Tempo (Zone 3)

Tempo is moderate-intensity riding — Coggan Zone 3, roughly 76–90% of FTP. It's 'sustainable but working': harder than conversational endurance, easier than threshold, the pace of a strong steady group ride or a long climb ridden briskly. It sits in the physiological middle ground, which makes it both genuinely useful and, if overused, the classic grey-zone trap.

Coggan Zone 3 (Tempo) ≈ 76–90% of FTP
    RPE ~5–6/10 · breathing rhythmic but controlled
    upper tempo blends into sweet spot (~88–94% FTP)

Tempo lives between the aerobic threshold and threshold proper — above LT1, below LT2. Ridden in volume it extends aerobic endurance, builds muscular endurance and fatigue resistance, and teaches sustained sub-threshold pacing, which makes it a staple of high-volume base blocks and long climbing days. The top of tempo shades into sweet spot (~88–94% FTP), where the adaptation-per-minute improves.

Tempo is also exactly the 'moderate middle' that polarized-training advocates like Seiler argue amateurs overdose on: it accumulates real fatigue and sympathetic stress while adding only a modest aerobic stimulus beyond what easier volume already delivers. The failure mode is unintentional tempo — endurance rides that drift up to 80% FTP because it feels productive — which leaves you too tired to hit the genuinely hard sessions that actually drive adaptation.

Used deliberately, tempo earns its place: muscular-endurance work, big aerobic days, and a bridge intensity in base. As a default, though, it's the textbook definition of junk intensity. The whole distinction is dose and intent — a planned 2×20 tempo block is training; letting every ride settle into tempo because it's comfortable is the trap.