As an endurance athlete or coach, you've probably heard about the importance of training at the right intensities. But with lactate testing, ventilatory analysis, and muscle oxygen measurement all claiming to identify your "thresholds," which method should you choose?
The answer might surprise you.
Spoiler: It's less about finding the perfect method and more about measuring consistently with whatever approach you pick.
Understanding the Three Measurement Approaches
Before diving into the specific differences, it's helpful to understand that there are three major physiological systems we can monitor to identify exercise thresholds:
1. Lactate (Blood Plasma Response)
Lactate measurement tracks the balance between lactate production and clearance in your blood. As exercise intensity increases, your muscles produce more lactate (converted from pyruvate) than your muscles can clear, causing blood lactate levels to rise. This rise isn't linear – it shows distinct inflection points that correspond to metabolic shifts.
Why it works: Lactate is directly tied to your body's energy systems. There are two points of lactate production we are interested in. The first is where blood lactate rises to a new, but higher, steady-state level; this is your lactate threshold 1 (LT1). The second is when lactate continues to rise, meaning you can no longer clear lactate as fast as you produce it, and you've crossed into unsustainable territory. This is lactate threshold 2 (LT2). These transition points reliably indicate when your body shifts from primarily aerobic to increasingly anaerobic energy production.
2. Ventilation (Breathing Response)
Ventilatory thresholds measure how your breathing patterns change with exercise intensity. As you work harder, your body needs to take in more oxygen and eliminate more carbon dioxide. At certain intensities, these breathing demands increase disproportionately.
Why it works: Your breathing is intimately connected to your metabolism. When your body starts producing more CO2 (from increased carbohydrate burning) or needs to buffer increasing acidity (from increased force production), your breathing rate and depth must increase dramatically. These ventilatory "threshold" correspond closely to the same metabolic transitions that lactate measurement identifies.
3. Muscle Oxygen (Local Tissue Response)
Muscle oxygen saturation (SmO2) measured by NIRS tracks the balance between oxygen delivery to your muscles and oxygen consumption by your muscles. As exercise intensity increases, this balance shifts in predictable patterns that reveal breakpoints.
Why it works: Your muscles are where the actual work happens – where oxygen is consumed to produce energy. By measuring oxygen saturation directly at the working muscle, you're getting real-time information about the supply-demand balance. The first shift is where your cardiovascular system can no longer oversupply oxygen to the muscle (NIRS BP1). The second shift occurs when oxygen demand consistently exceeds supply (indicated by continuously dropping SmO2), which means you've crossed into unsustainable intensity territory.
The Truth About Threshold Accuracy
Here's what the research shows: there is no evidence that one method is better than the others for identifying physiological thresholds. Yes, there are differences between methods, but none of these measurements are causative – they're all indicators, placeholders on the intensity scale that track the same underlying physiological changes.
All three methods are useful because they're measuring real changes in your physiology as you move through different exercise intensity domains.
The "Perfect" Threshold Doesn't Exist
Here's the thing that might surprise you: there's no single "correct" threshold value hiding inside your body waiting to be discovered. Each measurement method – lactate, ventilation, and muscle oxygen – is essentially taking a snapshot of different physiological processes that all change together during exercise.
Think of thresholds like measuring the temperature of a large lake. You could measure at the surface, at 10 feet deep, or near the bottom – each will give you slightly different readings, but they're all tracking the same underlying thermal changes. Similarly, lactate, ventilation, and SmO2 are all measuring different aspects of the same metabolic shifts happening in your body.
The real power isn't in finding the "perfect" number – it's in consistently tracking changes over time.
Why Consistency is Your Secret Weapon
The magic happens when you use the same measurement method consistently over weeks and months. Here's what you can track:
- Training adaptations: Are your thresholds shifting to higher intensities?
- Individualized zoning: How are your zones changing over time?
- Recovery status: Are your normal threshold patterns disrupted after hard training blocks?
- Daily readiness: How do today's responses compare to your baseline?
Whether your "threshold" is at 150 watts or 155 watts matters less than knowing that last month it was at 145 watts. That 10-watt improvement tells a story about your fitness that no single perfect measurement could.
The Moxy Advantage: Threshold Testing Without Compromise
This is where muscle oxygen measurement changes the game completely. Traditional threshold testing creates a frustrating dilemma:
Lactate testing requires lab visits, finger pricks, and expensive equipment. You might test every 6-8 weeks if you're dedicated.
Ventilatory testing needs metabolic carts and controlled environments. Again, you're looking at infrequent, formal testing sessions.
Muscle oxygen testing with Moxy eliminates this trade-off entirely. It's non-invasive, continuous, and you can use it every single day – during training AND on testing days. No trade-off. It's easy!
You Can Have It All:
- Formal testing days: Run a complete graded exercise test with full SmO2 breakpoint analysis
- Training integration: Monitor your threshold responses during actual workouts
- Daily check-ins: Quick 5-minute ramp tests or a standard warm-up protocol to assess readiness
- Race day insights: Real-time feedback on your intensity domains during competition
The consistency advantage is enormous. Instead of guessing where your thresholds are between quarterly lab tests, you're building a continuous picture of how your physiology responds to training stress.
The Bottom Line: Start Measuring, Keep Measuring
The perfect threshold measurement is a myth. Consistent threshold monitoring is a superpower.
Whether you choose lactate, ventilation, or muscle oxygen measurement, the key is picking one method and sticking with it. But if you want the method that lets you measure consistently without any downsides – one that you can use every single day, during training, and on race day – muscle oxygen with Moxy is the clear choice.
Your thresholds aren't fixed numbers carved in stone. They're dynamic indicators of your fitness, fatigue, and readiness to perform. The more consistently you can track them, the better you can optimize your training and racing.
Start measuring. Keep measuring. Watch your performance transform.
If you are interested in learning how you can determine your thresholds using the Moxy Monitor NIRS technology check out download the training and racing with Moxy ebook!
