Z3 : Zone 3: tempo / strong endurance
LoadThe "comfortably hard" pace : sustainable for 1-2 h but costly.
Z3 sits between Z2 (~76-90% FTP) and threshold (~91-105%). Breathing picks up, full sentences become uncomfortable. Living there too often piles up fatigue without delivering the threshold benefit. It's the zone polarized plans aim to skip.
In TriPaced:
In TriPaced, Z3 only shows up in specific blocks (progressive long, brick, short sweetspot). If you drift into Z3 on a Z2 session, the post-session analysis flags it.