Understanding direction of changes to TP and HIE

Customary apologies for a possible noob question. I’m still getting my arms around how individual workouts affect my fitness signature. If I take an easy ride with my kids, I notice that it drops both TP and HIE. I’m guessing the algorithm assumes that it’s the best I can do, and adjusts my fitness signature accordingly. Whether that’s the best approach I’ll leave to the experts, but I understand why my fitness signature moves in that direction. What I’m puzzling over is why those values sometimes drop after monster workouts. Today, tried Hardness Test 9, which has a target XSS of 130. I really pushed it, and ended up showing 180 XSS on the Xert Player, and then 214 XSS once the workout was uploaded. Does the algorithm look for peak performance numbers and then adjust downward if you haven’t matched your PRs? I’m also wondering why the Xert Player and uploaded workout show very different XSS figures. Thanks, and apologies if some of these questions have been asked and answered previously.

1 Like

Your XSS numbers change if the system determines a new fitness signature from the activity. A signature parameter can drop if you approach MPA but don’t surpass it. These have been termed near breakthroughs or fakethroughs by some (haha)… It just means that you came close to proving your current fitness level but not enough and the system lowers your numbers. This is not usually something to be concerned about as it doesn’t materially affect your training load or workouts and provides an opportunity to show that your fitness is indeed improving, the next time you have a chance. However, if this near breakthrough is a trend that doesn’t reverse, it could be the sign of overtraining or other performance issues that should be looked at.

Thanks, Armando. So that seems to mean that doing tons of repeats under your previous record MMPs will not increase (and may decrease) your fitness signature. But it would increase your “hardness” rating. If I’m right about that, then maybe a way to think about this is that an increase in your fitness signature reflects an increase in the size of your engine. Whereas an increase in your hardness rating reflects and increase in the size of your gas tank. Is that fair?

Not quite. Your signature is analogous to your engine with HIE like a refillable gas and. Hardness/Difficulty represents how hard can you run the engine. Does it breakdown with heat. Can you run it at sustained high power without the spark plugs misfiring.

Thank you again, Armando. That’s very helpful.