I'm not a coach, but those are just version of Chronic Training Load (Fitness), Training Stress Balance (Form), and Acute Training Load (Fatigue). If you look those up there is a ton of literature on them.

Strava's calculation may be some marginal variation on those, but it sure seems to correlate really well with the "real thing." And neither is anything new. The original concept has been around for what has to be decades now - used in products like WKO - and Strava has had it for at least 3 years or so.

Now that it's reality--I'm interested in expert opinions on its use, reliability, and construction as they relate to use by AGers. To me, it seems invaluable ... thanks for your direction.

With the advent of Strava and Zwift, I am predicting one of two things - a massive leap forward in performance OR, many burnt out and over trained before the season really get's going! I am guessing for more than a few, the latter.

You see years ago when we lived in dark caves for training, we rained long and slow all winter and then gradually built things up for racing our best in the late Summer when all the most important races of the year are! Worked well back then! :)

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Steve Fleck @stevefleck | Blog

Strava's weighted average power seems more accurate to me than wko's np, which in turn makes strava's training load seem more accurate than TSS, which in turn makes form/fitness seem more accurate than ctl/tsb.

I feel that wko puts too much emphasis on the short duration which skews np and tss. The other day I had a one hour "np buster" that was 50 watts higher than mftp which gave me a significantly higher tss than would be typical.

These are just observations based on my own numbers.

No idea if this is still the case but it used to be that when you'd update your FTP that the ENTIRE GRAPH would then change using the updated value - which would over/understate your current condition depending on the direction of your change.

As tim (poster above) said, last time I checked, as you changed threshold the entire graph would change (going from a 270 to 300 watt ftp shows a loss in fitness if thats how you want to use the term).

While there are pro's and con's to Strava vs TP vs WKO4... I find that really you just need to pick one and use it. These numbers are sort of like the birdseye view anyways. If you become familiar with any of them and track them on a general basis, you'll start to make educated decisions on training.

So basically... if you're going to use it, then understand it. Once you understand it, make better decisions on how to train. Once you make better decisions on how to train, dig deeper into the metrics that matter most for you. I know that doesn't really answer your question specifically, but even though it is a firm number, there still is an art to how you handle such data.

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COROS Sports Science

Over a decade, anyway. I first started playing with the idea (and it is *my* idea, not anyone else's) of what is now known as the PMC in the early 2000s, then publicly revealed it in 2006.

Thank you. I remember squinting often at the graph of fitness/fatigue/form in the Triathlete's Training Bible years ago and wondering how to measure fatigue and form ... I am thinking that the Strava feature is a big opportunity to someone like me who doesn't have a coach, and who can't measure how those three planes/metrics intersect on my own.

I'm an embodiment of Matt Dixon's "The ingredients are right, but the cake tastes nasty"--I train hard, but don't always improve--and that this tool can help me understand progress & lack thereof. Thank you.

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What are you people, on dope?

—Mr. Hand

The tool will show you if you're adding stress or training load along with your fatigue. That is extremely useful if you've never done that. That will make big changes to how you operate and your overall optimization of a week.

While it is great.. I would urge you to look further once you understand it. There are ways to trick the system to get a higher number that may not be relevant to you (example: training anaerobically to get a high number even though you want aerobic work). So again, its a great tool, but honestly its just the birdseye perspective... dig a bit further once you understand it.

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COROS Sports Science

Pubes? Puuuuuuuubes? Thought you'd be here by now.

Deal-killer.

I see wot you did there. Maybe he's still in the sensory deprivation tank

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What are you people, on dope?

—Mr. Hand