Re-Thinking CTL, ATL, and TSB For High Intensity Work

Hello everyone,

64636220I am about to dive into a complex topic, and I don’t have the time in this article to cover the basics of using a Performance Management Chart (PMC).  I am writing this article for the reader that is fairly well versed in using the PMC and the specifics within that training log/tracker.

This is the time of year where most cyclists in the northern hemisphere begin to switch from our base phase of training to our build phase of training. In my build phase of training I focus on VO2 Max intervals, Threshold Intervals, and try to get in one endurance ride every week or every 2 weeks depending on my schedule.  The problem I always have when rebuilding my fitness in the base phase (driving up CTL and ATL) and moving into the build phase of my training is, “TIME.”  Most of us average Joe or Jane cyclist have full time jobs and family commitments.  This lack of time forces me to maximize my use of time by completing workouts that are shorter in duration but higher in Intensity (IF).  This results in a flat CTL, meaning your CTL is not losing ground nor is it gaining ground.  The problem with this “Flatness” in my CTL is that it impacts TSB.  TSB becomes nearly useless for me as a gauge on how I’m feeling.  This could also be a condition of being north of 40 years old, I don’t know, but what I am about to propose is something different that I will try out this year.  I want to change the way I compute TSS so it does a better job of representing TSB and how I feel.  

Okay, see let’s get right to it.  Here is my problem.  The PMC becomes useless to me as a tool for training when I start the build phase of my training plan.  I cannot use TSB as an accurate measurement to understand if I am fresh or not.  For example, if I have a build week that has 4 workouts with IF’s above .90, I’m completely gutted that week.  Let’s say I’m carrying a current CTL of 70 into my build phase and the formula for calculating TSS as we all know, rewards us very well for those long rides.  These 4 workouts are under 90 minutes and give me a TSS of anywhere from 70 to 110.  With some easy recovery rides in there, you are looking at a weekly TSS in the 500’s with very tired legs (ATL of 71).  Your legs are tired because you are doing very intense work in short periods of time.  Just like a 3+ hour ride stresses your legs due solely to time pedaling (giving you a high TSS), these short duration rides stress your legs just as much.  However, our short duration rides carry a lower TSS value and never really raise our CTL.  We could have very tired legs with a flat CTL and a TSB near zero.  TSB is no longer an effective gauge on how we feel.

Screen Shot 2016-04-11 at 10.37.41 AM
This was last years base to build phase.  As you can see I took a decent rest after months of steady work slowly raising CTL.  However, once I started my build phase, the lower, but more intense workouts flatlined my CTL.  This chart now becomes a useless measurement tool for me.  If I had unlimited time to train, this chart would be more useful.

For me, this gets a bit frustrating.  I rely on the TSB to give me an accurate measurement on how I feel.  I believe it is an important element, if not one of the most important elements of the PMC.  However, it just doesn’t work for me anymore once I hit the build phase of my training.  It works very well in the base phase of my training and it would work very well if I had unlimited time to train.  However, a person who only has 8 to 10 hours a week… It just doesn’t work anymore.  So, here is what I am proposing and what I will try out this year.

I’m proposing a change to the TSS calculation once we move into the build and speciality phases of our training.  This only applies to people who have less than 10 hours a week to train and are forced to do most of their work using high intensity training with one long ride once or twice a week.  To explain this, let’s look at the current formula to calculate TSS.

(s = seconds in an hour, NP is Normalized Power, IF is Intensity Factor, FTP is Functional Threshold Power, and TSS is Training Stress Score.)

Here is how the formula works: The first bracket is Seconds in your workout multiplied by IF of your workout.  You divide that by your current FTP times 3,600 seconds which represent seconds in one hour.  Then you multiply everything by 100 to get TSS.

I plugged in one of my most recent workouts that was 72 minutes long, carried and IF of .94 under my current FTP of 305 watts.

[(s x NP x IF) / (FTP x 3,600)] x 100 = TSS

[(4320 x 286 x .94) / (305 x 3600)] x 100 = TSS

(1,161,388.8 / 1,098,000) x 100 = TSS

1.058 x 100 = 105.8


Pulling a TSS of 106 for 72 minutes of work was brutal to my legs.  This workout was a 2 x 20 workout with one 4 minute VO2 max effort at the end.  I can assure you my legs were demolished, and my legs would argue that the TSS should be higher.  After this workout, and two weeks into my build phase, I’m carrying a TSB load of -4.2. I can assure you it feels more like a -15 TSB today.  The TSB just isn’t representing how my legs feel.  So, what do we do?  Do we just disregard the PMC at this point?  Go off feel from here on out?  I propose we change things up and make the PMC work for us who, well, have to work.

Here is my new proposal that I will try out this year.  I’m not sure how effective this will be, or if I’m just going to hit that flat spot again at the end of my build phase.  To make things simple I will give you the answer right up front with a few conditions.  Workouts have to be longer than 40 minutes but less than 120 minutes.  We only adjust TSS for workouts with an IF higher than .90.

Below is my new formula.  To make this simple for the people who don’t like math, this is how you do it.  Let’s say your IF is .94.  You only look at the hundredths place in your IF.  Take that number, which is .04 and multiply it by 1000.  This give you 40.  Add that number to your TSS.  To make it even easier, for a workout with an IF of .91 you add 10 additional TSS, .92 you add 20 additional TSS, or 1.00 you add 100 additional TSS.  If you have a workout that is higher than 1.01, then I would look to do a new FTP test.  Pretty easy right?

Okay, same formula below but with my added component.

[(s x NP x IF) / (FTP x 3600)] x 100 = TSS + [(IF – .90) x -1000] 

[(4320 x 286 x .94) / (305 x 3600)] = TSS + [(.94 – .90)-1000]

(1,161,388.8 / 1,098,000) x 100 = TSS + (.04 x -1000)

1.058 x 100 = TSS + (-40)

105.8 – (-40) = TSS

TSS = 145.8

Now a TSS of 145.8 gets me closer to how I feel.  Will this inflate my CTL over time, sure!  What do I care more about CTL or TSB?  I care about them both.  Having a CTL that doesn’t move, even though you are burying yourself is not good.  We are trying to use the PMC so we don’t bury ourselves, and a steady diet of high intensity work with a flat CTL and flat TSB can lead to an injury.  So, us working folks need to make some adjustments or else injury could be rapidly approaching during our build and speciality phases of our cycling training.

Screen Shot 2016-04-11 at 10.33.01 AM
This is a current snapshot of my PMC.  As you can see, I started my  build phase towards the end of March and I’m already flatlining.  I’m flatlining because I can’t raise ATL on a steady diet of High Intensity work.  The TSS values just don’t reflect what is really going on right now with my legs.  Adjustments need to be made. 


I’m going to give this a try over the next 3 months and see how it works out.  Maybe it will, maybe it needs some more adjustment.  What I do know, is that my PMC is starting to become worthless at this point in my training and I want to use it.  If anyone has any other ideas or formulas, feedback is definitely appreciated.  One more thing, I don’t race longer than 90 minutes so we can take that out of this equation here.  Yes, if you race longer than 60 to 90 minutes, then I would stick with the standard PMC formulas because they are accurate for long distance events.  Take care everyone, and I can’t wait to see how my training plan has affected my performance this year.

Aaron Johnson

Aaron Johnson

Aaron served in the military for 20 years. Multiple tours in Iraq and Afghanistan. He retired from the military after 20 years of service to take care of our three small children in 2013 as a Stay At Home Dad.

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2 thoughts on “Re-Thinking CTL, ATL, and TSB For High Intensity Work

  • May 17, 2016 at 4:49 pm

    Any update on this now a month end? I am in same situation but just a month behind you (finding my CTL flat lined with high intensity work starting as I end a sweet spot base that includes VO2 work at the end).

    • May 17, 2016 at 5:03 pm

      Hello Chris. No update for this. I just accept that my CTL will flat line as I move into my build and speciality phases. At that point, the PMC starts to become worthless. You need to go off of feel. I usually need more recovery when I’m doing workouts with IF’s over .90. That leads to a flat or declining CTL which then throws off TSB.

      It is tempting to use a different formula, I just haven’t gotten around to it yet.


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