Ask ten amateur cyclists what sweet spot training is and you'll get ten approximate answers that all land near 'somewhere around threshold, but not quite'. Ask them what threshold training is and you'll get the same answer in reverse. The two intensities sit so close together on the FTP zone map that they're often treated as interchangeable — and the cycling internet has, over the last decade, quietly made sweet spot the default for amateur training plans while research on elite cyclists has been pointing in a different direction.
Both intensities are useful. Both have a place in a well-structured plan. But they are not the same thing, they produce different adaptations, and they have different fatigue profiles. The question of when to use each one — and when using one as a substitute for the other is a mistake — is one of the more practically important distinctions in cycling training, and it's worth getting right.
Where do sweet spot and threshold actually sit?
On the Coggan 7-zone FTP map, threshold is Zone 4, defined as 91–105% of FTP. Sweet spot is not a formal Coggan zone at all — it's a narrower band that overlaps the top of Zone 3 and the bottom of Zone 4, typically defined as 88–94% of FTP. The term was coined by Frank Overton of FasCat Coaching in the early 2010s to describe what he observed as the intensity that produced the best aerobic training load per unit of fatigue, and it took off because the practical logic was compelling.
The lactate-threshold framing is cleaner. In lactate terms, threshold training (also called 'LT2 work') targets your maximum lactate steady state — the highest intensity where your body can still clear lactate as fast as it produces it. Sweet spot sits just below that boundary — high enough to stimulate the same metabolic systems, low enough that lactate accumulation is slower and the session is more repeatable.
The difference in percentages is small. The difference in training feel and cost is not. A 20-minute effort at 100% of FTP (pure threshold) is genuinely hard — focused, close to unsustainable, leaving you emptied. A 20-minute effort at 90% of FTP (upper sweet spot) is challenging but manageable, and most trained cyclists can do two of them in the same session and still ride Zone 2 the next day. That difference is what everything else about the sweet spot vs threshold debate comes down to.
Why did sweet spot become so dominant in amateur cycling?
Sweet spot became the default for amateur training plans in the 2010s for three practical reasons, all of which are legitimate.
- Time efficiency. Amateur cyclists with 6 to 10 training hours per week cannot accumulate the volume that professionals use. Sweet spot delivers a high-quality training stimulus per hour of training, which is exactly what a time-crunched athlete needs. The early Zwift era, in particular, amplified this — short indoor sessions at 88–94% of FTP felt productive in a way that easier sessions didn't.
- Repeatability. You can do sweet spot work multiple times per week without being wrecked. A cyclist can do three 2×20 min sweet spot sessions in a week and hold it together. The same cyclist doing three 2×20 min threshold sessions in a week will usually break down by Thursday.
- Practical feel. Sweet spot is the intensity where a training session produces noticeable muscular and cardiovascular work without feeling like survival. Athletes leave the session feeling like they trained hard and progressed — which matters for motivation, consistency, and long-term compliance.
Those benefits are real, and the sweet spot evangelists who promote it are not wrong about them. The problem is that those benefits come with a tradeoff, and the tradeoff is where the elite research community has been pushing back.
What is the case against sweet spot as a default?
The counter-argument to sweet spot dominance came mostly from the polarized training research led by Stephen Seiler and others, plus the block periodization work from Bent Rønnestad's group in Norway. The core finding of that body of research is that elite endurance athletes tend to concentrate their training in two bands — a lot of very easy Zone 2 work and a small amount of high-intensity Zone 5+ work — with relatively little time in the middle, including sweet spot and low threshold.
The observation is that elite cyclists, when studied, don't spend much time in the sweet spot band at all. They do tons of Zone 2 and focused VO2max or threshold blocks, with the middle intensities used sparingly. When Seiler tested polarized training (roughly 80% of time below LT1, 20% above LT2, very little in between) against the more pyramidal structures amateurs often use, polarized generally came out ahead for performance in the well-trained athletes studied.
The critique of sweet spot isn't that it doesn't work — it clearly does produce training adaptations and improvements. It's that it's not the best training stimulus per unit of recovery cost when you actually have the time and capacity to do proper Zone 2 plus proper high-intensity work. Sweet spot is a compromise intensity — easier to schedule than threshold, harder than Zone 2, and it occupies a grey zone in the adaptation landscape that the polarized model argues should mostly be empty.
The honest synthesis is that both sides of this debate have a point. Sweet spot is a pragmatic tool for time-crunched amateurs who can't accumulate the volume that polarized training requires. But at higher volumes, or for athletes who are serious about maximizing adaptation, pure threshold and proper Zone 2 will probably outperform sweet-spot-dominated blocks.
What adaptations does each actually produce?
Sweet spot and threshold both hit the aerobic system, but they produce somewhat different adaptations at the margins.
- Threshold (95–105% FTP) sits right at your LT2, which means you are training at the exact intensity you want to push higher. This is the cleanest direct stimulus for raising FTP itself, and it produces the largest improvements in steady-state lactate clearance.
- Sweet spot (88–94% FTP) sits below LT2, which means it stimulates aerobic adaptations (mitochondrial density, capillary growth, fat oxidation to some extent) without pushing the lactate system as hard. It still raises FTP, but less directly and usually less efficiently per unit of focused effort.
- Recovery cost per minute is substantially lower at sweet spot than at threshold. This is why you can do more total sweet-spot time per week — but it's also why the training stimulus per minute is lower. You pay less and you get less; whether that tradeoff favours you depends on what you're trying to accomplish.
- Neural and muscular fatigue from sweet spot is lower than threshold, which makes it easier to stack on consecutive days without wrecking next-day recovery. Threshold work often requires a full recovery day afterward.
When should you use sweet spot?
Sweet spot has a genuine and valuable role in several specific contexts.
- Base-to-build transitions. After a base phase of mostly Zone 2 work, sweet spot is a useful bridge intensity to get the body used to sustained efforts above endurance pace before moving into true threshold work.
- Time-crunched training weeks. If you have 4 to 8 training hours per week and can't build a polarized plan around a lot of Zone 2, sweet spot is a practical way to extract a quality training load from short sessions. This is where sweet spot is strongest.
- Indoor trainer sessions. The controlled environment of a smart trainer is ideal for holding a precise sweet-spot effort, and sweet spot intervals feel like a productive use of a 45–60 minute indoor session in a way that pure Zone 2 often doesn't.
- Early build phase. In the early weeks of a build block, sweet spot produces useful adaptations without the fatigue that full threshold work would bring. As the block progresses, the work should shift toward true threshold and VO2max.
- Maintenance blocks. For athletes not actively building, occasional sweet spot sessions maintain aerobic capacity without the cost of harder work.
When should you use threshold instead?
Threshold work has its own distinct uses, and athletes who want to actually raise their FTP should not skip it.
- Focused FTP-raising blocks. If your explicit goal is to raise FTP in the next 4 to 8 weeks, threshold intervals (2 × 20 min, 3 × 15 min, 4 × 10 min) at 95–105% of FTP are the most direct stimulus. Nothing else produces the same effect as efficiently.
- Late build phase. After the early build has used sweet spot to ramp up, the late build is where threshold becomes the primary quality session, paired with VO2max work on other days.
- Time trial preparation. If your goal race is a 40k time trial or any effort sustained near threshold, you need to specifically train at that intensity — sweet spot is not a substitute.
- Half Ironman bike leg preparation. The 70.3 bike pace for most amateurs sits between sweet spot and threshold. Training at both intensities is useful, but threshold work is what teaches you to sustain the effort when you're 3 hours in and still have a half marathon to run.
How should you balance them in a training plan?
A reasonable annual structure that accommodates both sweet spot and threshold looks something like this:
- Base phase (8–16 weeks) — dominated by Zone 2 volume, with occasional sweet spot sessions (1 per week) as a minor quality stimulus. No true threshold work yet.
- Early build phase (3–4 weeks) — sweet spot becomes the primary quality session, 2 times per week, on top of continued Zone 2 volume. Introduces the body to sustained above-endurance work.
- Late build phase (3–4 weeks) — shift to true threshold work, 1 to 2 times per week, with sweet spot dropping to 0 or 1 session per week. VO2max work added on separate days.
- Specific / peak phase (3–4 weeks) — race-specific intensity dominates (VO2max, race-pace intervals). Threshold work maintains as a support intensity. Sweet spot drops out.
- Taper — everything short and sharp, including 1 or 2 short threshold or race-pace sets to maintain sharpness without adding fatigue.
Athletes with limited weekly time can compress this — even a short sweet-spot block of 6 to 8 weeks produces measurable FTP gains for cyclists who have been training consistently. But if you have the volume and the weeks, the progression above is more effective than a flat 'sweet spot every week' approach.
What are the most common sweet spot vs threshold mistakes?
Five mistakes catch most amateur cyclists.
- Doing sweet spot year-round. The most common modern error. A year of sweet spot produces some gains initially and then plateaus. Without genuine Zone 2 base or genuine above-threshold work, the middle-intensity stimulus loses its effect.
- Calling threshold work 'sweet spot' because it's easier that way. If you're doing intervals at 96–100% of FTP, you're doing threshold, not sweet spot. Mislabeling the intensity matters because it affects how you plan recovery.
- Doing too many sweet spot sessions in a single week. Sweet spot is forgiving enough that athletes often stack 3 or 4 sessions per week. This usually accumulates more fatigue than athletes realize and degrades session quality over time.
- Ignoring Zone 2 because sweet spot produces faster short-term gains. The polarized critique is most valid here: the short-term gains from heavy sweet spot come at the cost of the slow, deep base adaptations that Zone 2 produces. Athletes who skip base and live in sweet spot hit a ceiling within 12 to 18 months.
- Using sweet spot when you should be doing VO2max or race-pace work. Sweet spot does not raise VO2max and does not prepare you to sustain race pace. When your goals require those adaptations, sweet spot is the wrong tool.
Key takeaways
- Sweet spot is 88–94% of FTP; threshold is 91–105% of FTP. The overlap is real but the intensities produce different costs and different adaptations.
- Sweet spot is the best training load per fatigue unit for time-crunched athletes, which is why it dominates amateur plans.
- Threshold is the cleanest direct stimulus for raising FTP itself, and is harder to substitute at intensity.
- The polarized research (Seiler) argues that middle intensities like sweet spot are over-used by amateurs and that Zone 2 plus focused high-intensity work outperforms sweet-spot-dominated plans at higher volumes.
- Both work. The question is when to use which, not which is universally better.
- Use sweet spot in base-to-build transitions, time-crunched weeks, and indoor sessions. Use threshold in focused FTP-raising blocks and late build phases.
- Never substitute sweet spot for the session you actually need (VO2max, true threshold, or Zone 2). Plateau is the usual consequence.
Frequently asked questions
Is sweet spot just 'threshold light'?
Kind of, but it's a meaningful distinction. The 5 to 10 percent drop in intensity from threshold to sweet spot changes the fatigue profile substantially — sweet spot is below LT2, so lactate is cleared faster than it's produced and sessions stay repeatable. Threshold sits at or above LT2, where lactate accumulates and the session becomes sustainable for only about an hour. The difference in what the sessions feel like and what they cost afterward is not small.
Can I raise my FTP with just sweet spot training?
Somewhat, especially if you're under-trained to start with. Beginners and intermediates often see FTP rise with a sweet-spot-heavy plan because any structured aerobic work at that intensity is better than what they were doing before. But the gains tend to plateau, and athletes who never progress to true threshold work often stall out somewhere in the 3.0–3.5 W/kg range and can't break through. Advanced cyclists generally need a mix of both to keep moving.
What's a typical sweet spot session?
The classic is 2 × 20 minutes at 88–94% of FTP with 5 minutes easy between intervals, preceded by a 10–15 minute warm-up and followed by a 5–10 minute cool-down. 3 × 15 minutes, 2 × 30 minutes, and 4 × 10 minutes at the same intensity are all common variations. Most cyclists can do two of these per week without accumulating excess fatigue, and some can handle three.
What's a typical threshold session?
A typical threshold session is 2 × 20 minutes at 95–100% of FTP, 3 × 15 minutes at 98–102%, or 4 × 10 minutes at 100–105%. The total time at threshold is usually 40 to 60 minutes. One true threshold session per week is the usual limit during a focused block — the recovery cost is high enough that more than that tends to break down the quality.
Does Zwift SST (Sub-Threshold) count as sweet spot?
Generally yes. Zwift's 'Sub-Threshold' rides and workout sessions use the 88–94% FTP band that matches sweet spot. The Zwift era popularized sweet spot for a reason — it's well-matched to short indoor sessions that need to feel productive. Just know that the label 'sub-threshold' on Zwift means the same thing as 'sweet spot' in older coaching terminology.
Is sweet spot useful for runners?
Yes, with the same principles but different terminology. Running doesn't typically use 'sweet spot' as a label, but the equivalent intensity exists — it's the area just below running threshold pace, sometimes called tempo. Tempo runs in the 82–88% of HRmax range correspond roughly to cycling sweet spot in function. The same tradeoffs apply: useful for time-crunched weekly work, less effective as a pure FTP / threshold raiser than work at true threshold pace.
How CoreRise handles sweet spot and threshold work in your plan
When CoreRise builds your training plan, sweet spot and threshold are not interchangeable — they're prescribed for different phases and different purposes. Your early build phase might include 1 to 2 sweet spot sessions per week as the body ramps up; your late build phase shifts to true threshold work; your base phase keeps both to a minimum and emphasizes Zone 2 volume. The coach chooses the intensity based on where you are in your macrocycle, not as a default.
If your weekly time is limited and you need to extract maximum quality from short sessions, the coach leans more heavily on sweet spot because it's the right tool for that constraint. If you have more volume available, the coach is more likely to use the polarized structure — more Zone 2, focused threshold and VO2max blocks, fewer middle-intensity sessions. You can also ask the coach directly to explain why a given session is written at the intensity it is, and get an answer that ties the choice to your goals and phase rather than to a template.
- Sweet spot and threshold are selected based on training phase and weekly time budget, not used interchangeably.
- In time-crunched plans, sweet spot dominates early build phases. In higher-volume plans, polarized structures take over.
- Your coach can explain why a specific session is at sweet spot rather than threshold (or vice versa).
- Sweet spot is not used year-round by default — the plan progresses athletes toward true threshold and race-pace work when appropriate.
- Post-block analysis shows whether your FTP and zones are actually responding to the sessions you've been doing.