Anyone do intervals on singletrack?

I have heard that many people perform VO2 intervals by HR instead of power. When doing TR VO2 workouts, my HR may get to 181-182. If I am riding singletrack and go for a hard 4-5 minute effort, my HR will get to 186-187 no problem. I haven’t seen anything over 187 in a couple years so this is pretty much my max HR. I assume this is because I am using a lot more muscle requiring more oxygen. My NP and avg power is usually a little bit lower but there are way more anaerobic spikes when sprinting out of corners.

It is logical to me to complete some of my VO2 workouts on the trail. I could potentially alternate every other workout. I only race XC so specificity is there.

Anyone have any thoughts on this?

The problem for me would be that there is a lot of time in that 4-5 minutes where you won’t be pedaling. At least where I’m at, singletrack is super twisty with lots of ups and downs. Idk how you’d be able to pedal for more than like 50% of the time. I wouldn’t want to try any intervals on singletrack unless you had a long stretch of uphill riding.

As an aside, I think Jonathan has said on the podcast that he’s done some workouts where he does intervals up a fire road, then takes singletrack back down in the recoverys. That could be an option if you really want to add singletrack to an interval day.


It’s basically impossible to actually do VO2 intervals on singletrack. Even a 30 second VO2 interval is often too long before the next corner, let alone a 3-5 minute interval. Not sure where you’re at, but at least here for the Wisconsin XC series, I’d say my power profile during races ends up being more skewed towards short anerobic bursts than it does “steady” VO2. I actually just looked at a few of my past races and I tend to spend almost as much time in the anerobic zone as I do threshold and vo2 combined.

Now, a fireroad or gravel path, then sure you can do intervals, I do that all the time.


Over unders seem better suited for singletrack. Longer VO2 intervals (2-5 minutes) are supposed to give you that feeling in a race where you want to ease off for just a bit even though the lead pack is about to summit a climb 10 seconds in front of you. If you ease off, you lose contact. If you can sustain the suffering and blurred vision for a few more pedal strokes, you stay attached. On singletrack, it would seem difficult to not ease off even for a few seconds.

Yeah there is definitely a lot of coasting, but if the goal is to get HR up high and keep it there, these efforts are more efficient than 4-5 minutes of steady pedaling.

My limiter in steady 5” efforts feels like muscle fatigue not oxygen consumption.

You can try it, but it’s not going to be as effective as indoors. Firetrail up, singletrack down is the best compromise, but the descent needs to be pretty direct or else you’ll get too much rest between efforts.

Below shows a 4x10m firetrail with 5m singletrack descent between each. Followed by a trip up the hill on singletrack - look how varied the fifth one is! TR’s ‘zone table’ shows the range onHover - i’ve screenshotted Threshold to highlight with a grey rectangle. Apparently I only did 14 minutes time in zone, over a 4x10m! Pretty poor compliance

Doing an hour of strict efforts first followed by a skills / fun / cooldown session of trail riding might be a good blend. Enjoy

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I guess if you race on the trainer, than do your intervals there too.

Of course you can do it on trail. SST intervals for sure on a flatter loop. The type of hills you have on your local single track will dictate what you can do there. Usually they top out at 2-3 minutes for me. Just make sure they are a steady hill, that’s not too twisty, you know well, is one-way, and at a non-busy time.

I have to concur with others that a nice gravel route is probably your best outdoor option. Keeps the speeds down a little and less likely to interact with other people.

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IMHO that’s a bad idea. Picking the right terrain for outdoor workouts is key, and single track isn’t it.

Single track to me means technical terrain, twists and turns, so you should have enough presence of mind to read the trail and decide on a line. Also, you will have to modulate power to suit the terrain. In all, that seems dangerous. I’d use single trail to either improve yoru skills, have fun or both.

For VO2max on a mountain bike I’d use a long, non-technical climb of suitable length and gradient, and preferably as straight as possible. Some climbs are so steep that you have to go beyond VO2max for some sections simply to preserve momentum and to avoid super low cadences. @MN_XC has mentioned the keyword “gravel bike”, and I think this is right: non-technical, not as steep (as gravel bikes have harder lowest gears than mountain bikes) and relatively steady.

If you have a good feel for RPE, training on the trail is good. I wouldnt look too far into your actual power numbers on the trail tho, since as others stated you might not even be on the pedals the whole time. Just call it ‘race pace’ training.
I used to do a 7 min loop with some punchy climbs and descents. I was on my limit for race pace, but could bang out 10 laps no problem. I just couldnt have really dont them any faster. Repetitive laps are super important for improving handling since you’ll get many turns over the terrain to improve your lines. ‘Variability factor’ of 1.35. No TR workout could mimic that… Check out this graph of one ‘rep / loop’

It is logical to me to complete some of my VO2 workouts on the trail. I could potentially alternate every other workout. I only race XC so specificity is there.

I think the problem with this question is one of semantics. If you are trying to hit a specific power target for a specific duration, no single track is not the right place. But if you race XC, that is also not what you do on race day. You [probably] need to be able to get up a tight, twisty switchbacks with minimal traction, without dabbing, while bleeding out your eyeballs from going as hard as you can. So maybe no it’s not logical to do VO2 workouts on the trail, but it is logical to do MTB hill climb workouts on the trail.

I have a few 3-4 minute tight technical climbs near me that I use for a “Langley” (3.5 on/7 recovery) or “Hurd” (3 on/4 rec) style workouts. I just go as hard as I possibly can, while fighting for traction and maintaining balance. If I had a power meter, I most certainly wouldn’t be at the required powers, but that’s OK. It’s still very valuable training because it is what is going to be required for the races.

Maybe the other thing to consider is at what point in your season you are. It probably doesn’t make a lot of sense to do these outdoor hill climbs 3 months away from race season, but once you get closer to/in race season, this becomes absolutely necessary in my opinion.


I’ve got a loop by me that’s great for intervals. Have a steady incline where I can do about 8.5 minutes at ftp without running out of space and a great short punchy climb that’s perfect for a 30 sec all out intervals. Can then finish off the loop with some easy z2-3. A month or so before cx season starts, I’m there at least twice a week

I find just having a loop that you can lap out and going out and doing a time trial on it works.

It’s not steady state, because of what has been said above about the terrain having you stop pedaling.

I do however think you practice how you intend to race, so I like hitting the trails hard as much as possible.



You only race XC… doing some VO2 on singletrack is going to be a HUGE benefit. Even if you don’t pedal around a turn or have a small dip, the race pace like effort will help your skills as much as your fitness. Do I dare say it is almost essential some sessions be done outside?

Personally I love pushing the pace on singletrack… it’s a lot of fun… but the trails here are multi-use and multi-directional. If that’s your trails just make sure you are doing the intervals in an open spot with good sight lines for your safety. Last thing you want is to be hurting, head down climbing and someone comes around a corner full send.

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Just because your HR is high, doesn’t mean you’re working at VO2max. Otherwise a whole XC race would be one long VO2max workout.

Your HR is constantely high because on some parts of the track, you go way above threshold, which brings your HR up. You might stop pedalling for the next bit, but your HR stays high because your body is still recovering from the previous effort, and HR is pretty sluggish to react. By the time its dropping, you’ve hit the next power bit of the trail, and it never really drops.

Imo, if you want to do effective VO2max intervalls, you have to be pedalling hard for the whole interval. If you can do that on singletrack, do that, but most find it easier on non-technical terrain.

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I’ve always noticed I can run 10 BPM higher on single track than I can on the road over an extended period of time. I’ve always kind of assumed this was due to the additional upper body contribution required to ride single-track at racing speeds.

For me, I think it’s best to take care of the structured training out on the road or gravel. This is where something like a low-volume plan comes in. Here’s how I had structured my low volume plan back when I was racing XC.

  • Tuesday : TR Workout
  • Wednesday: Singletrack Easy (skills)
  • Thursday: TR Workout
  • Friday: Chill Ride
  • Saturday: TR Workout + Bonus Miles, or Group ride
  • Sunday: Long MTB ride

I agree. I think there’s probably a case to make that the more specific workouts are going to serve most XC racers more any way. I don’t respond well to traditional VO2 Max workouts, so I use them very sparingly.

Another point to make is that race simulations are a lot more fun and therefore are typically much easier to accomplish than a classic steady state VO2 max workout.

Of course there’s an argument to work on all SS zones depending on the course and/or the need for a “base” fitness.

I would argue that since VO2 max revolves around the total amount of oxygen your body is consuming rather than the exact wattage at the pedals, then singletrack intervals should achieve a similar training effect.

I used to be an XC skier and could do VO2 max workouts without pedaling at all!


Agree with this post.

It’s also a terrific way to train yourself for dealing with the technical downhill sections whilst breathing through your eyeballs.