Sweet Spot training

Sweet Spot is sustained effort at roughly 88–94% of FTP — the upper end of tempo running into the lower edge of threshold. It is hard enough to drive most of the aerobic adaptations of true threshold work, but easy enough that you can accumulate far more weekly minutes at high intensity without the recovery cost. That favorable adaptation-to-fatigue ratio is the 'sweet spot.'

Sweet Spot ≈ 88–94% of FTP (Coggan power zones: top of Zone 3 / bottom of Zone 4)
    ≈ IF 0.88–0.94 · RPE ~7/10 · 'comfortably hard,' conversational only in short phrases

The concept grew out of Andrew Coggan and Hunter Allen's power-zone framework, formalized in Training and Racing with a Power Meter (first edition 2006). The label itself is usually credited to Frank Overton of FasCat Coaching around 2004–05: after Coggan presented his power-based impulse-response performance model at USA Cycling's Coaches Summit in Colorado Springs, coaches working to validate it noticed the most productive band of intensity sat just below threshold, where adaptation stayed high but fatigue dropped off sharply. FasCat then built much of its commercial coaching around dedicated sweet-spot plans, which is why the term is now near-universal in amateur cycling.

The physiological rationale is sub-threshold aerobic stimulus at a sustainable fatigue cost. Work in the high-tempo-to-low-threshold band sits below or right at the maximal lactate steady state, so blood lactate stabilizes rather than runs away. That lets you hold the effort for 10–30 minutes at a time and stack several intervals in a session — driving the central and peripheral aerobic adaptations (stroke volume, capillary density, mitochondrial volume and oxidative-enzyme activity) that underpin a higher FTP. You give up a little of the top-end stimulus of riding at 100% FTP, but you gain a lot back in total trainable volume and faster between-session recovery — the trade-off that makes sweet spot attractive for amateurs on 6–12 hours a week who can't absorb a steady diet of full threshold or VO2max work.

Common sweet-spot workout shapes: 2×20 min, 3×15 min, 3–4×10–12 min, or a 'sweet spot pyramid' (e.g. 10/15/20/15/10 min), all at 88–94% FTP with 5–10 minutes of easy spinning between reps. A practical session ceiling is roughly 40–70 minutes of total time-in-zone; weekly sweet-spot volume tends to top out around 90–150 minutes (spread over 2–3 sessions) before cumulative load starts to degrade execution and the work quietly slides into the very junk-intensity trap it's meant to avoid.

Where it fits in a periodized year: sweet spot is most valuable in the base-to-build transition and the early specific-prep block, where the goal is to raise sustainable power efficiently before layering on race-specific threshold and VO2max work. It is the workhorse for time-crunched indoor training and for riders rebuilding after a layoff. It is a poor primary stimulus during a peak or taper, when the plan needs sharpness from short, very-high-intensity efforts rather than more sub-threshold volume.

The classic mistakes are two sides of one coin. First, turning every ride into sweet spot: doing it 4–6 days a week leaves you chronically under-recovered, erodes the easy aerobic base that low-intensity volume builds, and produces a flat, monotone fitness that plateaus by year two. Second, the 'grey zone' trap — letting endurance rides drift up to 80–87% FTP without it being a structured sweet-spot effort, so you pay near-sweet-spot fatigue for sub-sweet-spot adaptation. Sweet spot earns its place as a deliberate, dosed block of work, not as the default intensity for everything. Critics — including Seiler's polarized camp — argue amateurs over-prescribe it precisely because it feels productive; the honest framing is that it is a high-value tool used sparingly, not a complete training philosophy.