Understanding your own Physiological Thresholds is important

In today's blog, we want to delve into two thresholds frequently discussed in the world of endurance sports: VT1 and VT2, also interchangeably known as LT1 and LT2 due to their close correlation.

VT1, or Ventilation Threshold 1, marks the point where your breathing intensifies for the first time during exertion. This threshold is a critical physiological marker, as it indicates a shift in how your body is utilizing energy. As you increase the intensity of your exercise, you'll reach VT1 before encountering VT2.

VT2, on the other hand, is analogous to what is known in cycling as FTP, or Functional Threshold Power. FTP represents the highest power output a cyclist can sustain over an hour. It's a cornerstone metric in virtually every power-based training plan. Recognizing the significance of FTP, it's essential to assess it accurately. However, it's important to note that, like any physiological threshold, FTP is not a fixed number. It can vary based on a multitude of factors, including your physical condition on any given day. For instance, on days when an athlete is well-rested and in peak form, their FTP might be slightly higher. Conversely, during periods of accumulated fatigue, whether from recent training sessions or other stressors, the FTP may dip below the typical tested value.

Given these fluctuations, it's advisable to evaluate FTP under consistent conditions. The objective is to compare like with like, ensuring that the testing methodology remains uniform. For example, a 20-minute FTP test conducted in warmer conditions, say at 25 degrees Celsius, may yield different results compared to the same test performed at a cooler 15 degrees Celsius.

The implications of this are significant, not just for cyclists but for athletes across various endurance sports. Understanding and accurately gauging your VT1 and VT2 (or LT1 and LT2) can profoundly impact your training effectiveness, race strategy, and overall performance. By tailoring your training to these physiological markers, you can optimize your efforts and ensure that you're training at the right intensity to meet your specific fitness and competition goals.

In the following sections, we'll dive deeper into how VT1 and VT2 are determined, their implications in training regimes, and the best practices for athletes to leverage this knowledge to their advantage.

Granted, staying abreast of the latest in sports science and training methodologies is not always straightforward. In this blog post, we won't necessarily dictate what's right or wrong, as the appropriateness of any training method or physiological marker heavily depends on the individual athlete. Instead, our focus is on exploring the variations among 15 cyclists, using real data to illuminate the diversity in athletic performance and physiology.

We've collected and analyzed data from 15 randomly selected athletes to determine their VT1 and VT2 levels. These thresholds were identified by examining ventilation metrics and data from the Moxy monitor, which tracks muscle oxygen saturation (SmO2). Additionally, we looked at two crucial breakpoints (BP1 and BP2) thought to closely correlate with VT1 and VT2, respectively (or LT1 and LT2, with LT standing for lactate threshold).

The use of Moxy monitoring provides a unique insight into how muscle oxygen levels change in response to increasing exercise intensity. This technology helps us understand the physiological shifts that occur at these critical thresholds. BP1 and BP2 are particularly significant because they represent noticeable changes in muscle oxygen utilization, which are generally aligned with the VT1 and VT2 thresholds.

The data from these 15 athletes offered a fascinating glimpse into the individual nature of physiological thresholds. Each athlete displayed unique VT1 and VT2 points, reflecting a wide range of aerobic and anaerobic capacities. These differences underscore the necessity of personalized training plans and the potential pitfalls of adopting a one-size-fits-all approach.

The diversity in athletic performance among cyclists, as evidenced by the data from 15 cycling tests, is profound. These athletes, ranging from beginners to experienced racers, triathletes to recreational riders, exhibit a wide array of physiological characteristics. The data visualization provided (assuming it's attached or described in detail) offers a unique insight into how VT1 percentages vary relative to VT2 among these individuals.

To clarify, VT1, or the first ventilation threshold, is the point at which an athlete's breathing becomes noticeably heavier. The change in breathing pattern can be noticed by every athlete if they pay attention to their breathing, given they are riding at easy enough intensities. VT1 is acknowledged as marking the upper end of Zone 2 or the onset of Zone 3. It's critical to note that VT1 should not be conflated with Zone 2 itself, as Zone 2 is typically considered to fall between 50% and 70% of an athlete's Functional Threshold Power (FTP) or 50-65% of their maximum heart rate, depending on the training zones one subscribes to.

In our analysis, we consider VT2 as 100% and plot the VT1 values against this benchmark. This approach reveals that the lowest VT1 is around 46% of an athlete's VT2, while the highest is at 67% of another athlete's VT2, with a median at approximately 50%. This illustrates not only the variability in VT1 but also how it diverges from the concept of Zone 2.

The correlation between higher VT2 and corresponding VT1, compared to lower VT2 and its VT1, is intriguing. For instance, the lowest recorded VT2 was about 150W with VT1 at 75W (49% of VT2), while the highest VT2 was around 299W with VT1 at 165W (55% of VT2). This data suggests that a higher FTP or VT2 doesn't necessarily mean a proportionally higher percentage of VT1. In other words, improving your FTP by a certain percentage doesn't automatically shift VT1 by the same percentage.

The correlation coefficients reinforce this:

• Correlation Coefficient (FTP & VT1 Power): 0.87

• Correlation Coefficient (FTP & VT1 %): 0.20

Regarding Zone 2 and FatMax training, the objective is to increase training volume at a relatively low cost of fatigue while potentially enhancing mitochondrial density. FatMax represents the intensity at which the body maximizes fat utilization as fuel, typically occurring in the lower to mid-range of Zone 2.

In the quest for optimized training, the focus often shifts to maximizing 'bang for the buck.' Riding in Zone 2, particularly near FatMax, seems logical for enhancing endurance and fat utilization. However, the fixation on metrics, especially in competitive environments like Strava, can skew perspectives on what's truly effective as athletes often focus then more on the per say higher number instead on what’s optimal.

So, what's the right approach? When asked about the ideal FTP percentage for Zone 2 training, our practical advice is to aim for 50% of your true 1-hour FTP – the power you believe you can sustain for an hour, not based on a 20-minute test or any other extrapolation. Dropping another 5% might not only be more ego-friendly but could also provide additional benefits, aligning you closer with Zone 2 and potentially enhancing fat utilization.

Practical Tipp: Watch your Breathing! Calibrate your feelings and sensations when riding. Especially your Breathing. Notice Changes in Breathing Patterns, when does your Breathing change? On your next Ramp Test, start at very low intensities and pay attention when your breathing starts to pick up the first time as your power output increases. That first initial increase in Ventilation is your VT1! Then pay close attention again around the Power what you believe is your FTP. There you will be able to notice again a that your breathing will pick up as you cross over FTP. This point is right around your VT2.

Of course the best would be to get your VT1 and VT2 determined with an actual Vo2Max test or a 4-1 Test. Then you have a better idea for what to look at while exercising. But in case you don't have any of these options available then it is as simple as calibrate your senses to your Body Feeling and get to know yourself again. Practice at every ride or run to find back to what your body is telling you.

In addition, watching things like cardiac drift for easy exercise will also give you some insightful information about where you are. For easy exercise your cardiac drift (pw:hr) should be relative small <3%. Given that temperature is not high, hydrated enough and also rested enough.