Maximizing Your Performance and Health with VO2 Threshold and Metabolic Testing

Are you gearing up for marathon season and wondering the best way to achieve your PR? Are you looking for a way to decrease fatigue and risk for injury this training season? Been trying to lose weight without success? We’ve got the answers for you: VO2 Threshold and Metabolic Testing! Performing these tests allow us to analyze physiological information necessary to provide insight on how to maximize your aerobic potential, establish appropriate training zones, assist with weight loss goals, predict risk for chronic disease, and improve overall performance.


Now that we know what to do, where can we do this? Precision Performance and Physical Therapy is now offering VO2 Threshold and Metabolic Testing for all endurance athletes, fitness lovers, and health enthusiasts out there! VO2 Threshold testing is one of the many options for looking at cardiovascular fitness and aerobic capacity. Resting Metabolic Rate Testing demonstrates how many calories you burn at rest, providing us with data to help plan weight loss, gain, or maintenance. These tests provide us with values including your VO2 max, ventilatory thresholds (VT1 and VT2), caloric burn, accurate percentages of fat vs carbohydrate use, maximal heart rate, and optimal heart rate zones to use for training. Let's dive into these specific terms, how they apply to you, and what testing looks like.



Important Test Values and What They Mean


VO2 Max:

This value represents the maximal amount of oxygen that a person can consume during exercise. It is measured based on how many milliliters of oxygen you are consuming per kilogram of body weight in a single minute. It serves as the gold standard for measuring a person’s overall cardiorespiratory fitness and endurance potential and is the strongest independent predictor of future life expectancy in both healthy and cardiorespiratory diseased individuals [1]. This correlates with an intensity that can be maintained approximately 5-8 minutes. To put it simply, the higher the VO2 max, the higher the aerobic capacity. This means that your cardiovascular system can deliver more oxygen to your muscles, allowing your body to tolerate more work for longer periods of time! How high is high enough? This depends on a multitude of factors including genetics, gender, age, and fitness level, to name a few. The average untrained, healthy male has a VO2 Max of approximately 35-40 mL/kg/min, while the average untrained, healthy female has a VO2 Max of approximately 27-31 mL/kg/min [2]. In sports where cardiovascular endurance is a major component of performance such as cycling, running, swimming, cross-country skiing, or rowing, these athletes typically have very high VO2 max values. Fun fact: the highest known recorded VO2 max score for a male was documented at 96.7 mL/kg/min by Oskar Svendsen, a cyclist, and for a female was 78.6 mL/kg/min by Joan Benoit Samuelson, an Olympic marathoner!


VO2 max values are not only helpful for endurance athletes, but also provide valuable information for those that do not participate in endurance-based activities. Testing results also predict risk for chronic disease, helps in development of exercise prescription and training, and give us the means to monitor if a client is exercising at an intensity that may slow healing times.


Ventilatory Threshold (VT) 1:

This sub-maximal value represents your aerobic threshold. This is the moment where ventilation begins to increase and your body first begins to accumulate lactate in the blood. This value is important to know for long course (half-marathon, marathon, ultra-marathons) pacing and calorie burn. It is approximately the highest intensity that can be maintained for 1-2 hours.


Ventilatory Threshold (VT) 2:

This sub-maximal value represents your lactate threshold, meaning that lactate is accumulating in your blood faster than it can be cleared out of the blood. This correlates with an intensity that can be maintained for 60 mins. This is the value most commonly used to create heart rate and pace ranges.


Resting Metabolic Rate (RMR):

RMR is the total number of calories burned when your body is completely at rest. This is the amount of energy your body needs to perform basic functions including breathing, digestion, body temperature, muscle tone, and blood circulation. This value can be a great tool used to estimate individual caloric needs. Knowing this information can help individuals plan amount of calories to consume necessary to achieve weight loss, weight gain, or maintenance goals.


Respiratory Exchange Ratio (RER):

Respiratory exchange ratio is the ratio of expired carbon dioxide (CO2) and amount of oxygen (O2) consumed that is used to determine the type of fuel source (fat vs carbohydrate vs protein) and amount of calories burned during activity. RER under normal metabolic conditions ranges from 0.7 to 1.0. The body is mostly consuming fats at 0.7 RER, while a value of 1.0 is indicative of the body utilizing carbohydrates as the main fuel source.


These are just a handful of the values that we obtain and look at after VO2 Threshold and Metabolic testing. We also look at values including maximal heart rate, lipid metabolism, respiratory rate, work rate, and heart rate zones optimal for training.


What does the testing process look like?


VO2 Threshold Testing:

VO2 Max/Threshold testing is a maximal exercise test performed on a treadmill while connected to a machine that has the capability to analyze expired air. The test is designed to push you to your maximal fitness limits in order to fully tax your aerobic system. Due to the intense nature of the test, we have our clients fill out a Par-Q form to ensure that it is safe for each individual to undergo testing. It is important that each client is well rested, well nourished, and well hydrated prior to the test. We recommend avoiding alcohol, caffeine, and tobacco at least 4 hours prior to testing. It is also recommended to avoid exercise for at least 12 hours prior to the assessment in order to get the most accurate results. It is best to wear comfortable clothes and shoes that you would race in.


Prior to the test, information will be obtained such as height, weight, goals, and current training regimen. The client will go through a brief warm-up to establish starting speed for the maximal exercise test. Throughout the test, clients will wear a heart rate monitor and a mask that covers the mouth and nose. These devices will capture data based on the exhaled air and heart rate during the test that will be used to calculate your VO2 max, VT1, VT2, respiratory rate, work rate, respiratory exchange ratio, lipid metabolism, maximal heart rate, and heart rate zones that can be utilized for training. The test will begin at your starting speed and increase in speed and/or incline every 3 minutes until a maximal workload is obtained. Once the treadmill gets going, it is important for the client to push as long as possible to obtain the most data. The actual test itself is designed to last about 8-15 minutes. Once the test is over, we will provide you with a report including all important data listed above.


Metabolic Testing:

Metabolic testing looks a bit different than the VO2 max test. For the Resting Metabolic Rate testing, we will ask that you follow the same recommendations as VO2 testing to obtain accurate results. This test is looking at how many calories your body burns at rest.


We perform this test by attaching a chest heart rate monitor and mask to cover the mouth and nose in order to measure the concentrations of inhaled and expired air. During the test, you will be asked to lay down, in a comfortable environment for 15-30 minutes, without distraction. It is important that you are fully relaxed for the full test. This test provides us with an accurate measurement of how many calories we are burning at rest and the type of fuel we are burning (fats, carbs, or proteins). Knowing this information allows individuals to more accurately calculate the amount of calories to consume in order to lose, gain, or maintain weight.


If you are interested in performing VO2 Threshold Testing and/or Resting Metabolic Rate Testing, please visit our website or give us a call at 404-343-3314 to schedule your test or if you have any questions! We can’t wait to help you reach your maximum potential!



References:

1. Strasser B, Burtscher M. Survival of the fittest: VO2max, a key predictor of longevity? Front Biosci (Landmark Ed). 2018 Mar 1;23(8):1505-1516. doi: 10.2741/4657. PMID: 29293447.

2. Heyward, V. Advance Fitness Assessment & Exercise Prescription, 3rd Ed. 1998. p. 48.