"One of the questions I hear time and again relate to how someone actually benefits from a VO2 test and establishing heart rate training zones. So I would like to take this opportunity to explore the question in some detail.
No doubt you’ve heard the terms “Aerobic” and “Anaerobic” thrown around in conversation. For anyone that is aspiring to peak endurance performance – or just wanting to drop a few pounds and stay in shape – these terms are ultra important. Luckily, the concepts are relatively simple:
· The Aerobic system burns mostly fat
· The Anaerobic system burns mostly carbohydrates
As a source of fuel, fat is certainly the most abundant; it provides hours of energy. Carbohydrates, in the form of muscle and liver glycogen, deliver energy – but it comes at a higher cost. Glycogen is consumed faster than it can be replaced.
Now, one thing to keep in mind is that the systems are not either on or off. In other words, we’re always burning some mixture of fats and carbohydrates to produce energy. That’s why energy gels, nutrition bars, and other products providing concentrated carbohydrates are used on long rides and runs – we need to keep replenishing our carbohydrates.
So the key for endurance athletes and those looking to stay fit and trim is to burn the most abundant fuel available – fat! Or, a higher percentage of fats relative to carbohydrates.
But how do we control what fuels we burn?
It’s All In The Zones
Unlocking your metabolism is as easy as strapping on a heart rate monitor and exercising within specific zones. A key heart rate indicator is Anaerobic Threshold (AT). AT indicates the point at which your body can no longer deliver oxygen to your muscles in quantities necessary to burn fat as a primary fuel source. As the stores of muscle glycogen are depleted, your energy begins to decrease – and if you’re able to continue exercising through the fatigue, eventually liver glycogen is utilized…and that’s pretty much when you either “hit the wall” or “bonk.” Not a good feeling!
There is a variety of methods for determining Anaerobic Threshold – problem is, most methods are merely averages of people in your age and weight group.
A Better Way
A more accurate way to get your Anaerobic Threshold and target heart rate zones is to measure how much oxygen your body is using as you increase the intensity of your workout. This can be accomplished through VO2 testing. Through a simple, graded exercise test, you can target Anaerobic Threshold and determine a range of zones corresponding to recovery, aerobic or endurance, tempo, and interval workouts.
Beyond the Aerobic Zone
Of course, as an athlete, you know you have to take things outside the endurance zone – Race Pace Runs, Fartleks, Track Intervals…workouts that push your body into new levels of fitness. It just comes down to knowing when and how much intensity to add. And that’s where knowing your heart rate zones can make all the difference.
Benefits of Knowing Your Zones
With all that being said, what are the advantages of VO2 testing and knowing your heart rate training zones. By far, the biggest advantage is that you get accurate answers (not from a one size fits all formula) and take the guess work out of training. Here are some more of the specifics…
- Monitor Your Intensity Level: Are your recovery days truly allowing your body to recover? Are your speed intervals truly pushing you to the next level or do it just “feel” like you are giving an adequate effort. If you know your zones, you know you are training at the right level to maximize performance.
- Prevent Over-Training: For some very competitive athletes, every workout can be a fine line between optimal training and over-training. Heart rate zone training helps to avoid unnecessary stress on your body. You can maximize the efficiency of your training, while minimizing the potential for injury.
- Prevent Under-Training: Usually less common, but some athletes are not tapping into their true potential and can handle more intense training. There are some potential Ironmen/Ironwomen/Boston Qualifiers out there, and they don’t even know it!
- Pacing: What intensity level should I be at for endurance workouts, tempo workouts, speed work on the track, etc.? Am I aerobic or anaerobic? Knowing your zones eliminates the guess work."
