Proper science or hocus pocus? Pros and cons of using VLamax

Physiological metrics like VO2max and anaerobic threshold are commonplace for professional and recreational cyclists alike, and, in short, the higher the better. Over the past couple of years, however, a new kid on the performance block’s begun to appear on training plans – one that confuses and excites in equal measure. According to this new metric, a higher score is good in some situations, but a lower one is preferred in others. Its name is VLamax. How can it benefit your performance? Let’s dig deep to find out.

Energy providers

To understand VLamax, first we must understand VO2max. VO2max measures the maximum volume of oxygen transported in the body to the working muscles. It’s colloquially known as ‘the size of the engine’ because it estimates how much potential endurance athletes have. The highest-recorded scores are above 90ml/kg/min (for male cyclists), while a fit recreational cyclist would be around 40-50 and a sedentary individual around 35-40.

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However, our bodies don’t just produce energy through the exclusive use of oxygen. They do it in at least two other ways, and one of them is by using carbohydrates as the primary fuel source (through the glycolytic system). Through the use of carbohydrates, another misunderstood physiological molecule is produced: lactate. And here’s where VLamax makes its appearance.

What VLmax measures

Among the teams measuring VLamax with consistency there's Team Jumbo-Visma. Photo: Getty Images

“So we have a proxy to benchmark the aerobic system: VO2max. VLamax is the same proxy or marker but for the glycolytic system. It uses the same V-dot (flux rate), but instead of O2, it’s related to La = Lactate. This is because lactate production rate is proportional to the energy – or, more precisely, ATP – generated through glycolysis," explains Sebastian Weber, former coach of Tony Martin and founder of INSCYD, which measures VLamax.
 
Weber explains that race-decisive moments (like a sprint, or a rider trying to reach the breakaway) are decided by high glycolytic contributions, and a higher VLamax would benefit these attacks. Hence, to test VLamax in training is, according to Weber, paramount to understand it and then schedule appropriate training sessions to fine-tune it for the specific race demands. But that’s not the only reason.

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"VLamax also influences sub-max intensities,” Weber continues, “so if an athlete has a highly trained glycolytic system, it’ll contribute to a greater extent than it would in athletes with a lower glycolytic performance. More glycolytic activity means more lactate production, lower lactate thresholds (power wise) and higher carbohydrate combustion rates.”
 
That's why a sprinter or a one-day specialist would benefit from having a higher VLamax, while GC contenders wouldn’t. More lactate production and higher carbohydrate combustion rates can help one type of rider but hinder the performances of others. A high VLamax may correspond to your high-octane petrol engine; a lower one represents more of a diesel.

Critical appraisal

On the other hand, Team UAE is not measuring VLamax at all. Photo: Getty Images.

VLamax has been studied for many years, but it became more popular over the last five years. In this time, its theoretical and practical limitations have been fiercely criticised within sports-science circles. “There is a fundamental error within this concept,” says exercise physiologist Peter Leo. “While initial studies used muscle biopsies to analyse glycolytic activity at the muscular level (like quadriceps), this cannot be directly related to a whole-body exercise marker.” 
 
In essence, Leo and other researchers have pointed out that taking studies conducted on specific muscles (or even single cells) and applying those findings to the whole body is fraught with inaccuracies.

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"Although the underlying idea of measuring anaerobic flux and maximum lactate accumulation rate (VLamax) is tempting, at the moment there’s not a single piece of scientific evidence that supports this hypothesis," says Leo
 
Jiri Dostal, a sports physician and performance director of the Czech Olympic Comitte, also highlights the inconsistency of the testing procedures. “We don’t have a standard test for VLamax, meaning the measured value is heavily influenced by the protocol and the exercise itself," he says. Despite that, Dostal still sees benefit in using VLamax, but he warns that people should look at it as a guideline rather than a set rule. 

Alternative ways to use VLamax

VLamax can be measured either through lactate tests (like the one in the picture), or power-only tests. Photo: Getty Images.

“We went through a painful and costly process of adopting this metric over the past few years," says Dostal. "We had high hopes and made a lot of mistakes. However, after all those failures, we realised that VLamax is a fantastic concept explaining many questions we have had about lactate metabolism. It helps to understand, for example, unexplained underperformance.”
 
For example, Dostal now uses VLamax as a long-term metric to monitor track sprinters. “A decline in VLamax partly shows overreaching and overtraining,” he explains. “That's why we have our protocol on Wattbike Pro suitable for track sprinters and custom-made Excel sheet calculations. Thus we know our data is reliable and trackable."

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Dostal uses his VLamax calculations on sprinters because they rely on the glycolytic power more than anyone else. But he specifies that they "call it VLamax, however this can be a misleading name. We use this measure not to guide the training, but as part of the regular check ups to avoid overtraining or any other issues."
 
In response to their critiques, VLamax users cite other studies and alternative ways to calculate it that are supposedly more reliable. Among them there’s Joachim Magera, Founder of Mesics, a company that offers several software that use a mathematical model to calculate VLamax. Magera says that Mesics software take in consideration what happen in the whole body, and not only in the single working muscles.
 
"We have implemented this complex model in our simulation software MetabolFX and have already been able to explain effects qualitatively and, in part, quantitatively with astonishing accuracy."A high VLamax is beneficial in critical moments of a race, for example an attack or a sprint. Photo: Getty Images

But even Magera agrees that "models never fully reflect reality. But they offer the possibility to understand measurements better” and predict performances in the real world with a high degree of accuracy.
 
So, it seems, VLamax has its limitations. But, Weber reminds us, that’s true for many physiological measurements when looking to apply them to peak performance including VO2max testing.

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Takeaway message

Exercise physiologists may be polarised in their views of VLamax. However, it's a fact that many coaches have been highly successful since adopting it, including Team Jumbo-Visma, Movistar and BORA-Hansgrohe.
 
Similar to VLamax, many physiologists and coaches have also highlighted the limitations of FTP. Still, the metric remains widespread and has been used successfully as a functional way to predict performances and assess riders’ fitness levels. Ultimately, as long as you can understand its limitations and use it as a guide, it can probably still help you better understand your physiology and help you find ways to improve it.