HIIT Maintenance in the Off Season

I’ve gone from HIIT training year-round per the “Time-Crunched Athlete” style of training over the past 10 years to a more traditional, linear periodization schedule this season. I spent Nov-Feb doing mostly Zone 2/3 as well as cadence drills and workouts with bursts/accelerations to maintain/build neuromuscular coordination, leg speed, economy, etc. I trained 12-16 hours/week and maintained a CTL of 80-85. It was 3 weeks of work and then an easier recovery week. My coach would prescribe 1 hard workout per month, typically AC (Zone 6), like 1-2 min efforts in Zone 6, and maybe one sprint workout per month. The prediction was I would build a solid base of fitness and my FTP would likely stay the same or increase by 10W.
Now, in retrospect, the prescribed training did provide a solid base (aerobic endurance) but my FTP dropped about 15W (from 280W-265W) and my 4-5 min MMP dropped from 340W to about 310W.
As an older athlete (54), I think maintenance of your high end aerobic power (VO2 Max) is necessary during the off season because it is hard to get it back. Although things are improving now, I felt I had lost a lot unnecessarily.
The reasoning for not prescribing more HIIT in the off-season was that “you don’t want to peak in January”. (My MTB Races are June-Sept).
My question is: Would a once weekly VO2 Maintenance session with the aim of 10-15 min of time under VO2 Max be enough to trigger an early peak? My hope is to not lose that ability in the off-season and be able to maintain it.
A related question or stated another way: How often can one tap into activating Type 2 muscle fibers in the base phase (General Prep) without it negatively impacting Type 1 fiber development/aerobic endurance or causing premature fatigue and hindering performance/adaptation in the build (Specific Prep) and Competition phases…Thanks!

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I’ve pondered the same question. I wonder if it would be better to maintain HIIT 2X per week all season (except rest weeks) but periodize the intensity meaning sub threshold in the winter, threshold late winter/spring, above threshold closer to races. Dr. Seiler’s presentations on pro-level athletes seem to suggest this is common at that level. Is it the right approach for amateurs training 8-10 hours per week?

I do have that progression of starting with endurance and tempo and doing progressively longer time and then in Feb start doing Sweet Spot and muscular endurance and then progress into FTP work and VO2 max in the Spring. I just think one needs to tap on that Zone 5(90-100% of VO2 Max) as well as AC at least once/week to not lose those abilities and so when you start doing it, it’s not that shocking to the system…

Good points @josemd. I hardly did any VO2/MAP work this winter and I felt it when trying to really go hard this spring. Once per week all winter sounds like too much to me though. Maybe once per 3 week cycle in the winter??

You may be right. Certainly doing AC and NMP work once/month helped the glycolytic power (the turbo) for sure even though I am Type I dominant but my aerobic capacity suffered and my “diesel engine” shrunk, which is not great since most of my races are 5-7 hours and I rely mostly on aerobic endurance. Perhaps changing to VO2 work once/month would do it although once weekly and limiting it to 10-15 min of VO2 (as opposed to 20-30 min in build period) I’m hoping will do the trick…Certainly the intensity is more entertaining but I certainly don’t want to over do it as I have in the past…

HI @josemd,

Thanks for sharing your story. I have a couple quick thoughts…

Something that we seem to be addressing a fair amount lately is that question of training VO2max. This is controversial, but our overall position is that unless you are a novice, VO2max is not very trainable. More importantly, a lot of riders talk about “VO2max intervals” but they are a bit of a misnomer. They are done at approximately the same power you’d hit in a standard lab VO2max test, but they don’t necessarily train your VO2max.

My personal feeling is that they hit a combination of your top end aerobic energy systems and anaerobic energy systems. So they can cause a lot of stress. I don’t personally prescribe them, but if I did, I’d prescribe them much closer to the height of the race season. I wouldn’t have an athlete do them in January.

All that being said, I do agree completely with you that high intensity work is needed in the off-season. And I also agree that 1-2 sessions per week is about right. I personally prefer to prescribe work more around the anaerobic threshold at that time of year. There’s a ton of options, but my two favorites are 5x5 min intervals with 1 minute rests and 4x8 min intervals with 2 min rests. I find they can really stimulate a strong adaptation, but they aren’t too hard to execute. You want some efforts in the base season, but you don’t want your tongue hanging all the way out.

I also agree that it can be beneficial, once or twice per month, to add in some shorter higher intensity work just to keep your legs familiar with the feel. Especially as we get older. You can do that with structured work. Personally, I like to just jump into the periodic Zwift race and get 20 minutes of intensity.

In terms of tapping into type II fibers vs type I, I’m not aware of any research saying that activating your type II’s is going to have any impact on your ability to train your type I’s. In fact, training type II fibers is going to help them to learn to work more aerobically and improve your overall aerobic capacity. Plus, even if you go out for a 5 hour zone 1 ride, you’re going to give your IIb fibers a decent workout.

The issue isn’t using your type II fibers. The issue is that harder work does produce a certain level of neurological stress that if done too often for too long can lead to overreach and even overtraining.

Hope that helps!

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Thank you for your reply @trevor; thanks for taking the time. A follow-up question to the off season (Base 1,2,3) threshold training. Is there any logic in doing a progression where one would spend a few months doing only endurance/tempo and then transitioning into sweet spot and then finally into threshold, in say, Base 3 (for me March)? Is there a downside to doing work around threshold in the early Base period? Thank you!

Hi @josemd, there are benefits to doing a transition over the base period, but I wouldn’t go from sweet spot to threshold. Still working different systems. More importantly, if you’re going to do threshold work in the base period, it takes 10-14 weeks to see the full gains. If you do the math, that means starting in December to see the gains by sometime in March.

So, the transition I prefer is to build the time at intensity. So, the very early season, I’ll start my athletes with just one session per week of something as easy as 4x4 minutes at threshold. Just to get the feel of it. Then I may move them to 5x5s two times per week for about six weeks and then finally four to six weeks of 4x8 minute intervals twice per week.

If I’m going to give an athlete any sweet spot work, I tend to do that towards the end of the base phase as they begin to transition into the race period. But, I’ll add that to the existing work (during an overload phase.) I won’t use it to replace the existing HIT work.

Hope that answers your question!


@trevor, is there data to clarify if the same benefits can be gained by spreading the threshold intervals over a longer time period? If a person did the same number of threshold sessions (say 28) spread over a longer time period (say 20-24 weeks), would the same results be likely to be achieved? I’m curious because I find it hard to fit in 2 interval sessions per week in ski touring season.

Thank you @trevor, that’s great information! Very different from what I did in my Base period this season…

I don’t want to steal the conversation from Trevor, but will just add (having worked with a number of ski mountaineers that also race bikes) that during the ski season we’ll use “skintervals” to help find a balance. Since they are spending so much time on the snow, we’ll use their uphill skinning times wisely and do skinning intervals to mimic what we’re doing on the bike. So that allows us to still get 2 sessions in per week while their cycling volume is lower.

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@robertehall1, glad @ryan stole my thunder here. Got way behind last week.

But I fully agree. I haven’t seen specific research on spreading the work out over twice the time period. But, just thinking out loud, the principles of training are about producing a sufficient stressor to create an adaptation. Threshold work tends to be less stressful on the body than anaerobic capacity work. So, my feeling is that once per week is not enough and doing once per week over 24 weeks would just cause you to stagnate.

So, I fully agree with Ryan’s suggestions. Threshold work is also a little less specific than other types of work since you’re trying to hit your aerobic engine. You’re going to get most of the same gains if one session per week is on the skis.


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@trevor, when you say 10-14 weeks to see full gains from threshold work, do you mean when doing two HIT sessions per week? If that means a total of 20-28 threshold HIT sessions , when you include rest weeks every 4th week, that would take ~ 5 months to accomplish.

Hi @robertehall1, no it’s not about counting the number of sessions. The period to see gains is 10-14 weeks. Beyond that I think you’re going to stagnate if you don’t change things up regardless of whether you did two sessions per week or one session per week and whether or not you did them every week.

During that period, I personally recommend doing thresholds twice per week (and maybe once towards the end of the recovery weeks.) If you only do them once per week, my impression is that you are going to see minimal gains even if you trained for 4-5 months. Individual threshold sessions are less damaging, so to produce enough stress to get a training stimulus, they need to be executed regularly (i.e. twice per week.)

But I definitely wouldn’t do them straight for five months. You’ll stagnate for sure.

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@robertehall1 I would agree that 8-12 weeks is a bit of a magic window.

There should be some solid gains around 8 weeks and maybe up to 12.

If you aren’t seeing gains then there should likely be another type of training stimulus to see some gains.

If you find the right intensity for gains and repetition of the stimulus you may be able to handle 3x per week.