Yesterday I wrote about my experience getting a lab test done to measure ventilatory threshold so that I could calculate accurate heart rate zones. My test produced a bunch of different data points [photos of results here]. I do not yet understand all of them, but will explain my understanding of the key points I am interested in now.
The test calculated my ventilatory threshold to be at a heart rate of 142. I believe it is accurate to describe this as being the rate at which I can no longer produce enough oxygen to replenish during exercise. I think this would also be equivalent to ‘going anaerobic’. I used this to calculate my heart rate zones using The Ironman Training Bible’s calculations (discussed briefly here). A quick Google search would give other ways to figure out training zones; most of which should be about the same and will either be based on the ventilatory threshold (may also be called lactate threshold) or maximum heart rate–which should be close to the max heart rate that I hit during my test.
I also think that the respiratory exchange ratio is interesting. This shows the percentage of calories that are being burnt as fat or carbs. For myself, at a heart rate of 121, I am burning 50% carbs and 50% fat. If I get my heart rate above that number, I will be burning more overall calories, but the percentage of fat calories will be lower; and when I’m at a lower heart rate I will be burning a higher ratio of fat calories. This could be important over long course racing since it is harder to replenish carb calories throughout the day, as well as understanding why lower intensity exercise can be better for fat loss.
My V02 Max was calculated in my testing as well. This is a measure of fitness that I have read a fair bit about, but I am not convinced that it is something I am too concerned about tracking. It has to do with the volume of oxygen one can consume during exercise, and I believe that the relative VO2 is used to compare different individuals (since the absolute number would be different based on the size of an individual).
Quick note — since my test was done on a treadmill, these numbers are my running numbers. Cycling heart rate zones are lower. One could have a test done on a bike, though Staci said that the cycling rates are likely to be about 10 beats per minute lower, which seems about right for me.
Training with personalized heart rate zones
First, I mentioned here that the standard calculation to find max heart rate – 220 minus your age – didn’t seem right to me. Based on that calculation, my max heart rate should be 184. My max heart rate is actually around 158. This is a HUGE difference that confirms my feeling that I’m not just insane for having trouble getting into the ‘standard’ zones.
I also discovered that when I have been aiming for Zone 2 through perceived exertion, I have probably been closer to mid-range Zone 1. In other words, while I want to be keeping it low intensity, I could be training at harder and faster pace and still keeping my heart rate well below the high end of Zone 2. I have really enjoyed the push that this has given me to push a little bit harder.
I have heard that for many people it’s the opposite – they tend to train higher than they should be. Numbers to prove my laziness and get me moving!
I also have found it ‘fun’ to get my butt up into Zone 4. It is really hard, but I am more likely to get here now that I know I can get there and have before with numbers to prove it. Overall, being quite low tech with my tri training, I am surprised by how much I am loving these numbers. I feel it is very worth the investment!!
If you are interested in testing for yourself, many big gyms are doing it, as well as Universities and other places that may have a fitness lab. There is SO much more info out there that I do not know and haven’t covered — part of what I love about tri is the fact that I’m always learning. I’ll continue to share as I learn more about this and continue to ‘use my numbers’ in training and maybe racing.