Tuesday, November 15, 2011


I'm finally sitting down to write about my date with the Exercise Physiology and Human Performance Laboratory. I can't believe it's been a week and a half. Cripes.  Fair warning, this is a long one. If you're interested, (all four of you), click through after the jump break.  It's a long post, so if you don't want to read the whole thing, the short version is: I need to go slower, if I want to get faster. And I need to lay off the M&Ms (actually, that one's all me. We didn't talk about nutrition.). But I will get there, eventually, on the M&Ms.

I found out about the testing they do there from this post Shut Up and Run. Beth Risdon lives in Longmont and while I've never met her (although we've run two of the same races--maybe she's avoiding me?) when I read about this testing I wanted to do it immediately.  But with one thing and another, I held off until after the Portland Marathon.  After Portland, I was disappointed with my time, even though I PR'd, because I really felt I should be able to do better, but really hadn't seen any progress in my running in the last year.  I couldn't understand why I wasn't getting faster (every time I tried the speedwork I ended up injured). And so a 5:02 marathon time was enough to nudge me off to the lab.

I called right after the marathon, but decided to give myself a couple of weeks to be a slug recover before I went in to try and push my limits.

As Dr. San Millan tells it, this is the testing protocol:
An incremental maximal protocol is performed until exhaustion on an mechanical treadmill
(StairMaster, Clubtrack), Ventilation (E), Oxygen consumption (O2) and gas exchange was measured throughout the whole test. Heart rate was monitored during the whole test with a heart monitor (Polar S725x, Polar Electro, Kempele, Finland). At the end of every stage throughout the test a sample of capillary blood is collected to analyze both intra- and extra-cellular levels of L-lactate. (Physiological resting range: 0.5-2.2 mmol/L).

That translates into the following: you get on the treadmill, put on a heart rate monitor. He hooks you up to a mask that measures your VO2 max, and test your blood at five minute intervals to determine your lactate threshold.

What is your lactate threshold? I'm so glad you asked. Lactate is a byproduct of your cells' consumption of glycogen. In your normal every day life, your body is able to keep up the rate of removal of lactate. But when you exercise vigourously, your muscles are contracting faster, and with the faster rate of contractions comes more of this byproduct, lactate. At a certain level of exertion your body can't burn fat fast enough to produce enough force to match demand, so it switches to muscle cells that oxidize glycogen instead, which is creates lactate as a byproduct. Your lactate threshold is the point at which your body ceases to be able to keep up with removal of the lactate, and it begins to build up in your muscles, and interferes with their ability to contract. At least as I understand it, this is also what makes you sore after exercise.

What is your VO2 max, you ask? It is the upper threshold of the capacity of your body to transport and use oxygen during incremental exercise.  It essentially is an indicator of cardiovascular health.
I really wish I had Dr. San Millan's powerpoint presentation on all this stuff.  It would make this so much easier to explain. I know I'm going to get some of this wrong, so if something I've said doesn't make sense based on the science you know, then please correct me.  This is what I remember him telling me.

So initially Dr. San Millan weighed me, recorded my height (they always trust you to tell them the correct height) and got out the pinchers to get my body fat percentage. According to those calculations, I'm at 17.5% body fat, but honestly that seems really low to me. I mean, the way I jiggle it feels much more like 25%. But he's the doctor, so we'll give him that one.  He says my ideal weight is between 159 and 161 pounds, which is around the high end of "normal" for my BMI. So that makes sense.

Then we went on out to the treadmill, where he asked me to warm up on the treadmill for about ten minutes or so, making sure I didn't go faster than 5 mph.  It ended up being closer to 20 minutes by the time he had everything set up.  I was good and warm. Eventually we turned a fan on in front of the treadmill because it was so warm, but I was worried he wouldn't want me to. Turns out he just forgot to mention it.  I walked for about five minutes, and then jogged another 13 or so.
That's right. I'm bringing sexy back.
After he hooked me up to the gas mask (smelled just like the bottom of a swimming pool, yum), made sure the heart rate monitor was working, and gave me the rundown on how the testing would work. I would run 5 minutes at 5 mph, then a finger prick blood test, and then he'd crank the treadmill up another .5 mph. Off we went.  Five minutes at 5 mph was no biggie, 5 minutes at 5.5 mph not so bad, 5 minutes at 6 mph were hard but I knew it wasn't for a long time, and 6.5 mph was hard to the point where I wasn't sure I could finish. He ended up stopping the test at 19 minutes total, so I didn't quite make it to 5 minutes on the last threshold. 

(He gave me this great little pep talk while I was on the treadmill, by the way. It was great. Every 20 seconds or so, he'd say "You're doing great Lana!" or "We're getting some great data here!" "Keep it up!"  Toward the end he also started calling off a cadence, "tuk! tuk! tuk! tuk!" for me to run at. I've decided everyone needs a little megaphone cheerleader while they're on the treadmill.)

And that was it. Dr. San Millan had been double-booked at the hospital and the clinic, so we made another appointment to talk about the results in a week. But he did let it slip that my VO2 max was 135% of normal for my age, which was very indicative of someone at my level of fitness.  Very good.  He said, however, that the lactate was "a mess" and after asking me what my heart rate normally is when I'm training (160-168), he said I'm probably going to need to "back off a bit."

I spent a whole week in suspense about what my body was up to down in the cells. The notion of "backing off a bit" sounded great to me, but I couldn't understand how going slower was going to help me get faster.

So last Friday Mr. Bump and I trooped back over to the lab to look over the data.  He spent a lot of time explaining what mitochondria, what types of muscle fibers you have, and what happens when the garbageman can't keep up with the lactate garbage.  It all made perfect sense at the time, but I also knew at the time I wasn't going to be able to do it justice here.

But let's start with the data:

5 mph
I started out ok at 5mph. My heart rate was at 155, which is normal for the beginning part of a run for me. My lactate was at 1.7. There's an error on the table for CHO (oxidizing glycogen or carbohydrates); it should indicate 1.85. I was oxidizing fat at the rate of .46 grams per minute. My energy expenditure was 648 calories per hour. Not so bad.

5.5 mph
We kicked it up a notch to 10:54 per mile, and you can see my heart rate jumped as well, up to 166. Here my lactate bumped up a bit, to 1.95, and I've begun to burn more glycogen, 2.6 grams/minute. My fat oxidation rate, interestingly enough, goes down from here, to .34 grams/minute. But since I'm oxidizing fat and glycogen, my energy expenditure goes up to 738 calories per hour. Seems ok.

6 mph
This is where the wheels start to come off the bus. My heart rate is 178. The lactate almost doubled from the first test to 2.9. Carbohydrate consumption up another .9 grams/minute. But you can see the fax oxidation going way down, to .09. I'm almost exclusively using glycogen at this point.  My VO2 consumption is up, as well as my calorie burning climbing to 810. But we know from the data that these calories aren't fat calories.

6.5 mph
I said before that this was a pace I couldn't maintain, and that is demonstrated in my body by the test results.  My lactate goes from 2.9 to 6.3. Boom, threshold met.  My muscles aren't at all keeping pace with the amount of lactate my cells are kicking up. I am, however, burning 4.5 g/minute of carbohydrates.  But that's all I'm burning. No fat at  all. Only glycogen.

Here is what it looks like when you plug this into a graph:

Fat and Carbohydrate Oxidation rates, with respect to my heart rate.  The amount of fat I'm oxidizing looks pretty good at 155 bpm versus even 166 bpm. But between 166 and 178, it plummets.

I know you're thinking hey, I love a Fat Oxidation and Lactate vs. Heart Rate graph as much as the next guy, but really, what the hell does this mean?

I have no idea.

Ok, that's not true.  What it means is that as my heart rate climbs, the rate I burn fat drops, and the rate I burn carbohydrates rises.  The spot right in the middle there, where those two lines cross, is essentially where I've been training, between 160 and 170 or so. I've been training there for the past couple of years. The past couple of years where I haven't lost any weight, or gotten any faster.

This explains a lot of things, but one of the things Dr. San Millan told me was that only your brain needs glycogen. The rest of your body can either burn fat or glycogen. Glycogen is just a faster solution than fat burning, when the muscles are contracting at a higher rate than your body can metabolize the fat and or reabsorb the glycogen.  Your body has roughly 500 grams of glycogen stored in muscle tissue, ready for the next time you need to outrun a lion.  At 6+ mph my body is burning 3.5 - 4.5 grams per minute, which will exhaust that entire reserve after 2 hours, give or take. (Conversely, the body holds 100,000 calories in fat. That's enough for a very long walk back to your tent after you've outrun that lion.) So if during the marathon your body is using all the glycogen to keep going, then you're probably going to be stupid, because your brain is not adequately carb-loading.  Based on the out of body experience I had toward the end of the marathon, I am sure my brain was being deprived of the carbohydrates it needed. That was a puzzle piece clicking into place.

He went on to explain the difference between slow twitch and fast twitch muscles (here's where we talked about mitochondria for about 15 minutes), and while I found ever morsel of it fascinating, I'm not convinced you will be as riveted. But the nutshell is this. The slow twitch muscle fibers (type I) are much more efficient at burning fat for energy, resisting fatigue, in part because they have a high density of mitochondria.

Types IIa and Type IIb use carbohydrates because they're contracting faster, and they need faster fuel.

This is the last of the graphics!
When you're in the light orange circle, you're burning mostly fat, and a little glucose. This is when you're using mostly slow twitch muscle fibers.  My corresponding heart rate for Zone 1 is below 150 bpm. This is walking.  My corresponding heart rate for Zone 2 is between 150 and 160. This, for me, is somewhere around a 5-5.5 minute/mile pace. Slow. 

Where I've been training has been in Zones 3-4, heart rate between 161 and 180. That's the middle circle above, which uses Type IIa muscle fibers, which don't burn much fat at all, only glycogen. No wonder I'm not losing weight. I'm not in the fat burning zone. Literally!  This was another piece of the puzzle fitting into place.  

This brings us back to the lactate threshold.  Your body has two mechanisms for dealing with lactate; both convert it back into glycogen, but one is relatively slow, and one is very fast.  Your liver can convert lactate into glycogen, but at a much slower pace than you generate lactate during vigorous exercise.  Your Type I slow twitch muscles--the ones that mostly burn fat--can also convert lactate into glycogen, and they can do this quickly enough to keep pace with some levels of exertion, depending on your metabolic health.  World class athletes have very developed Type I cells, and their ability to rapidly recycle lactate into glycogen translates into exceptional performance.  Not only are they able to clear the lactate that interferes with muscle function, they are also replenishing their glucose supply as they do so, which is why they can perform for hours and hours.  In contrast, people who have not developed Type I muscles build up lactate, and exhaust their glucose reserves--a double whammy.  If you continue to exercise in Zones 3 or higher after depleting glucose, your muscle cells will merrily start burning muscle tissue instead.  This was the party happening in my muscle cells that last six miles of the marathon.

Ok, so now I know what I've been doing wrong. But the question that was looming large in my mind was how do I get faster, then? The best part of the whole thing was Dr. San Millan's explanation that I can increase my light orange circle through training.  By training in that zone, I will build up my Type I muscles, ultimately improving my lacate "clearance capacity." As a bonus, I'll burn more fat rather than carbohydrates, which should jump start some weight loss. And as I lose weight, less mass, faster Lana. Party on.

Dr. San Millan gave me some training suggestions for the next three months, which include 4 days of running in Zone 2 for the next month, and then some more complicated workouts for the next two months after that. Once we get to January, he suggests re-testing me to see where I'm at, so we can tweak my training zones more specifically for a marathon next year. He promises me that I can improve, as long as I train at the appropriate intensities for the next three months.

I'm certainly willing to give it a try. In fact, I'm off to run my 1 hour at Zone 2 intensity right now. **Update, it was long, and slow, and not at all exciting. But I was on the treadmill, watching television in my basement. I don't know what I expected.** I'll keep you posted on how it goes, and how my training goes for the next few months.  I'm really excited about the possibilities for improvement.

If you want to do this (and you know you do!) you can call for information or to schedule testing with Dr. San Millan at (720) 848-8208.  And if you don't live in Denver, it's worth checking around to see if you can get some metabolic testing somewhere else.

One more thing--a big shout out to Mr. Bump for coming along with me to both appointments, taking some sneaky photos, and absorbing the large amount of science-y information that wouldn't fit in my little brain. Also, thanks to him for editing this post, particularly the coherence he's added to the whole discussion. Mwah, baby!

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