RunningSpeed and sprintsAdvanced 40 min

Supramaximal 15/15 running intervals (2 × 12)

Supramaximal 15/15 running intervals: two sets of 12 × 15 seconds at 115–120% of vVO₂max, with 15 seconds' walking between reps. Twelve minutes of efforts in a 40-minute session. Faster than vVO₂max pace, with breathing that stays high to the end.

Written by Pierre Halloo · Updated 25 October 2026

Session profile50 blocks

At a glance

Duration: 40 min
Main target: 115–120%vVO₂max7 Z7 · Neuromuscular
Time at target: 6 min
Estimated load: 39
Structure: 2 × (12 × 15″ at 115–120% vVO₂max, 15″ recovery), 3′ between sets
Level: Advanced
Equipment: GPS watch · Track (optional)

The session in detail

vVO₂max

Time in zone

Z129 min
Z25 min
Z76 min

What the targets mean

The session's targets, as paces for three reference speeds
Target	Zone	Time	vVO₂max 14 km/h	vVO₂max 16 km/h	vVO₂max 18 km/h
115–120%	7Neuromuscular	6 min	3:44/km–3:34/km 67–70 m per rep	3:16/km–3:08/km 77–80 m per rep	2:54/km–2:47/km 86–90 m per rep
25–35%	1Recovery	9 min	17:09/km–12:15/km	15:00/km–10:43/km	13:20/km–9:31/km

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What this session is for

15-second efforts let you run well above your vVO₂max without wearing yourself out straight away. Your speed and tolerance for very hard efforts get worked, and your aerobic system too: with only 15 seconds' break, your breathing never has time to settle.

The format was studied in the lab by Grégory Dupont and Serge Berthoin. Their most useful finding: with a passive recovery rather than jogging, runners lasted far longer, for roughly the same time spent close to VO₂max. Hence the walking here. No multi-week training study of this format was found, though.

Who it's for

Experienced runners already comfortable with short intervals, such as 15/15s or 30/30s. You need a recently measured vVO₂max: every distance depends on it. Not for beginners, or when you're tired.

When to do it

It's a full hard session in its own right: once a week at most, over a few weeks, in place of your usual interval session rather than on top of it. Put it after an easy day or a rest day, never the day before a long run, another hard session or a race.

How to do it

Warm-up
15 min
10′ at 60–65% vVO₂max + 5′ at 66–72% vVO₂max
10 minutes of easy running at 60–65% of vVO₂max, then 5 minutes at 66–72%, with a few gradual strides. On a track, put a cone at your effort distance: at 16 km/h, 77 to 80 metres from the start line.
Main set
15 min
2 × (12 × 15″ at 115–120% vVO₂max, 15″ recovery), 3′ between sets
Two sets of 12 × 15 seconds at 115–120% of vVO₂max, each followed by 15 seconds' walking, with 3 minutes' walking between sets. At 16 km/h, that's 77 to 80 metres in 15 seconds, between 3:16 and 3:08/km. Run at an even speed, like a controlled sprint, not flat out. The 15 seconds' walking takes you back to your start point: simpler than a full stop, which your watch can't programme. If your speed drops clearly, stop the set.
Cool-down
10 min
10′ at 55–65% vVO₂max
10 minutes of very easy running at 55–65% of vVO₂max. If you had to stop a set early, note which rep: next time, start with the easier version rather than forcing it.

How it should feel

Each effort feels like a controlled sprint: fast, but held together. 15 seconds' walking isn't enough to get your breath back, and your breathing climbs rep after rep. The last three or four of each set are very hard. Guide: 8 to 9 out of 10.

Common mistakes

Mixing it up with classic 15/15s

Classic 15/15s are run at 100% of vVO₂max with a jogged recovery. These are run at 115–120% with a walked recovery. They're two different sessions: don't combine the pace of one with the recovery of the other.

Running a true sprint

The target is above your vVO₂max, not your top speed. Sprinting off the line takes you past the distance early on, then leaves you with no legs halfway through the set.

Adding it to your interval session

It replaces an interval session; it doesn't go on top. Two sessions this hard in a week risk fatigue and injury for an uncertain benefit.

Jogging the recoveries

The session is built around a walked recovery. Jog it and you tire faster, and the second set falls apart. Walk briskly, without stopping.

When to skip it

Before you start

A recently measured vVO₂max: every distance depends on it.
Several short-interval sessions already done, such as 15/15s or 30/30s.

Skip it if

You're new to running, or going through a tired patch.
You have pain or a recent injury, especially in your calves or hamstrings.
A long run, another hard session or a race is planned for the next day.

Origin and evidence

Level of evidence

Limited evidenceLevel 2 of 5

Dupont and Berthoin (Can J Appl Physiol 2004;29(Suppl):S3-S16), 12 men: 15 seconds at 120% of vVO₂max alternating with 15 seconds of passive or active recovery, at 50% of vVO₂max, to exhaustion. With passive recovery, runners lasted 745 ± 171 seconds, against 445 ± 79 with active recovery, for similar time at VO₂max (191 ± 135 seconds against 180 ± 121). Dupont and colleagues (Can J Appl Physiol 2002;27:103-115) had already studied this kind of short effort above vVO₂max. Billat (Sports Med 2001;31(2):75-90) notes that formats of 10 to 15 seconds with 15 to 40 seconds of rest struggle to tax the anaerobic system alone. These are one-off lab studies: no multi-week training study was found. The 10/20 at 110% format comes from a programme by the Auvergne-Rhône-Alpes regional football league in France (2025): the practice is documented, its origin wasn't found. The 2 × 12 split, close to the time sustained with passive recovery in the study, the 115–120% range, walking in place of standing still, the 3-minute break, the warm-up and the cool-down are Wattson choices. Bottom line: good evidence on the immediate response, weak on long-term adaptation.

Sources

Dupont G., Berthoin S., Can J Appl Physiol 2004;29(Suppl):S3-S16
Dupont G. et al., Can J Appl Physiol 2002;27:103-115
Billat V. L., Sports Med 2001;31(2):75-90

Frequently asked questions

How fast should supramaximal 15/15s be run?

At 115–120% of your vVO₂max. In 15 seconds, that's 67 to 70 metres at 14 km/h, 77 to 80 metres at 16 km/h, 86 to 90 metres at 18 km/h. Put cones at those distances: over 15 seconds, they're more reliable than your watch.

Supramaximal or classic 15/15s?

Classic 15/15s are run at 100% with a jogged recovery: a VO₂max session. Supramaximal 15/15s are run at 115–120% with a walked recovery: punchier, they lean more on speed and the anaerobic system. Start with the classic version.

Why walk during the recovery?

Because in the lab, a passive recovery let runners last far longer than a jogged one, for comparable time close to VO₂max. A full stop can't be programmed on a watch, and it stiffens the legs: walking is the sensible middle ground.

How many reps to start with?

Two sets of 8 to 10, using the 110% version with jogged recoveries if the format is new to you. Then move to 115–120% with walked recoveries, and build to 12 per set as long as your speed holds. If it drops, the set ends there.

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