Recently reader Kevin Wellenius asked if I would define some sports science terms that pop up from time to time in books, magazines and on websites. I thought that was a great idea as I frequently am asked about each of the terms in his list below. It’ll make my life a bit easier if I can just point someone at this blog rather than explain again and again. Not that I’m lazy… Below are Kevin’s terms and my definitions. I added one to his list - FTP.
Note that not everyone in the field of sport science will agree with me on each of these. Scientists can - and do - argue about how many angels can dance on the head of a pin. There’s nothing wrong with that, I guess, so long as you have the time. And it's quite understandable as precision is quite important in the scientist’s lab. When exercise moves from the lab to the real world, precision is nearly always compromised. In the lab almost everything is tightly controlled so precise definitions are also necessary. In the real world weather, traffic, hills, stoplights, safety and scores of other variables crowd out much of the precision. We’re left with ballpark definitions. So that’s mostly where I’m going with the following – kind of a mix of science and real world training.
Aerobic threshold (AeT). This is a relatively low level of intensity marked by light breathing and the feeling that you could maintain the effort for a few hours. It occurs at about 60% of your aerobic capacity or at about 70% of max heart rate or around 80% of lactate threshold. A ballpark way of determining your aerobic threshold is to subtract 30 beats per minute from your lactate threshold (see below) heart rate. In a sport science lab aerobic threshold is usually defined as the intensity at which lactate just begins to accumulate above the resting level. For more info.
Anaerobic threshold (AnT). This is usually determined in the lab by a gas analysis “ramp” test while running on a treadmill or pedaling an ergometer. A mask with a breathing tube is placed over your nose and mouth allowing the monitoring system to measure how much oxygen you breathe in and out. The difference between these is the oxygen your body is using to produce energy. At a low intensity at the start of the test you are burning mostly fat, but as the test intensity gradually increases more glycogen (storage form of carbs) is used. At the effort level where glycogen becomes the dominant fuel you are crossing the threshold between aerobic and anaerobic exercise. The AnT effort is often referred to as “redlining.” It’s common for well-trained endurance athletes to be able to sustain their AnT effort for about an hour (see FTP). A common field test for determining AnT involves a 20-minute time trial after which 5% is subtracted from the average heart rate, speed or power. AnT is sometimes referred to as the “lactate threshold.”
Lactate threshold (LT). This is quite similar to AnT (to everyone except sport scientists), but a major difference is that it is commonly determined by measuring the amount of lactate in the athlete’s blood during a ramp test in a lab rather than measuring oxygen consumed. When the lactate volume in the blood reaches 4mmol/L (“millimoles per liter”—a tiny amount) the athlete is assumed to be at LT. As with AnT, LT can be maintained for about an hour (see FTP). For more info.
Aerobic capacity. This is the same as VO2max which refers to the “maximum volume of oxygen” an athlete can use per minute relative to body weight to produce energy during an all-out, sustained effort of a few minutes that is well above the AnT. It’s also usually determined in a lab by using a gas analysis ramp test that lasts for several minutes. In such a test the workload is increased every few minutes (usually 3 minutes) until the athlete can no longer continue. The amount of oxygen (in milliliters) used per minute per kilogram of body weight at around the time of stopping the test is the athlete’s VO2max. In elite athletes the VO2max is often in the 70s or 80s with even a few testing into the 90s. Generally, the more aerobically fit an athlete is, the higher the VO2max. Highly trained endurance athletes can usually sustain their VO2max effort for around 5 minutes. So a simple (but painful!) field test of aerobic capacity involves doing a 5-minute time trial to determine your VO2max speed, pace or power. For more info.
Anaerobic capacity. This is a measure of how much maximal power or speed an athlete can produce in an all-out sprint effort lasting only a few seconds, usually 30. For more info.
VO2max. See “aerobic capacity.” For more info.
Functional threshold power or pace (FTP). This is an excellent concept created by scientist Dr. Andy Coggan. It refers to the power or pace (or speed) that an athlete can sustain for an hour since that is commonly how long well-trained athletes can maintain their AnT or LT pace or power in a race effort. This concept is athlete-friendly since it simplifies the explanation of “AnT” and “LT” making it no longer necessary to understand lactate levels or gas analysis to grasp the most important part of the concept. The 20-minute test described in “AnT” above may be used to determine FTP. There is also a 30-minute test for determining FTP. Knowing your FTP allows you to establish training zones based on power. For more info.