The Dynamic Shift in Endurance Modeling: Understanding VLamax for Cycling & Running
- Mark Turnbull
- 21 hours ago
- 5 min read
You’re likely familiar with VO2 max, a measure of aerobic capacity, but there’s another performance metric that could revolutionise your training: VLamax.
Consider it the “hidden dial” that determines whether you excel in sprinting or endurance. A higher VLamax indicates explosive speed and power, while a lower one enhances long-distance efficiency. Understanding and adjusting this could be crucial for unlocking your potential as a cyclist or runner.
This guide will explain what VLamax is, why it’s important, and how you can incorporate it into your training.
Key takeaways at a glance:
VLamax = maximum lactate production rate (anaerobic capacity)
High VLamax = sprint power, rapid acceleration
Low VLamax = endurance efficiency, improved fat metabolism
You can test and train to modify your VLamax
Combine VLamax with VO2 max to tailor your training
What is VLamax?
VLamax refers to the maximum lactate accumulation rate. It indicates how rapidly your body can generate lactate during anaerobic metabolism (energy production without oxygen).
High VLamax: Greater glycolytic power enhances sprint and acceleration capabilities
Low VLamax: Improved aerobic metabolism boosts endurance
In summary: VO2 max represents your aerobic limit, while VLamax indicates your anaerobic threshold. Together, they create your distinct performance profile.
Why Is It Important?
Your VLamax affects:
Endurance: Lower values decrease carbohydrate consumption, postponing fatigue
Sprint & Power: Higher values enhance acceleration
FTP & Threshold: It directly influences Functional Threshold Power (FTP) by impacting lactate clearance
How to Measure VLamax
There is no VLamax calculator based on certain efforts. To obtain an accurate measurement, two VLamax test protocols exist: one involving a 15-second sprint and another consisting of several sub-maximal tests.
INSCYD is the sole tool that offers a scientifically validated VLamax. More importantly, it helps you understand its impact on your performance and determine your optimal VLamax.
The INSCYD VLamax test can be conducted in a laboratory setting, but you can also perform a VLamax field test or even a remote Zwift test.
Athletes can schedule their INSCYD test and consultation via this link.
Understanding VLamax Results
What is considered a high or low VLamax?
Determining your VLamax requires specific testing; it cannot be estimated.
Athlete Type | Optimal VLamax Profile | Significance |
Sprinter / Racer | High (0.6+ mmol/l/s) | Provides explosive power and strong sprint finishes |
Time Trialist | Medium (0.4–0.6) | Offers a balance of endurance and power |
Ironman Triathlete | Low (<0.4) | Enhances fat efficiency and supports sustainable long efforts |
Keep in mind: A higher VLamax isn't always preferable. The appropriate VLamax is aligned with your specific sport and objectives.
Limitations and Reliability
As with any performance metric, VLamax has its imperfections. Consider the following:
Testing variability: Outcomes are influenced by effort quality, pacing, and the timing of lactate measurement
Individual differences: Athletes with identical VLamax values may perform differently due to variations in muscle fibre type, training background, or VO2 max
Limited accessibility: Lab tests can be costly, and calculators require accurate data input
Importance of context: VLamax is most effective when used alongside VO2 max, FTP, and race requirements, rather than as an isolated metric
‘VLamax is a relevant indicator of maximal glycolytic rate. However, this metric provides minimal extra information over using the power output from the isokinetic test alone. Practitioners may simply measure power over glycolytically demanding efforts to understand the maximal glycolytic rate of their athletes’
Consider VLamax as a guide, not an absolute truth. It aids in refining training, but true progress is reflected in actual performance on the road, track, or trail.
How to Utilise VLamax in Training
Once you determine your VLamax, you can begin customising your training sessions. Consider it your metabolic fingerprint—it reveals how your body generates energy and where your training emphasis should be.
If your VLamax is high: You possess explosive power but deplete glycogen rapidly. Focus your training on endurance, threshold work, and longer steady sessions.
If your VLamax is low: You are efficient but might lack high-intensity power. Incorporate sprints, VO2 max intervals, and strength training to enhance glycolytic power.
How to Reduce VLamax
A lower VLamax is beneficial for endurance athletes who aim to conserve glycogen and depend more on fat metabolism. To decrease it, consider:
Endurance rides: Engage in long, steady Zone 2 sessions to enhance aerobic efficiency
Sweet spot / threshold intervals: Train to sustain high output without heavily relying on glycolysis
Reduced carb workouts and rides (with caution): Occasionally riding with low glycogen can promote fat adaptation
Reduce sprint work: Limit high-intensity, short-burst training if your goal is pure endurance
Result: A more efficient energy system that enables you to maintain race pace for longer.
Ways to Boost VLamax
If you're aiming for more sprint power, you'll want to elevate your VLamax. Here's how:
Sprint training: Perform 10–15 second maximum effort sprints with ample recovery time
Strength training: Engage in gym exercises like squats and lunges
High-intensity intervals: Execute brief, intense efforts at over 120% FTP with sufficient rest
Outcome: The ability to accelerate when needed.
VLamax in Running
Runners must balance explosive power with efficiency.
Sprinters and middle-distance runners gain from a higher VLamax to enhance speed and anaerobic power bursts. Conversely, marathoners and ultrarunners benefit from a lower VLamax, which postpones glycogen depletion and enhances fat utilisation.
Conclusion: Performing 400m intervals or hill sprints will increase VLamax, while long, steady runs will help decrease it.
VLamax and Cycling
Cyclists can adjust VLamax according to their discipline:
Road sprinters and speed racers: Require a higher VLamax for maximum power. Emphasise sprints, strength training, and VO2 max intervals
Climbers and time trialists: Excel with a moderate VLamax, balancing power with efficiency. Train across a wide range
Ironman / endurance cyclists: Perform best with a low VLamax. Focus on long endurance rides, threshold training, and minimise sprint sessions
FAQs about VLamax Training
How is VLamax calculated? It is determined through lab tests, lactate sampling, or modeling software following sprint protocols.
What is considered a high VLamax? Typically, it is >0.6 mmol/l/s. This is advantageous for sprinters but less favorable for endurance athletes.
What’s the difference between VLamax and VO2max? VO2 max represents the maximum oxygen your body can utilise during exercise. It sets the upper boundary of your aerobic capacity, whereas VLamax determines the lower boundary of your anaerobic threshold. Together, they influence performance potential.