October 26, 2022
I was in my physical therapist’s office the other day telling her about my change to zone training. When I finished, she said something that surprised me. “I’m glad to hear about the change to your training. Guys like you that are in really good shape have a tendency to just drop dead from heart attacks when they are out running. Everyone is surprised because it’s just so unexpected.”
This got me thinking about the effect of zone training on heart health. A quick search of the internet brought up this article by Howard Luks, MD (https://www.howardluksmd.com/zone-2-hr-training-live-longer-less-injury/). He makes lots of good points in the article. I’m going to focus on three: mitochondria, his Zone 2 threshold measure and my experience thus far.
Mitochondria are the powerhouses of our cells. Dr Luks argues, and I believe the science shows, that Zone 2 training improves heart health by improving mitochondrial efficiency. Mitochondria can work by burning fats if they are trained to do so, otherwise they just burn glucose. Zone 2 training is the key to training mitochondria to burn fats. He argues that mitochondria that are inflexible, i.e., that will only burn glucose, are indicated in a number of serious health issues. He lists a number of benefits of Zone 2 training, four of which I can evaluate for myself as I continue this training:
· lower resting heart rate
· a decrease in blood pressure
· lower injury risk
· an ability to run longer
My Garmin gives me my resting heart every morning, and being 65, I already monitor my blood pressure. A lower injury risk is harder to evaluate, but I will be thrilled if I get through the 2023 racing season without injuries. Training days, miles per week, hours of training and vertical feet will provide measures of how much more I am able to train.
Dr Luks uses the following formula to estimate the Zone 2 upper bound: 0.7*(HR max – HR at rest) + HR at rest. My Garmin estimates my maximum and resting heart rates as 159 and 59 respectively which yields 129 as my Zone 2 maximum.
Using a formula I discussed in Training Log 2, I currently have my Zone 2 maximum set at 119. I think, for now at least, it’s okay if I keep this conservative setting for my Zone 2 cap, and hence run in Zone 1 and the bottom of Zone 2 more than I expect. For one, this should speed up the rate that I increase the rate at which my mitochondria adapt to burning fat. Second, I run hills and I find staying tightly within Zone 2 as I run up and down hills to be impossible. I’m getting better at it, but I still sometimes find my heart rate in the 120s. Knowing that this may also be in Zone 2 provides some comfort that I have not suddenly jumped into Zone 3—which can be a problem, because your physiological processes change away from fat burning when you go into Zone 3 and they do not shift back immediately when you drop back into Zone 2. Dr Luks provides details as to why this is, I will leave it to him to explain.
As for my experience in my first three weeks of zone training, I find that I am more able to stay in Zones 1 and 2 than when I started. It still isn’t easy and requires lots of concentration. When I run on roads, I find myself checking the heart rate reading on my watch every few seconds, and I am constantly modulating my pace to stay in zone. Going out and just running as fast as I am inclined to each day is definitely more fun, but I am already seeing some benefits from this type of training. For one, I am able to run most every day whereas I used to only run 3 days a week to allow my body to recover. I am not beating myself up so I recover in a few hours.
I did my first mountain run in more than 3 weeks today and I was shocked to find that I could jog uphill at a steady 20 minute/mile pace in Zone 1. I climbed 815 vertical feet in 1.4 miles, all in Zone 1. I did a second climb after a short downhill and I found that I was mostly able to keep my heart rate below 120 beats per minute. Over the 6 miles I ran while climbing 1775 feet, I stayed in Zones 1 and 2 90 percent of the time, only walked a few times and didn’t have to constantly modulate my pace. I was slow, 19:40/mile overall, but still, this made me hopeful that this training is already having an effect. I have been running roads a lot more often that I usually do, this tells me that I can get back into the mountains. Yahoo!
Finally, the possibility that this training reduces the stress on my heart muscle while offering longevity benefits is a big selling point.
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