32 minutes just above threshold, and the same 2-minute recovery. But Seiler splits it into four 8-minute efforts, Stepto into eight 4-minute ones. The 4 × 8 asks you to hold on longer in one go; the 8 × 4 gives you more restarts.
Eight minutes is twice as long. Riding the first effort at 4 × 4 power all but ensures a failed fourth. The goal is evenness, not the number on the first one.
If you need more than 2 minutes, decide before you start and keep it the same throughout. Adding rest on the fly at the third effort usually means the intensity is too high.
Even in the study, two sessions a week were enough, surrounded by easy riding. A third adds far more fatigue than progress.
Seiler et al. (Scand J Med Sci Sports 2013): 35 trained cyclists, 2 sessions a week for 7 weeks. The 4 × 8 group improved by about 11% (VO₂peak, power at VO₂peak, power at 4 mmol of lactate), against about 5% for the 4 × 4 and 4 × 16 groups. Seiler didn't prescribe a % of FTP: participants rode at the maximum tolerable intensity for the whole session, around 90% of maximum heart rate. The 102–110% FTP range is the usual translation used by riders. The 2-minute recovery comes from secondary sources, not from the study abstract. Caveat: in 63 cyclists, sequencing 4 × 16, 4 × 8 and 4 × 4 in different orders didn't change the results for the same load (Sylta et al., 2016). The warm-up and cool-down are Wattson choices. Bottom line: good evidence.
At 102–110% of FTP: 204 to 220 W for an FTP of 200 W, 255 to 275 W for 250 W, 306 to 330 W for 300 W. Seiler didn't prescribe a percentage: his riders went at the highest level they could hold evenly across all four efforts. This range is the usual translation; adjust it to how you feel.
How the work is cut. Both give 32 minutes just above threshold with 2 minutes' recovery, at similar intensities. Seiler uses four 8-minute efforts, Stepto eight 4-minute ones. The first asks you to hold on longer in one go and prepares you for sustained efforts; the second, more broken up, is often ridden a touch higher.
In Seiler's 2013 study, the 4 × 8 produced bigger gains than the 4 × 4 in trained amateur cyclists. But a larger study from his group in 2016 found no clear difference when the total load was the same. Both are good sessions: alternate them depending on your goal and how fresh you are.
2 easy minutes at 50–60% of FTP. That figure comes from secondary sources on the study. If it feels too short at first, take 3 to 4 minutes for the first few weeks, then cut it back. What matters is even efforts, not a heroic recovery.
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