What’s the difference between a lactate threshold test and a VO2max test?

Lactate threshold and VO2max tests are both incremental stage tests that can be completed on a computrainer or treadmill.  They both involve collecting physiological variables to assess fitness.  But, they are very different!  VO2max tests measure the maximum volume of oxygen a person can utilize during intense exercise and is the gold standard for assessing aerobic capacity.  Completed wearing a mask which collects oxygen and carbon dioxide, a VO2max test also provides a person with a measure of their max heart rate.  This test is used more often in clinical settings than athletic setting.  In athletic settings, the test provides the best measure of aerobic fitness you can get, but typically is just a marker and the information from the test cannot be used to assist with training itself. 

The lactate threshold test, on the other hand, is the most useful physiological test for training and racing in aerobic sports, whether your specialty is cycling, running, or triathlons (or a number of other sports).  Lactate is the end product of glycolysis, the predominant energy system utilized while exercising at high intensities.  As lactic acid builds up in the system, it often feels like your legs are burning or you want to throw up.  The body produces lactate all the time, but typically at very low levels where the body is able to remove lactate at the same rate it produces lactate.  When we exercise at increasingly higher intensities, we build up lactic acid at a higher rate than it can be removed by the body and our legs begin to shut down/move at a snail’s pace.  Lactate threshold tests take all of this into account. 

​During the incremental stage test, heart rate, wattage, rating of perceived exertion, and blood lactate are all analyzed during each stage, with blood lactate measured via a finger prick.  This test is useful in determining optimal race pace, which occurs at lactate threshold, the highest workload a person can work without a dramatic increase in blood lactate levels.  The test also serves to nail down heart rate training zones based on your blood lactate levels.  While heart rate is a useful tool, lactate threshold can occur between 50-90% of max, and setting up heart rate training zones based on just max heart rate does not take this into account.  Rather, the equations/charts estimate where lactate threshold occurs.  Understanding blood lactate, and at what heart rate and workload the values occur, give us the availability to know with confidence where our heart rate zones are based on physiological measures. 

Through training, a person’s lactate threshold as a percentage of their max, can increase, in some cases, substantially.  A person’s lactate threshold, for example, could move from 75% to 85% of their max, meaning that in a race that person could hold a higher pace without lactic acid build-up than previously.  This translates to a faster race pace and times.  Getting lactate threshold testing completed 2-3 times a season is ideal.  This allows for a very specific training program based on heart rate zones and it also is useful for tracking progress.