CyclingThreshold and sweet spotIntermediate 77 min

High threshold 5 × 8 min

5x8 threshold intervals: five 8-minute efforts at 98–102% of FTP, roughly your 40-minute power, with 3 minutes of active recovery. 40 minutes at high threshold in a 77-minute session. For trained riders with a recent FTP.

Written by Pierre Halloo · Updated 25 October 2026

Session profile13 blocks

At a glance

Duration: 77 min
Main target: 98–102%FTP4 Z4 · Threshold
Time at target: 40 min
Estimated load: 86
Structure: 5 × 8′ at 98–102% FTP, 3′ recovery
Level: Intermediate
Equipment: Power meter · Smart trainer

The session in detail

FTP

Time in zone

Z127 min
Z210 min
Z440 min

What the targets mean

The session's targets, in watts for three reference FTPs
Target	Zone	Time	FTP 200 W	FTP 250 W	FTP 300 W
98–102%	4Threshold	40 min	196–204 W	245–255 W	294–306 W
50–60%	1Recovery	12 min	100–120 W	125–150 W	150–180 W

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Wattson works out the targets from your FTP and sends the session to your Garmin, Wahoo, Coros or Suunto.

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What this session is for

The target here isn't strictly your FTP, but the power you'd hold for a 40-minute effort, a little above it. Take that 40-minute time trial and cut it into five: with 3 minutes' recovery between pieces, you hold the whole session at an intensity you couldn't sustain in one go. Heart rate and breathing climb high, close to their maximum by the end of each effort.

The format comes from a 2024 study in well-trained cyclists: 21 sessions over 9 weeks. The riders who reached the highest share of their VO₂max during the efforts improved the most. That's an observed link, not proof that going higher always means improving more.

Who it's for

Trained to advanced riders with a recent FTP and several threshold sessions behind them, like the 2 × 20. The study looked at high-level cyclists; the session is still within reach of intermediate riders, as long as they start with four efforts.

When to do it

In the study, riders did a little over two a week within a supervised programme. Outside the lab, one or two hard sessions a week is plenty, with an easy day between and none the day before a race. To ease in, start with 4 × 8 minutes, then go to five once the fourth effort stays level with the first.

How to do it

Warm-up
15 min
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. You should feel ready to ride hard, not already tired.
Main set
52 min
5 × 8′ at 98–102% FTP, 3′ recovery
Five 8-minute efforts at 98–102% of FTP, or 245 to 255 W for an FTP of 250 W, with 3 minutes of active recovery at 50–60% between them. The range is narrow: aim for the middle and hold the same number from the first to the fifth. If your FTP comes from an hour-long test rather than a short one, your 40-minute power is a little higher, and you can aim for the top of the range. During recovery, keep pedalling at an easy cadence rather than stopping.
Cool-down
10 min
10′ at 40–55% FTP
10 very easy minutes at 40–55% of FTP. Check your heart rate over the last two efforts: if it was brushing your maximum, you were probably a little above the right target.

How it should feel

Hard, but evenly hard. The first three efforts are manageable; the last two get very demanding because 3 minutes no longer wipes the slate clean. The narrow range means checking your head unit a lot, which at least keeps your mind busy. Guide: 7 to 8 out of 10.

Common mistakes

Going off too hard

It's the most common mistake on this format. The first effort at 102% feels easy; the fifth, at the same power, really doesn't. Stay mid-range until the first four are done.

Confusing it with Seiler's 4 × 8

Same effort length, but Seiler has you ride at the maximum you can hold evenly, with 2 minutes' recovery, which ends up higher. Here the target is set at your 40-minute power, and recovery lasts 3 minutes.

Stopping during recovery

The recovery is active: easy pedalling helps you go again. Stopping dead, especially outside, makes the first seconds of the next effort grim.

Riding to an old FTP

With a range this narrow, an FTP that's off by a few watts changes the whole session. Retest if your last test is more than two months old.

When to skip it

Before you start

A recently measured FTP.
Several threshold sessions already done, such as a 2 × 20.

Skip it if

You're tired, or a race or long ride is planned for the next day.
You're coming back from a break: go back to shorter blocks first.
You have doubts about your health: get medical advice before sustained hard efforts.

Origin and evidence

Level of evidence

Moderate evidenceLevel 3 of 5

2024 study: 22 well-trained cyclists (mean VO₂max of 67 mL/kg/min), 21 sessions of 5 × 8 min over 9 weeks. The higher the percentage of VO₂max reached during the efforts, the greater the improvement: that's a correlation, not a comparison between groups. The study prescribes the maximal average power over a 40-minute test; equating that with 98–102% of FTP is a Wattson choice. The intensity of the 3-minute recoveries, which the source doesn't specify, the warm-up and the cool-down are also Wattson choices. The study's authors aren't named here, for lack of a verified full reference. Bottom line: published protocol, moderate evidence.

Sources

Étude de 2024 : 22 cyclistes bien entraînés, 21 séances de 5 × 8 min en 9 semaines

Frequently asked questions

What power should I ride 5x8 threshold intervals at?

At 98–102% of FTP: 196 to 204 W for an FTP of 200 W, 245 to 255 W for 250 W, 294 to 306 W for 300 W. The study targeted your maximal power over 40 minutes, which Wattson equates with your FTP. If your FTP reflects an hour-long effort, aim for the top of the range.

Why target 40-minute power rather than FTP?

Because that's how the study set the target: your maximal average over a 40-minute test. Over an effort shorter than an hour, you can hold a little more than your FTP. In practice, the difference is small, and the 98–102% range covers both cases depending on how your FTP was measured.

How is 5x8 different from a 2x20 threshold session?

The time on effort is the same, 40 minutes, but the 5 × 8 cuts it into five pieces with 3 minutes' recovery, which lets you ride slightly higher. The 2 × 20 trains patience over long blocks; the 5 × 8 pushes heart rate and breathing closer to their maximum.

How many 5x8 sessions should I do a week?

One, sometimes two in a build phase, with an easy day between. In the study, riders did a little over two a week, but within a supervised programme and at a high level. For most riders, one session like this a week is enough.

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