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Glossary · Mechanical Efficiency · Adaptation Rate · True Normal · Sub-threshold Ceiling
The protocol Veloarchitect uses for 55–75% FTP sub-threshold work. The 8–12 week progression that extends the Athlete’s sub-threshold ceiling against their own 100-day personal record.
Definition
Zone Endurance is the load-bearing protocol of every Athlete block — the Z2 work that the supra-threshold protocols rebuild against. Standard Z2 prescription fixes the intensity at "conversational" and the duration at the calendar. Veloarchitect dispatches Zone Endurance as a longitudinal envelope: the system reads the Athlete’s longest sub-threshold ride in the last 100 days against the Athlete’s True Normal, extends the duration by 30–45 minutes per week only when Mechanical Efficiency moves positive, and gates any supra-threshold block on the ceiling having moved. The Athlete with a 3:30 ceiling who jumps to a 5:00 prescription collapses the Adaptation Rate within 4 weeks.
Protocols: Protocol 10 — Adaptive Workout; Protocol 11 — Failure Horizon
Closed Loop
The metric traverses the closed loop: Intent is the .zwo prescription the system computed against the Athlete’s True Normal. Telemetry is the .fit recording of the executed session. Adaptation is the longitudinal movement of the metric itself, logged against the True Normal and feeding back into the next day’s prescription via Protocol 10 (Adaptive Workout).
Worked Example
Athlete: 41y/o, 254W FTP, 1.43 W/bpm. Initial sub-threshold ceiling in last 100 days: 3:15. Block: 3 weekly Z2 (60→90→120 min progression) + 1 weekly Threshold Sustain + 1 weekly Recovery Spin. Weeks 1–4 durations: 60, 90, 120, 150 minutes; Mechanical Efficiency 1.43 → 1.52 W/bpm. Weeks 5–8: 165, 180, 195, 210 minutes; Mechanical Efficiency plateaus at 1.55 W/bpm by week 7. Adaptation Rate gates the 210-minute week behind the plateau read; final week held at 195. Sub-threshold ceiling post-block: 5:45. FTP test on week 9: +9W. The ceiling doubled; the FTP moved less than a Sweet-Spot-only block would produce.
Common assumption inverted
Zone Endurance is not "easy day" and not "junk miles." The 65% target is specific; the Athlete who rides Z2 at 72% produces different physiology (more threshold stress, less aerobic base) and a lower Mechanical Efficiency shift. The Athlete who skips Z2 to add another Threshold Sustain session will see FTP gains plateau within 4 weeks because the aerobic base cannot support the supra-threshold load. Zone Endurance is the structural floor Veloarchitect builds every block on.
Related Terms
Mechanical Efficiency — Mechanical Efficiency
True Normal — True Normal
Adaptation Rate — Adaptation Rate
Full Glossary
See all eleven proprietary metrics or the platform comparison for the closed-loop claims against the field.