Physiological Testing

Physiological Testing in Denver, CO

Physiological testing provides us, you, and your coach the data needed to make informed decisions regarding your training and nutrition programs.

Through testing, we gain a better understanding of how the key systems in your body are functioning during training and racing, and are able to identify areas in need of improvement as well as determine optimal strategies for success. Our professionals use state-of-the-art equipment and protocols with both VO2 max and lactate threshold testing.


VO2 stands for oxygen consumption and is a picture of your metabolism. As we know, the body needs oxygen to create energy for training and racing. Therefore, the better your body is at delivering oxygen and using it, the more fit you are and the more power and speed you are able to generate and sustain. Your VO2 max is an indicator of your fitness and economy refers to how efficiently you use energy at your race pace. What you’ll learn from a VO2 test:

  • Your VO2 Max score (how fit you are)
  • Your maximal or near maximal heart rate
  • Training zones customized to your unique physiology (HR, Power, Pace)
  • How much fat and carb you burn at different intensities
  • How many calories you burn per minute/hour at different intensities
  • Insight into physiological limitations
  • Key action strategies to help you meet your goals


A byproduct of energy production during exercise and a secondary source of energy, blood Lactate (aka lactic acid) production increases as our body shift to burning more carbohydrates at faster rates. The term “threshold” refers to the intensity at which your body shifts from sustainable energy production (supply meeting demands) to a point at which energy production and turnover is failing to keep up with demand and intensity and effort is no longer sustainable. What you learn from this test:

  • Training zones customized to your body’s unique physiology (HR, Power, Pace)
  • Insight into physiological limitations
  • Key action strategies to help you meet your goals


The Complete Picture: VO2max, substrate oxidation, training zones, and Lactate Threshold – $389


VO2 Metabolic Testing: VO2max, substrate oxidation, and training zones – $249


Lactate Threshold Testing: Including training zones for Power & HR – $175

Packages can be purchased for running or cycling


Contact us today to schedule your appointment!


Understanding the Basic Physiology of VO2Max Testing

Obviously, if you were physically capable of running that marathon on Day 1, you wouldn’t need to train. Therefore, the overarching purpose of training is to cause your body to adapt so that you can reach your race goals. Through training, you can cause adaptations that make you faster, stronger, better at endurance, or more powerful. More specifically, basic physiology adaptations as an endurance athlete come down to how well you can use and create energy in the working muscle for the total duration of your event. There are two primary energy sources for an endurance athlete – Fat and Carbohydrate (CHO).

Depending on the intensity, the body will either increase or decrease fat and CHO breakdown to supply the necessary energy for your workout. The harder you work out, the more energy you need. At lower intensities, the preferred fuel source should be fat; at mid ranges, it’s mixed fat and CHO, and at high intensities, it’s CHO. The terms aerobic and anaerobic come from the process of how fat or CHO is broken down and used for energy. Fat and some CHO breakdown requires oxygen and therefore is an Aerobic (with oxygen) process. CHO is most often broken down anaerobically (or without oxygen). Hence you hear people say your aerobic training zones are best for burning fat or losing weight (although there is a lot more to it).

During a VO2Max test, we not only see whether you’re using fat or CHO as fuel, we see how much of each. We also get a glimpse of how well the lungs and heart are functioning. One of the primary roles of your heart and lungs is to transfer the necessary fuel and oxygen to the working muscles to be used for energy. Therefore, they play key roles in your success.

Understanding Why You Must Train Smarter

How you improve fitness, endurance, etc., to reach your goals is by manipulating training stress. The stress caused to the body during workouts causes your body to adapt its physiology in order to maximize energy consumption and usage in order to meet the demands being placed on it. That’s why it may feel very hard the first time you run 5 miles, but soon, it is no longer a challenge. Stress can be the fatigue and muscular breakdown in speed work, or stress to your lungs and heart during a long run. The adaptations to this stress occur in the cells of your muscle, lungs, and heart cells. These adaptations will help you:

  • Burn fat in higher volumes
  • Burn fat at higher intensities
  • Burn CHO more efficiently
  • Strengthen the muscle and neurological drive to the heart that will, in turn, allow you to deliver oxygen and glucose (CHO) faster and more efficiently to the needed muscles
  • Strengthen the muscles of the lungs (better oxygen intake and CO2 expiration)
  • Improve the ability of the body to absorb oxygen from the lungs
  • Improving the mechanical and neurological drive to the muscles will improve efficiency
  • Improve blood supply & oxygen delivery

*not an all-inclusive list

However, your body will not adapt to everything at the same time, and not all training stress is created equal.

The Rule of Specificity states that the body will adapt to the demands of training in kind, or with a specific adaptation to meet the specific demand. For example, if at 110% of your threshold, you burn 90% sugar, and you spend most of your training time at or above 110% of your threshold, your body will get really good at training at that intensity. This means your body will adapt in favor of burning more sugars and clearing blood lactate because that’s what your body needs to do so that running at that intensity is no longer stressful. This isn’t necessarily a bad thing if that is what you need for your goals. But the Rule of Specificity also states that we can’t effectively adapt two different and opposing physiological systems at the same time. So while you may get better at burning sugar (CHO), you may get worse at burning fat. Which is a problem if you’re an endurance athlete.

So why testing? Physiological testing is one way of safeguarding against taking your training in the wrong direction and ensuring you adapt to your training in a way that supports and enhances your desired performance. We’ve seen many athletes struggle to make the improvements that they are looking for, and with testing, we are better able to determine why that is happening and help the athlete and coach adjust their training to get the desired results.