Lactate Threshold Fully Explained: LT1, LT2, and the Anchors of Training Zones

Coach’s Opening: That “Line” You Think Exists—But Doesn’t

In fifteen years of coaching athletes—from office workers chasing their first sprint triathlon finish to veterans chasing Kona slots, staring at their power meters until their eyes glaze over—I’ve noticed one thing: Most people plateau not because they lack fitness, but because their mental model of “threshold” is fundamentally wrong.

Many people picture this: there’s a clear line in the body. Cross it, and lactate “explodes,” your legs “burn,” and you “go anaerobic.” It’s intuitive and easy to explain, but almost every word of it is imprecise. Lactate isn’t waste, isn’t the culprit behind soreness, and your body doesn’t suddenly switch to “anaerobic mode” at some wattage. What’s really happening is a smooth, continuous curve that rises with intensity, with two physiologically meaningful inflection points—we call them LT1 and LT2.

I had an athlete, A-Kai, who trained for two and a half years and was stuck at the same half-marathon time. Every “easy run” was run to the point of huffing and puffing, and every “interval” wasn’t painful enough. The result: he trained every day at the same mediocre intensity. Once I mapped out his LT1 and LT2 and re-anchored his training zones, his plan didn’t get harder—it got easier. Three months later, his half-marathon improved by nearly eight minutes. The problem was never a lack of effort; it was that he was spending his energy in the wrong places.

In this article, I want to explain lactate threshold properly, in the language I use with my athletes. We’ll cover the physiological meaning of the curve, how to do a field test on Taiwan’s own roads and trails, and how to use thresholds as anchors to design training plans. By the end, you’ll have a framework you can put to use immediately.

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1. Conceptual Foundation: What the Lactate Curve Is Really Saying

First, Let’s Clear Lactate’s Name

Let’s start where most people are mistaken. Lactate (more precisely, lactate salt) is not the culprit behind your soreness, nor is it a waste product of anaerobic metabolism. It’s actually a fuel. When your carbohydrate breakdown is rapid, lactate is produced; this lactate can be taken up and reused by the heart, slow-twitch muscle fibers, and even the liver, converting it back into energy. So blood lactate concentration doesn’t reflect “how much waste you produced,” but rather the dynamic balance between production and clearance rates.

This concept is crucial because it determines how you understand the two thresholds:

• When production ≈ clearance, blood lactate stays at a low, stable level.
• When production begins to slightly exceed clearance, blood lactate slowly rises from baseline—this is the first inflection point, LT1.
• When production far exceeds clearance and the body can no longer keep up, blood lactate continuously climbs over time, with no steady state possible—this is the second inflection point, LT2.

LT1: The Aerobic Threshold, That “Not-So-Dramatic” First Inflection

LT1 (first lactate threshold, also often called the aerobic threshold) is the intensity point where lactate shows its first measurable rise from resting baseline, corresponding to roughly around 2 mmol/L in blood lactate concentration (this is a rough population average range, not a number everyone lands on exactly).

Here’s a crucial detail that’s rarely explained clearly: LT1 isn’t really a true “threshold.” Cross slightly above LT1 and nothing dramatic happens—lactate will still settle at a new, slightly higher stable level. So rather than thinking of LT1 as a wall, think of it as the ceiling of “the highest intensity you can sustain for many, many hours.” This is exactly why the long aerobic base for marathons and full 226 iron-distance racing sits largely at or below LT1.

LT2: The Ceiling of Lactate Steady State

LT2 (second lactate threshold, also called the anaerobic threshold) is stricter. It is the highest intensity at which blood lactate can still maintain a steady state—beyond this point, lactate accumulates continuously over time and you can’t last long. In the lab, this concept has a more precise counterpart called MLSS (maximal lactate steady state)—the highest exercise intensity at which blood lactate can remain constant without continuously rising—commonly falling around 4 mmol/L in the population (again, a rough figure; individual variation can be large).

I want to emphasize this: “4 mmol/L = your LT2” is a convenient default, not an iron law. Some athletes have an MLSS corresponding to lactate levels clearly below 4; others above 4. So if you have the chance to do lab testing, focus on “the shape of the curve and your personal steady state,” not on forcing that 4.

Let me give you an example I witnessed firsthand while coaching. In the same training camp, two age-group athletes did lab testing. Athlete A’s MLSS corresponded to a lactate level around 3.3 mmol/L, while B’s was close to 5 mmol/L—yet their race results were comparable. If they had both forced “4 mmol/L is my threshold,” A would have chronically set training intensity too high, living on the edge of overreaching daily; B would have set it too conservatively, turning threshold stimulus that should have been hard into easy workouts. This is why I always stress: Numbers should serve you, not the other way around.

A Table for Understanding Lactate Levels, Feel, and Fuel

To give you a more three-dimensional picture of the “lactate curve,” I’ve organized the approximate lactate ranges, physical sensations, and fuel characteristics for different intensity zones in the table below. Again, these lactate numbers are rough population averages; individual variation is large. Treat this as a framework for understanding, not a diagnostic standard:

Intensity Zone	Approx. Blood Lactate	Breathing/Speech	Primary Fuel	Approx. Sustainable Duration
Recovery/Very Easy	Near resting baseline	Nasal breathing, can sing	Fat dominant	Nearly unlimited
Aerobic Base (below LT1)	Slightly above baseline to ~2 mmol/L	Can hold full conversation	Fat + some carbohydrate	Several hours
Threshold Zone (LT1–LT2)	~2–4 mmol/L	Speech starts breaking up	Carbohydrate share increases	Tens of minutes to ~1 hour
Near LT2/MLSS	Around 4 mmol/L	Can only utter a few words	Carbohydrate dominant	~30–60 minutes
Above LT2 (High Intensity)	Continuously rising, unstable	Barely able to speak	Carbohydrate dominant, rapidly depleted	A few minutes

The point of this table isn’t to memorize numbers, but to grasp one thing: from recovery to limit, it’s a continuous, smooth climb, not a series of sudden steps between floors. LT1 and LT2 are just two particularly meaningful coordinates on that slope.

Coach’s Plain-Language Version:

• LT1 = the ceiling of intensity where you can ride and chat all afternoon (the core of aerobic base).
• LT2 = the intensity where you’re gritting your teeth, can only manage a few words, and can hold on for roughly thirty to sixty minutes (the core of race pace).

The Three-Zone Model: Why Thresholds Are the Best Anchors

Once you have LT1 and LT2, the entire training intensity spectrum naturally divides into three blocks. This is one of the most practical frameworks in endurance training:

Intensity Zone	Relative Position	Subjective Feel	Physiological Meaning	Primary Purpose
Zone 1 (Low Intensity)	Below LT1	Can speak in full sentences, nasal breathing still fine	Lactate near baseline, high fat utilization	Aerobic base, recovery, building volume
Zone 2 (Threshold Zone)	Between LT1 and LT2	Speech becomes effortful, breathing noticeably heavier	Lactate elevated but still somewhat balanced	Tempo runs/rides, race pace, threshold stimulus
Zone 3 (High Intensity)	Above LT2	Can only utter single words, quickly wants to stop	Lactate continuously accumulating, unstable	VO2max, anaerobic capacity, maximal oxygen stimulus

Note that this “three-zone” model doesn’t conflict with the five-zone or seven-zone systems some watches use—five or seven zones just subdivide these three blocks further. But for the vast majority of amateur triathletes and cyclists, getting these three blocks clear and knowing which block each workout targets is a hundred times more important than memorizing the boundaries of seven zones.

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2. Practical Methods: Finding Your Thresholds on Taiwan’s Own Routes

Without a lab or a lactate analyzer, you can still anchor LT2 quite accurately. Here’s the field test process I actually use with athletes, broken down for cycling and running.

Cycling: Power/Heart Rate FTP Test

The most practical anchor for amateurs is FTP (functional threshold power). FTP is defined as “the highest average power you can sustain for approximately one hour,” and in practice it’s a very good approximation of LT2/MLSS.

The most common and easiest to perform is the 20-minute test:

1. Warm up thoroughly: At least 15–20 minutes, with a few 30-second accelerations interspersed to “open up” the body. Taiwan’s summer heat and humidity mean don’t overdo the warm-up and exhaust yourself before you start.
2. 5-minute all-out opener: This segment isn’t the main test; its purpose is to burn off some of your anaerobic “allowance” so the following 20 minutes more closely reflects your true threshold. After the 5-minute all-out effort, spin easy for 10 minutes.
3. 20-minute all-out time trial: Find a route with no traffic lights and a gentle, steady grade. Don’t go out too hard; aim for an intensity that’s “painful but sustainable to the end, with a little left to accelerate in the final three minutes.” Record the average power for these 20 minutes.
4. Calculate FTP: Multiply the 20-minute average power by 0.95 to get your FTP estimate.
5. Cool down.

Route suggestions for Taiwan: Finding a stretch you can ride continuously is the most important thing. The Fengguizui climb in the north, the outer ring of the Zhongtou Highway in central Taiwan, and certain sections of Provincial Highway 17 along the south coast with few traffic lights are all used by people. A smart trainer (e.g., indoor rollers) is actually the most stable environment for an FTP test—no traffic lights, no coasting on descents, constant wind resistance, much cleaner data. I strongly recommend doing it on a trainer in an air-conditioned room in summer.

If you only have heart rate and no power, you can still do it, but know that heart rate lags and is heavily influenced by heat, dehydration, caffeine, and sleep—its accuracy is inherently worse than power. Doing a heart-rate threshold test in Taiwan’s summer can easily overestimate your threshold due to “heart rate drift” from the heat.

Running: 30-Minute TT to Find Threshold Pace and Threshold Heart Rate

The classic field test for running is the 30-minute time trial (30-min TT):

1. After a thorough warm-up, find a flat route with few traffic lights (riverside paths are the top choice).
2. Run 30 minutes all-out at “the hardest pace you can sustain steadily for 30 minutes.”
3. Record the average heart rate of the final 20 minutes—this is your threshold heart rate, very close to LT2.
4. The average pace for the full 30 minutes is your practical estimate of threshold pace.

Taiwan’s riverside paths are a gift for testing: The Xindian River, Dahan River, and Keelung River riverside bike/run paths in Greater Taipei, the Love River in Kaohsiung, and the Fazi River in Taichung—these routes are flat, straight, have few traffic lights, and have distance markers, making them excellent venues for a TT. The only thing to watch is timing—in Taiwan’s summer, test before 6 a.m. or after sunset in the evening. Doing a TT on the riverside at noon measures not your threshold, but your heat tolerance limit.

The “Talk Test” You Can Use Without Any Equipment

The most primitive but surprisingly effective method is the talk test:

• You can still speak a full sentence smoothly and chat comfortably → you’re likely below LT1 (Zone 1).
• Speech starts requiring extra breaths, sentences get cut off → you’re likely crossing LT1, entering Zone 2.
• Can only utter a few words, don’t want to talk at all → you’re at or above LT2.

This method isn’t precise, but for beginners who haven’t yet bought a power meter or heart rate strap, it’s an excellent real-time calibration tool. I often have new athletes try reciting a commercial jingle while riding—if they can’t finish it, they’re going too fast.

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3. Designing Training Plans with Thresholds as Anchors

Knowing where LT1 and LT2 are is just the first step. The real value lies in whether you can place every single workout precisely in the right zone.

First, the Most Important Principle: Polarized vs. Pyramidal

There are two mainstream philosophies for intensity distribution in endurance training, both anchored on thresholds:

• Pyramidal: Lots of Zone 1, a moderate amount of Zone 2, a small amount of Zone 3. Like a pyramid—wide base, narrow top.
• Polarized: Lots of Zone 1, very little Zone 2, and a small amount of solid Zone 3. The middle “in-between” threshold zone is deliberately compressed.

What they share—and what I hammer into every athlete’s head—is this:

The vast majority of training time should be spent at low intensity (Zone 1), below LT1.

This sounds counterintuitive—“I want to get faster, why should I keep training slow?” But this was exactly A-Kai’s problem. He spent eighty percent of his time in Zone 2, that “in-between” gray zone: the easy parts weren’t easy enough to accumulate aerobic base and recovery, and the hard parts weren’t hard enough to stimulate high-intensity adaptations. So he was tired every day, yet hadn’t truly trained any block.

The most common ailment among amateurs, I call it “everyday moderate-intensity syndrome.” The fix is simple and blunt: make easy days truly easy, and hard days truly hard. The middle ground (threshold days) should of course be trained, but deliberately and planned—not by accidentally drifting into it every day.

A Sample Weekly Plan (for Intermediate Triathletes/Cyclists)

Below is a skeleton I often give athletes with some foundation and a weekly training volume of about 8–12 hours. Adjust based on your own recovery status:

Day	Workout	Intensity Zone	Purpose
Monday	Complete rest OR 30–40 min very easy recovery ride	Zone 1 (Low)	Recovery
Tuesday	Run threshold intervals: 3–4 × 8 min @ threshold pace, 2 min easy jog between	Zone 2 (Threshold)	Raise LT2
Wednesday	Cycling aerobic endurance ride, 90 min	Zone 1 (Low)	Aerobic base
Thursday	Cycling VO2max intervals: 5 × 4 min @ above LT2, 4 min easy spin between	Zone 3 (High)	Raise the ceiling
Friday	Swim aerobic + 30 min easy run	Zone 1 (Low)	Recovery and technique
Saturday	Long cycling ride 2.5–4 hrs, mostly Zone 1, with 2 × 20 min @ near FTP in the middle	Zone 1 primarily + Zone 2	Endurance + rhythm
Sunday	Long run 75–110 min, entirely below LT1	Zone 1 (Low)	Endurance base

You’ll notice that only two to three workouts in the week are truly “painful” (Tuesday, Thursday, and the middle of Saturday); everything else is low intensity. This isn’t laziness; it’s design. High-intensity stimulus must be built on a sufficient low-intensity foundation to be absorbed.

Here I want to lay out A-Kai’s before-and-after comparison in detail, because it’s almost a microcosm of every “everyday moderate-intensity” athlete. Before the restructure, he trained six days a week, and nearly every day was “a bit breathless, a bit tired, but still manageable” moderate intensity—it sounded diligent, but no day was truly easy enough to recover, and no day was truly hard enough to stimulate. The result was compounding chronic fatigue and stalled progress. After the restructure, I only did three things: forced Monday, Wednesday, and Friday down below LT1 (he initially protested, “this is way too easy”), pulled out two genuinely effective threshold and VO2max sessions on Tuesday and Thursday, and kept the weekend long sessions mostly low intensity with just one tempo segment in the middle. Training “volume” barely changed—it even decreased slightly—but the distribution of training became clean. Three months later, his half-marathon improved by nearly eight minutes. He later said something I really liked: “I used to be using busyness to fake effort.”

Three Signature Workouts Anchored on Thresholds

1. Threshold Continuous Ride/Run (Threshold / Sweet Spot)

• Cycling: 2–3 × 15–20 min @ 88–94% of FTP (sweet spot to threshold), 5 min easy between.
• Running: 25–35 min continuous threshold pace run (tempo).
• What it trains: Directly pushes the LT2 ceiling upward while improving your ability to sustain near-threshold intensity. This is the highest cost-performance workout for improving race results.

2. VO2max Intervals Above LT2

• 3–6 × 3–5 min @ clearly above LT2, with equal or slightly shorter easy recovery between.
• What it trains: Stimulates maximal oxygen uptake, pushing the entire lactate curve to the right.

3. Long Aerobic Sessions Below LT1

• Cycling 3+ hours, long run 90+ minutes, entirely below LT1.
• What it trains: This is the most underestimated yet most important session. It increases mitochondria, capillary density, and fat oxidation capacity—directly shifting your LT1 to the right, meaning “at the same pace, you’re more economical and less fatigued.” For ultra-long distances like a 226 full ironman, LT1 is the true race engine.

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4. Common Mistakes and Fixes

Having coached so many athletes, I’ve seen the same pitfalls far too many times. Here are the most frequent ones—see which apply to you:

Mistake 1: Easy Days Aren’t Easy Enough

This is the number one killer—the “everyday moderate-intensity syndrome” mentioned earlier. Fix: On recovery and aerobic days, force yourself to stay below LT1. If you have power or heart rate, set an upper limit and strictly obey it; if not, use the talk test—if you can’t recite a full commercial jingle, you’re going too fast. At first you’ll think, “this is way too slow.” Hold the urge—that “slowness” is what builds your foundation.

Mistake 2: Treating FTP or Threshold as a Fixed Number That Never Changes

Thresholds fluctuate with training status. The FTP built during winter base phase can differ by 20–30 watts by race season peak. Fix: Retest every 6–8 weeks and update your training zones accordingly. Using a three-month-old FTP to set today’s workout will only have you training at the wrong intensity.

Mistake 3: Ignoring Taiwan’s Summer Heat and Applying Zones Directly

This is a trap unique to Taiwan athletes. At the same power on a 35°C afternoon, your heart rate will be several beats higher than in cool conditions, and perceived exertion skyrockets. Fix: On hot days, use power or pace as the primary anchor, heart rate as secondary; if you only have heart rate, allow it to run a bit higher than usual and proactively lower the intensity target for that session. Outdoor threshold workouts at noon in summer have a very low success rate—move them to early morning, evening, or indoors whenever possible.

Mistake 4: Scheduling Threshold Workouts Too Densely, Insufficient Recovery

The benefits of threshold and VO2max workouts are realized during recovery. Several consecutive hard days only accumulate fatigue and degrade the quality of every session. Fix: Between hard sessions, include at least one low-intensity day or rest day; sleep, nutrition, and hydration are all part of training.

Mistake 5: Looking Only at Numbers, Not at Your Body

Watch zones are tools, not scripture. After a cold, a late night, or jet lag, your threshold will drop that day. Fix: Learn to cross-reference subjective feel (RPE, talk test) with objective data. When your body clearly says “not today,” swap the hard session for an aerobic day—this isn’t regression; it’s the necessary wisdom for long-term progress.

The Heat and Hydration Challenge for Taiwan Athletes

Because I’ve repeatedly mentioned Taiwan’s oppressive heat, let me dedicate a section to it. Taiwan’s summers are hot and humid, and high humidity severely impairs the evaporative cooling efficiency of sweat—at the same air temperature, conditions that might be tolerable in a dry region will cause your core temperature to climb faster in Taiwan’s sticky air. The direct impact on threshold training is: cardiac drift is amplified. Your power and pace may be unchanged, but in the latter half of the same workout, your heart rate will drift upward by several beats, and perceived exertion rises accordingly.

This isn’t you getting weaker; it’s your body diverting blood flow to the skin for cooling, forcing the heart to work overtime. Practical handling principles:

• Use power or pace as the primary anchor, treating heart rate as a reference, not an iron law.
• Hydrate before the session and at regular intervals during it—don’t wait until you’re thirsty; by then you’re already mildly dehydrated.
• Add electrolytes on long sessions—drinking only plain water with heavy sweating can actually dilute blood sodium.
• Accept that your zones will “shrink” in summer: adjust training targets flexibly based on the day’s weather and your body’s condition. If it’s time to go indoors to the trainer, go—don’t fight the sun.

For Taiwan athletes targeting races in hot, humid seasons (like Challenge Taiwan in Taitung at the end of April), a moderate amount of heat adaptation training is actually valuable—deliberately scheduling some sessions in warm environments so your body learns to cool and hydrate more efficiently. But this should be progressive, not self-flagellation on midday asphalt. Hydration and electrolyte strategies vary greatly by individual and sweat rate; I recommend adjusting with individual assessment.

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5. Actionable Advice for Athletes at Different Levels

Beginner: Goal is First Triathlon Finish / First Half Marathon

At this stage, you don’t need to worry about your LT2 wattage at all. Your primary tasks are:

1. Learn to distinguish “easy” from “hard.” Use the talk test; spend eighty percent of your time training at a conversational pace.
2. Build volume steadily and establish consistency. Aerobic base (the LT1 block) is the only thing you need to build right now.
3. Schedule one slightly challenging tempo session per week as a garnish—that’s more than enough.

Don’t rush to buy a bunch of devices. A pair of well-fitting shoes, a heart rate strap you know how to use, plus discipline, are worth more than anything else.

Intermediate: Chasing PBs and Progress

1. Do a proper field test (20-min FTP or 30-min running TT) to anchor your threshold clearly.
2. Introduce structured threshold and VO2max workouts—two to three hard sessions per week, everything else low intensity.
3. Retest every 6–8 weeks and update your zones dynamically.
4. Start taking recovery seriously: sleep, nutrition, foam rolling—these are the invisible engine behind your next PB.

Advanced: Chasing Age-Group Podiums and Kona Slots

1. If conditions allow, do a lab lactate/metabolic test to get truly individualized LT1, LT2, and fuel characteristics, rather than relying on the 2/4 mmol population averages.
2. Specialize your pacing for your target race: For a 226 full ironman, invest heavily in “raising LT1 and improving fat oxidation,” because your race intensity will mostly sit near LT1; for standard-distance and sprint triathlons, increase the weight on LT2 and VO2max.
3. Race scenario simulation: Challenge Taiwan (Taitung, offering the 226 full distance, 113 half distance, and 51.5 standard distance) has a bike course that heads from Taitung City toward the east coast, turns around at Dulan, and loops back for a second lap. Before the race, do pacing rehearsals on similar grades and distances, in similar hot and humid conditions, to calibrate your zones to “race-day body,” not “cool morning training body.”

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FAQ

Q: Is LT2 the same as FTP?
A: Not exactly equal, but in practice FTP is a very good approximation of LT2/MLSS. Lab MLSS is “the highest intensity at which blood lactate can remain stable,” while FTP is “the highest power you can sustain for about an hour”—the two overlap heavily. For amateurs, using FTP as an anchor for LT2 is more than sufficient.

Q: Do I have to get blood drawn to test lactate to train?
A: Absolutely not. Lactate analyzers are great tools, but the 20-minute FTP test, 30-minute running TT, and even the talk test can anchor your threshold to a practically useful level of accuracy. Master the free methods first; consider the lab only if you have extra capacity.

Q: Why does everyone tell me to “train slow”? I want to get faster.
A: Because low intensity (below LT1) builds mitochondria, capillaries, and fat oxidation capacity—adaptations that push the entire lactate curve to the right. The result is “more economical at the same pace, faster at the same heart rate.” High intensity is the spark; low intensity is the fuel. Without fuel, no amount of sparking will get you far.

Q: My heart rate keeps spiking in Taiwan’s summer. Am I regressing?
A: Most likely not. High temperatures cause heart rate to rise significantly at the same intensity—that’s a normal physiological response. In summer, use power/pace as your primary anchor and moderately lower your intensity targets. Don’t let a drifting heart rate scare you into overdoing it.

Q: Is 4 mmol/L definitely my LT2?
A: Not necessarily. 4 mmol/L is a convenient population average default; individual variation can be large—some people’s MLSS corresponds to lactate below 4, others above 4. For true precision, you’d need individualized testing. But for training planning, the threshold pace/power you capture from a field test is more than sufficient.

Q: How often should I retest FTP or threshold?
A: I generally recommend every 6–8 weeks, or after completing a clear training block (e.g., finishing a base phase and entering an intensity phase). Testing too frequently means the fluctuations might just be noise from that day’s condition; waiting too long means applying old zones to a new body—both will throw your training plan off.

Q: I don’t have a coach. Can I train on my own with this framework?
A: Yes, you can, and many people start exactly this way. First, anchor your LT2 with a field test, get the three zones clear, ensure eighty percent of your time is at low intensity, and schedule two to three quality hard sessions per week—just getting these things right will put you ahead of most people who “train by feel.” When you encounter more nuanced periodization, return-from-injury protocols, or specific weakness corrections, that’s when to seek professional help.

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Conclusion: Spend Your Effort in the Right Places

Back to A-Kai’s story. His half-marathon improved by eight minutes not because he trained more or harder, but because every workout landed in the right zone—easy days truly easy, hard days truly hard, threshold workouts precisely hitting LT2.

Lactate threshold isn’t a mysterious red line that makes you “blow up.” It’s a map for allocating your effort. LT1 tells you where the ceiling of your aerobic base is and where to stack your volume; LT2 tells you where the core of race pace is and where to place your most effective threshold stimulus. Understand these two anchors, and you’ll stop getting lost in the “in-between” gray zone every day.

Training has never been about who trains the hardest, but about who trains the smartest and can sustain it long-term. Go do a field test, anchor your LT2, then look back at this week’s plan—you might, like A-Kai, discover that the real answer was there all along.

Before your next session, ask yourself: “Which zone am I training in this time?” If you can answer that clearly, and keep asking it throughout the season, you’re already ahead of most people. Training is a long conversation, and threshold is the most honest ruler you have for talking to your own body.

This article is educational content and does not replace individual assessment by a physician, physical therapist, or nutritionist.

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References

• Lactate threshold — Wikipedia: https://en.wikipedia.org/wiki/Lactate_threshold
• The origin of the maximal lactate steady state (MLSS), PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC10840223/
• LT1, LT2, and the scientific basis of heart rate zones for runners — Running Writings: https://runningwritings.com/2025/02/lt1-lt2-heart-rate-zone-science.html
• Challenge Taiwan Official Website (Taitung International Triathlon): https://www.challenge-taiwan.com/

Related Reading

• The Science of Lactate Threshold Running: Training Zones for LT1 and LT2
• Lactate Threshold Training Science: Physiological Mechanisms and Training Applications of LT1 and LT2
• Lactate Threshold Training: How to Find Your Critical Cycling Pace
• Cycling Lactate Testing: Applications of Blood Lactate Concentration in Training Zone Setting