How Matthew Brennan Trains (Five Vuelta Stages at 21)
Brennan won five stages of the 2026 Vuelta on his Grand Tour debut at 21. Under the sprint sits a track pursuiter's engine. Here is how it works.
On Wednesday in Seville, Matthew Brennan won his fifth stage of the Vuelta a España. He is 21, it is his first Grand Tour, and he has won every bunch sprint he has contested in it. The last rider to take five stages on a Grand Tour debut was Fons De Wolf at the 1979 Vuelta.
The part that explains it happened three years ago, on a track in Colombia.
A junior world record over three kilometres
At the 2023 Junior Track World Championships in Cali, Brennan won the individual pursuit in 3:07.092, a junior world record, then won the Madison with Ben Wiggins.
Three kilometres in 3:07.092 is 57.7km/h, alone, for over three minutes. That is not a sprinter's test. An all-out three-minute effort sits on top of the aerobic system, with oxygen uptake pinned near maximum for most of it. A pursuit is closer to a VO2max test with a standing start on the front.
He went to Visma's development team in 2024 and the WorldTour in 2025, skipping the U23 route. He is 1.77m and 68kg.
He is probably not the fastest man in the race
Sixty-eight kilos is light for a sprinter. The specialists who win flat, straight finishes are five to eight kilos heavier and produce more raw watts.
Look at where his wins came from. Stage 2 into Manosque was an uphill sprint, and the riders he beat were Pau Miquel and race leader Tadej Pogačar. Stage 16 followed an hour over the hills above Cortegana. His own description: "I'm a sprinter but I can climb a little bit."
The question in a Grand Tour sprint is rarely who has the biggest ten seconds. It is who still has ten seconds after four and a half hours.
Critical power and W'
Critical power (CP) is the highest output you can hold in a metabolic steady state. Below it your muscles settle within a couple of minutes. Above it, nothing does.
W prime (W') is the fixed amount of work in kilojoules available above CP. It is a battery, not a tap. It drains above critical power and refills below it, more slowly than it drained. Empty it and you stop. That is Jones and Vanhatalo's formulation of a model going back to Monod and Scherrer.
A sprint spends W'. Winning one after five hours is a W' balance problem, and there are two ways to arrive with a full battery: raise the ceiling so more of the race sits below it, which is what a pursuit engine does, or spend less of the day above it.
Critical Power
229W
W′ (anaerobe arbeid)
12.9kJ
12857 J
| Zone | Bereik | Wat het traint |
|---|---|---|
| Z2 | Duurvermogen ≤ 183 W | Aerobe basis onder CP. Makkelijk, RPE 3–4. |
| Z3 | Tempo 183–206 W | Constant werk onder de drempel. Comfortabel zwaar, RPE 5–6. |
| Z4 | Drempel (CP) 206–229 W | Precies op critical power, maximale metabole steady state. Zwaar, RPE 7–8. |
| Z5 | VO₂ / W′-aanspraak 229–274 W | Boven CP put elke seconde je W′-batterij uit. Heel zwaar, RPE 9. |
| Z6 | Anaeroob ≥ 274 W | Zware W′-uitputting; korte maximale inspanningen. Maximaal, RPE 10. |
Z2 · Duurvermogen. Aerobe basis onder CP. Makkelijk, RPE 3–4.
Z3 · Tempo. Constant werk onder de drempel. Comfortabel zwaar, RPE 5–6.
Z4 · Drempel (CP). Precies op critical power, maximale metabole steady state. Zwaar, RPE 7–8.
Z5 · VO₂ / W′-aanspraak. Boven CP put elke seconde je W′-batterij uit. Heel zwaar, RPE 9.
Z6 · Anaeroob. Zware W′-uitputting; korte maximale inspanningen. Maximaal, RPE 10.
- Critical Power is de asymptoot van de vermogen-duurcurve: het hoogste vermogen dat je (in theorie) onbeperkt kunt volhouden. W′ is de vaste hoeveelheid arbeid die boven CP beschikbaar is, je anaerobe 'batterij'.
- Tweeparameter-CP vereist twee maximale inspanningen van duidelijk verschillende duur (bijv. 3 min en 12 min). Inspanningen die qua lengte te dicht bij elkaar liggen, geven een instabiele schatting.
- CP ligt meestal binnen enkele procenten van FTP, maar voegt W′ toe, wat modelleert hoe lang je boven de drempel kunt blijven.
Een PDF met je resultaten, plus een QR-code om ze altijd opnieuw te openen.
Use one effort around three minutes and one around twelve, both all out, on a climb or a turbo. You get CP in watts and W' in kilojoules. CP anchors your power zones. W' tells you what you have left at the top.
The lead-out is battery management
Sitting in a wheel cuts the power you need by roughly a quarter to a third. Across five hours that is the difference between nibbling at W' all day and arriving with it intact. A lead-out train protects as much as it delivers.
Before Seville, Visma reviewed the sprint Wout van Aert lost in the same city in 2024. Brennan: "We discussed this morning the sprint in Seville in La Vuelta '24 and what went wrong for Wout van Aert." They rode the wide approach along the Guadalquivir accordingly, and he opened his sprint at about 300 metres.
Van Aert has won two stages of this Vuelta and holds the green jersey. He has spent the final week leading out a 21-year-old.
What the last 200 metres is fighting
Air. Drag rises with the square of speed and the power to overcome it with the cube, so at 65 to 70km/h a smaller frontal area is worth a lot of watts. That is the Mark Cavendish model, and Brennan is within a couple of centimetres and kilos of Cavendish's dimensions. It is also why watts per kilo is the wrong lens for a sprint.
What is known about his training
Visma publish nothing, so anyone quoting his intervals is guessing. On the record: a track endurance upbringing rather than a track sprint one, altitude blocks in the Sierra Nevada, strength work prescribed by bar velocity, and WorldTour races at 19. He arrived with a three-minute engine and was handed races that reward a three-minute engine with a finish attached.
What you can steal from it
- A sprint you cannot reach is worth nothing. If you arrive empty, the fix is critical power, not sprint drills.
- Measure both numbers. Critical power gives CP and W' together. FTP gives the ceiling and says nothing about the battery on top of it.
- Train three-minute efforts. The most neglected duration in amateur training, and the one that raises the ceiling fastest.
- Sit in. A quarter to a third less power for the same speed, for free.
- Get low before you get strong. At sprint speeds, position beats watts more often than amateurs expect.
More in this series: Wout van Aert, Mathieu van der Poel, Tadej Pogačar and Marianne Vos.
Sources
- Wikipedia
- UCI on the 2023 Junior Track Worlds
- La Vuelta on stage 17
- La Vuelta interview after stage 5
- NBC Sports on the fifth win
- CyclingUpToDate on Visma's record seventh win
- Jones et al. on critical power
Cover photo by Txapisotegi, CC BY-SA 3.0, via Wikimedia Commons.
