How often do you hear this phrase? “My coach has me training in Zone 2 today”. The first time I heard this phrase I wondered to myself, what, why, what is Zone 2, is that a place you go, why do you have to worry about being in Zone 2, can’t you just run and have a great time, or go for a personal best, or why Zone 2 isn’t that for dead people. I know, silly questions right. Of course those were some of my thoughts along time ago.
As a Ironman Certified Coach, I ask my athletes, do you know your training zones? Have you done a test to determine your Lactate Threshold Heart Rates (LTHR)? I am surprised at how many athletes haven’t heard of LTHR. Let us explore the concept of heart rate training for a bit. Don’t worry, I promise not to bore you with all the scientific jargon.
First of all, what are the basic heart rate zones? The Revise Borg Scale, defines 5 zones, these zones correlate to your heart rate during exercise (measured in beats per minute). Why is this important? Well, simply put, keeping your heart rate within specific zones while training and racing will maximize the use of your body’s natural reserve of energy. Within each zone your body relies on different energy sources. Below is a very brief explanation of each of the 5 zones, along with when each zone is used in your typical training plan and the energy system tapped for fuel:
Zone 1 - Is used most often for warmup, cool down, recovery and when you want to really slow down and focus on developing good technique. The main source of energy derived in zone 1 is from aerobic energy metabolism. The main fuel sources include your blood glucose, muscle glycogen, and body fat.
Zone 2 - Is used most often (and is the very basic component) for all endurance training. Most of your long training sessions are done in zone 2. Training in zone 2 promotes aerobic capacity and endurance. The main source of energy derived in zone 2 is from aerobic energy metabolism. The main fuel sources include your blood glucose, muscle glycogen, and body fat.
Zone 3 - Is used most often (and is the component of progressive training) for time trials and repetitions. In zone 3 the source of energy begins to shift from aerobic to anaerobic energy. In addition the main fuel sources begin to also shift, with heavier reliance on your blood glucose, muscle glycogen, and just a little of your body fat. Your training should have some Zone 3 workouts.
Zone 4 - Is used mostly for race pace training for middle distance (a planned race up to 2 hours) and is a smaller component of training for long distance (if your planned race is > 2 hours). Why the difference in the amount of zone 4 in your training between middle and longer distances? Because when you are training for a long distance race there is so much more training volume and that alone attributes to more stresses on your body. Managing the amount of zone 4 training appropriately can also help to prevent injuries, overtraining and other issues. On the flip side, if you are training for your best ever 5K race, then a bit more zone 4 session can be included in your training plan as the training volume for a 5K run is much less than that of a long distance race. Training could include time trials, intervals, and repetitions. Training in zone 4 promotes both muscular endurance and lactate threshold endurance. The fuel sources include your blood glucose and muscle glycogen. Without going into all the details of body fuel reserves, just keep in mind that your body only has so much natural reserve and can only process so much glycogen in a given time, thus racing in zone 4 can only be sustained for a short period of time (shorter races).
Zone 5 - Is used mostly for speed training, often referred to as speed work (repetitions at close to maximum pace with short recovery in between). I like to do these on a track, or using my watch and setting it for a given time (2 minutes or longer depending on the goal to run near max, then setting a minute of slow jog recovery). Zone 5 training promotes muscular endurance, speed endurance, anaerobic capacity and power. Your aerobic energy system awakens the anaerobic responses with a larger dependence on anaerobic energy metabolism. You just are out of breath here, and of course your legs and lungs feel like they are on fire. Zone 5 fuel sources include your blood glucose and muscle glycogen
I always include some zone 4 and 5 training within my athlete’s training plan. Also when teaching my indoor cycling class I keep the Zone 4 and 5 portions of my class to less than 10% of the class format. Why? Well as I mention in class, I love teaching, I love my students, and I want my students to be injury free and able to be cycling when they are over 100 years old. I absolutely cringe when I see or hear of athletes pushing into Zones 4 and 5 too long, too early (in their training), too much, and too often. Exercise can be performed above Zone 5, but only for extremely brief periods of time. Too much training in Zones 4 and 5 is hard on the body, and will eventually lead to injury, over training, and other issues. Did I say cringe? Okay I think you get the point of the importance of managing the amount of training in these upper zones. I want to see you being actively fit well beyond your 100 years as well.
Check back next month for Part 2 of this blog, where I will provide more information regarding LTHR, a method used to derive your LTHR, and how to calculate training zones for your run discipline.
Until then safe trainings… go out and get it done!
Coach Richard Nevarez
Ironman Certified Coach