TSS Augmentation?

Unfortunately TSS treats every hour linearly (i.e. just the same) — so a 4 hour ride averaging 200W results in the 1st and 4th hours being identical in terms of accounting for TSS. We all know the 4th hour, while the same load, it’s a much higher stress level.

Anyone accounting for this? Can’t be a plug figure or algorithm for everyone as too much physiological divergence.

I once stood still for an extended time at a traffic light and my Tss was still ticking over. I’m guessing my Hear Rate influenced it?

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Crazy stuff! I can’t see my TSS accumulating in real time, only the aggregation after I download it (from SRM PC8).
I’ve been playing with an additive % for each subsequent time increment of similar output (watts) and also looking at increasing HR as an augmentation factor as the latter accounts for heat/humidity as well as increasing fatigue although there is a tipping point where neuromuscular fatigue prevents HR increase although stress is clearly still going up.

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Must be a modern feature then only found on new bike gps computers. I’m using a Garmin Edge 530 now.

There was a similar question presented about TSS. In that post @Lacey_Rivette answered with some TSS estimates based on time spent in your power zones Entire Season Plan? - #11 by Lacey_Rivette.

Hope this helps.

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Unfortunately, she is just aggregating in a linear fashion and making no upwards adjustment for time spent later in the ride in the same zones as earlier in the ride. My point is that being in zone 2,3,4, whatever is more stressful after fatigue sets in than it is when fresh.

There is such a thing by feel of how 50 TSS feels in the fourth hour of ride compared to the first hour. However, that doesn’t mean you weight it heavier - to me as a coach it just means you need to do more 4 hour rides so that the final hour doesn’t feel so difficult.

In other words the first few long rides of the year feel much more difficult than when you are trained and a 4 hour ride is no longer a big deal. You can handle those and then be able to ride 5-6 hours.

Andy Coggan would answer the same way I think.


Great objective (to train so that the 4th hour @L2 is the same “stress” as hour 1) but it’s really a data compilation question. Because even if one could become sufficiently fit to accomplish that @L2, the system will still be scoring hour 4 efforts @L3,4,5,6, etc. the same as if those were done during hour 1.

There needs to be an augmented scoring factor for efforts done while less than fresh — admittedly difficult to calculate and different for everyone and changing over the course of one’s season.

TSS is a direct measurement of the training you do - the positive physiological adaptation. You are talking about Acute Training Load, I think.

If you artificially inflate TSS due to feel you will essentially be ‘messing up’ the model"

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I agree that “load” is the same regardless of when done during a fatiguing session but load is simply the output (Watts). What I’m questioning (along with many others including Dr. Stephen Seiler, PhD) is the “cost” of that output (“TSS”) and when fatigued that cost is higher but TSS doesn’t reflect that.

@MainerBill The same could be said for 5x8 threshold intervals vs 40 minute straight threshold effort. One definitely feels harder, but would have the same TSS.

Yes, true re PE, but what I’m looking at is actual physiological cost of the efforts. As muscles become fatigued, one must use an ever increasing percentage of the muscle fibers in order to generate the same force. Looking at TSS as a metric regarding one’s ability to recover, doing L4 intervals in the 4th hour instead of the 1st hour of a ride is physiologically much more expensive and stressful and quantifying recovery will be different even though the two rides will show the same TSS.

Hold up. Don’t Coggan/Allen go into the fact that the TSS model, while based on Bannister’s impulse-response model is not, itself, measuring adaptation (i.e., response) to training load. Rather, TSS is a measure of stress only.

I agree with your basic point – TSS has its limitations and doesn’t differentiate between 4 1 hour rides and 1 4 hour ride, for instance. IDK whether some of the other metrics out there try to measure that. Seems like part of the value of a good training planner/coach is dealing with training composition that the single number doesn’t capture, but that is pretty artsy, isn’t it?

No question. Effective coaching is the artful application of science and there are certainly times when the “art” part of the equation becomes most important in getting the best out of a trainee.

Load (watts) and duration (time) are easy to quantify but combining those to somehow calculate the resultant stress gets complicated — especially when the distribution of that load changes.

wheres the Topica Power group when we need them, this brings me back to 2004

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I can tell you Andy would not be in favor of artificially inflating/augmenting TSS

The folks who crafted the original WKO have acknowledged the issue and agree that WKO calculates TSS across durations linearly. I am in no way demeaning the accomplishment of Dr. Coggan or any of the others involved with WKO. It is also clear that “stress” calculations are highly individualized and it is impossible to have one algorithm that accurately calculates ongoing stress over prolonged efforts (barring some sort of genius compilation of numerous physiological markers in real time) — however, my question remains whether anyone has successfully found a means of discerning their own increased stress factor over prolonged sessions and resultant necessary recovery.

Have a look/listen here, thought provoking and clearly explanatory. (121) Load, Stress, Strain: Understanding the difference can make you fitter and faster! - YouTube