Short on time, keep it specific.
This is a great question I got asked on the Velo Performance YouTube channel.
Here’s my take based on both coaching experience and what the science tells us.
Technically, yes, you can. But would I recommend it? Not really. Here's why.
When you’re doing hard VO₂ intervals, the goal is quality. That means hitting the right power, holding it consistently, and doing it while you’re fresh both mentally and physically. You’re also likely to have more muscle glycogen early in the ride, which helps drive those high-intensity efforts properly.
Now, if you drop those intervals into the middle or end of a long ride, you’re fatigued, your output drops, and the session loses its value.
You end up with poor VO₂ quality and you interrupt the aerobic adaptations you're trying to build with steady Zone 2.
Why?
After a hard VO₂ set, lactate stays elevated for 30–60 minutes, and that high-lactate environment blunts the mitochondrial and fat-burning adaptations you want from endurance work.
As Iñigo San Millán, Pogacar’s coach, points out VO₂max and aerobic work are two different training signals, and when you mix them, you dilute both.
If you must add hard sessions such as VO₂ into a long ride, put these at the front after a warm up, when fresh and muscles full of glycogen to maintain quality and accept it takes 30 -60 mins to drop lactate back to the aerobic adaptation phase.
There are exceptions. If you're training for fatigue resistance, sometimes I’ll have a cyclist do a steady aerobic ride and then finish with some long, hard hill reps at high tempo or sweet spot. Not full VO₂, but tough enough to build that ability to push when tired. The other reason is that keeping the intensity at the end of a longer ride (as long as you're well-fuelled and well-trained/conditioned to do so) keeps the training stimuli as separate as you can. It is a tool in the training toolbox.
FINAL THOUGHT: You can, but keep in mind that mixing hard efforts in long rides usually means you’re not getting the full benefit of either.
Keep on keeping on.
Simon
Founder of VPCC
www.veloperformance.club
Everything good comes downstream of what you do now!