Hi - My TP is on the rise in a really satisfactory way, however HIE is declining slightly… What approach / type of training should I use to get the HIE on the rise?
Thanks!
You will probably need to shorten focus e.g. athlete type Rouleur or even shorter, like breakaway specialist… depends what you’ve been doing so far of course
Before doing that though, what I guess you’re looking for is ability to ride at higher powers for those shorter durations? In which case you may find that e.g. your 5 minute power has improved, even though HIE has dropped, due to the higher TP… so it may be good to continue building from the bottom up (whatever you’ve been doing) for a while longer, or until you stop improving? Just a thought
I wouldn’t worry about slight changes in either direction. 
It’s not necessarily a bad thing.
Here’s a post from @xertedbrain from a while back –
HIE is … a number that represents the shape of [the power] curve with larger HIE values meaning the curve is wider to the right. Smaller HIE values make it more narrower.
HIE … is conceptually in line with burning carbs. A bigger HIE allows you to hold higher intensity longer and this essentially means you’re better at burning carbs. Burning carbs faster is equivalent to able to produce more power . They are synonymous. So while having a bigger HIE might mean ability to ride higher intensity for longer durations, it also means that you’re burning up carbs more too. This isn’t ideal for longer races or ultra-distance events. Hence having a smaller HIE in favour of a higher TP is better, even if that means lesser power at shorter durations. This is captured in LTP which is inversely proportional to HIE.
Related posts –
What kinds of workouts improve HIE? - Support - Xert Community Forum (xertonline.com)
PP, HIE and TP relationships - General - Xert Community Forum (xertonline.com)
Thanks for the insight!
Very clear, thanks for the information! It seems that for the type of event I’m aiming at which is a 200km TTT I really need not worry abt declining HIE, and should continue what im doing which is having a great positive impact on my TP and overall strength and fitness!
Thanks!
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I was just about to asked a similar question but saw this thread open. Over the last year I feel I have made some real gains - beating a lot of my PR on local Strava segments and feeling like I was riding reasonably ok on a club trip to the alps. One major change I made last winter was adding weight training and I felt this helped. Xert is reporting my TP has risen from ~260 this time last year to ~290 now - this is based mostly on outdoor data, and my local area where I ride is rolling countryside with some hills up to 150m height gain (never more than about 8 mins climbing).
Now I get bored easily so I tend to split up the winter season into blocks and use different tools etc, currently I would like to spend 6 weeks or so leading up to the end of year using TrainerRoad, so I just completed the Ramp-Test (I follow the theory that I should use the fitness test for the tool I am using), and guess what my FTP came back almost exactly the same as last year - no improvement… Looking again at my Fitness Signature chart I see my HIE has also dropped off a fair bit.
My question is not which one is or isnt more accurate, but to me this highlights that I must have areas of weakness in my fitness, but can anyone give me any advice on what I should be doing with a target of being a well rounded athlete? My “target” next year is a hilly 300km (~4500m ascent) Granfondo next summer, which I am nervous about being able to complete