Never Plan Steady Threshold Intervals

After racing this year, I am rethinking my approach to polarized training and currently need a hard focus on lactate threshold (FTP) work.  Yesterday, I rode the classic 2 x 20min at FTP and failed miserably.  I thought this was odd because I succeeded in riding the same workout less than a week ago.  Now, I’ve found a better way and so I’m sharing it today.

Cancellera in a TTNever Do Threshold Intervals?

First I need to clarify one point.  I didn’t say “never DO steady threshold intervals”.  That’s because threshold intervals done properly are probably the biggest stimuli possible for driving up your lactate threshold power and making you a better runner or cyclist.  Instead, I wrote, “never PLAN steady threshold intervals”.  The reason for the distinction is the purpose of this post.

Second, I also need to emphasize the word “steady” in the title of my post.  What I’m talking about here are intervals that are of steady long duration.  I’m not talking about interval workouts that include “micro-recoveries” like I’ve blogged about in the past.  Micro-recoveries are another great way of doing this kind of work.   Instead, we’re talking about gold standard workouts like 2 x 20min at FTP or 2-3 x 20min at half-marathon pace or faster.  These are LONG intervals at a tough pace.

Why Should I Not Plan Steady Threshold Intervals?

These workouts are tough, physically and mentally.  In a race, there is a ton of motivation around you and so it’s easy to keep up the focus and the effort.  But when training (particularly when training alone), it’s really hard to keep the focus.  Plus, if your recovery is off or you’ve had a stressful day, it’s all too easy for that focus to slip off the table.

After I aborted my 2x20min workout after only the first interval, I started surfing around the web and came across Jesper Medhus’s ideas of focusing on sub-threshold intervals instead.  Jesper coaches a lot of very elite up-and-coming stars so he knows a thing or two about coaching.  He notes,

VO2 max intervals and threshold power intervals are the two most time effective ways to increase performance. But there is one major problem: high intensity intervals only work when you finish them. If you do not manage to maintain the correct intensity throughout the interval session, the effectiveness decreases. Thus, you will achieve better training if you choose an intensity with a higher success rate.

It is my experience that the success rate of high intensity intervals is lower than sub-maximum intensity intervals. Still, sub-threshold power intervals do offer significant improvements when made in appropriate doses. Also there is an argument that there is a physiological sweet spot because you can train at quite a high oxygen consumption without going anaerobic. Thus, you will give a great lift to your aerobic system (and almost nothing to your anaerobic performance).

On these points, I couldn’t agree more.  When I quit my 2x20min workout, I was pretty shredded and there wasn’t much more I could have done.  But I also left half the workout (and half the fitness gains) on the table.  So I definitely should have done sub-threshold work yesterday instead.

But, on the other hand, I don’t want all my FTP-boosting work to come from these less-effective sub-threshold intervals.  There are some days when the stars align and it’s possible to reach a little higher and get a little more training effect.  Those are the kind of days when true lactate intervals are in the cards.

Solution: Plan Sub-Threshold Intervals But Be Nimble and READY for Threshold Intervals

So what’s the solution?  When you’re planning your training schedule, PLAN for sub-threshold intervals but BE READY for true threshold intervals.  The way this works is to plan for and be fully onboard with the idea of sub-threshold intervals but have a true threshold workout in your back pocket “just in case.”  So start your sub-threshold intervals and nudge up the power on the first set.  Because these are all long interval workouts, you’ll know pretty quickly whether you’re feeling spunky and able to reach a lot higher or if you’re feeling tired and need to keep it under control.

A specific example may be useful.  Instead of planning 2 x 20 minutes on 3-5 minutes recovery  at FTP, I should have planned a sub-threshold workout like 4 x 15min at 90-95% FTP on 3 minutes recovery.  During the first interval, I should slowly ramp from 90-95% FTP during the first 10 minutes.  If I’m feeling good, I should punch it up to 100% FTP for a minute or two and assess how I feel.  Let’s say I feel great and by 15 minutes, I’m thinking I can easily go for five minutes more.  Then I can do a quick switch and convert the workout into a true threshold interval set and go for 2 or possibly even 3 20-minute intervals at 100% FTP.  But let’s say that bump to 100% felt like scaling Everest and and I’m pretty miserable 2 minutes into the set.  Then I need to bump it back down to 90% and finish the workout as planned.  More often than not, it won’t be quite as clear.  In this case, I should ride out the entire first interval (last 5 minutes at 100% FTP) and ask myself if 2 x 20 minutes at this intensity is possible or not.  If in doubt, just opt for the easier (but longer) sub threshold workout.  To do that, I just have to tell myself that aborting the workout is the worst outcome for my fitness– better to stick to the plan and complete the original workout than to fail.

What’s Next

So have I given up on polarized training?  Or is it useful in specific conditions?  And just how do I decide if I need to focus on lactate threshold or maxVO2 work?  All of this is for an upcoming post.

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2 thoughts on “Never Plan Steady Threshold Intervals

  1. Good observations Ken! Having workout contingencies is always a good idea.

    The only limitation of the workout readiness = stars aligning analogy is that, unlike stars aligning, athletes actually have control (to varying degrees) over their preparedness for high intensity workouts. How you time vo2/anaerobic/supra-threshold work relative to other workouts can affect how prepared you are for it.


    • Thanks Colin! Absolutely agree that timing is the most critical aspect. But I’ve still gone into plenty of workouts that I should do well on paper but haven’t. Maybe it was a bad night of sleep? Maybe it was a bad day at work? I think this strategy is really all a mental game. It’s easier to feel better about workouts if initial expectations start a little lower and build upwards than if workouts start high and occasionally fall flat.


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