One of the unique advantages of Cenegenics’ Age Management program is the comprehensive testing performed by our clinical team. With a full panel of age management experts, we thoroughly screen each patient to achieve as robust a measurement of overall wellness as possible. While each test we perform holds tremendous value in terms of directing our physicians in developing an individualized program, one of the most significant parameters analyzed is a patient’s ability to utilize oxygen during exercise. This is measured through VO2 max testing.
Importance of VO2 Max Testing at Cenegenics
VO2 max testing assesses the maximal oxygen consumption of an individual during periods of intense, strenuous exercise. It is currently considered to be the gold standard of measuring cardiovascular fitness among medical experts and is hailed for its ability to accurately assess cardiorespiratory functioning.
Not only does this test indicate aerobic fitness levels of a specific individual, it also provides a wealth of useful information on which specific directions can be provided for training purposes. Additionally, VO2 max testing unlocks powerful insights into overall wellness, including warnings of potential cardiac or respiratory disease symptoms.
At Cenegenics, VO2 max testing is a primary component of each Elite Health Evaluation, and our clinical team uses the results of this test to create your individualized program for optimal results.
What is VO2 Max Testing?
There are various ways to perform a VO2 max test, the most common including use of a treadmill or cycle ergometer, both of which measure energy expenditure. Through the treadmill method, the participant begins by walking on a treadmill at a 10% grade.
Every two minutes, both the treadmill’s speed and grade will increase until a maximal work output or volitional failure is achieved. While this is considered to be the most thorough means of testing, as it requires the use of the entire body, it also presents significant risk of injury.
This is a maximal exercise test that is intended to push participants to reach levels of exhaustion, which, on a treadmill, can lead to the risk of falling. The proper precautions must therefore be implemented to ensure the safety of participants.
As an alternative to the treadmill test, the cycle ergometer is used as a safer option. At Cenegenics, we perform VO2 max tests via cycle as it is a much more efficient and less dangerous method for our clients. Additionally, it still provides valid, valuable results and information.
How Does a VO2 Max Test Measure?
A VO2 max test employs the use of a mask, which is worn by the participant during the exercise and connected to a metabolic cart where biometric measurements are recorded. As the participants breathe, the air is collected in a mixing chamber where the gas is analyzed.
When the air enters the chamber, both the volume of air and the ratio of carbon dioxide to oxygen are measured. The testing system uses specialized software, which can determine the energy expenditure of the exercise.
As the level of exercise intensity increases, the amount of carbon dioxide expelled while breathing also increases. These readings allow physicians to determine which fuel sources are being used in the body, (fats or carbohydrates) during a given point of time throughout the test. This proves to be beneficial for assigning customized training values for patients.
How to Read VO2 Max Test Results
Our cutting-edge VO2 max software provides a host of extremely useful information. Here, we will discuss the practicality and application of the data derived from the testing.
One of the most outstanding qualities of this test is its ability to track all of the following data in 15-second intervals for the duration of the entire test, allowing our physicians to observe not only the changes that occur but also how quickly physiologic markers shift as the exercise intensity increases.
Relative and Absolute VO2 Max
Absolute VO2 max (L/min) is a total value, while relative VO2 max (ml/kg/min) takes body weight into consideration. The relative value is therefore a more precise indicator of overall health than the absolute value.
For example, an individual may have a high absolute value, but when factoring in body weight, it is determined that they have a very low relative value which indicates less than ideal health. See the below chart for Relative VO2 Max Norms from the American College of Sports Medicine.
Metabolic Equivalents (METS)
Also known as metabolic equivalents, METS identify the amount of oxygen consumed at rest. One MET is defined as 3.5 ml/kg/hour, which is equivalent to the energy cost of sitting idly. This measurement provides a simple and straightforward means of measuring exercise intensity via oxygen consumption, and may be particularly beneficial for training.
Most treadmills now have a feature that will display the METS of a certain intensity level. An exercise physiologist or similar professional may prescribe an exercise plan using METS as a frame of reference for appropriate levels of intensity during physical activity.
Carbon Dioxide Expelled (VCO2)
VCO2 (L/min) is a value that goes hand-in-hand with VO2. As exercise intensity increases, so too does oxygen consumption (VO2). Thus, as more oxygen is consumed, more CO2 is created and expired through breathing.
The volume of carbon dioxide expelled after transporting oxygen throughout the body is measured by VCO2. CO2 is also created as a byproduct of energy production inside the body during rigorous exercise; we will cover that in greater detail in an upcoming section.
VE (L/min) refers to ventilation. In simpler terms, VE defines the movement of air via breathing. Ventilation therefore increases with exercise intensity, as the need to supply the body with oxygen and remove carbon dioxide increases. VE can also be correlated with the ventilatory threshold (described below) and used for training purposes
Tidal Volume (VT)
VT (L) is tidal volume. It is the volume of air that is transported into and out of the lungs with each respiratory cycle or breath. As exercise intensity increases, a larger oxygen demand is placed on the working tissue, demanding a larger volume of air per breath, more breaths per minute and an increased heart rate.
Respiratory Rate (RR)
Respiratory rate, or RR, is measured in breaths per minute. At rest, an adult averages 12 to 20 breaths per minute. As activity intensifies, respiratory rate will increase. With that said, elite athletes have the ability to maintain a lower RR even while performing high-intensity exercise, due to optimal cardiovascular conditioning.
Heart Rate (HR)
Heart rate (HR) is measured in beats per minute (bpm). Increased exercise intensity requires an increased oxygen demand to the body. In order to meet that demand, heart rate must increase to facilitate the transportation of oxygen to the working muscles. Both resting and exercising heart rate can be influenced by factors such as medication, stress levels, hormones, weight, and fitness level.
Most individuals have a resting heart rate between 60 and 100 bpm, but trained athletes may have a resting HR as low as 40 bpm. In general, physicians tend to recommend a target heart rate during moderate exercise of roughly 50-70% of maximum HR, or 70-80% of maximum HR during vigorous exercise. Keep in mind that maximum heart rate may vary by age and other factors, so physician oversight is essential to ensuring patients are exercising within safe HR zones .
Respiratory Exchange Ratio (RER)
RER stands for respiratory exchange ratio. It is among the most valuable pieces of information derived from a VO2 max test. RER determines the ratio of CO2 to O2 used, and it is indicative of the fuel source being used by the body. RER operates on a scale of 0.7 to upwards of 1.0, with 0.7 indicating utilization of fats for fuel and a measure of 1.0 or higher designating use of carbohydrates. This can be determined by the amount of CO2 in the air exhaled by the subject.
During periods of rest, we utilize fats as a fuel source and would therefore have an RER of 0.7. This is because breaking fat down for fuel requires oxygen and time. It is a slow process, so while at rest or during low-intensity exercise, our bodies are able to get enough oxygen to break down fats for fuel.
As exercise intensity increases, however, the body is no longer able to break down fats quickly enough to provide energy. It therefore needs to pull from carbohydrates stored in the muscles, known as glycogen stores. Carbohydrates require little oxygen to be broken down as fuel, and compared to breaking down fats, the process is completed fairly quickly.
As more carbohydrates are utilized to keep up with energy demands, however, fewer fats are used. The RER will then begin to shift up to 1.0. Typically, around the 1.0 mark the individual is anaerobic, meaning energy production depends fully on carbohydrates and there is a lack of oxygen to create energy.
Why Do a VO2 Max Test?
With all of the aforementioned data points provided by a VO2 max test, participants are provided with a better understanding of their overall health, potential disease risk factors, and fitness levels. The VO2 max test is one of the most effective predictor methods of long-term health and significant disease risk – so much so, in fact, that the American Heart Association (AHA) has released a statement on the reliability of cardiorespiratory fitness (synonymous with VO2 max) as an effective indicator of health risk factors.
Additionally, emerging evidence is increasingly linking low VO2 max values with high risk of cardiovascular disease and all-cause mortality. It is even proving to be a more dependable indicator than other risk factors, including smoking, hypertension, diabetes, and high cholesterol.
When evaluating overall health, the relative VO2 max and METS are the values of most importance. The relative value provides an accurate determination with oxygen consumption levels with regards to weight, which provides greater insight into an individual’s overall wellness. Meanwhile, per the AHA, METS can be used as an indicator of high-risk mortality, with a measure of less than five indicating high risk, and a METS of 8 to 10 associated with a better chance of survival.
Not only does VO2 testing accurately assess health, but it also measures overall fitness levels and provides practical information, in order to prescribe precise training plans to further improve fitness and health. While not all exercise equipment or fitness trackers have the ability to analyze VO2, one of the best ways to apply this data to an individualized training program is by using a common, accessible value such as heart rate (HR).
Most modern exercise equipment, fitness trackers, and smartphones have the ability to measure heart rate and provide the user with instant feedback. By using heart rate as a method of prescribing exercise, patients can match a heart rate zone to a desired intensity to elicit a specific result.
How, precisely, is this done? If a lower training intensity or steady-state cardiovascular exercise is ideal for the patient’s need, the physician would match the RER of roughly 0.85 to the patient’s respective heart rate value and recommend that they stay in that range.
Likewise, if high-intensity interval training (HIIT) would best support the patient’s goals, the physician would recommend a heart rate value that could be achieved in accordance with an RER of 1.1. (If not 1.1., the patient might aim for the highest value over 1.0 prior to cooling down). That heart rate value is the target HR to shoot for when doing HIIT to achieve an anaerobic state, which ensures the full benefits of this style of training are realized. If the heart rate is too low, on the other hand, there may be insufficient stimulus to truly achieve the benefits of HIIT training.
Maximizing Results at Cenegenics with VO2
At Cenegenics, we do not simply use VO2 max testing as a means of assessing health; we also use the data derived from the test to continuously support a demanding, comprehensive program to potentiate real results and minimize risk factors for age-related disease. After completing a VO2 max assessment at a Cenegenics facility, the patient’s data is then analyzed by an age management physician, as well as a qualified exercise and nutrition counselor, and used to assess risk and develop a training program created exclusively for that individual.
Using the aforementioned process and associating heart rate values with target RERs, a target heart rate zone will be prescribed as a goal to reach during exercise. By working within this target range, the patient will achieve anaerobic exercise and stimulate the EPOC response.
EPOC stands for excess post-exercise oxygen consumption, which refers to the period of time following physical activity during which the body uses oxygen to generate adenosine triphosphate (ATP), clear out lactate, return normal oxygen flow to the rest of the body, and restore the body temperature to a normal level. During this time frame, the body will be more metabolically active and continue to burn additional calories as a result. HIIT training is the most effective way to achieve EPOC, whether through running, rowing, biking, or using resistance exercise.
HIIT training involves short bursts of exercise performed at an all-out intensity level, typically lasting from 10 to 30 seconds, followed by a short 45 to 60 second rest period. These durations vary based on fitness level. For instance, after a five-minute warmup, a HIIT routine might involve a 15-second max sprint followed by a 45-second rest, repeated for a total of ten minutes and followed by a five-minute cool down.
In just 20 minutes, the amount of work done and caloric expenditure can exceed that of a 30 to 45 minute low-intensity steady state workout. It is for this reason that HIIT is widely recommended by Cenegenics physicians and favored by Cenegenics patients.
The results of using VO2 max testing to prescribe exercise programs and implement wellness measures to lower disease risk speak for themselves. Cenegenics patients are not only better able to achieve their weight loss goals and maintain their results; they are also more energized, alert, and healthier overall. If you are interested in discovering the power of VO2 max testing firsthand, contact your nearest Cenegenics location today.
This guide was produced with contributions from the following key resources:
The Cenegenics Education and Research Foundation
The Textbook of Age Management Medicine Volume 1: Mastering Healthy Aging Nutrition, Exercise and Hormone Replacement Therapy
Jeffrey Park Leake, M.D., CPT
Dr. Jeffrey Park Leake is a Partner and Director of Education at Cenegenics Elite Health specializing in age management and wellness. Having trained hundreds of physicians worldwide, Dr. Leake is also the Director of Education for the Clinical Strategies for Healthy Aging course at AMM Educational Foundation.
Todd David Greenberg, M.D., CSCS
Dr. Todd Greenberg is a practicing physician with a broad range of expertise, including wellness, exercise, sports injuries, and MRI of sports injuries. He is a Radiology Clinical Associate Professor at the University of Washington.
 “Know Your Target Heart Rates for Exercise, Losing Weight and Health.” American Heart Association, Inc. 2018. Retrieved from URL: http://www.heart.org/en/healthy-living/fitness/fitness-basics/target-heart-rates