Decay Mode and Training Phases

I’ve been listening to Episode 12 on of the Breakthrough Podcasts today and was intrigued to hear that the No Decay model should be used during the base phase of a training programme. As I left mine on the default Optimal Decay setting and am now about half way through the build phase will my signature and training recommendations have been affected? Should the XTA automatically move athletes to the No Decay mode from the base phase at the start of a new programme?

Really depends how often you had breakthroughs in the meantime / how stale you let your signature get… if you had extended periods without a BT on the default decay setting, then yes there will be some impacts e.g. workouts may have been a little too easy, and you may have reported a greater training load than what it ‘should’ have been.

Materiality is the main consideration for me - if it’s a up to a few percent it won’t matter much, but if you let it decay by 10% more then it may… made that mistake in my first winter, but in hindsight it meant I didn’t do my endurance / base at too high an intensity which is no bad thing

Thanks Wesley. I initiated the programme quite soon after joining Xert but I did get it to pull in loads of history from my Zwift account and it did create a signature from the off pretty similar to that from Strava (which I have pulling in all my exercise data), albeit slightly lower. As I’m targeting GC Specialist a lot of my workouts are endurance focused but doing a few Zwift events aiming for LTP with a few sprints or tougher intervals helped tweak it up. More recently I maxed on an Xert breakthrough workout and got a gold breakthrough - I think the signature is pretty spot-on now, and as I move into the later-build and peak phases of this sequence I guess I’ll be assigned some more 6-8 minute-focused workouts. You get so many insights with this system!

New-ish Xert user here - I have been learning more about features and came across the decay settings the other day. Prior to Xmas I was just doing base / Z2 rides, then in Jan I have been including threshold sessions that whilst not testing my peak power are testing for me in terms of power I can sustain for 12-16 mins, they are hard efforts - but none have been recorded as breakthrough however my TP has stopped “decaying” on the XPMC. Is this the correct approach or do I need be throwing in the odd VO2 max / peak power effort to keep the fitness signature accurate?

That means your TL (training load) is enough to maintain your TP but you haven’t fully validated your signature values during that time.
See this post for details –
MPA on Endurance Rides - General - Xert Community Forum (

Reference – Breaking Through the Xert Way! – Xert (
Examples – Let’s See Some Recent BT’s - General - Xert Community Forum (

Yeah I’d still switch to ‘no decay’ properly if ‘only’ doing threshold sessions or below. The your TP will go up as you increase load.

If you want to do VO2 work as part of your plan or enjoy it then yes, do a BT from time to time, but if it doesn’t fit your planned focus then I wouldn’t… in other words, I wouldn’t materially change my training plan just to get regular breakthroughs