Why is rest between intervals (almost) always at 40% ftp?

Hi,

I love TR for the multitude of workouts, but am a bit surprised that no matter what type of workout I do, I always have my rest-interval at the same 40% ftp.

Don’t get me wrong, after 8 minutes of lactate-building on 108% ftp I definitely NEED that 40% break but after 20 minutes at 88% ftp I am bored out of my minder after minute 2 of a 6 minute rest interval at 40%. Then I wish the rest-interval would be more like 60% ftp or something.

Off course I press the +1% intensity button 50 times if I want to go from 40% to 60% but I want to learn about the rational behind it. Is 40% always the best recovery intensity?

I reckon it strikes the right balance between “easy enough to allow for fast recovery without feeling the need to stop” and “not so easy that you’re literally just spinning your legs round and round”.

I suspect that sometimes the rest intervals are longer than they absolutely need to be in order to make the overall session hit a nice round number (1 hour, 90 minutes, etc). If you find this a bore and genuinely think you’re ready for the next interval sooner, you can always skip forward in the workout, or create a shorter version in Workout Creator.

I am pretty sure the 40% for rest intervals is in response to research that shows this percentag of threshold is the most efficient level to reduce lactate. I could be wrong butthought i read that somewhere.

Workouts like North Pack or Aniakchak’s rest intervals are closer to endurance level. You can find those in the short power build program.

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I imagine that it’s because 40% would allow almost everyone to recover from the hard intervals and be ready for the next one while 60% may leave you a little flat for higher intensity intervals. So the cost of higher power recovery intervals (not recovering and maybe boredom) far outweigh the benefits (negligible aerobic benefit, less boring). You can always increase the power if you feel that you are still able to hit the hard stuff as intended.

It’s probably mostly just a simplification reason that almost all are the same percentage. You can’t get uber specific workout to workout and athlete to athlete when you are building 1000s of workouts for 1000s of riders.

When I do the outdoor workouts I just kinda pedal at an intensity that feels super easy. So between VO2s that might be 120 watts and between SS that might be closer to 200 (330 FTP for reference)

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I treat it as a plug number for light spinning – keep the legs moving but don’t do any real work. The text often says the precise output is irrelevant, and to get off the bike and stretch if you prefer.

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Those workouts are in all the MV build programs.

40% is enough to keep the blood flowing and avoid trainer power floors or overspinning (or falling over sideways out on the road!), but low enough to recover HR and respiration quickly before the next interval. Doing Z2 in between muscular endurance intervals can be detrimental to completing the prescribed work and the benefit is minimal. You can probably get away with it sometimes on easier workouts, but I wouldn’t make it a habit to dial recovery intervals up to 60%, etc.

They just talked about this in podcast episode 259 too, right about midway through.

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I think it’s just one of those, ‘It is what it is’ things.

You probably could get away with doing anywhere between 30-50% and still recover. But if they put it at 40% everytime, you come to get comfortable with that power output and mentally you find some comfort, which helps you relax. Also, regardless of where you are in Z1, you really are not getting a lot of training benefit there.

Regarding the fact that intervals are too long or too short. That is subjective to the rider. If you have been training a while you can start to reduce the amount of rest inbetween intervals. I believe that some coaches do this during their planning for people who are interested in TT’s. As you progress through the training blocks, you do longer intervals and shorter rests. As amazing as TR is, I’m not sure that they can develop that for an individual since it is very subjective to the rider and where they are in the training cycle. So, if you are feeling good to go, you should skip ahead to the next interval and not spend time in Z1.

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A large percentage of my failed workouts stop during those long rest intervals. It may be because I’m conditioned for riding off road, but in general the recoveries are too long and boring for me. It’s very difficult to stay focused. It’s not that I don’t need a rest interval, but I just don’t need so long between work intervals.

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Someone may correct me if I’m wrong…

But I think if you are on a PC or Mac you can pause the workout and then skip ahead. So if you are 2 min into a 5 min recovery interval and you are losing it then you could skip forward to minute 4 and get back into the work. If you don’t need the recovery to complete the work then that may be a viable option. You will lose a couple TSS but you will get 99% of the benefit compared to just quitting the workout.

Also, sometime the -1 versions will drop some of the time between intervals in order to shorten the overall workout time.

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40 because 41% is too much.

Honestly, there is only 1 workout I’ve done in the years of TR where I’ve thought this is way too much rest. That workout is Hunter with 15 min recovery intervals. I alway sub a different 2hr SS workout when I see that. But otherwise, I am really thankful for the 2-6 min of easy spin recovery.

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Before using TR, I followed another set of structured training plans where rest intervals were almost always at 75%. I was specifically training for a Gran Fondo / Century with much more steady state effort, compared to a crit that surges a lot (look at any of the TR race analysis videos to see that about 25% of the race is VO2Max or above, 25% coasting or active recovery, and the rest in the middle across all zones).

There is an argument to be made that if you can recover at 75% FTP (or so) then maybe your FTP is too low, but I’ll posit (bro-science with N=1 data points) that it depends on what you’re training for.

I seem better suited for longer, more steady state efforts so I prefer 70-75% for any recovery interval 3 minutes or longer. Much below that and I start to cool off too much and find getting back up for the next interval takes more demand than what it’s worth. Specifically, I like my recovery HR in the 130s (max is probably high 170s or low 180s). 70% puts my HR at 132ish, 75% at 137ish.

For shorter recoveries, especially 20/40s, 30/30s, and 40/20s I set the recovery to 50%.

I use Workout creator to edit all interval workouts to 1) change the warm up to a 15-minute ramp and 2) raise recovery intervals to 70-75% (3-minute or longer recoveries). Take my last two interval workouts, for example (see below). I altered the workout recoveries to 75% but ended up dialing them down to 70% due to increased temp and humidity in the basement. Also, I find that if I can do a bunch of workouts in a row recovering at 75% then it is in fact time for a ramp test.

Anyway, just my two cents.

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“40%” is “%04” spelled backwards.

Just thought I’d share.

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@rkoswald indeed i also feel it would aid more for being able to recover at a higher % of ftp. For me 60% would be ideal. If i ride at a lower % then my rpm goes down to keep having enough muscle tension