Thresh w Bursts - Wasting intensity points? Or great adaptations?

Trying to decide if these are super valuable and should be part of my mix, or I should skip this type and focus on others; supras, over unders, etc.

Hoping someone can shed some light on the benefits of workouts like Hilgard +1. Bursts are only 12 s long. So HR won’t have time to react, neither will O2 supply to cells, etc.

Are these specifically to force a lactate surge in the cells, and subsequent clearing at high intensity, so like a burst into VO2 max processing territory & recovery back into threshold zone? Like what metabolic processes are we able to activate with such short bursts, and are they actually valuable?

Or by spiking so hard for so short a time, are you really just creating a metabolic deficit at the cellular level that is impossible to properly recover from, and is creating massive intensity load, with very little positive adaptations?

Or are they to increase maximum muscular strength and safely / gradually strengthen tendons from the spikes in total force applied so you don’t tear something in a race when you hammer it to a stupid degree?

I’m leaning towards thinking that gradually hammering the gas, rather than OFF-SPIKE-OFF, might be both more valuable, and be better training for real-world situations. Like holding 90 - 95% FTP for 5 mins, ramp up to 150% over 10 - 20 s, hold 30 s - 2 min, spin back down and hold 95% for 5 mins, would sorta mimic climbing a short hill on a flat course.

What are these bursts trying to mimic and train for?

Secondary question is their value vs Heston, which I def do want to be part of the mix; standing burst efforts to practice surges out of turns, etc. If I’m definitely doing Heston, are these same bases all covered, and I can skip seated bursts like Hilgard +1 ? Or is there a big benefit to doing both seated and standing bursts of various intensities & lengths?

As always, super appreciate any insight & input!

I’d say “neither”.

One thing is abundantly clear: the ability to “clear” lactate is neither a determinant of performance nor something that can be trained independently. (I guess that’s two things.)

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Have you ever done a crit, or any type of bunch racing? I mean even in a TT, I might try and sit at threshold, but there’s a bump up the road, or a guest of wind, or I might need to overtake someone (I wish, hah).

I don’t think you need to look at every workout from a physiological perspective. some are just, erm, training for bike riding.


Race specific training? Maybe

Are you trying to raise threshold/improve time to exhaustion at threshold? These are not useful workouts IMO. It’s just going to make you fatigue faster and make it harder to maintain threshold for the block.

These fall into the “gimmick” type workouts where they try to make things more interesting than long blue blocks working on improving time at threshold. It’s the same argument at doing threshold workouts at 105% versus just doing them at 95-100%. Why add the extra fatigue for potentially not more adaptations

Again, race specifity? maybe it’s useful.


@The_Cog When you say “neither”, what do you mean? Like neither of these WOs would be particularly useful?

On the lactate thing, you mean the ability to process lactate can’t be trained / improved independent of other related metabolic processes, right? Like you’re working on that while working on increasing your VO2 max, max sustainable HR, etc, and there is no specific drills that can focus on lactate processing?

That’s was my current understanding, no clue if correct.

What I meant in the post is that these huge OFF-ON-OFF spikes [must?] cause a sudden lactate buildup, and then you drop back to 95 - 99% FTP, processing that lactate off at threshold pace. I’m guessing to increase your max O2 processing / lactate processing / max power output, all at once, right?

I mean, it’s gotta be a very different bio process & result than just holding 99% FTP for 10 or even 20 mins… right? And a massively increased intensity & fatigue load?

@splash that’s sort of exactly what I’m asking / talking about. Not well worded, apparently! :smiley:

“What is the point of doing these spikes?”, I guess.

Because, as you brought up, you might surge in a race with a pack, or against a burst of wind, or a short & steep uphill, etc. But those scenarios won’t look anything like these spikes. You’re not going to pop FTP → 200% FTP FOR 12s → INSTA-KILL THE GAS, BACK IMMEDIATELY TO FTP.

So we certainly ain’t ‘practicing for something’. And if I do want to practice surges, etc, I should probably pick a WO where the power curve is more reflective of what actually happens. Right?

I’m 99% sure they are designed to cause a huge deficit of the delicious stuff [O2, ketones, sugar) and huge surplus of the gross stuff [heat, lactate, etc], instantly, in the cells. Because your system can’t ramp up that fast.

I’m wondering what beneficial adaptation that kind of extreme stress gives. Or if they’re really just a lot of intensity points just for the fun & burn of it. In which case, that’d be a hard pass from me! :smiley:

Copy/paste from workout goals description


I think above scenario is closer to race experiences I have had than the below scenario:

I can’t think of a time where I slowly increased power over 10-20s, held the power, and then decreased it in a race. If I am in a pack it is always bursts (to get up a short hill, coming out of corner, covering an attack, etc). If I am by myself, I try to keep it as steady as possible.


FWIW here are the FasCat notes for sweet spot with bursts:

Perform the effort at Sweet Spot Wattages, then ‘burst’ out of the saddle for 5 secs at 200% of your FTP then return to sweet spot wattages.

Bursts are meant to help emulate the stochastic nature of bike rides, where you have to give it some ‘gas’/hard efforts to get up a steep section, out of a corner or close a gap to a wheel.

You should feel like you are working but not “suffering”

I love doing these.


you’re way smarter than me, but I’m with @splash here…these are great if you plan on racing or just riding with stronger riders…when they surge and force us above our threshold, but then still have to settle back at, well, threshold!

It’s on the rivet ++

very applicable to road and gravel… maybe not as much for MTB and cross unless a reallllly smooth course.

If looking at it from a physiological standpoint, I’d slot these under lactate tolerance. I’m a big fan of over unders and such for increasing FTP, but still think there’s a place for just drowning in lactate and having the body figure out what to do!

good luck with whatever route you go!



@splash nailed it for you here!

In almost every bike race, you’ll have to respond to surges or surge yourself depending on the people racing around you and/or the terrain you’re riding over. I also agree with @voldemort – the big power surges I personally experience in most (all?) of my races are typically quite sharp getting both on and off the gas.

Sustained power intervals with bursts are meant to simulate this scenario. It can be great practice for adjusting to the feeling of already going sustainably hard, needing to really push the pedals for a short burst, and then settling back in.

Short power bursts also aim to increase your ability to generate a lot of power in a very short period of time. Workouts with these bursts increase how much muscle you can activate and how quickly you can do it.

These bursts can be done seated or standing, depending on what you feel would be most applicable to your training and racing. It would be worth trying out both ways to see if you have a preference for one or the other.

Hope this helps! Feel free to let me know if you have any other questions.


I mean that they are likely neither a waste of “intensity points” (your glycogen budget) nor are they going to lead to “great (unique, especially large) adaptations”.

As others have indicated, they seem like a reasonable way of introducing some “stochasticity” into a trainer session, to better simulate actual cycling. Whether they are necessary or even beneficial, though, would depend on the rest of your training program.

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These are so short you are unlikely to burn thru anaerobic capacity. Well, if you are doing them under FTP. In any case, the FasCat notes I posted above are the way to do them. Don’t suffer. Burst out of the saddle as if you have to chase a move. Repeat.

Everything should be based on what you can actually do, not constrained to a % of FTP


You might say “alls you can do is alls you can do…”


Indeed, you might. :+1:


@empiricalcycling you care to weigh on on threshold w burst

There’s uhhh 2 whole podcasts about it

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If he doesn’t use the expression “spicy over/unders” I shall be very disappointed. :blush:

Not really. :upside_down_face: