For years, World cycling teams have used VLa Max to check whether or not riders are in shape — with the general practice of raising VLa Max for sprinters and lowering it for GC and time trialists. You can estimate the balance of glycolytic to oxidative energy contributions without lactate, and you can spot an athlete with likely (but not definite) high VLa Max from a power curve visible in the TrainingPeaks dashboard.
Just as VO2 Max is often referred to as aerobic capacity or power, consider VLa Max as glycolytic capacity or, glycolytic power. Understanding VLa max and how to test it can help coaches better understand an athlete and guide training decisions.
What Is VLa Max?
VLa Max represents the maximum rate of lactate production. It’s linked to the energy generated through glycolysis, serving as an indicator of the anaerobic (glycolytic) energy system’s effectiveness. Essentially, VLa is the key indicator of your glycolytic system’s maximum performance capacity.
Athletes engaged in brief bursts of intensity — like 100m sprinters or 50m freestylers — need to increase their VLa Max because it directly correlates with heightened glycolytic energy production. For athletes training in mid-distance events, like cyclocross riders or grand tour sprinters, VLa Max must be tuned to the demands of the race. Long-distance triathletes and marathon runners, on the other hand, should lower their VLa Max as much as possible.
Tailoring VLa Max for Different Athletic Needs
Variations in VLa Max across athletes highlight the unique demands of respective sports and events, as well as the nature of the athlete’s training. For example, an athlete transitioning from an off-season spent weight training may exhibit a raised VLa Max compared to their in-season shape, showing the intricate interplay between training and the fluctuating nature of VLa Max. This emphasizes the adaptability and responsiveness of the glycolytic system across different sport types and seasonal training priorities.
Coaches often notice the glycolytic system’s ability to adapt to training stimuli throughout the course of a season. While it may only take a short training duration to develop high-intensity power numbers, more aerobic efforts take longer to develop. How much VLa Max changes depends not only on the training method but on the athlete as well.
How Do You Test VLa Max? A Step-by-Step Guide
If you want to test an athlete’s VLa Max, you’ll need to test their lactate at various points during a training session. This means you’ll need access to a lactate analyzer (like the Lactate Pro 2). You’ll also need a power meter.
If you’ve never tested lactate at home before, check out High North’s protocol for an in-depth guide. (There are ways to test your lactate without pricking your finger, but for the purpose of measuring VLa Max, an accurate lactate reading is necessary.)
Step 1: Collect Your Initial Sample
Following 15 minutes of easy riding, take a 5-minute rest before obtaining a lactate sample. If the level exceeds 2.5 mmol/L, extend the rest period before attempting another sample. (For additional information on blood lactate levels at various intensities, refer to the National Library of Medicine’s comprehensive guide.)
Step 2: Perform a Maximum Intensity Effort
Complete a maximum-intensity effort lasting 20 seconds, avoiding ERG mode. If you’re outside, a short, steep hill also works. Once completed, stop pedaling entirely — continuous pedaling will skew lactate readings downward.
Step 3: Collect Post-Exertion Samples
Sit down and remain stationary. Take samples at three, five, and seven minutes post exertion. For enhanced precision, additional samples can be taken at four and six minutes and continually until a decline in lactate levels is observed.
Step 4: Take a Final Sample (Optional)
Optionally, remain stationary for 20 minutes following the 20-second maximum effort to take a final lactate sample. This will provide insight into the system’s ability to clear lactate.
Once the lactate numbers from the maximal effort are collected, subtract the baseline value taken in Step 1 and divide by 16. (This removes the contribution from the creatine phosphate system for the first four seconds.) This number is the VLa Max. Once several tests have been conducted, compare the maximum lactate value reached to asses whether the VLa max is rising or declining.
Interpreting VLa Max Results
After a VLa Max test, use the equation above to calculate the VLa Max value in mmol/L/sec. Generally speaking, for endurance athletes, the value should be between 1.0mmol/L/sec and 0.2mmol/L/sec — with a pure sprinter being closer to 1.0mmol/L/sec and a professional long-distance triathlete being closer to 0.2mmol/L/sec.
Outside of endurance athletes, VLa Max numbers are often much higher, with particularly large VLa Max readings seen in track cycling, rowing, and middle-distance swimmers.
Criticisms and Limitations of VLa Max
There are four main criticisms of VLa Max as a metric to determine training:
- VLa Max doesn’t represent anything real. For example, it doesn’t tell us the maximal lactate-building rate in muscles, even though that’s what the number supposedly represents.
- The true peak lactate value could be missed during the VLa Max test, as measurements are taken at discrete time intervals. To overcome this, implement a best-fit curve to visually spot if it’s likely the peak lactate value has been missed.
- VLa Max requires a maximum sprint, which can be hard to achieve and standardize. However, we can check power values to see if these align with what an athlete has produced in the past.
- Peak lactate production depends on fatigue levels and carbohydrate availability, so care must be taken to standardize these two aspects. Methods for this will depend on the training program and coaching methods in place.
Using VLa Max in Training
Personally, I like to think of VLa Max as a tuning tool more than anything else. It has utility, it’s easy to measure, the test has almost zero energy cost to an athlete (it’s much easier than a 20-minute FTP test), and it offers a rough idea of an athlete’s fitness. Whether or not it represents some measure of ‘peak glycolytic flux’ or has any real physiological meaning is irrelevant as it’s useful as a number in its own right.
VLa Max is a useful tool, but it’s just one of many lactate measurements that inform an athlete’s training progress. Use it alongside power, heart rate, and subjective data from the athlete. Ultimately, it’s important to remember that performance is the main goal, and it’s best not to get too lost in the weeds.
References
Eriksson, M. (2019, February 18). FTP, VO2max and VLaMax: what triathletes need to know with Sebastian Weber | EP#169. Retrieved from https://scientifictriathlon.com/tts169/
Mavroudi, M., et al. (2023, April 19). Blood Lactate and Maximal Lactate Accumulation Rate at Three Sprint Swimming Distances in Highly Trained and Elite Swimmers. Retrieved from https://www.mdpi.com/2075-4663/11/4/87
Nitzsche, N., et al. (2018, November 20). Reproducibility of Blood Lactate Concentration Rate under Isokinetic Force Loads. Retrieved from https://www.mdpi.com/2075-4663/6/4/150
