Frequently Asked Questions about Physiology Testing

Why would I have a Lactate Profile, FUEL, or VO2 Max test?
With these tests we can evaluate your fitness level, make exercise recommendations--such as training zones based on heart rate, speed and power--and, with subsequent testing, measure your improvement.  These tests are valuable because they offer individualized, objective and repeatable measurements of your body’s response to exercise at a range of intensities.  The information gained from these tests can help you improve your health, your sports performance or both.  Furthermore, we can evaluate your current exercise regime in terms of the effects of its volume, duration and intensity.

We will also help you gain a greater understanding of exercise principles, so that you can apply this knowledge to your workouts.

Who can benefit from VO2 Max and Lactate Profile testing?
These tests can help anyone who wishes to get the information they need to train smarter to meet their fitness goals, whether for improving health or for sports performance enhancement.  Here are some examples of typical clients:

Recreational athlete: someone who trains and competes mainly for the sheer fun of it, but still wants to improve and have some structure and purpose in their training.

Elite athlete: to fine-tune each training bout, avoid injury and overtraining, monitor changes in fitness status, gain a competitive edge through application of sport science principles

Former couch potato: someone who’s decided it’s time to get fit, and knows that a proper exercise regime is crucial to one’s physical and emotional health; wants to be informed and make the most of exercise time.

Overtrained athletes: athletes who notice their performance is getting worse, notice a change in mood, get sick more easily than before, or have other signs that might suggest overtraining.  We can also help healthy athletes avoid overtraining.

Someone who’s not getting results: one who’s been exercising for a while, but isn’t seeing much improvement anymore; wants to learn how to change their exercise to continue improving.

In short, our doors are open to everyone.

What is the Lactate Threshold?

The Lactate Threshold is the point in exercise intensity where lactate begins to accumulate rapidly in the blood.  It is not necessarily your race pace, though your race intensity may occur near the threshold point - slightly above or slightly below the LT.  This, of course, depends on the length of the race, too.  The lactate threshold is important because the amount of time that you can exercise above the LT is limited.  You can train to increase the speed or power at which you reach your Lactate Threshold, thus making it possible for you to maintain a higher power output or faster speed.  The Lactate Profile test measures when you reach your lactate threshold.  See "How are the tests done" below for a description of the test.  Specific results include heart rate and power or pace at lactate threshold as well as power or pace training and heart rate training zones.

What is VO2max?

VO2max is the fastest rate at which your body can use oxygen to make energy.  Your body uses oxygen at a low rate at rest, a faster rate as you begin to exercise, and reaches its fastest rate of oxygen uptake near your maximum heart rate.  As it is an excellent indicator of cardiorespiratory fitness, each of us should achieve a certain minimum level of VO2max.  For endurance athletes, a higher VO2max indicates a higher potential for performance.

What is a FUEL Test?
The FUEL test is similar to the lactate profile test (see above), but also measures how many carbohydrate and fat calories are being burned during each stage.  These measurements come from analyzing the air that you breathe in and breathe out, using a technique known as indirect calorimetry, to determine how your body is fueling your exercise.  This test is very good for individuals who are interested in weight loss as well as athletes who perform long-distance endurance events where proper nutrition is important.  The FUEL test includes a 30-minute consultation with our physiologist and a 30-minute consultation with our sports dietitian.

How do I know which test I want?
If you want to learn specific training intensities, then the Lactate Profile is the best test for you.  This is the ‘Gold Standard’ used by athletes, especially elite athletes, to prescribe and monitor their training.  The Lactate Profile measures your body’s response to exercise of gradually increasing intensity.  This test yields precise, individualized training information that can be used to hone your exercise bouts for optimal improvement.  Changes in your fitness and performance can be measured with serial lactate testing over time.

If you are primarily interested in determining your fitness level, we'd recommend the VO2max test.  VO2max is important because it is the prime indicator of your cardiorespiratory fitness, an important indicator of overall health.  VO2max can be improved with proper training, but everyone has genetic limitations.  Being re-tested a few months after your initial test can measure the effect of your training on your cardiorespiratory fitness. 

If you are interested in the training recommendations from the lactate profile in addition to knowing how many calories you burn during exercise, and how many of those calories are from fat and how many are from carbohydrates, then the FUEL test is for you.   The FUEL test includes a lactate profile and a VO2max test.

How are the tests done?
After a gentle warm up the testing starts at a low level of intensity, about equal to a nice easy workout.  (The level is adjusted to match each person’s ability.)  Then every few minutes the intensity increases.  On the treadmill we increase speed first, then grade; on the bike we increase the wattage.

The Lactate Profile consists of a series of four-minute stages, or exercise periods at a constant exercise level.  Each subsequent stage is slightly harder than the previous.  At the end of each stage a finger stick is performed and a small sample of blood is taken.  The blood is analyzed for lactate concentration.  We also record your heart rate and your perception of the effort.  After several stages, there will be a large rise in blood lactate.  You will reach this point below a maximum effort, though well-trained athletes may be close to their max at the final stage.  We use the information from each stage to gauge the effectiveness of your training and to give you exercise recommendations.

The VO2max test begins at a workload you can easily handle, and gradually gets more difficult.  It’s relatively short, but you’ll eventually get to the point where you’re working as hard as you can.  It’s a good idea to be very well rested for this test!  All along we measure how fast your body is consuming oxygen.  This rate of oxygen consumption (VO2) rises as you work harder.  Your VO2max is the highest rate your body can consume oxygen, usually very close to your level of maximal exertion.

What will I learn from these tests?
Each Lactate Profile or VO2max test appointment concludes with a consultation.  We will tell you what your test results are, what the information means, and how to incorporate that information into an exercise program to meet your goals.  These recommendations are based on scientific principles of stimulus, response and adaptation.  You will also receive specific training zones to help you train effectively.  If you are looking for specific training recommendations, an additional training consultation would be a good option to schedule a couple weeks after your initial test consultation to answer follow-up questions.

Do the test results include information about power or pace?
Yes.  You will take home a report that shows the bicycle ergometer watts, or treadmill speed and grade, for each stage of the test that you took.

Will these tests indicate my cardiac health?
The primary goal of these tests is to help improve your sports performance or fitness, not to diagnose disease.  If you feel there is any reason to question your cardiac health, you should see your doctor.  She or he may be able to give you a prescription for an Exercise Tolerance Test at the Boulder Center for Sports Medicine.

Will I learn my maximum heart rate?
Maybe...but it doesn’t really matter; see the next paragraph.  If you’re doing a Lactate Profile test, you won’t be working as hard as you can, so you won’t get to your maximum heart rate.  You will come very close, or even reach it if you do a VO2max test.  However, you might get your heart rate even higher when you are outside, which is normal.  That is why we call the highest heart rate seen in the lab the ‘peak heart rate’, not maximum heart rate.

We do not emphasize learning maximum heart rate during these tests.  This is because we prescribe individual exercise intensities based on the Lactate Profile or on VO2max.   This method is much more precise because it is based on your own body’s response to exercise, not on a formula designed with average values or fixed percentages.

Should I warm up outside before my appointment time?
You can if you like, but we do allow about twenty minutes of warm up as part of your appointment.

How long does the appointment take?
For a Lactate Profile test, about two and a half hours.  If you’re doing both Lactate Profile and VO2max or a FUEL test, about three hours.

Is there a group discount for these tests?
Yes there is.  A group is five or more people doing the same test.  And there’s an even better price if you do a group follow up consultation, rather than individual consultations.

Can you do these tests in a field setting, or only at the Center?
Absolutely.  We have done tests in the field for various teams and sport groups, and have gone to local health clubs to perform tests for their members.  These tests are a lot of fun, for us and for the athletes.  We can easily arrange to do testing specific to your sport and the needs of your team.

How far in advance should I book my appointment?
During times of high demand, the schedule may be booked over one month out.  It's best to call several weeks prior to the time that you would like to be tested to ensure that you are able to come in when you want to.  If you want to have additional services such as a bike fit or nutrition consultation on the same day, you might need more advanced notice.

Does insurance cover the cost of these tests?
The tests described here are for performance enhancement, so insurance can not be billed.  However, the Center does perform other tests for diagnostic purposes.  If they are medically necessary insurance may cover the costs of those tests.

Will I need an EKG during my test?
For VO2Max, FUEL and Lactate Profile tests, a 12 Lead EKG is recorded for men 45 years or older, women 55 years or older, and for people who have two or more risk factors for coronary heart disease (hypertension, family history of heart disease, elevated cholesterol, smoking, diabetes, etc.). Our Medical Director will read and interpret the results. The cost for the EKG is $65 and is added to the cost of your physiology test.