Improving Lactate Threshold Is Not the Whole Answer
Lactate threshold is one of the most discussed metrics in endurance sport.
Athletes want to increase it. Coaches build training blocks around it. Cyclists talk about FTP. Runners compare threshold pace. Triathletes look at heart rate, power, and lactate values and ask a simple question:
How can I push my threshold higher?
It is a reasonable question.
But it is not always the first question I ask.
After decades of racing, coaching, and testing athletes, I am usually more interested in something else:
What is actually limiting this athlete’s performance?
Because a higher lactate threshold alone does not guarantee a better race.
Threshold Is Part of a Larger System
When we talk about lactate threshold, we are often referring to the upper physiological threshold commonly described as LT2.
The terminology can become confusing quickly. LT2, maximal lactate steady state, anaerobic threshold, and OBLA are often discussed together, although they are not necessarily interchangeable definitions.
For the athlete, the more important point is this:
As exercise intensity increases, there comes a stage where lactate production and the associated metabolic demands begin to rise more rapidly. The ability to sustain work around this region is highly relevant to endurance performance.
But threshold does not exist in isolation.
An athlete may have a strong LT2 and still struggle in a long race.
Why?
Perhaps aerobic durability is limited.
Perhaps carbohydrate utilization is too high for the event.
Perhaps muscular endurance becomes the limiter after three or four hours.
Perhaps the athlete’s movement economy deteriorates.
Perhaps fueling is insufficient.
Perhaps the athlete arrives at the race carrying too much fatigue.
Or perhaps the fitness is there, but the athlete does not execute the race well.
One number cannot explain the entire athlete.
I Don’t Test Lactate Just to Find a Threshold
When I perform a blood lactate step test, I am not simply looking for the point where lactate reaches a particular number.
I am looking at the shape of the response.
How does lactate behave as workload increases?
What happens around the first physiological threshold, LT1?
Where does the curve begin to rise more aggressively?
How does heart rate respond?
How does the athlete describe the effort?
What do power or pace tell us?
And most importantly:
Does the physiological profile make sense for the athlete’s event and goals?
A 40-kilometer time trialist and an Ironman athlete do not need exactly the same physiological profile.
Neither do a marathon runner and a sprint-distance triathlete.
Testing should help us understand the athlete.
It should not simply produce a threshold number to upload into a training platform.
VO₂max Matters. So Does How Much of It You Can Use.
VO₂max describes the maximum rate at which the body can take in, transport, and utilize oxygen during intense exercise.
It matters.
A large aerobic capacity provides a higher physiological ceiling.
But having a high ceiling does not tell us how much of that capacity an athlete can sustain.
This is where fractional utilization becomes important.
Two athletes may have similar VO₂max values but very different sustainable performances.
One athlete may be able to operate at a greater percentage of their aerobic capacity before reaching the upper threshold region.
The other may have an impressive VO₂max but be unable to use as much of it sustainably.
This is one reason I am cautious about celebrating isolated physiological numbers.
The question is not only how large the engine is.
The question is how effectively the athlete can use it for the demands of their event.
For Long-Course Athletes, I Often Look Lower
This is one area where my thinking has become increasingly clear over the years.
For an Ironman athlete, I am often just as interested—sometimes more interested—in what is happening around LT1 and below.
Why?
Because an Ironman is not raced at LT2.
The athlete needs to produce energy aerobically for many hours.
They need to preserve glycogen.
They need to oxidize fat effectively.
They need to tolerate a large amount of work without accumulating excessive metabolic and muscular fatigue.
And they need to arrive at the run with enough physiological stability to continue performing.
A strong upper threshold is useful.
But if the aerobic floor underneath it is weak, the athlete may have an impressive FTP and still struggle to convert that fitness into long-course performance.
This is why I spend so much time developing what I call a robust aerobic floor.
Lactate Production and Lactate Clearance
Lactate is often misunderstood as simply a waste product or the reason an athlete becomes tired.
The reality is more complex.
Lactate is continuously produced and utilized within the body. What we observe in the blood reflects the relationship between its appearance and removal.
From a training perspective, I may use sessions that challenge lactate production and sessions that develop the athlete’s ability to continue working while processing and utilizing lactate.
But again, the correct training depends on the athlete.
Some athletes already have plenty of glycolytic power.
They can accelerate.
They can produce high power.
They can hurt.
Their problem is not a lack of intensity.
In fact, adding more high-intensity work may move them further away from the physiological profile required for their primary event.
Other athletes may have developed a large aerobic base but lack the upper-end stimulus required to raise their performance ceiling.
The same workout does not solve every athlete’s problem.
VLamax and the Cost of Producing Power
VLamax is an estimate of maximal glycolytic lactate production rate.
In simple terms, it gives us information about the contribution and power of the glycolytic system.
A higher VLamax can be advantageous for athletes who need rapid energy production and high power.
Think of sprinting and repeated explosive efforts.
But there can be a cost.
An athlete with a stronger glycolytic contribution may rely more heavily on carbohydrate and produce lactate at a greater rate at a given workload.
For a long-course athlete, this may not be desirable.
An Ironman athlete needs to manage limited carbohydrate stores over many hours.
The ability to produce a huge amount of power for a short period is far less important than the ability to produce sustainable power economically for a very long time.
This does not mean every endurance athlete should simply chase the lowest possible VLamax.
Physiology is not that simple.
It means the athlete’s metabolic profile should support the demands of the event.
Train the Limiter, Not the Trend
Endurance training moves through trends.
VO₂max becomes popular.
Then Zone 2.
Then lactate testing.
Then VLamax.
Then heat training.
Then something else.
These are all potentially useful tools and concepts.
But a training method is only useful if it addresses the athlete in front of us.
If an athlete has poor aerobic durability, more threshold work may not be the answer.
If an athlete already produces a great deal of glycolytic power, repeated high-intensity sessions may not be what they need.
If an athlete has excellent laboratory numbers but consistently fades late in races, I want to understand why.
And if an athlete is chronically tired, adding another “performance session” may simply make the problem worse.
Before deciding how to improve lactate threshold, we need to understand whether lactate threshold is actually the limiter.
Testing Should Lead to Better Decisions
This is ultimately why I use blood lactate testing.
Not to give an athlete an impressive report.
Not to identify a magical 4 mmol/L number.
And not to replace coaching with data.
I test because good physiological information can help us ask better questions.
Where is the athlete today?
What appears well developed?
What is limiting performance?
Does the athlete’s physiology match the demands of the event?
What should we prioritize next?
And then we train.
We observe.
We adapt.
Eventually, we test again and look at what changed.
Data shows us what the body is doing. Coaching is the process of understanding why—and deciding what to do next.
Improving Performance Means Improving the Athlete
Yes, lactate threshold matters.
VO₂max matters.
Fractional utilization matters.
Fat oxidation matters.
Economy matters.
Strength and muscular endurance matter.
But endurance performance is not created by maximizing every physiological metric independently.
The goal is to develop the right qualities, in the right athlete, for the right event, at the right time.
Sometimes that means raising LT2.
Sometimes it means building the aerobic floor around LT1.
Sometimes it means improving durability.
Sometimes it means reducing unnecessary intensity and allowing the athlete to absorb the training they are already doing.
The answer is not always more.
The answer is to understand what the athlete needs next.
And that is where testing becomes useful.
Not as the final answer.
As part of the decision-making process.
