Zone 2

What is Zone 2 and why is it important? How does it relate to weight loss? How does it relate to marathon training?

I made a video about the Magic Mile and why it's important. I shared the video with my run club. A magic mile is a time trial that you do every 3-4 weeks. You can take that one simple number and plug it into a VDOT calculator or JeffGalloway.com to determine what pace you can expect to do for different distances. The advantage of the magic mile is that it's very simple to measure. And it's an accurate predictor of performance on race day.

After recording, editing, posting, and sharing that video, I attended the LA Road Runners Thursday chat with coach David and he showed a graph of his heart rate and lactic acid from running and cycling. The way he explained it was kind of confusing to me, so I wanted to do a bit of WRITING TO LEARN, hoping that I would be able to understand all the colorful designations on the graph a little bit better.

Heart Rate-based training zones are a big thing now. Apparently, the big thing in exercise science a few years back was HIIT which is high-intensity interval training. Now the big thing is Zone 2 training.

• Zone 1 You can easily hold a conversation with someone.
• Zone 2 Roughly 65% of the calories you burn are fat.
• Zone 3 Talking in this zone takes effort, but you could sustain this pace for hours?
• Zone 4 You are no longer burning fat to fuel your effort. Lactic acid production increases dramatically as you switch to burning carbohydrates for energy.
• Zone 5 Your heart is beating at 90-100% of the max heart rate. Talking is out of the question. Cannot hold effort for more than a minute or two.

The goal of the coach's chat was to discuss speed work and how that plays a role in training for a marathon. A way to lengthen your baseline (extending the scope of zones 1 and 2, preventing lactic acid build-up) is to train in some of your workouts at or near the anaerobic threshold. You can achieve this by running intervals or doing a HIIT workout. The LA Marathon training plan I'm following has only 15% of the workouts doing speed work or intervals. I have been trying to incorporate some of this as hill workouts.

• R-pace (repetition): VDOT = 10:43 mile
• I-pace (interval): VDOT = 11:07 mile
• T-pace (threshold): VDOT = 13:32 mile
• HMRP (half-marathon race pace): VDOT = 16:23 mile
• MRP (marathon race pace): VDOT = 16:32 mile
• easy: VDOT says 14:13 ~ 15:30 miles

VO2max is the “maximum volume of oxygen” an athlete can use per minute relative to body weight to produce energy during an all-out, sustained effort of a few minutes that is well above the anaerobic threshold. This has to be measured while running on a treadmill or biking on a stationary bike while hooked up to a ventilator and doing your max effort. It's very uncomfortable but I actually participated in a research study on cyclists while I was in graduate school. They measured my VO2max to qualify me for the study, to see if I had the aerobic capacity, in fact, of a trained cyclist. Then they measured my bone density to see if there were significant differences in the arm and leg bone density of runners vs. cyclists. The PI was Dr. Michael Liang at  California State Polytechnic Institute, Pomona.

A higher VO2 max is indicative of a higher anaerobic threshold, which, by definition, means a higher level of lactic acid tolerance. Functionally, this means that a level of exertion that used to be anaerobic (for you when you were a beginner) can now become aerobic with longer duration potential.

Lactate Threshold is defined by a specific concentration of lactate in the blood. (2 mmol/L) So you have to have blood drawn to measure this. Functionally, this means when you are putting your body through more stress, which takes longer to recover from.

Below your aerobic threshold, exercise is sustainable ‘indefinitely.’ Even very lean people have reserves of fat stored. However, if we can only store 2000 calories as glycogen in the muscles, this is why people tend to hit the wall at mile 20 of a marathon if they're running too fast (zone 3 or above), because the rate of calorie burning is 100 cal/mile. The point of fatigue will be determined by muscle glycogen stores, and at some point, you’ll hit a wall where exercise cannot be continued due to glycogen depletion.

See, the marathon training plan from the LA Road Runners is so confusing to me because it's like an alphabet soup. Last Wednesday's run was supposed to be 10 min easy + (3 min T-Pace + 2 min HMRP)x3 + 4 min T-Pace + 10 min easy. I don't hate math and I hate looking at this. If it were always the same, I would program my Seconds Pro app and then go from there, but this is just too confusing.

10 min 15 min mile = 0.66 of a mile 

3 min / 13.5 min mile = 0.22 of a mile 

2 min / 16.5 min mile = 0.12 of a mile

4 min / 13.5 min mile = 0.29 of a mile

total distance         =         2.63 miles

Honestly, I just can't do this math at 4:30am and it doesn't really work with the distances I have that I regularly run. Is this just to make sure we're not getting bored or is it really doing something for the anaerobic threshold? Last time I trained for a half marathon, I just ran through the city every other day. Sometimes with my dogs and sometimes without. I did two weekday runs and one long weekend run. I did about a 5k on weekday mornings before work and between 10 and 13 miles on the weekend. I had no training plan, no coach, no goal. Back then, my only goal was to maintain my sanity while finishing my PhD.

Okay, admittedly this blog post is a real jumble of ideas. But in all that confusion, I came out with an answer to my question, why am I going for a speed limit of 20:54 per mile in long runs? That seems very slow to me. The answer is that it keeps me in zone 2 or below. I've been tracking my heart rate as I walk Albert to school and as we go on long walks on Saturdays. If Albert is in the jogging stroller and we're going along at a pretty good pace (let's say less than 20-minute miles) then we're in zone 2.

The data above is from a 4-mile walk where we did about 18-minute miles. It was a conversational pace, we were chatting the whole time. I don't know how SamsungWatch5 sets the heart rate zones, whether these are defaults, or whether they're based on my age and max heart rate. I guess it's the formula 220 - age, which for me is 220 - 44 = 176.

I was starting to get bummed out because I've been running for a year now and I haven't experienced any significant weight loss. I was starting to accept the fact that just like breastfeeding where some people drop weight right away and some people maintain or gain weight, maybe I was that type of runner who doesn't lose weight while training for a marathon, maybe I am just destined to maintain or gain weight. But now this reveals that I might just need to slow down to stay in a fat-burning heart rate zone.

Coach Bennett on the Nike Run Club app is always telling us to run the mile we're in and have a goal for each run, even a goal for each mile. Don't worry about how fast you're going because sometimes faster is not better. You want the workout you're doing to meet your goal for that workout.

The only reason I was trying to get faster is that the LA Marathon has a time cut-off of 6.5 hours. So to run 26.2 miles in 6.5 hours, I would need to be running about 14.9 minute miles. So I've been obsessed with getting to that pace or faster for my training runs. It's very easy to get caught up in PRs if you look at your training data on Strava. There are no awards for going slower. But there might be rewards if what you are looking for is losing fat (inches).