Z1 - Recovery: Very easy pace. Should be used primarily between hard (Zone 4+) efforts and rest days (should you choose to ride). There should be no effort required to pedal. Though not a source of any “real” physiological gains, Zone 1 is still a vital part of your training repetoire due to the therapeutic effect on the muscles and aerobic system.
Z2 – Aerobic: The foundation of all of your training is laid here. Aerobic endurance is vital because of the changes in your body that it facilitates. Aerobic work increases blood plasma volume, muscle glycogen storage (carbohydrate), and mitochondrial enzyme levels, all of which are vital for higher intensity efforts. Longer Z2 efforts (2.5H +) may require increased recovery time, especially in newer riders.
Z3 – Tempo: The start of “true” performance training, Zone 3 efforts are vital. From riding a brisk paceline to riding a strong rhythm on long climbs, Z3 is noted for the hard, but sustainable, breathing and muscle work. Mental focus is required to maintain this effort, especially in the top 5 beats of the zone. Over time you will be able to do multiple days of Zone 3 training, but recognize that these efforts will require additional carbohydrate intake, and may require additional recovery time.
Z4 – Sub Threshold: Power at threshold is THE most important element of performance. Your ability to ride at, and improve, this element will determine your success as a cyclist. LTHR is generally defined as the MAXIMUM HR you can sustain for roughly 1 hour. The top 5 beats of this range are the area to focus on. There is a high mental demand to sustain this effort and leg/lung effort is substantial. Typically you will break these efforts into 10-30 minute intervals and do several of them in a training session with adequate recovery between efforts (generally .5 – 1.5x duration depending on fitness level and goals). Z4 efforts will almost always require additional recovery time, though multiple days of Z4 training are possible when fit and well rested. Increased VO2max , Cardiac Output (the amount of blood pumped each beat), and perhaps most importantly increased Lactate tolerance are direct results of this training.
Z5a – Super Threshold: The point just above LT is typically sustainable for up to several minutes at a time (up to 10-15) but will require athlete to slow down and recover. Attempt intervals of varying length up to 10+ minutes. Recovery intervals should start at 2x interval duration and gradually decrease week to week as fitness improves. Always endeavor to repeat the workload on the intervals rather than have 1 or 2 good intervals and the rest mediocre.
Z5b – Aerobic Capacity (VO2max): Typically a near maximal effort performed in short bouts of 3 – 10 minutes for a total of up to 30 – 45 minutes in a workout are possible. Breathing should be very forced and conversation is not possible. Very hard leg and lung effort. Only attempt Z5+ efforts after adequate recovery from other training, and when well conditioned. NOTE: at this exertion level HR may not be an adequate predictor of effort due to both the HR response lag time and overall fatigue from previous training and previous intervals (within workout).
Z5c – Anaerobic Capacity/Neuromuscular: Short, very high intensity effort of between 30s and 3 minutes that function to increase anaerobic capacity and muscloskeletal/neuromuscular efficiency. Not a steady state effort so HR is not a good guideline. Generally as hard as you can possibly go! Consecutive Z5c days are not attempted. Neuromuscular efforts are even shorter – on the order of 10-15s and are not Heart Rate dependent.