The Training Zones
The training zones that I assign are based largely on generally accepted exercise science and the power zones as defined by Andy Coggan. You need to know what they are, how they feel, and how to identify them through objective and subjective measures.
<55% FTP (functional threshold power) or < 68% FTHR (functional threshold HR)
RPE (rate of perceived exertion) 1-2
This is easy-peasy. You may be nose breathing. This is light work designed to loosen you up but not tire you out in any way. Active recovery should count as time off without the negative side effects that complete inactivity can sometimes carry. There is a time and a place for both inactive and active recovery.
56-75% FTP, 69-83% FTHR
This is the meat and potatoes of the training plan. Most work, all long sessions, and races longer than 300 mins will be performed at aerobic. You are primarily using the oxidative pathway and fat play a slightly higher role as an energy source here than the zone 3 and above. You should be able to speak in full sentences and carry on conversation, but certainly not sing. You don't feel like you are going easy. You are working but you could maintain this for a very long time if fit enough.
76-90% FTP, 84-94% FTHR
This is harder, more deliberate effort. The effort duration for tempo will be roughly 60-180 minutes before you run out of steam. This is the 2-3 hour road race, Olympic distance triathlon, half marathon, etc. You can speak, though your breathing has become more pronounced. Full sentences are possible still but conversation is not comfortable. By the end of a long tempo effort, you will feel decidedly fatigued.
91-105% FTP, 95-105% FTHR
This is your 1 hour max. It represents the highest effort possible before crossing the lactate threshold, the point where your body can no longer clear lactate as fast as it produces it. Once you go above threshold, you resources are limited. You can only go over that for so long and so many times before your body will be spent. Time spent above threshold is call “burning a match”. When you are out of matches, you are done until you get substantial recovery time. Threshold will feel like a firm tempo at first but begin to build to a difficult to hold effort where speaking more than a few words is too much work. You will notice a burn in your legs and your breathing will be heavy and measured. By the end of even a 20 minute effort, you will be pretty exhausted, winded, and done.
106-120% FTP, >106% FTHR
This zone is based off of your Vo2 max which is your max oxygen uptake. This effort is only sustainable for about 7-8 minutes. It is barely sustainable and will require you to dig deep before it's over. Your legs will burn, your breathing will be heavy, you can only get out a word or two (and doing that will not make you happy). Vo2 intervals will usually be less than 5 minutes but can be longer for very fit athletes.