Your Metabolism

Yes, you have one. I know, I know you’ve read all those scary magazine articles like “10 ways to boost your metabolism” or “Are you killing your metabolism?” or even depressing research that says your metabolism is mostly genetic and thus negating all the articles you’ve just finished reading, and now you think that either your metabolism is hopelessly mutilated or is the ultimate biological prankster (unless you’ve birthed kids and then that honor is reserved for your bladder).

In a conversation with Andrew, I asked him if he had ever undergone metabolic testing to which he replied, “no, I don’t care about what’s going on with my metabolism, as it’s not dysfunctional.” Which of course is a thoroughly sensible and reasonable answer. Being that I am neither sensible nor reasonable (and highly excitable, especially when it comes to numbers), I set my sights on getting a test done as soon as possible. Thankfully, my friend Personal Trainer D (of the fabled other gym), is as excitable as I am and arranged for me to get the exercise metabolic test of my dreams.

Bring on the numbers!!

The Basics
Your metabolism is simply the way that your body burns calories. Just like that birthmark that looks exactly like George Clooney or that third nipple you’ve never told anyone about, everyone’s is a little different. This is why your best friend can eat the same sushi roll as you and yet you are the only one ending up wearing said roll around your waist. Within a certain range set by your genetics, everyone has some influence as to how hot you burn.

Exercise metabolism is the way your body burns calories during exercise. Specifically they look at the proportion of fats and sugars you are burning. The goal is to maximize calorie burn without sacrificing fat utilization. This is what I had tested.

Your VO2 Max is your maximal oxygen uptake and reflects how well your body takes in and uses oxygen while you exercise. VO2 max “is widely accepted as the single best measure of cardiovascular fitness and maximal aerobic power. Absolute values of VO₂max are typically 40-60% higher in men than in women.” Your average man has a VO2 max of 45, while an average woman’s is 38. Just for comparison, Greg LeMond’s is 92.5 and the highest ever recorded, belonging to a Scandinavian cross country skier for which my keyboard doesn’t even have the ability to type his name, is 96 – in his off season.

Your AT is your anaerobic threshold. According to Jordan, my exceptionally fit and educated Personal Trainer for An Hour, your AT is the point at which your body pretty much stops burning any fat for fuel and relies almost entirely on stored glucose. You can only go so much longer exercising past your AT before you start to really feel like crap.

Your aerobic base is the heart rate below which at least 50% of your burned calories are coming from fat. In Jordan’s words: the highest point of intensity of at least 50% fat utilization out of total calories. Officially it’s between Zone 1 and Zone 2. Unofficially, it’s the zone that all your aerobics instructors scream at you – you know, the one where you are breathing hard but can still talk to your neighbor. Yeah, I know, like you would even want to talk to your neighbor. Snob.

Testing
So how do you get these glorious numbers? It involves running on a treadmill in a glorified scuba mask while the trainer continually ups the speed & incline in an effort to extort more money. Kidding. Actually, they’re trying to get you to pass out. Or nearly so. I hope you’re not claustrophobic.

I already know I’m not a good scuba diver. (Seriously, my greatest fear is being trapped in an underwater cave so why anyone would want to swim into one intentionally and then hang around for a barracuda-guided tour is beyond me.) I tried not to show my unease though as My Personal Trainer for An Hour Jordan (hereafter abbreviated as just Jordan) strapped the gas mask over my mouth. Suddenly I had a lot more sympathy for our armed forces. And for Darth Vader. I was tempted to make a “I am your father” joke but I didn’t know Jordan all that well yet and it’s best not to mess with someone who has the power to cut off your oxygen supply (not that he would have, being very professional and all – plus, killing clients is bad for business). Besides, he’d figure out soon enough that I’m insane. Why rush that moment?

By the time I finished thinking about neoprene, mustard gas and barracudas, I was past the warm-up phase and into the slow jog phase. Basically the test is designed to increasingly stress your heart and lungs and then measure your oxygen and carbon dioxide output via the funfunfun mask. The mixture of O2 and CO2 that you exhale is an indicator of how much fat and sugar you are burning. You’re hooked up to a fancy laptop that records all the numbers and puts them in nicely colored bar graphs for you. The hardest part at first was trying not to look at the laptop and run at the same time. I don’t know if anyone has ever fallen off the treadmill during their test but I didn’t want to be the first.

After that point, the hard part was trying to run up a crazy incline while resisting the urge to rip the mask off my face. Well that and ignoring the Ashlee Simpson video playing on 100 life-size television screens. (Note to Other Gym: Ashlee Simpson? Really?? Certainly money can do better than that. Although this being Minnesota I should have just been grateful it wasn’t Prince.) Before I knew it, the test was over and I was sucking wind like an asthmatic middle schooler trying to pass the Presidential Fitness Test in order to keep her precious 4.0 GPA (wow, there’s a memory I’ve spent years trying to repress).

Whole thing took less than 15 minutes.

The Results
Numbers! Glorious numbers!

My AT: 176 (decent – nothing to scream about)

My estimated max heart rate: 196 (which I have never, ever done. I know, I’m a wuss.)

My estimated VO2 max: 57.4 ml/kg/min (wahoo, I outdid a sedentary male! That’s over the 90th percentile for my age thankyouverymuch) and my threshold (49.3) occurred at about 86% of my VO2 max, which Jordan says is “good.” He’s not one to give out indiscriminate praise so as far as I’m concerned it’s rockstar.

My aerobic base: 157 beats/min (much higher than I thought, giving me much to think about in regards to my training regimen. )

My exercise metabolism: officially functioning (I know Andrew, you’re surprised.)

But what does it all mean?
What is the point of knowing all these numbers? Well, besides adding to my geek credibility of course. Jordan summed it up for me by saying that the ultimate training goal is to build exercise efficiency. And greater efficiency = greater endurance. The way to build efficiency is to build your base first by working just above where you are most efficient. Once you have greater than 30% fat utilization in Zone 3 then you know you are ready to up your training intensity. Note girls: he did NOT say to shuffle slowly around the track for two hours in an effort to “stay in your fat burning zone.”

And, the question I know you all are thinking, Does it burn fat? Says Jordan, “If your caloric intake stays the same and your caloric expenditure stays the same (from your old program to this new program) then yes, LONG TERM, your body composition should reduce. Remember, the adaptation we are looking for is increasing caloric expenditure while increasing aerobic efficiency (which will lead to a higher absolute amount of fat calorie expenditure).”

The point for me was that by knowing my numbers, I have yet another yardstick to measure progress. With weight lifting it is fairly obvious when you are improving (um, can you add? Are the weights going up?) but it’s harder to measure aerobic progress. Sure, running a faster 10K is one way but it’s nice to have another objective measure. Plus, I’m just a numbers nerd at heart:)

PS> Keep an eye out for more information from Jordan – After my test was over and I got my breath back I spent the next 45 minutes peppering him with all the questions that I like to ask Personal Trainers when they can’t get away from me. He was a veritable wealth of knowledge. And he even volunteered to be a guinea pig for a future experiment – gotta love that!