Learning the Language

RPE, HR Max, FTP, LT, VO2 Max.  These terms are thrown around a lot in the endurance athlete community and when you listen to many of us talk, it may seem like we are speaking a language that is anything but English.  While more and more athletes have adopted these acronyms into their everyday language, there still seems to be a lot of confusion as to what many of these mean and how and when they can be used to help increase performance.  The goal of this post is to hopefully serve as an Enduance Athlete to English translator so that you will know if someone is making fun of you by stating that their 40k TT will be faster than yours because they have a higher FTP than you and they are only working at an RPE of 7 instead of 10!


Let's start with what is probably the easiest acronym to understand; RPE.  RPE stands for Rating of Perceived Exertion and is based on a scale of 1-10 where 1 is walking and 10 is all-out.  This method of training is commonly used by coaches and athletes alike because it requires no expensive or sophisticated equipment, just an understanding of how your body feels at a given level of intensity.  If your coach tells you to do a 30 min run at an RPE of 3, you now know that this should be an easy recovery run.  Unfortunately, most endurance athletes tend to have a Type A personality and 'easy' is a subjective term and your RPE 3 workout can easily become a RPE 5 run, especially if you are training with a partner.  Therefore, while RPE is a simple method to use while training, it is often difficult to tell if you actually accomplished the goal of the workout.


Next is HR Max.  This stands for Heart Rate maximum and this type of training, as the name implies, uses percentages of your maximum heart rate broken into 5 different zones.  Zone 1 represents the lowest intensity zone (think brisk walking) while zone 5 once again represents an all-out effort.  This is also a very common method  used by coaches and athletes because it only requires a heart rate monitor and a simple test to determine the athletes HR Max.  After determining your HR Max, you can then use any number of websites to calculate your HR training zones.  While this method is considered better than RPE because you are getting some objective data, there are still flaws in using this method of training.  First, every heart is different, so if you use a simple calculation (often 220-age) to determine your HR Max, you most likely are not going to have very accurate zones.  Furthermore, HR is very sensitive to many outside influences.  Anything from lack of sleep, stress, caffeine, and even weather, can affect an individuals HR while not necessarily impacting the work you are actually doing.  Simply put, your HR may tell you that you are in zone 5 while your muscles are only working out in zone 4!


FTP is yet another method to determine your athletic performance.  FTP stands for Functional Threshold Power and is often described as the maximum effort that can be sustained for 1 hour.  Cyclists are the athletes primarily concerned with this type of training because it gives them an accurate picture of the work their muscles are doing, expressed in terms of watts.  To determine an athlete's FTP, they have to complete one of many available protocols using a power meter and then, once again, use any number of websites to calculate your FTP zones (this time broken into 7 different zones).  Using this method of training is preferable to the two above because it is based off of actual work.  For example, if an athlete with a FTP of 275 watts is supposed to be doing a zone 2 (endurance) ride, they should keep their power output between 146-196 watts.  If the athlete is above or below the minimum and maximum values, they know that they are working too hard or not hard enough and that the coffee they had that morning isn't affecting their numbers.  The downside to FTP training is that, for it to be effective, the athlete needs a power meter, which can be pretty pricey.  An alternative to this is to have the test done at a performance lab and have their FTP associated with their HR during the test and then use their HR as a way to do their training on a daily basis, returning the lab periodically to retest.

A lactate analyzer, like the one shown here, along with a
graded exercise test can give you a good idea as to your body's
physiological response to exercise.

LT stands for Lactate Threshold.  LT is similar to FTP but it goes a step further in that it gives the athlete a look at their body's physiological response to exercise.  The athlete is given a graded exercise test in a performance lab setting and the test administrator takes a blood sample, often from the fingertip of the athlete, to determine the amount of lactate (often referred to as lactic acid) in the blood.  At rest and low levels of exercise intensity, humans primarily utilize fat as their main source of energy.  The byproducts of fat metabolism are carbon dioxide, water, and ATP (energy), all of which do not have much effect on the muscles response to energy.  This is why we can maintain an easy pace for long periods of time!  However, as the intensity of exercise increases, our bodies require a faster source of energy, which comes from carbohydrates.  While carbohydrates provide a faster fuel source, it also produces lactate and hydrogen ions.  Lactate itself has been shown to be an additional source of energy for working muscles, primarily the heart, but it's the buildup of the hydrogen ions that causes the muscle cells to become more acidic.  Fortunately, the increase in lactate in the blood gives us a good idea of what is going on in the muscles and with a lactate analyzer and a graded exercise test, the test administrator can determine the exercise intensity at which this process is occurring.  For runners, this number is determined by pace and for cyclists, wattage.  Periodic retesting will give the coach/athlete an idea as to just how well their training regimen is working and if any adjustments need to be made. 

A VO2 Max test is a good indication of
aerobic performance.

Finally, there is VO2 max.  VO2 max refers to the maximum amount of oxygen an individual can utilize during exercise.  It is measured using a graded exercise test where the athlete is attached to a metabolic cart that analyzes oxygen and carbon dioxide levels.  The results are expressed in milliliters of oxygen per kilogram of body weight per minute of exercise (mlO2/kg/min).  For those looking to increase their aerobic fitness for long distance events, this is a good test to have done periodically to see if you are properly training your aerobic fitness.  While it is not really practical to use the information from this test in your daily training, the test does give the athlete an accurate HR max which can be correlated to the proper training zones.

Hopefully after reading this post, you now have a better understanding of the Endurance Athlete language and can start impressing your training partners by incorporating some of this terminology into your daily vocabulary.  For those of you with a coach, I encourage you to discuss these different types of training with him/her to determine the best way for you to reach your goals next season.  Now get out there and Work Hard, Don't Stop!!!